The Planetary Society Spring 2020 Public Talk

ExoMars: The Search for Life in Martian Clays

Monday 30th March 2020, 7.30pm, Theatre 001, TUD, Tallaght Campus (formerly IT Tallaght)

Main Building, Belgard Road,Tallaght, D24 FKT9.

Talk Description

Is there life on Mars? Could there have been in the past?  The ESA ExoMars rover will launch in July 2020 and land on Mars in February 2021 are to search for signs of past or present life. This public talk, for non-expert and expert alike, explores now ESA’s ExoMars – of which Ireland is a part – will search for that evidence.

Speaker: Amy Dugdale

Amy Dugdale, final year Chemistry & Biology student of NUI Maynooth and who interned on the ExoMars mission through The Open University and the University of Kent will talk about the science objectives of, and about her internship on, the imminent and ground breaking ExoMars mission.

Kevin Nolan, volunteer for The Planetary Society will also give a brief talk about the society and it’s significant open access online resources for all interested in Space Exploration.


This is a free event and all are welcome on the evening without booking; though you are welcome to reserve seats by emailing:


Update (9th March 2020) – As of today this event is going ahead, but please check back before attending to see any updates concerning the impact of COVID-19 on the running of this event. 




TUD Tallaght Campus is 50 minutes from Dublin City Centre on the Luas Red line. The campus resides within a 5-7 minute walk from the Luas Red Line Tallaght Terminus.


M50 Motorway: South

Take Exit 10 (Marked Ballymount/Belgard Rd)
Take right turn at top of ramp (heading for Belgard Road)
Follow R838 straight through 2 sets of lights (Luas tracks will be on the right hand side)
At the junction with Belgard Road (R113), take the left turn.
Travel straight along Belgard Road (through four sets of traffic lights)
Take the first exit at the roundabout

M50 Motorway: North

Take Exit 10 (Marked Ballymount/Belgard Rd)
Take left turn at top of ramp (heading for Belgard Road)
Instructions as above for M50 South.


To adjacent to TUD Tallaght Campus:

175      From UCD

75        From Dun Laoghaire

27        From Clare Hall

54A     From Eden Quay

65        From Hawkin’s Street

77A     From Ringsend Rd


To The Square (5-7 minute walk from Campus)

49        From Pearse St

76        From Chapelizod

76A     From Blanchardstown


The Planetary Society’s LightSail 2


On June 24th at 22.30 EST (4.30am BST on June 25th), The Planetary Society (TPS) launches it’s CubeSat space probe called LightSail 2 on board the mighty SpaceX Falcon Heavy rocket.  All going well, LightSail 2 will deploy a 32 square-metre Solar Sail, and commence it’s enigmatic mission to orbit the Earth propelled only by the momentum of sunlight, and steered by the Earth’s magnetic field.

If successful, LightSail 2 will use the momentum of the Sun’s light to move about the Earth while using orientation changes in relation to the Sun to tack into a higher Earth orbit, in a manner similar to how a sailing ship tacks through wind to traverse it.

The outcomes of LightSail 2 will herald a new era in innovative propulsion whose value has long been understood and which is now in our sights – that of using sailed spacecraft to beach the enormous distances to the planets, and even the nearest stars, potentially within our lifetime.

Crowd funded by The Planetary Society – the largest non-profit space interest organisation in the World – more than 40,000 people have made the LightSail 2 mission possible: a mission of our time, but one in the hearts and minds of those who founded The Planetary Society in 1980 when co-founders Carl Sagan and Louis Friedman then championed the idea, through to the present day where Planetary Society CEO Bill Nye and Director of Projects Bruce Betts now carry the baton toward a fully operational Light Sail space craft.


Figure 1: An artists impression Light Sail 2 fully deployed in Earth orbit. Credit: The Planetary Society

Sunlight Propulsion – The Background

The Principle

Although light – a form of energy – has no mass, it does possess momentum. As a result, if a ray of light (or a photon of light – depending on how you regard it) impacts on any surface, it constitutes a momentum collision, where a momentum transfer occurs between the ray of light and the object it collides with, producing what is often termed radiation pressure that causes the object to move.

Although the momentum and resulting pressure from sunlight is tiny, it is not totally insignificant. The radiation pressure upon the palm of your hand facing the Sun is about equivalent to that of a grain of pepper landing gently upon it.

But such is the supply of sunlight, inexhaustible in the vacuum of space, that the affect of such a tiny pressure can build up over time. As just one example, each of the two 1970s Viking missions to Mars weighted in at a hefty 3.5 Tonnes each, yet had NASA not corrected for the radiation pressure from sunlight falling upon each spacecraft as it travelled to Mars, they would have missed the planet by 15,000 kilometres on arrival! Such a tiny pressure, experienced relentlessly in the vacuum of space, builds up to a significant factor in space flight.


Figure 2: A diagrammatic representation of sunlight impacting upon a solar sail, causing it to move Credit: Physics dot org

History and Context

The idea that sunlight might bare a propulsive pressure is not new. Johannes Kepler, as far back as 1619, proposed a pressure associated with sunlight when attempting to explain why comet tails always point away from the Sun; and indeed Kepler is partly correct in this assessment, though he couldn’t have known that the Sun also emits high energy particles, and possesses a vast magnetic field that combine to produce a Solar Wind that also contributes significantly to comet tails being pushed outward from the Sun.

Jules Verne in his 1867 novel “From the Earth to the Moon” also hypothesised the use of  sunlight pressure as an alternative to the 900-foot canon used to fire his fictitious ship to the Moon. And indeed, at that same time the Scottish scientist James Maxwell actually produced the theoretical principles that revealed that light does indeed possess momentum; not long after experimentally verified at the turn of the 20th century by the scientists Ernst Fox Nichols and Gordon Ferrie Hull.

Light Sail Propulsion

As the new century unfolded and we began to understand more acutely the vastness of space, the realization of the necessity for new and innovative propulsion systems began to arise if we were to breach the distances to the planets and stars.

Of course since the dawn of the space era spaceflight has been dominated by chemical rockets: burn chemical propellants and they produce enormous quantities of gas at high pressure, released through a nozzle to create a thrust that propels the rocket upwards. From the earliest Chinese rockets over a thousand years ago to the great Saturn V that carried people to the Moon, all have been based on the principle of the chemical propellant rocket.

And while the extraordinary efficiency and reusability of SpaceX’s Falcon rockets will help revolutionize space enterprise in Earth orbit and beyond; and the gargantuan power of Boeing/NASA’s new Space Launch System (SLS) – one and a quarter times as powerful as Saturn V – will be capable of getting people to Mars and back, it has also been known from the outset that chemical rockets can only get us so far into space.

Even sending unmanned space probes to the outer planets of the Solar System using chemical rocket alone is an enormous challenge. The Voyagers to the Gas Giants, Cassini to Saturn and New Horizon to Pluto all needed extra propulsion from gravity assist manoeuvres as they passed the Gas Giant planets, to take years off their travel time.

We have known from the outset, that if we wish for long-term and sustainable engagement with the Solar System; and if we hope to reach the stars, then better propulsion systems are needed, a realisation perhaps more poignantly today as our ambitions towards deep space become ever clearer.

There is no shortage of contenders however: Ramjets, Nuclear Thermal Rockets, Fusion Propulsion and indeed Light Sails among others – all contend for future space propulsion.

While such contenders have remained on the drawing board, the idea of spacecraft using sails to harness the radiation pressure of light has garnered particular interest. Firstly, it does not require an extreme or currently unrealized energy source. And while the idea of propelling a sailed spacecraft by the minute pressure from light may seem at first impractical, means have been realized by which it might become a viable alternative to chemical rockets for long time-scale space missions to the planets and even potentially the nearest stars.

For example, using only sunlight, a solar sail measuring hundreds of metres along each side can generate enough thrust to navigate across the Solar System – endlessly. A solar sail spacecraft with an albeit enormous sail of dimensions 100km square and made of an extremely thin material could achieve extraordinary velocities – in the order of 4 million kilometres per hour – enabling such a craft to reach the our nearest stellar neighbour Alpha Centauri at 4 light years distance in approximately 1000 years. While sounding like a long time, when compared to the Voyagers propelled by chemical rockets and gravity assist and achieving velocities of 20,000 km/h and requiring 70,000 years to reach Alpha Centauri, then the benefit becomes clear.

An alternative to constructing such an enormous sail propelled by sunlight is to construct tiny space craft attached to sails of dimensions of perhaps 5 metre square, then propelled by powerful lasers on Earth or the Moon rather than by Sunlight. Such a system could in principle propel the spacecraft at a staggering 200 million kilometres per hour – one fifth of the speed of light – enabling it to reach the nearest stars in only 20 years or so. The Breakthrough Starshot program, currently underway, is investigating such a possibility, with an aspiration to realising a real mission to Proxima Centauri using light sails in only a few decades from now.

While using light sailed space craft would be impractical for short journeys to the Moon and near by planets, as Bill Nye says: “…[for] interstellar travel, really the only way to do it that anybody can think of right now is with solar sail[s]…”

Light Sail

And so it has been on this basis that alternative propulsion systems, and light sails in particular, have remained of keen interest over the years.

Carl Sagan himself championed the idea in the 1970s, famously showing a model of a light sail on the Johnny Carson Show. Subsequently he, along with Ann Druyan (author, co-writer of the original Cosmos series, principal writer and Executive Producer of Neil deGrasse Tyson’s Cosmos and spouse to Carl Sagan) and NASA Engineer and TPS Co-founder Louis Friedman all progressed the idea from the outset of the formation of The Planetary Society.


Figure 3: Carl Sagan on The Johnny Carson Show, demonstrating a solar sail spacecraft.

And while it is currently unfeasible to construct 100km square sails, or propel sails in space via powerful lasers, it is completely possible to do an enormous amount of preliminary work with a light sail mission: construct light sails with innovative materials capable of being pushed by sunlight; learn how to launch and deploy such sails in space safely and securely; learn to control and steer lights sails deployed in space and develop the mechanisms to do so; and examine the theory of light sail propulsion through experimentation: in short, devise missions that take light sail propulsion off the drawing board and into space. Such preliminary but ground-breaking work is what has underpinned TPS Light Sail.

Cosmos-1 and Light Sail 1

TPS’s first light sail attempt in 2005 was called Cosmos 1: a light sail mission launched in collaboration with Ann Druyan’s company Cosmos Studios. The light sail was launched upon a Russian converted military rocket from a submarine in the Barents Sea. Unfortunately the rocket did not reach its intended orbit and Cosmos 1 could not be deployed.

A planned replacement – Cosmos 2 was subsequently replaced by a new approach using lower mass sail technology, announced in 2009 as LightSail 1. Using a NASA designed Nano-Sail D and deployed into Earth Orbit as a CubeSat in 2015, LightSail 1 successfully deployed it’s sail; albeit in an orbit too low to allow for the Sun’s photons to propel it.


Figure 4: Artists impression of Cosmos 1 deployed in Earth orbit. Credit: The Planetary Society / Cosmos Studios

JAXA Ikaros

Indeed, LightSail 1 was not the first successful solar sail mission – that honour goes to the 2010 Japanese Aerospace Exploration Agency (JAXA) Ikaros mission – a light sail larger than LightSail 1 (14m along each side) that deployed successfully in interplanetary space close to the planet Venus where it established a 10 month orbit about the Sun, sending data back to Earth and providing valuable insights into attitude control of a light sail craft that has helped the development of TPS’s LightSail 2.

JAXA are fully committed to solar sail propulsion, and intend to use an enormous 250m x 250m sail to send a research probe to the Trojan Asteroids out near Jupiter in the early 2020’s, cementing solar sail propulsion as a viable means of travelling to the planets. Both JAXA and TPS maintain active communications and a sharing of expertise and knowhow to strengthen the future for light sail technology.


