Issue 6 of the Europlanet Magazine is out now!

Issue 6 of the Europlanet Magazine is out now!

In this issue:

In Focus

round up of news from Europlanet and the planetary community, including:

Cover of issue 6 of the Europlanet Magazine.
Cover of Issue 6 of the Europlanet Magazine.

• New Board Members of the Europlanet Society
• New EPEC Co-Chairs
• Join us on Discord!
• DPS-EPSC Joint Meeting 2023
• EPSC in Berlin and Beyond!
• GMAP Winter School
• Europlanet at Space Tech Expo Europe
• European Space Weather Week
• 1st Europlanet Latin America Workshop
• Europlanet Committee Funding Scheme Results 2023
• Europlanet Prize for Public Engagement 2023
• Farinella Prize 2023
• Students as Planetary Defenders
• Blink of a Star
• Polish Experiments to Fly on ISS
• EXPLORE Apps for Lunar, Stellar & Galactic Research

Machine Learning for a Data Driven Era of Planetary Science 

Stavro Ivanovski (INAF-Trieste Astronomical Observatory, Italy), Angelo Pio Rossi (Constructor University, Germany), Jeronimo Bernard-Salas (ACRI-ST, France), and Anita Heward (DFET, UK) look at how Machine Learning (ML) is revolutionising planetary science

Planetary Perspectives: Meet the New Europlanet Society Board

This edition of Planetary Perspectives finds out more about interests, backgrounds and ambitions for the Europlanet Society of the members of the Executive Board elected and taking up new roles in November 2023. 

Supporting Astronomy in Ukraine

Gražina Tautvaišienė (Vilnius University, Lithuania), describes how a Europlanet programme is supporting Ukrainian colleagues to continue their research.

ERIM 2023: A New Kind of Europlanet Meeting 

Anita Heward (Chair of the ERIM Organising Committee and Europlanet Sustainability Committee) reports on how the Europlanet Research Infrastructure Meeting (ERIM) in Bratislava has helped to lay the foundations for a sustainable Europlanet. 

EPEC Annual Week: A Melting Pot of Ideas 

James McKevitt (University of Vienna, Austria and UCL, UK) reflects on the outcomes of the Europlanet Early Career event, EPEC Annual Week, held in Bratislava, Slovakia in June 2023. 

Bridging the Gap Between Policy and Science 

The Europlanet Policy Team reports on a policy workshop that took place as part of the Europlanet Research Infrastructure Meeting (ERIM) 2023 last June. 

The Ecological Footprint of Astronomy 

Thibaut Roger (University of Bern, Switzerland) reports on a session at ERIM to initiate a discussion about the ecological impact of astronomy and planetary research activities 

ERIM Goes to Schools 

Thibaut Roger (University of Bern, Switzerland) and Barbara Cavalazzi (University of Bologna, Italy) bring astrobiology and planetary science to schools in Bratislava.

Diving into the Heavens: The Solar System Scope Project 

Jozef Bodlak (Solar System Scope) tells the story behind the Solar System Scope – an app that takes users on an immersive journey with the aim of bringing the grandeur of space to the fingertips of people around the world. 

The Making of ‘The Making of Juice’ 

Maarten Roos-Serote (Lightcurve Films, Portugal) shares a unique view behind the scenes of the making of the Juice mission

Molėtai Magic 

Alejandro Luis García Muñoz reports on the Europlanet Summer School 2023 at the Molėtai Astronomical Observatory in Lithuania. 

Orionids Workshop 2023 

Miloš Obert, Chair of the Slovak Union of Astronomers, reports on the Orionids 2023 astro-camp on meteor observations. 

Dusting the Moon 

Karolien Lefever and Sylvain Ranvier (BIRA-IASB, Belgium) report on DUSTER, a project that gets to grips with lunar dust in preparation for future exploration missions. 

Commkit – The Dream of AI

Thibaut Roger (University of Bern, Switzerland) examines how AI can be useful for scientific outreach and communication, as well as the limitations.