Figure 5: JAXA Ikaros deployed in space near the planet Venus. Credit: JAXA

Lights Sail 2

And so for TPS the culmination of more than 40 years thought and effort in light sail technology is the Light Sail 2 mission, to launch at 22.30 EST on June 24th 2019.

Mission Objectives

So what are the objectives of LightSail 2? In short, to fully deploy a 32 square metre (5.6m x 5.6m) solar sail spacecraft at a high enough altitude orbit (720km above the Earth), free of Earth’s atmospheric drag so as to enable the Sun’s photons to move the spacecraft.

Once secure in orbit, LightSail 2 will continually reorienting it’s solar sails as it orbits the Earth so that it only captures sunlight when moving away from it, receiving a momentum push to raise its orbit and demonstrate solar sail propulsion at work.

And so the primary objective of LightSail 2 is to attempt to elevate it’s orbit from an initial 720km by about half a kilometre each day as it orbits the Earth. If this can be achieved, it will successfully demonstrate both the capability of sunlight to propel the spacecraft, and the ability to adjust its attitude with precision in order to enable its orbit to grow.


Figure 6: LightSail 2 reorientation its sail so as to gain a push from the Sun’s light when pointing away from it, delivering energy to the spacecraft to raise it’s orbit. Credit: The Planetary Society

The People

While LightSail 2 is a TPS driven project, no fewer than 40,000 people world wide crowd funded a sizeable part of the $7 million total budget, making it a true citizen-science mission. True to TPS’s ethos of democratizing the exploration of space, LightSail 2 is a mission made possible by citizens across the planet passionate about space exploration. It is a truly international mission.

Under the TPS stewardship of CEO Bill Nye, Director of Projects Bruce Betts and Purdue University’s David Spencer, the funding raised have enabled TPS to employ necessary expert space systems design and testing companies Stellar Explorations Inc. and Ecliptic Enterprises Corp. Meanwhile, many LightSail 2 and associated ground station and software systems have also been designed and tested by students in Georgia Tech and Cal Poly.

With such talent on board from so many quarters, the systems of LightSail 2 have been designed and tested to extraordinary levels. As just one example, even if LightSail 2 looses contact with Earth, it has the ability to reboot its systems and initiate contact with Earth of its own accord – a very sophisticated capability for a mission costing about 1/20th as much as an equivalent NASA mission!


Figure 7: TPS CEO Bill Nye demonstrates the Mylar Sail material

Spacecraft Characteristics

Perhaps the most intriguing aspect to LightSail 2 is it’s tiny CubeSat foot print. On launch, it measures no more than the size of a loaf of bread! Once deployed in space, 4 mini solar panels will open from its sides to power the on-board computers, communications systems, detectors and sail actuators.

The sails themselves are made of Mylar, and at just 4.5 microns thick (one tenth the width of a human hair) are light and reflective enough for sunlight alone to push them into a higher orbit.

Before deployment the entire spacecraft measures just 30 x 10 x 10 cm, while when fully open the sails span an area of 5.6 x 5.6 m or about 32 square metres; and an entire spacecraft weights just 5kg!




Figures 8 and 9: Images showing LightSail 2 Solar Panel Deployed and Solar Sail Deployed. Credit: The Planetary Society

Mission timeline

The Falcon Heavy mission upon which LightSail 2 is attached is due for launch on June 24th at 22.30 EST (4.30am BST on June 25th). With a three hour launch window on that day, all being well LightSail 2 will be deployed into an orbit at 720km altitude (by comparison the ISS is at 408km).

LightSail 2 is a secondary payload attached to the Falcon Rocket in a small washing machine-sized spacecraft called a Prox-1. Once detached from the Falcon rocket and at a safe distance, Prox-1 will eject LightSail 2 for orbital insertion.

The orbit LightSail 2 initially settles into will be circular, and of low inclination meaning it will remain within about 24 degrees north and south of the Earth’s equator and unlikely therefore to be visible in skies from latitudes beyond 42 degrees north and south.

After about 5 days of testing, the sails will be deployed. Four Cobalt-alloy tape-like booms unroll from within the tiny spacecraft, and attached are the four wedge shapes Mylar sails which when fully deployed cover an area of 32 square metres.

As the spacecraft orbits the Earth, momentum wheels will enable LightSail 2 to change orientation with respect to the Sun: on the part of it’s orbit facing the Sun it will orientate the thin edge of its sails toward the Sun so as not to be affected by the Sun’s radiation pressure, while on the part of its orbit moving away from the Sun it will re-orientate itself by 90 degrees face on to the Sun, experiencing a slight radiation pressure push that will accelerate the spacecraft by a tiny amount of just 0.058 mm/s². While this sounds like a tiny acceleration, it is continuous, unlike with a chemical rocket whose acceleration ceases once it’s fuel is used up, and so in just one one month of constant sunlight, LightSail 2’s speed will increase by 549 kilometers per hour!

In this way it will gain energy and rise up to a higher orbit. Small mirrors on the edges of the sails will hopefully be tracked from the ground using laser-ranging, and if successful, will enable us to track and determine LightSail 2’s orbit with exquisite precision, gaining new insight into the workings of solar sails.

Alas LightSail 2 does not have full attitude control, and so as one side of its orbit increases (apogee) the other side of its orbit (perigee) will decrease, getting ever closer to the Earth on each successive orbit. And so it is expected that within about a year of operation LightSail 2’s perigee will be close enough to the Earth’s atmosphere to succumb to drag forces that will cause it to finally re-enter the atmosphere where it will burn up, ending the mission.

As of June 24th 2019 you can follow the mission daily from the online feeds presented below, and if you are a radio expert you can track it live via radio receiver – again details provided in list of resources below.

The Future – NASA, JAXA and Breakthrough Starshot

While the science and know-how gleaned from LightSail 2 will be invaluable to all interested in light sail spacecraft, The Planetary Society will likely not pursue further light sail missions. Upon completion, LightSail 2 will have fulfilled the dreams of Carl Sagan, Ann Druyan and Louis Friedman of a successful light sail mission.

As a non-profit organisation whose central remit is to enthuse and inspire citizens across the planet in space exploration, TPS will move onto other projects. Nevertheless, to ensure that the results of LightSail 2 help future light sail missions, TPS have been working through the entirety of LightSail 2 with a team from NASA toward conducting a follow on light sail mission called Near-Earth Asteroid Scout – a fully fledged solar sail mission to conduct reconnaissance of an asteroid, to be launched as one of 13 CubeSats on the first SLS mission. Meanwhile the planned solar sail mission of JAXA to the Trojan asteroids and Breakthrough Starshot’s aspiration so using powerful lasers to send no less than one thousand 4 metre squared space craft to Proxima Centauri all mean that the future for light sail propulsion is very bright, and here to stay.

Perhaps most poignant and gratifying of all is that, at a time of increased awareness of the necessity of environmental sustainability on out planet, it so happens that among the most innovative space missions being planned is for a sustainable model of propulsion, based purely on sunlight.


Figure 10: NASA’s Near-Earth Asteroid Scout, based on a similar configuration to LightSail 2. Credit: NASA


Figure 11: Breakthrough Starshot proposes sending no fewer than 1000 light sails, each almost identical in size to LightSail 2 but with their attached spacecraft only grams in weight, and to fire a 1 Giga Watt Laser array situated on the Earth’s surface to accelerate them by 100km/s/s for 10 minutes in order to achieve a velocity of 0.2 the speed of light. With 1000 light sails sent on the journey, the hope is that at least a few would reach Proxima Centauri after (more…)

Mars InSight


For twenty one years we have been engaged in one of the most coordinated and successful campaigns in the history of science – a phased program of robotic exploration of the planet Mars.

Underpinned by a ground breaking 1996 document titled “An Exobiological Strategy for Mars” which proposed that the chances of life originating on early Mars were about equal to on Earth; NASA, in tandem with ESA, set in motion a multi-decadal phased strategy to characterise the Red Planet from global to molecular scales in an attempt to determine a planetary context for the origin of life as we know it, and whether life ever arose on Mars.

In the intervening years, orbiters such as NASA’s Mars Reconnaissance Orbiter (MRO) and ESA’s Mars Express, as well as the surface landers and rovers Pathfinder, Phoenix, Spirit, Opportunity and Curiosity have all scanned the planet and traversed its vast craters, plains and ancient dried seas; and have accumulated compelling evidence that billions of years ago Mars harboured a dense atmosphere, was characterised by volcanic and tectonic activity similar to Earth; and even retained seas, lakes and rivers over millions of years.

While such results point to a possibility of ancient prebiotic or biotic activity there, significant questions remain. In particular, the precise timings and extent of Mars’ early activities remain elusive; and consequently the precise nature and duration of its atmosphere, hydrological systems and their true potential for life-related activity remain largely a mystery.

A lack of knowledge of the internal structure of the planet in particular muddies our understanding; and so the need to send a probe capable of analysing the planet’s interior has become an imperative.

And so the Mars InSight lander had been sent to the Red Planet. Launched on May 5th and landing on November 26th 2018 on Elysium Planatia – one of Mars’ most tectonically active regions of recent geological time – InSight is set to operate for at least one full Martian year (two Earth years). It carries instruments able of determining the planet’s internal structure and thermal characteristics, and whether seismic activity persists to this day. It will enable us to better determine the history and evolution of early planetary activity on Mars, what early surface conditions resulted and whether they were favourable to life-related activity. It will reveal the internal dynamics of the planet today and whether it might support underground aquifers and hydrothermal systems important to life as we know it. Its findings will contribute to answering our deep rooted questions regarding how all rocky planets form; and offer fresh insights into the present state of the planet – so important to know about as we begin to contemplate sending the first humans there in the coming decades.

The Mars Insight Lander (Courtesy NASA/JPL)

Mars The Planet

Even a passing glance of Mars peeks interest. It’s one of four rocky planets in the inner Solar System along with Mercury, Venus and Earth. Orbiting the Sun at just one and a half times the distance of the Earth, Mars resides on the outer edge of what we call the Goldilocks Zone for the Solar System – the region of the Solar System conducive to life as we know it.

And while it is only half the diameter of Earth and one tenth the mass, at eight times the mass of our Moon it is still a substantial planet with a surface area equal to the land area of Earth, a year that lasts two Earth years, a day that’s just over 24 hours long and an axial tilt of 25 degrees that’s so similar to Earth’s that it too enjoys the four seasons of winter, spring, summer and autumn – though in its case each season lasts six months and not three.

Uncovering such seemingly Earth-like characteristics since the 17th century has led to a long standing fascination with the Red Planet that shows no signs of abating.

A Brief History of Our Engagement Mars

But Mars is not just a source of idle fascination. From the outset it has been important to us. Johannes Kepler in 1605 determined that the Earth orbits the Sun and not the other way round. And to do this he studied Mars’ motion across the sky – showing that it must be orbiting the Sun and not the Earth; and hence that all the planets – including Earth – are likely orbiting the Sun too.

And as mentioned in the previous section, from the invention of the astronomical telescope at time of Kepler and through the centuries, the Earth-like nature of Mars became every more compelling; culminating in the famous and controversial Mars Canals episode that lasted from around 1850 to 1960.

From the best telescopes available in the late 19th century, astronomers such as Schiaparelli and Lowell claimed to see dozens of straight line channels of canals across the surface of Mars, while other leading astronomers like Antoniadi and Barnard saw no such features. For decades the astronomical community was split on the issue, so much so that when H.G Wells wrote The War of The Worlds around 1897, it was based not on fantasy but on a widely held scientific opinion that an ancient race of Martians capable of constructing a planetary canal system had lived there in its distant past.

As a result of this controversy however, Mars became increasingly taboo as an object of scientific study during the first half of the 20th century. Of the one thousand or so professional astronomers in the US at that time, barely a handful would have anything to do with Mars.

Mars as imagined by Lowell, and how it actually is
Credit: Tom Ruen, Eugene Antoniadi, Lowell Hess, Roy A. Gallant, HST, NASA

All of that changed in the 1950s with the discovery of a biochemical and microbiological context for life. Leading and Nobel winning scientist such as Lederberg, Calvin and Sagan reasoned that if the origin of life on Earth had a planetary context rooted in molecular chemistry, then it might be that life similarly arose on other planets too.

And so from the birth of the US Space Program in the late 1950s President Eisenhower demilitarised institutions such as the Jet Propulsion Laboratory (JPL) in California and charged them with devising a civilian planetary science program to explore the planets of the Solar System, with Mars – and what it might have to say regarding a planetary context for the origin of life – at the top of the list.

The Mariner space probes of the 60’s and the Viking 1 & 2 Landers and Orbiters of the 70’s scrutinised the planet in search of evidence of past or present microbial life there; but the result were so overwhelmingly negative that by 1980 NASA had all but shut down its Mars program; and so for a second period in the 20th century Mars was a no-go area for much of science and space exploration.

Despite this setback, the 100,000 or so images of Mars obtained from orbit provided planetary scientists with a treasure trove of information about the planet. From 1980 to 1996, they pieced together a broad history of the planet from four billion years ago to the present day; and what they uncovered laid the foundation for the current revolution in Mars exploration we know today.

Revealed was evidence of a planetary surface which over three billion years ago harboured thousands of flowing rivers, including many lakes; as well as planet-wide tectonic and volcanic activity that likely lead to the creation of a dense atmosphere. It appears that Mars’ distant past, called the Noachian period, was a very active one in ways similar to Earth – and critically – in ways that we now believe lead to the creation of the first microbial life on Earth. So strong was this evidence that a 1996 document titled “An Exobiological Strategy for Mars” even rated the chances of life originating on Mars as about equal to Earth.

This was sufficient for both NASA and ESA to once again engage Mars; and so was born a new era in Mars exploration that persists to the present day.

But this time we’d do it right – and thoroughly. That meant doing it in a phased and planned way over many years. Phase one would send orbiters to characterise the planet’s geology and geochemistry globally from orbit, but with surface mapping to single-metre resolution. Next, landers and rovers would travel down to the surface to characterise the planet’s geochemistry to molecular levels; and crucially here, to search for direct evidence of past or present water on Mars. Only then would we be in a position to send exobiological landers and rovers in an attempt to identify any evidence that might point to past or present life-related activity there. Also envisaged are future missions to return samples from Mars to Earth, and even to send people there.

And so we have been engaged in this extensive program since 1997. Already there are the orbiters Mars Global Surveyor (1997), Mars Odyssey (2001), Mars Express (2003), Mars Reconnaissance Orbiter (2007), Mars Maven (2014) and Mars Trace Gas Orbiter (2016).

Just as many landers and rovers have also successfully landed on the surface: Pathfinder (1997), Spirit & Opportunity (2003), Phoenix (2008), Curiosity (2012) and in 2020 we will see the first exobiological rovers to be sent to the Red Planet: NASA’s 2020 Mars Rover and ESA’s ExoMars Rover.

The results from these missions have been hugely successful. We have discovered that Mars did harbour not only rivers and lakes in its distant past, but also seas, and likely a great northern hemisphere ocean too. Tectonic and volcanic activity were so predominant that it is plausible they created an atmosphere even more dense than Earth’s atmosphere today. And with a surface geology essentially identical to Earth’s, there continues a strong possibility that planetary activity occurred there in it’s distant past relevant to origin-of-life processes we suspect gave rise to life on Earth at the same time.

Mars Reconnaissance Orbiter (Credit NASA/JPL)

The Curiosity Rover (Credit NASA/JPL)

A location in Gale Crater where Curiosity has discovered evidence of past water based habitable conditions on Mars (Credit NASA/JPL)

Furthermore, we’ve also discovered that Mars is far from being a dead world today. It retains enough water as a permafrost in its far northern and southern latitudes which if melted would cover the entire globe to a depth of 50 metres. Meanwhile the planet likely has a subsurface thermal gradient that might support underground aquifers and hydrothermal systems.

But for all of our discoveries to date, major questions persist. For example, we cannot pin down with sufficient accuracy what Mars’ planetary surface conditions were like in its distant past. Was it a clement planet that supported a planetary hydrological system similar to Earth, or did it remain a cold, artic-like world characterised by briny flows and sub-ice sheet liquid water systems? Overall, just how capable Mars was in supporting the kinds of activity we believed important to initiating the first steps toward life remains a mystery.

And in all of our explorations to date, the one kind of mission we have not engaged is one to determine the interior structure and activity of the planet. The nature, extent and dynamics of Mars core, mantle and crust remain largely unknown; and since all that happens on the surface is a result of what happens inside the planet, we cannot hope to fully answer our deep-seated questions about Mars’ past and present conditions until we analyse, once and for all, the internal structure and processes occurring inside the planet.

And so while we will continue to send exobiological rovers to the planet, and plan for sample return missions and even humans there in the coming decades; it has also become an imperative to send a mission to Mars capable of analysing the interior of the planet. Mars InSight is that mission; and is set on providing radical new insights into our neighbouring world.

Mars Insight Mission

Unlike the rovers of recent times, Mars InSight is a fixed position lander. Indeed, its success depends completely on landing on as flat a surface as can be found on Mars, and then to remain in one, immovable, position for the entire duration of it’s mission.

This is because the nature of the mission is to determine the internal structure and activity of the planet, with all three on-board experiments requiring absolutely stability and as close to zero interfering motion as can be achieved.


So what, precisely, are the objective of Mars InSight?

Firstly, we hope to understand the formation and evolution of all terrestrial planets by investigating the internal structure and processes on Mars. We can largely achieve this because, uniquely, Mars seems to have internally frozen out in time just as it was getting going as a planet. So, unlike on Earth which has been churning it’s insides for billions of Years, Mars retains an internal planet-scale record of the processes that lead to its formation in the first place.

Mars InSight will therefore seek to determine the size, composition and current state of activity of Mars’ iron-rich core, its silicon-rich mantle and its outer crust. As mentioned in the previous sections, such details will not only tell us how Mars itself formed – and therefore provide insights into how all rocky planets form – but will also reveal new details on how and for how long tectonic and volcanic activity persisted on Mars in its distant past, and therefore what its resulting surface conditions were also like.

Two experiments on Mars InSight named SEIS and RISE will carry out these investigations; and as we’ll see in the next section, both are surely among the most innovative experiments ever sent to Mars if not into space in general. Indeed SEIS will also enable InSight to identify the magnitude, rate and distribution of seismic activity occurring on Mars today; and also monitor meteorites as they impact on Mars through the vibrations they cause.

Another goal for InSight is to directly measure the heat being radiated from within Mars. To achieve this, InSight will burrow to no less than 5 metres into the surface and place a thermal sensor rod into the ground that will directly measure the heat emanating from the planet, in so doing reveal much about the internal dynamic processes occurring within the planet today that generate that heat.

The internal structure of Mars as we currently imagine it (Credit NASA/JPL)

Mars Insight Spacecraft

Although most Mars landers are designed and build by JPL, in this instance Mars InSight Lander was designed and build by Lockheed Martin (LM). This was a money saving exercise because InSight’s design is heavily based on the 2008 LM built Phoenix Mars Lander which successfully verified the existence of water-ice across the high latitudes of Mars.

The lander supports two large flat disc-shaped solar panels with a span of 6 metres, within which is a central platform containing all of the landers required power, telecommunication and computer systems. Sitting upon the central platform is a 2m robotic arm with shoulder, elbow and wrist joints. This robotic arm will lift from the platform and deploy onto Mars’ surface two of the three main experiments from the lander – the SEIS seismometer, and the HP-Cubed Thermal Burrowing Rod.

Once deployed on the surface at about 1.5 metres from the lander, both SEIS and HP-Cubed will remain connected to the lander via tethers containing the required power and data communications cables needed to communicate with the lander. This will be the first time ever that a robotic arm deploys experiments from a lander platform to the surface of another world.

Both SEIS and HP-Cubes are European designed and build: SEIS by the French Space Agency (CNES) and HP-Cubed by the German Space Agency (DLR). Other on-board sensors for measuring air temperature, pressure and wind speed were built and designed by the Spanish Centre for Astrobiology (CAB). All told, about two thirds of the instruments on InSight are of European origin.

And it’s also worth mentioning that Irish scientist Dr. Michael Moloney was Director of The Space Studies Board for The National Academy of Sciences who authored the decadal plan document titled “Vision and Voyages for Planetary Science in the Decade 2013-2022” from which the Mars InSight mission arose.

Mars Insight graphic showing it’s instrument deployed onto – and into – the Martian surface (Credit NASA/JPL

Mars Insight Instruments

Seismic Experiment for Interior Structure (SEIS)
SEIS is a seismometer composed of six sensors capable of monitoring Mars seismic activity, including marsquakes anywhere on the planet. The instrument is placed onto the surface of Mars by the InSight robotic arm, and has a protective case to shield it from wind and dust movement (wind gusts on Mars can be up to 120km per hour). The Spanish made air temperature and pressure and wind sensors will be vital in enabling us to determine whether detected vibrations are from true seismic activity or caused by local air pressure or wind induced vibrations.

With the seismometer capable of detecting vibrations with frequencies from 1/1000th of a Hertz to 50 Hertz, and with an ability to detect seismic primary (P) and secondary (S) waves, it will be able to detect both the direction and distance travelled from origin of any seismic activity. The instrument is so sensitive that it can detect a movement within its inner workings less than the width of a single hydrogen atom; and it is through such extraordinary sensitive and innovative design that it will examine the internal structure of the planet down to the mantle.

The French made SEIS Seismometer (Credit NASA/JPL)

Heat Flow & Physical Properties Probe (H-P cubed)
This German Space Agency built instrument is the second of InSight’s instruments to be deployed onto the surface via the robotic arm.

HP-Cubed is a self-burrowing mole. Over a 30 day period and with upwards of 20,000 burrowing strokes, HP-Cubed will burrow between 10 to 16 feet (3-5 metres) below the Martian surface. Once in the ground, it will use thermal sensors along its length to identify any heat coming directly from within Mars and in so doing reveal much about the interior heat engine of the planet – that is – how active Mars is internally today.

Rotation and Interior Structure Experiment (RISE)
Among the most impressive aspect of this mission is the JPL designed and built RISE Instrument, to determine the internal structure of Core of the planet. RISE will do this by monitoring minute timing changes in Mars’ rotation. And it will do this using one of the most innovative ideas surely ever conceived in space exploration.

The instrument is based on the principle that all rotating objects try to resist any impulse that causes them to rotate (called inertia). Furthermore, objects that are the same size but different in internal make up will resist that impulse differently. For example, a raw egg will not spin as well as a hard boiled egg, because the raw egg has a fluid interior which resists rotation more than the solid-interior hard boiled egg. And, if you change how such an object rotates, then each will resist that change in or impulse causing the rotation differently. Finally, we can even determine what the internal make up of an object is by how it resists such change in rotation.

So for RISE, it will monitor how Mars reacts to minute changes in its rotation by monitoring minute time changes in the length of its day (to the order of millionths of a second); and from that (and using some heavy maths!) infer what its internal structure is – whether the core is solid or fluid, what size it is, and so on.

So one might ask: what is it that is going to cause Mars’ rotation period (it’s length of day) to vary by minute fractions that RISE is going to monitor? The answer is mind boggling, and utterly unique to the planet Mars.

As winter moves from, say, the southern hemisphere of Mars to the northern hemisphere then Mars will transfer no less than 15% of its atmospheric CO-2 – 40 Trillion Tonnes – from it’s southern polar ice cap to its northern polar ice cap. And this will cause Mars to wobble by a tiny amount, affecting it’s length of day by tiny fractions of a second as the seasons proceed; and it is these minute time variations on a day to day basis that RISE will monitor, so as to determine the size of that wobble, and hence the internal make up of he core of the planet!