The Last Word – Europlanet: A Page Turns 

Ann Carine Vandaele, President of the Europlanet Society, reflects on sustainability plans for Europlanet

New space companies and planetary science

New space companies and planetary science

This article has been contributed by Hans Huybrighs and Ottaviano Ruesch of the EPEC Future Research Working Group.

In the news, we often hear about New Space companies and their goals to ‘revolutionise’ the access and use of space. Think, for example, of Blue Origin and their planned Blue Moon lunar lander. These new opportunities to access planetary bodies are not, however, always considered in the planetary science community as serious options.

We wonder: are private space companies overlooked because there is some uncertainty as to whether they will eventually launch? Is it worth considering such opportunities when we think of the future of planetary science?

Here at the EPEC Future Research Working Group, we want to explore whether New Space companies will affect how we do research in the future. To find out more, we spoke with Dr Thorben Könemann, Deputy Scientific Director of the ZARM Drop Tower Operation and Service Company at the Center of Applied Space Technology and Microgravity (ZARM) in Bremen, and Dr Erika Wagner, payload sales director at Blue Origin in Kent, Washington.

‘Complementary’ is the keyword that Dr Könemann uses to describe the opportunities provided by New Space companies. His engineering team at ZARM integrates and supports microgravity experiments that have also flown onboard Blue Origin’s reusable launch vehicle, New Shepard, and Dr Könemann has been involved in those experiments from the beginning. 

‘Blue Origin provides complementary access to space with a different set of boundary conditions for the payload than was previously available,’ Dr Könemann says. ‘Examples of such boundary conditions are: payload mass, duration and quality of microgravity, performance of the vehicle, and finally pricing. The availability of a new option increases the chance of finding a launcher that meets the requirement of an experiment and thus the chance to obtain an opportunity to fly.’

Although those experiments are generally more focused on microgravity research and less on planetary science, ZARM’s experience of becoming involved with Blue Origin still gives us lessons that can be applied to planetary science.

Through talking to Dr Könemann, it is clear that today, we are not necessarily witnessing a radical change in how space missions are developed, but rather an increase in the ways that space can be reached and studied. Flights provided by Blue Origin’s suborbital New Shepard rocket are an example of such new methods.

Dr Könemann states, ‘ZARM reached out early to potential new launch providers a decade ago. We not only contacted Blue Origin but also spoke to other upcoming companies, some of which don’t exist anymore.’

Therefore, even though the flight opportunities from new space companies for planetary science beyond Earth do not exist at present, it does make sense to establish relations with these companies early, so as not to miss out on these new opportunities later down the line.

Blue Origin's Blue Moon lunar lander. Credit: Blue Origin.
The Blue Moon lunar lander. Credit: Blue Origin.

Looking at the future and at rockets that can reach deep space, Dr Wagner says,  ‘Blue Origin will be able to bring a considerable mass and volume of payload onto the surface of the Moon with the Blue Moon lunar lander. This would offer the opportunity to build heavier and more voluminous instruments.’

This is somewhat contrary to the trend of miniaturisation. It is the view of the EPEC Future Research WG that being aware of these opportunities from now will enable the community to develop instrumentation that makes optimal use of the new diverse platforms when they become available (and planning space missions is a long process – check out our series on the ESA Voyage 2050 white papers).

Dr Wagner also explains that of the 100 experiments to have flown on New Shepard, only 3 were funded by European agencies. Thus, it seems that there is a slower uptake on commercial opportunities in Europe when compared with the USA.

Dr Wagner suggests, “If early career researchers want to see an increase in this uptake, they could enable this change by advocating for the potential use of these new opportunities.”

For example, early career researchers can include these possibilities in white papers for government surveys equivalent to the US decadal survey, or through bodies such as the Space Generation Advisory Council (SGAC).

We conclude that new space companies could provide further opportunities in the future to reach our planetary destinations. To make the most of these opportunities, however, it helps to establish connections early, and early career researchers can encourage a move in this direction by advocating for links between planetary science and future launches by private space companies.

What are your thoughts about new space and planetary science? Let us know:

Find out more about the EPEC Future Research WG.

Banner image credit: Blue Origin.

Calls for Europlanet Outreach Funding Scheme and Prize 2020 – Deadlines extended to 3rd July.