Mars does this gargantuan CO-2 transfer – back and forth – every Martian year – 40 Trillion Tonnes of CO-2 from south to north and then north to south – over and over through the ages. And it is this vast CO-2 transfer that RISE is going to monitor, determining how this shift of CO-2 affects how Mars rotates over the duration of one Martian year.

How RISE measures the timing difference of Mars rotation is equally intriguing. It will measure the time of Mars rotation by sending radio signals back to Earth continuously for a full Martian year – whereby we on Earth will receive those radio signals on a near-continuous basis and from that determine the position of the Mars Insight RISE experiment to an accuracy of just 10cm (that’s to an accuracy of one part in 10 trillion, or 10 million times more accurate than GPS) – and from this, determine the variations in timing of Mars’ rotation with extraordinary accuracy.

Then, as the planet’s rotation varies, we’ll be able to also monitor how it’s inertia is resisting that rotation change – and from this, figure out what the internal structure of the planet’s core is.

This is why InSight’s primary mission must be for at least one Martian year – so that we can witness the transfer of CO-2 from pole to pole and back again and the associated Mars wobbling; and if all goes well, we’ll use this gargantuan natural process on the planet to determine Mars interior core structure. Surely one of the most innovative science experiments ever devised, and a true benchmark of how far we have come in the exploration of our next door neighbour world.

Mars Cube One

One of the most intriguing aspects of this entire mission was the decision to launch and deploy two other tiny space probes with Mars InSight and send them to Mars as well.

Called Mars Cube One A and Mars Cube One B (MarCO-A and MarCO-B for short) these two Cubesats – each about the size of a 1-litre carton of milk – were launched by the same Atlas V rocked that sent InSight to Mars, whereby they separate from the Atlas V launcher a shortly after InSight had successfully separated (for safety), then tasked with making their own journey all the way to Mars.

And so what has been travelling to Mars over the past six months has not been just the Mars InSight lander, but a mini-convoy of three space probes – InSight and the two tiny MarCo’s.

This aspect of the mission was deemed completely exploratory. The success of InSight does not depend on any way on whether the MarCo’s made it all the way to Mars under their own steam – but as of the writing of this blog – just one day before they reach Mars, I can happily report that they have been an overwhelming success, having reached the Red Planet.

Indeed they have by now verified that such tiny probes can be sent into deep space and as far as Mars; and even correct their trajectories on route operating with a total power of just 17 watts of solar power each. And with thruster propellant for course corrections composed of the same material in the fire extinguisher in the film Wall-e, it has been decided to rename MarCo-A and MarCo-B as Wall-e and Eve!

These tiny probes point to a new and innovative way of doing planetary exploration into the future. And, as small as the MarsCo’s are, they are equipped with more advanced telecommunications equipment than on the huge Mars Reconnaissance Orbiter (MRO) in orbit around Mars since 2007 and which will act as the primary telecommunications relay for InSight over the next year. While MRO can only receive or transmit radio data to/from Mars or to/from Earth at any one time, both MarCOs can receive AND transmit simultaneously.

So, when InSight is landing, MarCO-A and MarCO-B will be monitoring InSight continuously, and if all goes well, will relay information about InSight’s landing back to Earth in real time for the first time ever (with just an 8.1 minute light-time delay from Mars to Earth). MRO would have to communicate with Insight, and only after it landed, then start to communicate with Earth about the landing – a delay of an extra hour.

Overall, the MarCo’s represent an exhilarating new development in planetary exploration, and at a cost of a mere $18 million each – about 2% the cost of a traditional planetary probe, are by now garnering significant interest globally.

The tiny, but enigmatic MarCo-A and MarCo-B as they arrive at Mars (Credit NASA/JPL)

MarCo up close (Credit NASA/JPL)

Animation showing MarCo-A and B tracking the signal from Insight as it lands on November 26th 2018 (Credit NASA/JPL)

Mars Insight – Entry, Descent and Landing (EDL), and Surface Operations

Subsequent to its 205 day ‘cruise phase’ from Earth to Mars, InSight has to ready itself for entry and descent through the Martian atmosphere, and landing on the surface. Cruising at six times the speed of a high velocity bullet at about 18,000 kilometres per hour (kph) and having to slow to just 5 kph at a height of just 50 metres above the Martins surface in only 7 minutes; the Entry, Descent and Landing phase of a Martian lander is termed the “7 minutes of terror” by NASA and JPL.

Mars InSight as it enters Mars’ atmosphere at over 12,000 kph (Credit NASA/JPL)

Through a massively rehearsed sequence of autonomous and automatic steps that are completely out of the hands of NASA and JPL engineers, the InSight lander has to navigate this treacherous journey from interplanetary space and to the surface of Mars completely on its own. One mishap, and the mission is over before it begins. Here is a brief list of the sequencing of the events to occur leading up to and over the seven minutes of terror to end by 19.54 GMT (UTC) (and Irish local time) on Monday November 26th:

• Interplanetary Flight – cruise phase – 205 days (calibration, path adjustments)
• Velocity: 6 times speed of high velocity bullet – 5.5 km per second – 18,000 kph
• Upcoming EDL – 6.5 minutes from cruse to surface – almost 7 minutes of Terror: Mars atmosphere dense enough to burn the space probe up if unprotected, not dense enough to use only a parachute to soft land it!
• Entry point – a 10km by 24km rectangular piece of atmosphere 130km above and 440km west of Elysium Planitia (@ 500millon km – equivalent to aiming at and hitting an iPhone from New York to Denver)
• Ground target: an ellipse of dimensions 27 x 130 km on Elysium Planitia
• 7 minutes before Entry, cruse phase ends and InSight reorients to point it’s heat shield toward the planet
• 2 minutes before entry – InSight starts transmitting simple carrier signal with no data to Mars Reconnaissance Orbiter. MarCo-A and MarCo-B also identify the signal and transmit it back to Earth (8.1 minute deliver time)
• Atmospheric entry: InSight enters the atmosphere at 12,300 kph with respect to the Mars surface, whereby the heat shield remove 99.5 % of Kinetic Energy of the space probe.
• After 1.5 mins in, the heat shield is at 1500 degrees Celsius
• For two more minutes (to 3.5 minutes in) the space probe continues to decelerate at 7.6 ‘g’ to 2000 kph, whereby the head shield is jettisoned and, now at just 11km from the surface, a huge 12m parachute deploys.
• Over the next two minutes (to 5.5 minutes in) the Parachute slows Insight to just 200kph and a height of just 1km above the surface, during which Insight’s radar and altimeter systems are activated and its legs are deployed. It’s back-shell and parachute are jettisoned
• InSight’s 12 descent thrusters initiate burning, slowing the lander to 25kph at 50m altitude, and then to 7kph to touch down
• Insight’s shock absorbing legs shut off the retro thrusters – sending a UHF landing signal which MarCo-A and B will pick up and transmit to Greenbank, Max Plank and Canberra Deep Sky Network back on Earth (MRO and Odyssey will also receive this signal and relay it back to Earth).

If all worked, InSight will have landed safely on Elysium Planitia; a vast area on Mars once among the most tectonically and volcanically active regions on the planet. The location Insight will set down will be just north of the equator at 4.5 degrees north, 136 degrees east – some 550km from where the Curiosity rover landed in Gale crater.

Mars InSight coming in to land, using it’s retro rockets for a controlled landing (Credit NASA/JPL)

While Elysium Planitia is incredibly flat and therefore hopefully ideal for InSight operations, there is strong evidence from orbital investigations that the region has also been tectonically active as recently as 20 million years ago – meaning – the current geological epoch of the planet. It may turn out to be an intriguing location with regard to current seismic activity.

Ground operations commence immediately and autonomously within minutes of touch down – including taking some images and transmitting back to Earth. If MarCo-A and B are still operating, those images may be relayed back to Earth as soon as 20 minutes after landing, or before 20.30 hours local Irish time on Monday 26th.

Just 16 minutes after landing, InSight must deploy its solar panels. Operating on battery power, it must rapidly start to harness solar energy or it would otherwise shut down prematurely! It’s primary mission – to last one Martian year plus 40 days – will commence only after 10 weeks of instrument testing and calibration, whereby the robotic arm will finally place the SEIS and HP-Cubed instruments gently onto the Martian surface. Indeed in placing SEIS onto the ground, it will first place the instrument itself down, and as a separate operation carefully cover it with the wind and dust shield. Cameras on board the rover will hopefully reveal this elegant operation taking place, so it will be worth keeping an eye on InSight operations over the coming seeks.

The sinking of the HP-Cubed heat probe will take an additional 7 weeks to complete, after which all of InSight’s instruments will work silently away on the surface until at least November 2021, and most likely well beyond.

While InSight will not deliver the spectacular image vistas of the likes of the Opportunity and Curiosity rovers, the science it is set to uncover over the next two years will radically transform our understanding of the Red Planet.

To follow Mars Insight’s landing – and beyond – check out the links below.

The 7 minutes of terror actually start at 19.40 UTC (local Irish time) and the probe due to land at 19.47. if all goes to plan the MarCo probes could let us know if they are safely on the Martian surface as early as 19.54 hrs.

To be sure to catch all the live events, I’d recommend tuning into NASA TV online at 19.30 at the latest, and expect to have to wait to upwards of 21.00hrs for a confirmation of the landing from MRO in the event that the MarCo’s don’t transmit a live signal back to Earth. However it pans out, it should be an exciting few hours – hopefully not of terror!

Mars InSight Landing
Youtube broadcast of Landing

Mars Insight on Facebook
Mars Insight

Mars Insight on Twitter

Mars Insight Mission Home Page
Mars InSight Mission Web Site

Main JPL Mars Homepage
JPL Mars Website

The Planetary Society
The Planetary Society

The Planetary Society Ireland on Twitter

Detection of Terrestrial Planet Candidate in a Temperate Orbit about Proxima Centauri

Proxima Centauri is the closest star to our Solar System. At 4.24 light years distant, it is the closest of a triple star system called the Alpha Centauri system comprising of two Sun-like stars at a distance of 4.38 light years, and Proxima Centauri, a red dwarf star residing about two trillion kilometres or a little under 0.2 light years closer to us, and in orbit of its two companions. In our night sky they are located in the southern hemisphere constellation of Centaurus.

Given the detection in recent years of thousands of planets around other stars, called exoplanets, there has been a major aspiration to detect a planet around any of the three stars of the Alpha Centauri system. To this end, the European Southern Observatory (ESO), the largest astronomical institution in the world, set a science (and science-outreach) project in motion in January 2016 called PaleRedDot – a specific search for the existence of a planet exhibiting potential Earth-like characteristics around Proxima Centauri; and on August 24th 2016 the PaleRedDot consortium of scientists from the UK, Spain, Chile, the US and other countries published findings in the journal Nature that strongly indicates the presence of an Earth-sized planet orbiting Proxima Centauri. PaleRedDot has achieved success – within just months of its initiation!

What is intriguing about this discovery is that the planet, currently designated Proxima B, is similar in size to the Earth at around 1.3 Earth masses, and also resides at a distance of 7.4 million kilometres from its cool red parent star within what is called its habitable zone – the region about the star that could allow any water on an orbiting planet to exist in liquid state. These characteristics make Proxima B a candidate terrestrial or candidate Earth-like planet.

While details of the planet’s make up and surface conditions are currently unknown and none of the new evidence suggests any actual terrestrial characteristics, such is the rapid development of telescopes and analysis techniques that it is likely only a matter of a years before we gain sound insight into many of Proxima B’s characteristics, including whether any of its potential for terrestrial-like behaviour has been realised.

And so this discovery marks the beginning of an intensive period of endeavour and discovery, heralds a new era in exoplanetary science given the proximity of the planet, that will surely lead to significant new insights into Proxima B in particular and planets and solar systems in general.

With highly innovative technical proposals emerging for long range robotic exploration of the outer Solar System and beyond, the discovery of Proxima B also offers a new and unprecedented planetary target at our closest stellar neighbour, and will act as a major sign post toward the stars in the coming decades. We have our first confirmed planetary exploration destination beyond our own Solar System!

This artist’s impression shows the planet Proxima b orbiting the red dwarf star Proxima Centauri, the closest star to the Solar System. The double star Alpha Centauri AB also appears in the image between the planet and Proxima itself. Proxima b is a little more massive than the Earth and orbits in the habitable zone around Proxima Centauri, where the temperature is suitable for liquid water to exist on its surface.

This artist’s impression shows the planet Proxima b orbiting the red dwarf star Proxima Centauri, the closest star to the Solar System. The double star Alpha Centauri AB also appears in the image between the planet and Proxima itself. Proxima b is a little more massive than the Earth and orbits in the habitable zone around Proxima Centauri, where the temperature is suitable for liquid water to exist on its surface. Credit: ESO/M. Kornmesser


The Sun and Stars
Our Sun provides virtually all energy in our Solar System and Earth could not have given rise to or sustained life as we know it without its presence. At just one hundred and fifty million kilometres distance, the Sun is a very close neighbour indeed.

All of the stars in the night sky are also suns, some much larger and hotter than ours such as the brilliant blue-white star Rigel in the constellation of Orion; with many others smaller and redder in colour and shining more dimly than our Sun. Such dim stars are called red dwarfs.

By contrast our Sun is an in-between star – yellow in colour – and with a diameter of one million kilometres is unremarkable in size, mass and brightness when compared to the most massive stars like Rigel.

Of the 400 billion of stars in our Milk Way galaxy, the vast majority (75%) are red dwarfs, while just 4% are like our Sun. Still, that’s approximately 16 billion Sun-like stars in just our galaxy.

The distances between the stars are truly vast. While we measure the distances between the planets of our Solar System in tens or hundreds of million of kilometres, stellar distances are typically many trillions of kilometres. Such distances are truly gargantuan and so the light year has been adopted to indicate the distances between the stars, where one light year is the distance travelled by a ray of light in one year – 10 trillion kilometres (well, 9.6 trillion km).

Our Milky Way galaxy, containing upwards of 400 billion stars, is a flattened disk extending more than one hundred thousand light years, and with a central bulge more than twenty thousand light years in thickness.

In the quest to fully understand our Milky Way galaxy and the Universe in general – and our place in the greater scheme – we have always wondered whether the far off stars are accompanied by planetary systems. But with such vast distances to contend with, evidence of planets around other stars, called exoplanets, has been beyond our detection capabilities until quite recently.

Over the past twenty years however, telescopes, detectors, computers and analytical techniques have improved so radically that we have been able to detect planets around many stars. And so today the detection of exoplanets is one of the most active fields of science, involving the World’s great telescopes such as the European Southern Observatory located in Chile, and space probes such as NASA’s Kepler Exoplanet Detector and the Hubble Space Telescope. As of the time of writing, approximately 3500 exoplanets have been confirmed, with new planets being discovered on a near daily basis.

Such has been the transformation of the detection and study of exoplanets that by now we have even achieved the first tentative census of planets in the entire Milky Way galaxy; and the numbers are staggering.

For example, we are confident that almost every star in the galaxy has at least one planet, so that makes for a minimum of four hundred billion planets, and the full count is likely to run into the trillions. It is estimated that there may be upwards of 30 billion Earth-sized planets in the Milky Way (note – ‘sized’ not ‘like’) and intriguingly we suspect that of the 16 billion Sun-like stars in the Milky Way, one in five of those has an Earth-sized planet residing in its habitable zone. That makes for about 3 billion stars like our Sun each with a planet the size of the Earth residing in its habitable zone, in just our Milky Way galaxy alone.

Exoplanet Detection
Detecting exoplanets is an extraordinarily challenging business even today. In most cases, our largest telescopes are still not powerful enough to actually see planets around other stars directly; and so we have had to develop sophisticated techniques to indirectly detect the existence of exoplanets.

Of the many techniques available, two stand out for now. The first is called the Transit Method. Here, we monitor a star’s brightness over a prolonged period of time, and if a planet happens to be orbiting the star along our line of sight, we should see the star temporarily dim in brightness as the planet passes in front of the star. The Kepler space probe has detected all of its exoplanets using this method, but as powerful as this techniques is, it only works if the alignment is right – and it’s only right for a few percent of all stars visible form Earth.

The second method is called the Doppler or Radial Velocity method. Here, we monitor changes in the spectrum or detailed colour of the star as it wobbles, where the wobble is caused by a nearby orbiting object such as planet. As the star wobbles toward us we see it more blue, and as it moves away from us we see it more red. The changes in colour are minute, but they are detectable, especially stellar wobbles caused by large Jupiter-sized planets orbiting their parent star.

Earth-like Planets and the search for Life in the Universe
Of course one of the fundamental quests for humanity is the two-pronged question of the origin of life on Earth and the cosmic abundance of life. With so many astounding advances in science, answers to those questions have remained frustratingly elusive.

But with the development of exoplanet detection we can begin to open new avenues of investigation, most especially in the search for planets like our own that might harbour life.

And so the search for both Earth-sized and Earth-like planets has become a hot pursuits in science today. While planets of Earth size may reside anywhere in a given solar system from the scorching inner regions to the frozen outskirts; Earth-like or potentially Earth-like suggests a planet of similar mass and make-up to Earth residing in a particular region of its solar system called the habitable zone – a relatively narrow zone around the star where liquid water may exist on the planet’s surface. Such a constraint renders the detection of such planets incredibly challenging, and as already indicated, so new are even our best detection techniques that the best we can hope for today is the detection of potential or candidate Earth-like planets, with actual confirmations of any present Earth-like characteristics being some years off. Nevertheless, significant progress is been made of late, and currently, of the 3,500 known exoplanets, about 600 are known to be Earth-sized, with approximately 40 of those being candidate Earth-like planets.

So while the search for candidate Earth-like planets is making ground-breaking progress, detailed examinations of the currently known potential Earth-liked planets remains firmly beyond our capabilities for now.

Red Dwarfs
But lets not forget about those 75%, or upwards of 300 billion red dwarf stars in our galaxy. While they are smaller, cooler and dimmer than the Sun, they are enormous in number, and each can of course possess a habitable zone, however close to the parent star that might be. And so of late there has been renewed interest in investigating red dwarfs too in the search for Earth-like planets. And while as indicated we have already detected about 40 potentially Earth-like planets, including red dwarfs in our search opens up one significant avenue of investigation – our closest stellar neighbour Proxima Centauri.

Alpha Centauri System and Proxima Centauri
The three closest stars to us – the gravitationally bound Alpha Centauri system – resides at a modest distance (on stellar scales) of just over 4 light years. While that’s still 40 trillion kilometres and currently too far to reach by space probe (the New Horizons space probe which took 10 years to travel to Pluto would take over 60,000 years to reach Alpha Centauri); nevertheless the three stars of the Alpha Centauri system are close enough that, if they contain exoplanets, we could determine the characteristics of those planets using our best current and near-future planned Earth-based observation techniques; and that would be a major break-through in exoplanet studies.

Of the three stars in the system, Alpha Centauri A and B are both very similar in age, size, mass and colour to our Sun. Nevertheless, given that they orbit each other at a distance equal to the distance of our Sun to the planet Saturn, Alpha Centauri A and B constitute a wholly different kind of system to our own. We can already tell there are no Jupiter-sized planets orbiting those stars for example, and while tentative evidence exists for an Earth-sized planet orbiting Alpha Centauri B, there is much debate on the interpretation of the available evidence.

Proxima Centauri on the other hand orbits both Alpha Centauri A and B at a distance of about 2 trillion kilometres, and indeed currently resides about two trillion kilometres closer to us than its stellar companions. It is a lot smaller than its far off stellar companions – a little larger than the planet Jupiter, but having accumulated more than 125 times the mass of Jupiter during its formation it was too massive to remain as a planet and became a red dwarf star, albeit with a luminosity far fainter than its companions or our Sun (about 0.0017 the Sun’s luminosity).

This picture combines a view of the southern skies over the ESO 3.6-metre telescope at the La Silla Observatory in Chile with images of the stars Proxima Centauri (lower-right) and the double star Alpha Centauri AB (lower-left) from the NASA/ESA Hubble Space Telescope. Proxima Centauri is the closest star to the Solar System and is orbited by the planet Proxima b, which was discovered using the HARPS instrument on the ESO 3.6-metre telescope.

This picture combines a view of the southern skies over the ESO 3.6-metre telescope at the La Silla Observatory in Chile with images of the stars Proxima Centauri (lower-right) and the double star Alpha Centauri AB (lower-left) from the NASA/ESA Hubble Space Telescope. Proxima Centauri is the closest star to the Solar System and is orbited by the planet Proxima b, which was discovered using the HARPS instrument on the ESO 3.6-metre telescope. Credit: Y. Beletsky (LCO)/ESO/ESA/NASA/M. Zamani

With a pressing desire to detect any planet close by and a potential Earth-like planet in particular, the European Southern Observatory decided in January 2016 to initiate a project to see if we could detect any Earth-sized planets orbiting Proxima Centauri. The project was given the apt title PaleRedDot, a play on the famous “Pale Blue Dot” phrase coined by Carl Sagan upon seeing an image of the Earth as a tiny pale blue dot in a Voyager 1 photograph taken in 1990.

PaleRedDot set itself the challenging task of identifying whether there are any small planets orbiting Proxima Centauri using the Doppler method. This is challenging because the Doppler method is best suited to detecting Jupiter sized planets rather than Earth-sized planets which only causes a minute wobble of their parent star. But given the closeness of Proxima Centauri, it was deemed worth the attempt.

And so the ESO consortium, lead by astronomer Guillem Andlada-Escude of Queen Mary University UK, initiated their search in January 2016, accompanied with a high profile science-outreach campaign allowing anyone to look in online at the project and see its progress. And to the amazement of all, the data gathered in just ninety days from January to March 2016 was sufficient to confidently identify the existence of at least one planet orbiting Proxima Centauri.

Pale Red Dot was an international search for an Earth-like exoplanet around the closest star to us, Proxima Centauri. It used HARPS, attached to ESO’s 3.6-metre telescope at La Silla Observatory, as well as other telescopes around the world.  It was one of the few outreach campaigns allowing the general public to witness the scientific process of data acquisition in modern observatories. The public could see how teams of astronomers with different specialities work together to collect, analyse and interpret data, which ultimately confirmed the presence of an Earth-like planet orbiting our nearest neighbour. The outreach campaign consisted of blog posts and social media updates on the Pale Red Dot Twitter account and using the hashtag #PaleRedDot. For more information visit the Pale Red Dot website: http://www.palereddot.org

Pale Red Dot was an international search for an Earth-like exoplanet around the closest star to us, Proxima Centauri. It used HARPS, attached to ESO’s 3.6-metre telescope at La Silla Observatory, as well as other telescopes around the world. It was one of the few outreach campaigns allowing the general public to witness the scientific process of data acquisition in modern observatories. The public could see how teams of astronomers with different specialities work together to collect, analyse and interpret data, which ultimately confirmed the presence of an Earth-like planet orbiting our nearest neighbour. The outreach campaign consisted of blog posts and social media updates on the Pale Red Dot Twitter account and using the hashtag #PaleRedDot. For more information visit the Pale Red Dot website: http://www.palereddot.org Credit: ESO/Pale Red Dot

Proxima B
Most extraordinary of all is that the planet, designated Proxima B, has been found to have a mass at least 1.3 Earth masses, making it likely Earth-sized; while its orbit about Proxima Centauri is a close orbit of just 7.4 million kilometres distance. Given the star’s cool atmospheric temperature of 3000K, this sets Proxima B within the star’s habitable zone, making it a potential or candidate Earth-like planet.

While such a close orbit may sound somewhat bizarre, it is worth remembering that Proxima Centauri is just 1.3 times the diameter of the planet Jupiter; where Jupiter’s outermost Galilean moon Callisto (itself about the size of the planet Mercury) orbits Jupiter at a distance of just two million kilometres. So Proxima B’s orbit of 7.4 million kilometres distance may be small by Earth-Sun standards, but for the Proxima Centauri system, it is just fine.