The Calls for the Europlanet Outreach Funding Scheme 2020 and for the Europlanet Prize for Public Engagement 2020 Deadlines extended to 3rd July.

Are you looking for funding to kickstart an outreach or education project related to planetary science? Or have you run a successful public engagement project for which you deserve some recognition?

The Calls are now open for applications for the Europlanet Outreach Funding Scheme 2020 and nominations for the Europlanet Prize for Public Engagement 2020.

**Deadline for submissions now extended to 3rd July 2020**

About the Europlanet Outreach Funding Scheme 2020

Europlanet awards grants of between 5 000 and 15 000 Euros to fund projects to engage the public with planetary science. Through the funding scheme, Europlanet aims to encourage new ways of sharing planetary science with different kinds of audiences across Europe (and beyond) to create socially impactful initiatives that combine research, learning, innovation and social development.

The call for applications is now open and closes on 3rd July 2020.

Find out more at:

About the Europlanet Prize For Public Engagement 2020

The Europlanet Prize for Public Engagement recognises achievements in engaging citizens with planetary science. The Prize of 4 000 Euros is awarded annually to individuals or groups who have developed innovative and socially impactful practices in planetary science communication and education.

The call for nominations for the Europlanet Prize for Public Engagement 2020 is now open and closes on 3rd July 2020.

Find out more at:

Farewell to the Dawn Mission

Farewell to the Dawn Mission

Yesterday, NASA announced the end of the Dawn mission after the spacecraft missed communications sessions on 31st October and 1st November. Mission managers have concluded that the spacecraft has finally run out of fuel and is no longer able to  keep its communications systems pointing at Earth or turn its solar panels to the Sun to recharge.

The Dawn spacecraft launched in 2007 to visit the two largest objects in the main asteroid belt, Vesta and Ceres. Although it has lost contact with Earth, the spacecraft will remain orbit around the dwarf planet Ceres for decades.

Two of Dawn’s three instruments were provided by European institutions:

  • The Max Planck Institute for Solar System Research (MPS), Gottingen, Germany, provided the Framing Cameras with significant contributions by the German Aerospace Center (DLR) Institute of Planetary Research, Berlin, and in coordination with the Institute of Computer and Communication Network Engineering, Braunschweig.
  • The Visible and Infrared Mapping Spectrometer (VIR-MS) was funded and coordinated by the Italian Space Agency and built by SELEX ES, with the scientific leadership of the Institute for Space Astrophysics and Planetology, Italian National Institute for Astrophysics, Italy, and is operated by the Institute for Space Astrophysics and Planetology, Rome, Italy.

Dr. Andreas Nathues © MPS

In this interview (re-posted with kind permission of MPS), Dawn’s Framing Camera Lead Investigator, Dr Andreas Nathues, looks back on the eleven-year mission with many surprises, important discoveries, and unexpected twists. He also speaks about the future of asteroid research.

Over the past 11 years, the Dawn mission has investigated two bodies in the main asteroid belt, the region between the orbits of Mars and Jupiter. From July 2011 to September 2012, the spacecraft accompanied asteroid Vesta, since March 2015, it has been orbiting dwarf planet Ceres. How many other asteroids have so far been studied using space probes?

Nathues: In recent years, there have been several space missions targeting asteroids. One of the most recent ones is the Japanese mission Hayabusa 2, which reached asteroid Ryugu this June. A total of 13 bodies of this type have been investigated up close by space probes. Hayabusa 1, the predecessor of the current mission, was even able to bring tiny rock particles back to Earth. Most missions, however, were fly-bys where scientific data was collected for only a few hours. Only Dawn has explored two large objects for over a year each. And there is another difference: with the exception of Vesta and Ceres, all previously visited asteroids were fragments of larger bodies. They are irregularly shaped, comparatively small chunks. Vesta and Ceres are different from those smaller bodies.

In what respect?

Nathues: Both are very special representatives of the asteroid belt. They are the two most massive bodies there. Vesta measures about 530 kilometers in diameter, Ceres even 950 kilometers. In addition, unlike other small bodies, they have a differentiated internal structure and are composed of several different layers. Vesta and Ceres are remnants of the formation phase of Earth-like planets and have developed very differently.