This PaleRedDot project has been an overwhelming success, and its discovery of a candidate Earth-like planet orbiting our closest stellar is truly significant.

This infographic compares the orbit of the planet around Proxima Centauri (Proxima b) with the same region of the Solar System. Proxima Centauri is smaller and cooler than the Sun and the planet orbits much closer to its star than Mercury. As a result it lies well within the habitable zone, where liquid water can exist on the planet’s surface.

This infographic compares the orbit of the planet around Proxima Centauri (Proxima b) with the same region of the Solar System. Proxima Centauri is smaller and cooler than the Sun and the planet orbits much closer to its star than Mercury. As a result it lies well within the habitable zone, where liquid water can exist on the planet’s surface. Credit:ESO/M. Kornmesser/G. Coleman

This plot shows how the motion of Proxima Centauri towards and away from Earth is changing with time over the first half of 2016. Sometimes Proxima Centauri is approaching Earth at about 5 kilometres per hour — normal human walking pace — and at times receding at the same speed. This regular pattern of changing radial velocities repeats with a period of 11.2 days. Careful analysis of the resulting tiny Doppler shifts showed that they indicated the presence of a planet with a mass at least 1.3 times that of the Earth, orbiting about 7 million kilometres from Proxima Centauri — only 5% of the Earth-Sun distance.

This plot shows how the motion of Proxima Centauri towards and away from Earth is changing with time over the first half of 2016. Sometimes Proxima Centauri is approaching Earth at about 5 kilometres per hour — normal human walking pace — and at times receding at the same speed. This regular pattern of changing radial velocities repeats with a period of 11.2 days. Careful analysis of the resulting tiny Doppler shifts showed that they indicated the presence of a planet with a mass at least 1.3 times that of the Earth, orbiting about 7 million kilometres from Proxima Centauri — only 5% of the Earth-Sun distance. Credit: ESO/G. Anglada-Escudé

Proxima B and Habitability
While Proxima B resides in the habitable zone of Proxima Centauri, it must be made clear that the evidence accumulated to date provide absolutely no insight into the characteristics of Proxima B, other than that it’s a rocky planet at least 1.3 time the mass of the Earth residing in its parent star’s habitable zone. No information is currently forthcoming on the material make-up of its surface, whether is has an atmosphere, volatile systems including water, or on its actual habitability.

Indeed, there are some issues mitigating against clemency and stability that we are already aware of, such as that Proxima B’s rotation is likely tidally locked to its orbit (like the Moon which only shows one face to Earth at all times), and hence the dark side of Proxima B never receiving any direct sun light at all; as well as other issues associated with Proxima Centauri itself such as its very powerful magnetic field, the fact that it’s a flare star and associated disproportionately strong X-Ray emissions.

None of these can be claimed to be fatal to life supporting systems on Proxima B however – indeed the fact that it resides close to such an energetic star makes for a potentially very interesting environment because it will likely be a dynamic world in non-extreme ways (on a cosmic scale), and likely not dormant as with many of our Solar System’s large moons, for example.

Scientific Relevance
And so the discovery of a planet orbiting out next door neighbour will provide for opportunities to investigate a planet orbiting a different kind of star to our sun in unprecedented detail. When techniques improve, likely within just years, we will determine it’s material make up, atmospheric and other volatile material systems, interaction with parent star, presence of other planets and moons and other dynamisms on the planet and within its system.

Already the available data tentatively suggests a second planet in the system with an orbit somewhere between 80 and 600 days, though it must be restated that the evidence is tentative.

At a minimum we can be optimistic that Proxima B will be a very interesting and dynamic world, and if it happens to involve liquid water and other planetary volatile material systems, it may turn out to be of fundamental importance to our quest for origins and the cosmic abundance of life.

Sociological Relevance
By all measures, the importance of the discovery of a candidate Earth-like planet orbiting our closest stellar neighbour cannot be overstated.

As just described, if it turns out that Proxima B is Earth-like, it will provide significant new insights into the age old questions of origins and the cosmic abundance of life.

And in the context of our push to the far outer reaches of the Solar System with New Horizons to Pluto and into the Kuiper Belt, and the development of NASA’s Space Launch System (SLS) in 2018 which could deliver spacecraft to Pluto in just 3 years and will likely enable deep space missions to the Kuiper belt beyond Pluto; the discovery of Proxima B offers the coming generations of space explorers a major new destination to aim for.

It may seem far fetched to us today to contemplate sending a space probe there, but it is likely that in the next few decades new mechanisms to send small space craft to the nearest stars will begin to emerge. The discovery of Proxima B will contribute fundamentally to that push, because it offers a destination to aim for. What has been until now a notion of travelling to unknown destinations among the stars becomes a tangible mission to reach a specific planet in the Proxima Centauri system. There cannot be a closer target beyond our Solar system, and such tangibility will likely precipitate into a specific and targeted mission over the coming decades. We can be confident that all involved today in spawning projects to reach the nearest stars in the coming decades will be transfixed by this discovery.

As just two examples, currently in the US both NASA and DARPA are considering interstellar travel within the next 100 years; while Russian Entrepreneur Yuri Milner has donated no less than 100 million dollars to develop tiny space probe technology through an initiative called Breakthrough Stardust that could enable tiny robotic probes to travel to the Alpha Centauri or Proxima Centauri in just 20 years.

In a nutshell, we now have a destination planet orbiting our next door neighbour; and that will surely spur on innovation for the coming decades in space exploration.

Future Work
As ground-breaking as the discovery of Proxima B is, it represents only the very beginning in a new era of both exoplanetary studies and of interstellar space exploration. We could not ask for a better scenario in the study of candidate Earth-like planets; while the presence of this planet sets space exploration onto a whole new path beyond the Solar System.

And so many new astronomical studies of Proxima Centauri, and indeed of all our nearest stellar neighbours, are already ramping up. PaleRedDot will now aim at improving our understanding of the Proxima Centauri system and Proxima B, and will also continue into the future to study many near by stars.

More broadly, exciting new missions about to get under way such as the next generation space telescope (called the James Webb Space Telescope JWST), the new TESS Exoplanet Finder both due to launch in 2018, as well as the development of ESO EELT – a gigantic telescope to see first light in 2024, among many other projects; all mean that Proxima B will come under intense scrutiny in the next few years, and will surely give up its secrets as to its characteristics and whether it is, or is not, Earth-like.

The discovery of Proxima B heralds a new era in exoplanet studies and space exploration, and is likely to become a very important, and very familiar world to us in the coming decades.

This artist’s impression shows a view of the surface of the planet Proxima b orbiting the red dwarf star Proxima Centauri, the closest star to the Solar System. The double star Alpha Centauri AB also appears in the image to the upper-right of Proxima itself. Proxima b is a little more massive than the Earth and orbits in the habitable zone around Proxima Centauri, where the temperature is suitable for liquid water to exist on its surface.

This artist’s impression shows a view of the surface of the planet Proxima b orbiting the red dwarf star Proxima Centauri, the closest star to the Solar System. The double star Alpha Centauri AB also appears in the image to the upper-right of Proxima itself. Proxima b is a little more massive than the Earth and orbits in the habitable zone around Proxima Centauri, where the temperature is suitable for liquid water to exist on its surface. Credit: ESO/José Francisco ( http://josefrancisco.org )

Acknowledgment: thanks to Will Goodbody, Science and Technology Correspondent, RTE, for laying the groundwork for this blog.

Follow Proxima B, PaleRedDot and Exoplanet developments:

Pale Red Dot:
Web: https://palereddot.org
Twitter: @Pale_red_dot #PaleRedDot
Facebook http://www.facebook.com/PaleRedDot

European Southern Observatory
News https://www.eso.org/public/news/eso1629/
ESO Press Conference:

Research Paper in Nature:

Click to access eso1629a.pdf


Breakthrough Initiatives

NASA / DARPA One Hundred Year Starship





Rosetta: Rendezvous with Comet 67P/Churyumov-Gerasimenko (“67P / CG”)

On Wednesday 6th of August 2014 and after a mammoth 10-year journey across the Solar System, the European Space Agency space probe Rosetta will rendezvous with a comet called “67P / Churyumov-Gerasimenko” (67P/CG) – a tiny icy worldlet just 4-5 kilometre long orbiting the Sun in an elliptical orbit and currently several hundred million kilometres distance from Earth.

By Wednesday 6th August, Rosetta will have settled into a 25-kilometer orbit around 67P/CG. In November 2014, a small automated Lander called Philae attached to Rosetta will be sent down to the surface. Both spacecraft will continue to travel with the comet for the next 16 months as it circles and approached the Sun (closest approach on August 13th 2015); scrutinizing its composition and behaviour as the Sun’s heat transforms the tiny frozen world into a hive of volatile activity that temporarily swells it into a gaseous entity many millions of kilometres in size.

By analysing the comet with a suite of 22 instruments, Rosetta and Philae will conduct a comprehensive analysis of the material makeup of the comet that will provide important new information regarding the origin of Earth, Earth’s oceans and life itself.

Overview and Objectives of the Rosetta Mission
Rosetta is a European Space Agency (ESA) mission to orbit and land on comet 67P /Churyumov-Gerasimenko (“67P/CG”) as it circles the Sun. The primary mission lasts from August 6th 2014 to December 31st 2015.

It is a mission made up of a main Rosetta space probe orbiter and a smaller lander attached to Rosetta named Philae. Rosetta will settle into orbit on August 6th 2014 and continue to orbit the comet over the next 16 months. In November 2014 Philae will land on the comet’s surface. Both will travel with the comet as it orbits the Sun and reaches closest approach to the Sun on August 13th 2015.

Comets are made up of icy volatile materials like water and carbon dioxide, as well as dust and other materials. So as 67P/CG approaches its closest point to the Sun in its orbit (called perihelion), its volatile materials will heat up and sublimate, forming a vast spherical gaseous coma and perhaps a tail, both of which will be more rarefied than the air we breathe and reach for millions of kilometres into space. Since 67P/CG does not approach the Sun too closely (as some other comets do), it is not likely to become as chaotic a ‘volatile cauldron’ as those which travel much closer to the Sun.

While Philae will measure the composition of, and activity on the comet directly from the surface; Rosetta, orbiting at a distance of just 25km, will also measure the volatile materials emanating from the comet into its immediate space vicinity, and indeed will be able to see how the comet changes and reacts to the Sun’s heat and solar wind as they move closer to the Sun in August 2015.

The data gleaned from the comet will reveal its internal makeup and composition, including any organic materials present, to the atomic and molecular levels; providing significant new insight into the origin of the Solar System, the origin of Earth and its oceans and the origin of life.

Journey to Comet 67P/Churyumov-Gerasimenko
Because no current rocket (including the powerful ESA Arianne-5 rocket upon which Rosetta was launched) has the capability to send such a large 3-Tonne spacecraft directly to a comet such as 67P/Churyumov-Gerasimenko, Rosetta was ‘bounced around the inner Solar System like a cosmic billiard ball’, during its ten-year trek to Comet 67P/Churyumov-Gerasimenko.

Since its launch in 2004 from Kourou in French Guiana, Rosetta has criss-crossed the inner Solar System four times, has travelled over 6 billion kilometres, including availing of three gravity-assist flybys of Earth (2005, 2007 and 2009) and one of Mars (2007); and is finally due to arrive at comet 67P/CG – just 4 to 5 kilometres in length – at a distance of several hundred million kilometres from Earth.

Hibernation and Wakeup
Rosetta’s 10 year deep-space odyssey comprised lengthy periods of inactivity, punctuated by relatively short spells of intense activity when encountering Earth, Mars, and several asteroids. Ensuring that the spacecraft survived the hazards of travelling through deep space for more than ten years has been one of the major challenges of the Rosetta mission, and has been hugely successful to date.

To that end, Rosetta was placed in hibernation between June 8th 2011 and January 20th 2014 in order to limit consumption of power and fuel. During that lengthy hibernation, the spacecraft rotated once each minute while facing the Sun for solar power; with the only electrical systems kept running being the radio receivers and command decoders. On January 20th 2014, a “wake-up” command was sent to Rosetta. ESA scientists were hugely relieved that the dormant spacecraft received the command and awoke from its hibernation in excellent health and ready to take on all challenges ahead of it.

August 2014 Rendezvous with Comet 67P/Churyumov-Gerasimenko
Since its reawakening in January, Rosetta has been steadily approaching the comet. For the past 90 days or so, it has been moving at only about 2 metres per second with respect to the comet. As you read this, the space probe is imaging the comet, allowing ESA scientists and engineers to determine the comet’s size, shape and orientation and rotation; allowing for Rosetta to complete its orbital insertion, which takes place on Wednesday August 6th 2014.

Using its approximately 1.7 Tonnes of propellant, the space probe’s propellant system and 24 thrusters recently manoeuvred the probe into an orbit just ahead of the comet, with the final orbit about the comet to be established on August 6th.

Rosetta will then start its science program, using eleven different instruments to photograph and map the comet to great precision, determine its internal structure and monitor any gas and dust emanating from the surface.

November Landing on Comet 67P/Churyumov-Gerasimenko
Once the comet has been mapped, five potential landing sites will be identified. Once ESA scientists have determined the best one, they will plan for a November landing. At that time Rosetta will move to within 1 kilometre of the comet, and release the lander Philae, which will set gently down on the comet at walking pace.

Once secure on the surface, it will anchor itself to the comet (because the comet’s gravity is too small to securely hold the lander on the surface) and proceed to conduct a series of sophisticated experiments, including drilling into the comet’s surface and placing surface materials into the body of the lander where their makeup can be determined to atomic and molecular levels.

Journey towards and away from the Sun
Comet 67P/CG is known as a Jupiter-class comet, meaning that its orbit is affected by the strong gravity of the giant planet Jupiter. Indeed Jupiter changed the orbit of 67P/CG in 1959, so that now the comet travels on an elliptical orbit that brings it to within 185 million kilometres of the Sun at closest approach (perihelion) and out to over 850 million kilometres at its furthest (aphelion).

Over the next 16 months and during the next perihelion on August 13th 2015, both Rosetta and Philae will monitor, image and measure all that happens on and around the comet as it draws nearer to the Sun. As already indicated, because 67P/CG will not travel too close to the Sun, so it is not expected to become as chaotic as comets which venture much closer to the Sun. Nevertheless, there will be plenty of activity, and as of June 2014, Rosetta has already begun to see small quantities of water emanating from the comet, and such activity will but increase greatly over the next year or so, providing both probes with an unprecedented opportunity to examine the makeup, composition and interaction of the comet as it orbits about the Sun.

Rosetta and Philae: Science Objectives and Instruments
Rosetta and Philae are charges with carrying out the following tasks:
• Detailed imaging and mapping of the comet
• Determination of the internal structure of the comet
• Determination of the material makeup, including elemental, isotopic and molecular details, of the comet’s volatile materials, dust and other materials and any organic materials expected to be present in the comet
• Image, monitor and measure the release of all materials, volatile or otherwise, from the comet as it reaches its closest point to the Sun in August 2015; and observe how these materials interact with the Sun’s solar wind and magnetic field

So how will Rosetta and Philae do all of that? The Rosetta orbiter contains no less than 11 scientific instruments including cameras for imaging the comet, a thermal camera to determine its material makeup, a type of radar know as radio-sounding that can penetrate the comet and determine its interior makeup, a mass-spectrometer and dust analyser to analyse materials emanating from the comet and plasma and magnetic field analysers for monitoring the interaction of the comet’s materials with the Sun’s solar wind and magnetic field.

Philae’s science package of 10 instruments is arguably more sophisticated; and includes an Alpha Proton X-Ray Spectrometer (as on the Mars Rovers) to determine the elemental makeup of the surface, a drill to drill into the surface and place samples into its body where a suite of instruments will determine the molecular makeup of the materials, including organic materials, and even determine the isotopic nature of the elements (critical for determining whether comets were the primeval source of all of Earth’s water). Radio-sounding and acoustic instruments will measure the internal structure of the comet, while high resolution cameras will image its surface.

Both the orbiter and the lander will conduct a suite of hard-science experiments typical of modern analytical laboratories. The instruments on board both Rosetta and Philae are more sophisticated than those on the Mars Exploration Rovers Spirit and Opportunity, and on a par with most of the instruments on the Mars Science Laboratory Curiosity; constituting one of the most sophisticated space science missions ever conducted.

Comets and Origins
Comets are tiny icy worlds usually only single kilometres in diameter. They are remnants of formation of the Solar System 4.6 billion years ago. As the Sun formed, countless trillions of tonnes of volatile materials such as water, carbon dioxide, ammonia and methane, as well as organic materials to the complexity of nucleic acids and amino acids that make up DNA ad proteins in life as we know it, were synthesized in the proto-planetary disk surrounding the Sun.

As the planets like Earth and Mars formed, the lighter elements and synthesized volatile materials moved further out from the Sun, contributing to the formation of the gas giant planets Jupiter, Saturn, Uranus and Neptune; but with the left over volatiles forming a vast swarm of perhaps a trillion comets, most of which reside in the Oort Cloud far out in the Solar System between 0.1 and 1 Light Year distance (one-hundred-billion to one-thousand-billion kilometres out – by comparison Pluto resides at approximately six-billion kilometres from the Sun.)

What is so crucial about comets is that they retain a record of the actual synthesis of both volatile materials such as water and carbon dioxide, and of organic molecules to the complexity of genetic nucleotides and amino acids known to be important to life as we know it, in the region of the Sun before the Earth itself had formed.

Hence “67P CG” represents one of a vast family of objects that are potentially older than the Earth, retaining a pristine record of complex chemistry occurring about the Sun relevant to the formation of life on Earth before and when the Earth was taking form. For this reason, comets are seen as very important in our search for the origin of the Solar System, of Earth and its oceans and of life itself.

Rosetta Mission – Relevance and Value to Science & Society
Given that we still have very little idea as to how life originated, studying such primeval evidence as retained in comets constitutes one of the most important endeavours in science. The Rosetta mission is arguably as important as the Mars exploration programme in search of evidence of origins on Mars, and perhaps The Hubble Space Telescope and the CERN Large Hadron Collider, both of which are currently revolutionising our understanding of the nature, origin and fate of the Universe itself.

Among the questions regarding the origin of life we must answer are:
• What is the origin of Earth oceans? In particular, is the water making up our oceans indigenous to our planet, or did it arrive from a mass bombardment of comets, asteroids and meteorites known to have occurred billions of years ago?
• Where did the basic organic materials for life originate – from organic synthesis on our planet, or from organic materials within comets and meteorites manufactured in the vicinity of the Sun before and during Earth formation?

The Rosetta mission may go some way toward answering both of these fundamental questions, among others.

And so we can see why this mission is named Rosetta. As with the Rosetta stone which allowed modern society to decipher the hieroglyphics of ancient Egypt – the Rosetta mission to 67P/CG may provide the cipher to enable us to better read the cosmic book of life – to see better the connection between the origin of life on Earth and its connection to the origin of the Solar System; and to link the origin of life on Earth to a deeper insight into the cosmic abundance of life.

This opportunity has been afforded to us through the technological and scientific endeavour of our ancestors and current generation of scientists alike, and we have taken that opportunity. To not do so would be a dereliction of duty to ourselves, to society, to our place in the great unfolding human story and to future generations who will need the insights we glean from this mission to make new and ever more enlightened decisions and undertake new endeavours to better understand who we are, where we have come from and what our cosmic fate can be.

I recommend that you follow the Rosetta mission over the next 16 months or so via the following links. In the Documents section of this blog (see Menu at top of Blog) you will also find a downloadable PDF document titled “TPS_ESA_Rosetta” containing this blog in a more bullet-point format, as well as containing greater detail on both the Rosetta Orbiter and Philae Lander and their science instruments, as well as a set of images including source URSs to hi-res versions, and required credits should you use any of the images.

Web (ESA):

Rosetta on Twitter:

Rosetta on Facebook:

Rosetta Blog:

Rosetta on Youtube:


1. Rosetta Space-probe and Philae Comet Lander:


Caption: In November 12014, Rosetta (upper) will set the Philae lander (lower) onto the surface of comet 67P / Churyumov-Gerasimenko as it closely approaches and then circles the Sun

Hi-Res Source: http://www.esa.int/spaceinimages/Images/2013/12/Rosetta_and_Philae_at_comet6

Credit: ESA–J. Huart

2. Illustration of the size of comet 67P/ Churyumov-Gerasimenko

Caption: Illustration showing the relative size of comet 67P / Churyumov-Gerasimenko to well known features on Earth. Though huge on a human scale, comet “67P” is a small celestial body and possesses only a very weak gravity.

Hi Res Source: http://www.esa.int/spaceinimages/Images/2014/07/How_big_is_Rosetta_s_comet

Credit: ESA

3. Comet images on August 1st 2014 67P / Churyumov-Gerasimenko


Caption: On 1st of August, Rosetta took this image of comet 67P / Churyumov-Gerasimenko, revealing it to be a double lobed, peanut shaped object.

Hi-Res Source:

Credit: ESA

The Summer Solstice 2014 and The Summer Night Sky

It’s been some time since I’ve blogged! I had hoped to blog a tad more regularly, but it’s becoming clear to me that it’ll take longer to get up to speed with regular blogging (with worthwhile content!).

So I’m still in a phase of extensive research and literature surveying for intended blogs on the future of Mars exploration, the changing landscape of space exploration and related sociological issue. When all of that is complete it will hopefully lead to some insightful blogs as there are many changes taking place right now in how space exploration is being planned and pursued, and on how people in general perceive it – and with MANY outstanding and issues too. Watch this space!

In the mean time, what a perfect opportunity to write a little about the summer solstice and the summer night sky from Ireland. As you may have heard on the RTE Radio 1 Marian Finucane Show on Sunday 22nd June, we chatted about the summer solstice, so I thought I’d post some details on the solstice from an astronomical point of view, and talk a little about what constellations are in the night sky over Ireland. A little rushed, but here goes:

Key Points:

– Moment / time each year when Sun reaches highest point in the sky
– When (2014): 11.51am on June 21st
– Height above the horizon from Ireland (Altitude): 60.5 degrees above the horizon
– For all points on Earth, including Ireland, the Sun reaches a different height in the sky for each and every day. In mid winter it reaches only about 13.5 degrees above the horizon (called the winter solstice), shortening our days; while in mid summer it reaches an altitude of 60.5 degrees (summer solstice), lengthening our days. Mid point between those extremes – at the spring equinox (March) and autumnal equinox (September) the Sun reaches an interim height (about 37 degrees) and we get approximately equal length days and nights
– Cause: Earth’s axis is tilted by 23.5 degrees, it is spinning and it is orbiting the Sun. So in summer Earth is tilted toward the Sun and we see it higher in the sky, in winter we’re tilted away from the Sun and we see it lower in the sky, and for every other day of the year the Sun reaches a height at noon between those extremes.
– To help visualize this, concentrate first on the extremes. So in summer we’re tilted 23.5 degrees towards the Sun meaning that when it rises into the sky it reaches a great height. Conversely in December we’re tilted 23.5 degrees away from the Sun so we see it correspondingly lower in the sky. On the equinoxes we’re neither tilted away nor toward the Sun so it reaches an interim height – and we get 12 hours day and night. Of course the Earth is always tilted at 23.5 degrees – that doesn’t change through the year; what we’re interested in here is the orientation of that tilt with respect to the Sun, and at the equinoxes the Earth is tilted at 23.5 degrees for sure, only neither towards nor away from the Sun.
– Each place on the Earth experiences the same affect but to differing amounts depending on its latitude on the globe; so every location in the northern hemisphere sees the Sun at its highest point in their sky on June 21st.
– To work out the maximum angle of the Sun above the horizon on the summer solstice at your latitude:
(90 degrees – your Latitude) + 23.5 degrees (that equals 60.5 degrees for Ireland)
– To work out the maximum angle of the Sun above the horizon at your latitude during the winter solstice:
(90 degrees – your Latitude) – 23.5 degrees (approximately 13.5 degrees for Ireland)