This mosaic synthesizes some of the best views Dawn captured of Vesta. The towering mountain at the south pole (more than twice the height of Mount Everest) is visible at the bottom of the image. The set of three craters known as the “snowman” can be seen at the top left. © NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

Understanding this evolution and gathering insights into the formation of the solar system was one of Dawn’s main goals. What was achieved in this regard?

Nathues: Very much. Vesta and Ceres indeed play a key role in understanding how this region of the Solar System was formed. It is only through Dawn that we have secure knowledge of how both bodies are built inside and what materials make up their surface. The internal layered structure of Vesta, consisting of a metallic core, rocky mantle, and crust as well as the composition of the surface prove that this body was once hot and melted. Only in such an environment can substances of different densities easily be separated in layers. Ceres, however, does not show this detailed structure, but also there a layered structure developed, possibly even a subsurface ocean from which parts may remain until today.

What can we conclude from this with regard to their evolution?

Nathues: We believe that in its formation phase Vesta captured a lot of radioactive aluminum from the explosion of an earlier star. This radioactive material provided the heat to completely melt Vesta. Since Ceres’ interior is less evolved, it probably did not originate until several million years later, at a time when most of the radioactive aluminum had already decayed. Dawn has also taught us that apparently the place of origin is crucial. Vesta probably originated where it is found today: in the middle part of the asteroid belt. Thus, it shows a similar internal structure as the inner planets Mercury, Venus, Earth and Mars, which underwent a similar development in their early stages. Ceres’ birthplace may be much farther, in the outer regions of the Solar System. This is indicated by ammonium compounds that Dawn found on its surface. Ceres probably migrated to the asteroid belt much later.

What else did we learn about Vesta?

Nathues: One of the key findings is that certain meteorites found on Earth are indeed fragments of Vesta. They are called HED meteorites. The capital letters stand for the volcanic rocks howardite, eucrite, and diogenite. In addition, we have learned that common models of planet formation do not apply. According to these models, there should be much olivine on Vesta only about 20 kilometers beneath its surface. However, we do not find a significant amount of this rock even in the huge impact basin in the southern hemisphere of Vesta. So the olivine has to be at least 40 kilometers deep. As another surprise, we discovered carbon rich minerals. These were brought to Vesta by smaller impacting asteroids. Vesta’s entire surface was gardened over billions of years after its formation by impacts like these, so that nothing of the original surface structures have been preserved.

Dwarf planet Ceres is shown in this false-color rendering, which highlights differences in surface materials. © NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

And Ceres?

Nathues: Ceres was the big surprise of the Dawn mission. Previously, some scientists believed it to be a rather simple body. There were theories that explained its low density with high porosity. Today we know that this is wrong. Below Ceres’ surface there are underground water and water ice reservoirs, from which a saline solution emerged to surface in the recent geological past. Traces of it can be found in the characteristic bright spots of Ceres, for example in the Occator crater, which already stood out while Dawn approached Ceres. These spots are made up of salt deposits. We believe, that the emerging water evaporated and was able to create a thin exosphere of water vapor.

In mid-2017, after a more than two-year stay at Ceres, it was discussed whether Dawn should use the remaining fuel to leave Ceres and head for a third body in the asteroid belt. Why?

Nathues: Dawn’s primary mission was successfully completed in June 2016. NASA initially extended the mission at Ceres by one year. Thereafter, there was still fuel available; Options were checked. One of these options was an asteroid of medium size (~150 km) called Adeona. The asteroid could have been reached at that time. It would have been a flyby, but still exciting. Adeona is an intriguing research object for many reasons. Among other things, one could have investigated the question whether midsized asteroids can be differentiated too, at least in part, within their interior.

NASA decided against Adeona and in favor of an extended mission at Ceres. Why?