– The Earth orbits the Sun once a year and so the Sun appears to traverse the sky once a year (from west to east)
– We don’t see the Sun actually move from west to east throughout the year, rather we see it at about the same position at the same time each day, with the background stars (from our line of sight) changing accordingly throughout the year. To visualize this, imagine asking a friend to stand still while you walk around them keeping your eyes firmly fixed on them at all times. As you circle your friend they will stay in the centre of your field of view. However, what you see behind them will continuously change as you circle them. It’s like this for the Earth circling the Sun. We see the Sun at approximately the same place in the sky at the same time each day, but the stars or constellations behind the Sun change as the year passes by.
– So as Earth orbits Sun it appears to move in relation to the background stars. Ancient civilisations organised groups of stars in the sky into patterns called constellations; and the Sun passes through one constellation per month. Hence the 12 constellations it passes through are called the constellations of the zodiac, and are named: Pisces, Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpio, Sagittarius, Capricorn and Aquarius. The path around the sky through the zodiac that the Sun appears to travel is called the ecliptic.
– But the tilt of the Earth has a significant effect on the Sun’s apparent yearly motion about the sky in a vertical sense (as in: higher in summer and lower in winter), and is the cause of us having longer days in summer and shorter days in winter.
– Because the Earths axis is tilted by 23.5 degrees the Sun moves around the sky once a year on a path that is tilted at an angle of 23.5 degrees to the celestial equator (the extension of the Earth’s equator into the sky that divides the sky into north and south). So the Sun’s yearly path is a great circle in the sky (called the ecliptic) that intersects the celestial equator at an angle of 23.5 degrees and so the Sun appears to travel from south to north and back again in a cyclical manner over its yearly path. The Sun is below the celestial equator for 6 months and so appears in southern part of the sky, and is above the equator for 6 months and appears in the northern sky. It is this south-to-north (and back again) apparent movement of the Sun in the sky over the course of a year that gives us longer and shorter days; where (for us in the north) the Sun reaches its furthest point north in the sky in summer, appearing higher in the sky and giving us longer days, while it reaches its furthers point south in winter and hence appears lower in the sky, giving us shorter day.
– The point when it traverses south to north – where the ecliptic intersects the celestial equator – is called spring equinox and gives us 12 hours of day and night (approximately). This is also called the First Point of Aries because when ancient civilisations discovered this phenomenon, the Sun appeared in the constellation of Aries as it travelled from south to north.
– Also, at the time of such celestial discovery about 2000 years ago, in mid-summer the Sun resided in the constellation of Cancer and also directly over head at a latitude of 23.5 degrees north of Earth’s equator. This is why that latitude is called the Tropic of Cancer. Similarly at mid winter in the north (mid summer in the south) the Sun resided in the constellation of Capricorn and also appeared directly overhead at a latitude of 23.5 degrees south of Earth’s equator and why that latitude is called the Tropic of Capricorn. Precession of the Earth’s axis over a 26,000 year period means that although Earth’s tilt remains about about 23 degrees, it’s orientation changes (think of a spinning top rapidly rotating at a tilt but the orientation of the tilt changing over time). As a result of this precession the constellation the Sun appears in at the equinoxes and solstices changes over time (by about 1 degree in the sky every 72 years) so that today the Sun no longer appears in Aries at the spring equinox but instead now appears in the constellation of Pisces; and similarly no longer appears in Cancer at the summer solstice and instead has moved into the constellation of Gemini at that time of the year.

Finally, Earth’s precession also means that, were it not for regular corrections we make to our calendar, mid-summer in the northern hemisphere would occur in December in about 13,000 years from now. To ensure we retain our existing calendar with mid-summer always in June, we add fractions of a second to our clocks every few years, nudging the calendar back into place to counteract the Earth’s precession.

The Summer Constellations

Of course, while we can’t directly see which constellation the Sun is in at any given moment (because that constellation is behind the Sun in the day time), as the Sun moves from constellation to constellation, it correspondingly affects which constellations we see at the night. In particular, those constellations on the far side of the sky to the Sun at any given moment will appear in the middle of the night.

This is why we see different constellations in the night sky during different times of the year. For example, the constellations of Taurus is visible in the southern sky in winter, but during the summer it is not visible at night because the Sun is actually in the constellation of Taurus so it is in the sky during the day.

So this gives us a lovely opportunity to ask what constellations are in the summer sky around the time of the summer solstice and though July? Though of course the skies are less dark than in winter (because the days are longer and the Sun does not set so far below the horizon at our latitude), the summer night sky from Ireland is nothing less than spectacular.

Firstly, traversing the sky from northeast towards southwest you see the faint white band of the Milky Way galaxy itself, of which we are a part. The Milky Way is a galaxy of perhaps 200 billion stars, each like our Sun, and the band of light is the combined starlight of all 200 billion of those stars.

The main feature of our summer skies is called the “Summer Triangle” made up of the three brightest stars you can see as you look overhead and south: the brilliant blue-white star Vega (in the constellation Lyra) almost directly over head at midnight through July, Deneb the strong white star in the magnificent constellation of Cygnus the Swan (also known as the Northern Cross) and the white-yellow star Altair furthest south in the constellation of Aquila. Altair is of particular note because, at just 16 light years distance, it is one of our closest cosmic neighbours (and is the star to which the gallant crew travelled in the iconic 1950’s film “Forbidden Planet”).

The constellation of Cygnus the Swan is also of particular interest. To find it, look for a large cross or crucifix outline of seven stars almost directly over head during July, of which the brightest star is Deneb. Cygnus lies within the rich star fields of the Milky Way, and viewing this constellation through binoculars is nothing short of spectacular, where you will witness countless thousands of stars to rival any Star Wars movie scene.

The Kepler exoplanet finder space probe, which has discovered about 2000 planets around other stars, concentrated its efforts exclusively within Cygnus, so it is surely intriguing to know, as you look through your binoculars at the stars within the constellation, that many of them possess families of planets.

Finally in the summer night sky we cannot ignore the giant ‘W’ of the sky: Cassiopeia. Though Cassiopeia is visible in the sky all year round from Ireland, it is particularly splendid in summer in the northeast region of the sky. Identifying it for the first time is hugely satisfying, and again observing it through binoculars is nothing short of spectacular. A particular treat through binoculars is the magnificent double star cluster in the constellation of Perseus, the next door constellation to Cassiopeia. and you can find the double cluster easily using Cassiopeia as a guide – from the left most star of Cassiopeia find the 2nd and 3rd stars of the great ‘W’ – then extend their line downwards for about twice their separation and you arrive at the fabulous double cluster in Perseus. Each of the clusters comprises more than 300 blue-white giant stars and are perhaps only 12 to 13 million years old – a blink of the eye in cosmological terms and when compared to our Sun’s 4,500 million year age!

I urge each and every one of you to come to know the motion of the Sun, Moon, Planets and stars in our sky. Read about it, learn how people of old figured out such motions. Convince yourself of Earth’s movement about the Sun and how it affects the seasons, length of day, how high the sun can reach in the sky and what constellations you can see at each time of the year. There is no doubt that gaining such insight delivers a great sense of connection and ‘place’ in the greater natural scheme.

Likewise, I strongly advise you to come to know the night sky at various times of the year. There is nothing more enthralling than identifying the constellations for yourself. The first time you see a constellation pattern in the sky is a very exciting moment; and without trying to be over the top about it, a quite personal moment. For me, that moment occurred when I was about 10 or 11. I had read about the constellation of Orion from a beautiful little book called the “Observers Book of Astronomy” my Patrick Moore, and set out on winter evenings to see it for myself. I spent no less than three winters looking for it, but to no avail. I just could not find it. For the first couple of winters I looked and looked. What kept drawing my attention, however, was three stars in a straight line that would appear in the autumn sky to the southeast , and fade in spring to the southwest. I found those stars fascinating, but for love nor money I could not find Orion. I read about it more and more, but nothing could reveal it to me.

And then, on the third winter, while looking at those intriguing three star, Orion presented itself to me in a moment of pure revelation. I looked at the three stars and realised in a moment of joy and exhilaration that they were actually at the centre of Orion! There was Orion, magnificent – HUGE – surrounding those three stars (the belt of Orion!) in the sky, dominating a much, much larger part of the southern sky than I had expected – in front of me all the time. My mistake over the previous years had been a lacking of perception of the size of the constellations in the sky. I had thought they were tiny, and that I would have to track them down with fine precision within a small part the sky! Nothing could have prepared me for the sheer size and scale of the the constellations in the sky and how readily visible they are to the unaided eye; and so I could not see Orion even on the most glorious of dark, crisp nights. I will never forget that night and that moment of personal discovery; and I urge each and every one of you to similarly explore the sky – most especially with your naked eye and at most with a pair of binoculars – but first and foremost with your eyes only (and a good night sky guide), to discover the constellations for yourself.

And be sure to look into the summer night sky on some calm cloudless evening – either with the naked eye to discover the constellations for yourself or with a pair of binoculars to witness the splendor of the heavens just beyond the perception of the naked eye. Find out a little of the mythology of each constellation you identify, learn what stars, nebulae and star clusters are in it, read a little of the astrophysics that describes the processes underlying the formation, evolution and fate of the stars and indeed the Milky Way itself. Finally, perhaps explore the magnificent and unique Hubble Space Telescope image archive on-line to witness visual details not visible from the ground and indeed to learn more about the powerful cosmological processes that drive the workings of the Universe itself. Make such a quest your own. From looking into the night sky to learning about the underlying cosmological forces at play, there is much you can do to enhance your sense and understanding of nature on the grandest scheme. You do not need to be a scientist or astronomer to do this, and each and every one of us has an entitlement to such a sense of connection and ownership of the universe within which we live.

Happy observing and learning!

TPS Ireland talks about Mars in Feb. and March (2014)

I’m delighted to say that I’ve been invited to give two talks through February and March as TPS Ireland representative, which anyone can attend. I’ll deliver the same talk on both occasions. It’s titled “Exploring Mars, Discovering Earth” which was the theme for The United Nations Space Week 2013, run in October 2013; and for which Mars geomorphologist Professor Mary Bourke at Trinity College Dublin ran a fabulous week of public events related to Mars.

The talk in Feb. and March will be an updated version of the talk I gave last October. So while I’ll talk about the basis for Mars exploration and discuss the latest missions and mission findings, I’ll also mention some arising issues such as newly announced robotic missions to Mars by both ESA and NASA; and if time permits, offer some context on recently proposed human missions to Mars such as “Inspiration Mars” and “Mars One”, looking at their merits and concerns.

I plan to write blogs on all of those issues in the coming months, and am as we speak drafting a blog on the basis of, and reasoning behind, current robotic Mars exploration. I hope to post that blog by mid February.

In the mean time, if you feel inclined, please do attend one of the upcoming talks. They are aimed at the general public, are rich in astounding Mars images (some in 3D) and video animations, and will also present the very latest findings from the MER Opportunity and MSL Curiosity rovers. The details are as follows:

Talk 1: Presented by Kevin Nolan of The Planetary Society to The Irish Skeptics Society, on Wednesday 26th February, at 8pm in the Davenport Hotel, Merrion Square. All are welcome.

Talk 2: Presented by Kevin Nolan of The Planetary Society to The Irish Astronomical Society, on Monday 31st March, at 8pm in Ely House, 8 Ely Place, Dublin 2. All welcome, free event.