Nathues: A decision like this is always very difficult. One option was a completely unexplored object, which of course arouses our curiosity. The other is a well-known, very exciting object without doubt, which could be examined more thoroughly. It is important to weigh what results are expected and how important they are. The risks and costs must also be taken into account. NASA concluded that the prospects at Ceres were better. An important role was played by the fact that the closest point on Ceres’ orbit around the Sun was still approaching. If Ceres emits water vapor, this process would have to be strongest there. In addition, the colleagues operating Dawn’s gamma radiation and neutron detector hoped for improved measurements of the chemical composition of Ceres’ surface.

Has this decision paid off?

Nathues: Yes. The past few months have once again exceeded all our expectations. Since June, Dawn is flying in highly elliptical orbits around Ceres, which lead the spacecraft within about 35 kilometers of the dwarf planet. We have obtained images with a resolution of less than five meters per pixel. That’s sensational!

In this image of the northern rim of Occator crater landlides can be seen. The image was obtained by NASA’s Dawn spacecraft on 16 Jue, 2018 from a distance of approximately 33 kilometers. © NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

Can the entire surface of Ceres be imaged with this resolution?

Nathues: No, not even remotely. Since three of Dawn’s four reaction wheels have failed by now, controlling the spacecraft’s orientation and aligning the antenna to communicate with Earth consumes a lot of fuel. That’s why we have focused on imaging the most important regions. Mainly we have concentrated on sections of a strip that extends from Occator crater to Urvara crater farther to the south.

What will be happening in space-based asteroid research in the next few years?

Nathues: In the near and mid future a lot, after that less. The Japanese probe Hayabusa 2 reached the asteroid Ryugu in June of this year and will even deposit three small landing units on its surface. NASA’s OSIRIS-REx mission will arrive at asteroid Bennu this December. However, both objects are no longer bodies of the asteroid belt, but so-called Near-Earth Objects, which come comparatively close to Earth. In 2022 another mission starts: NASA ‘s Psyche mission to a potential metallic asteroid of the same name, just before Lucy will be launched to visit Trojan asteroids near Jupiter. ESA, unfortunately, is not leading any mission to asteroids at this time.

If you could choose a target for an asteroid mission, which one would it be?

Nathues: My first choice would be Pallas. This asteroid is of about the same size as Vesta, but does not orbit the Sun in the same plane as the other asteroids and planets. Its orbital plane is strongly inclined. As a result, a lower number of bodies have probably impacted on Pallas since its formation; the asteroid could still be quite pristine. Unfortunately, for the same reason, Pallas is also difficult to reach: it takes a lot of energy to leave Earth’s orbital plane. My second choice would be an active asteroid. These are bodies that orbit the Sun within the asteroid belt, but show comet-like activity. A little bit like Ceres. It is conceivable that these bodies are fragments of larger objects that once existed in the asteroid belt.

For more information on MPS involvement in Dawn, please see:

PicSat prepares for launch

PicSat prepares for launch.

French nanosatellite to demonstrate capabilities for exoplanet observations.

PicSat, a French nanosatellite designed to study the young planetary system Beta-Pictoris, is preparing for launch this Friday morning, 12th January 2018, at 3:58 UTC (watch livestream). Constructed of three 10-cm cubes and holding a telescope of just 5cm diameter coupled to an innovative optical fibre system, PicSat will demonstrate the capabilities of small satellites for observing exoplanet transits.

Beta Pictoris is a young star (around 23 million years old) surrounded by a large debris disc where planetary formation is thought to still be in progress. PicSat’s mission is to observe a transit of Beta-Pictoris b, a giant gas planet about seven times the mass of Jupiter that orbits its star at about the same distance as Saturn from our Sun. The exoplanet takes about 18 years to complete an orbit and is expected to cross the line of sight between Earth and Beta-Pictoris during the summer of 2018. By measuring precisely the timings for the small dip in light as the planet blocks out some of the light from the star, PicSat will help define the diameter of the exoplanet. Starlight filtered through the planet’s atmosphere may carry some clues about chemical composition and cloud cover.

Artist’s impression of Beta Pictoris b. Credit: ESO/L. Calçada

PicSat is the brainchild of  Sylvestre Lacour, an astrophysicist at CNRS, in collaboration with Alain Lecavelier des Etangs, de l’Institut d’Astrophysique de Paris (CNRS/Sorbonne Université). The nanosatellite has been developed by the Observatoire de Paris and CNRS, with support from the Université PSL, CNES, the ERC and the FONDATION MERAC.

Sylvestre Lacour (left) and Lester David (right) working on PicSat integration. Credit: PicSat/Observatoire de Paris

For more information, see:

PicSat website:

CNRS Press Release:

Follow PicSat on Twitter and YouTube

Astrobiology Poster Giveaway

Win a set of four Astrobiology posters from Europlanet!

Following our successful video on Astrobiology, we have created four posters to giveaway during the holiday season. You can win not one, but all four posters through our Facebook, Twitter or Instagram.

How to enter? Very easy!
5 Winners on Facebook:
– Like Europlanet on Facebook
– Share any of the #AstrobiologyPosterGiveaway posts
– Tag a friend on comments

5 Winners on Twitter:
– Follow Europlanet on Twitter
– Retweet any of the #AstrobiologyPosterGiveaway Tweets

5 Winners on Instagram:
– Follow Europlanet on Instagram
– Like any of the #AstrobiologyPosterGiveaway posts
– Tag a friend on comments

Rules and guidelines? Very simple!
– The contest is open for anyone within the Europe (European postal address)
– It will run from 20-31 December 2017
– The winners will be announced on 10 January 2018
– Winner will be chosen in a randomised process
– Each winner will receive a set of four posters by post
– 5 winners will be selected on each social media platform
– Participate in all social media platforms to have a higher chance of winning
– Winners will be contacted to share their physical address to send the posters

If you haven’t already seen our video, watch it now!

PhysisArt – Photography of Danakil Exhibition

PhysisArt – Photography of Danakil Exhibition

The Danakil Depression – an extreme landscape between volcanoes and salty deserts – is the subject of a new photographic exhibition with images and works by the artist, Samantha Tistoni, who accompanied Europlanet researchers for a field trip to Danakil in January 2017.

Dr. Barbara Cavalazzi, a researcher at the Department of Biological, Geological and Environmental Sciences at the University of Bologna, and photographer Samantha Tistoni will tell the story, secrets and colours of the fascinating Danakil region. The Danakil Depression lies close to the sea, at the far north of the triangle of Afar, between Ethiopia and Eritrea. Danakil is perhaps the most active branch of the African Rift Valley and is a place where everything is dramatically influenced by the geology of an oceanization process that began some tens of millions of years ago. These incredible geological features make this a place where you can study the extremes of life, biological adaptation, and better understand the deep geobiological interactions. Discovering Danakil is a key to understanding alien life.

The exhibition will launched on 21 October in Bologna and will travel to Modena, Chieti and Pescara. The programme is:

21-29 October, Collezione di Geologia “Museo Giovanni Capellini”, via Zamboni 63, Bologna
Dr Barbara Cavalazzi will give a talk, “Danakil – at the bottom of a sea that is not there”, during the launch event on 21 October.

18 November – 2 December at the Museo Universitario Gemma Dipartimento di Scienze Chimiche e Geologiche, Modena
Dr Barbara Cavalazzi will give a talk, “Danakil – Martian atmospheres on Earth”, at 11am on 18 November.

8 March 2018 – Università G. d’Annunzio di Chieti-Pescara, Campus Universitario, via dei Vestini 31, Chieti Scalo
Dr Barbara Cavalazzi will give a talk, “Danakil – at the bottom of a sea that is not there” on 8 March.

17 March 2018 – Università G. d’Annunzio di Chieti-Pescara, viale Pindaro 42, Pescara
Dr Barbara Cavalazzi will give a talk, “Danakil – at the bottom of a sea that is not there” on 17 March.

Exhibition website

Download a flyer

Call for Europlanet Outreach Funding Scheme and Prize 2018 Now Open

The Call for the Europlanet Outreach Funding Scheme 2018 and Europlanet Prize for Public Engagement 2018 is now open.

Are you looking for funding to kickstart an outreach project related to planetary science? Or have you run a successful outreach project for which you deserve some recognition?

Applications are now open for the Europlanet Outreach Funding Scheme 2018 and Europlanet Prize for Public Engagement 2018.

About the Europlanet Outreach Funding Scheme 2018

Europlanet awards grants of between 5 000 and 15 000 Euros to fund projects to engage the public with planetary science. Through the funding scheme, Europlanet aims to encourage new ways of bringing planetary science to audiences across Europe and inspire the next generation of scientists and engineers. The call for applications is now open and closes on 31st January 2018.

Find out more at:

About the Europlanet Prize For Public Engagement 2018

The Europlanet Prize for Public Engagement recognises achievements in engaging European citizens with planetary science. The Prize of 4 000 Euros is awarded annually to individuals or groups who have developed innovative practices in planetary science communication and whose efforts have significantly contributed to a wider public engagement with planetary science.
The call for nominations for the Europlanet Prize for Public Engagement 2018 is now open and closes on 31st January 2018.

Find out more at:

Video: Astrobiology – Life in the Universe

Are we alone in the Universe? You have probably asked yourself this question at some point. Europlanet’s new video, “Astrobiology – Life in the Universe” shows how planetary scientists are looking for signs of life on other planets, using our very own Earth as a laboratory.

Cassini End of Mission

Professor Nicholas Achilleos of University College London (UCL) Physics & Astronomy has been at JPL for the Cassini End of Mission Event.

I am writing this  just after the End of Mission event. They announced the ‘loss of signal’ from Cassini in the last few minutes – and this is the sign of a transmission from a spacecraft burning up in Saturn’s atmosphere, taking over an hour to travel to mission control here on Earth.

They have been showing us footage from the control room and various other Cassini-related interviews on big screens here at Caltech. Most of the folks from the various instrument teams are here. We are incredibly proud and also sad at the same time. So many extraordinary scientists, engineers, and project managers have worked so hard for so long to make Cassini a success. The spacecraft, now a memory, leaves us with an enormous legacy dataset that will take decades to fully exploit, launching, I am sure, many more scientific careers in the process.

The team I belong to managed the magnetometer instrument and, collectively, are an extraordinary group of people. Using magnetic field measurements, we have probed Saturn’s interior, detected the first hints of the water geysers on the tiny icy moon Enceladus, probed the environment of the moon Titan, and explored Saturn’s global magnetic ‘heartbeat’ – a sign of the communication between its atmosphere and magnetosphere. And there have been many more discoveries and collaborations with other instrument teams along the way.

I have been proud to be part of this project and emphasise, once again, that it conveys a critical message in this day and age that people can achieve incredible things when they come together in a spirit of collaboration and mutual respect. Goodbye Cassini, you will be missed but never forgotten.

Prof. N. Achilleos, Los Angeles CA, Sept 15 2017

Featured image credit: NASA/Joel Kowsky

Farewell Cassini – and thanks for everything

It’s very sad to say goodbye to Cassini today, but it’s also a chance to celebrate the mission’s many achievements.

As well as Cassini-Huygen’s extraordinary scientific contribution, it has had a huge impact on the planetary science community around  the world.  Europlanet is a direct result of the collaboration between the European scientists involved in Cassini-Huygens who, in 2002, decided to found a network to build better links between European researchers involved in planetary science and overcome fragmentation within the community. In 2005, Europlanet received funding from the European Commission’s Framework 6 programme. 12 years later we have a sustainable community of more than 85 instiutions, with more than 800 planetary scientists preparing to attend our annual meeting in Riga, Latvia, next week.

On behalf of the Europlanet Community, we would like to express our admiration and gratitude to this incredible mission and all the people around the world that made it happen.


Cassini: Mission’s End at Saturn

Professor Nicholas Achilleos of University College London (UCL) Physics & Astronomy talks to Europlanet about Cassini’s final days and what working on the mission has meant to him  professionally and personally.

On the 15th of September, 2017, the Cassini spacecraft will plunge into the atmosphere of the planet Saturn, bringing to an end its mission as a dedicated orbiter of this beautiful ringed world, which it has been orbiting now for 13 years.

It is both an exciting and very sad occasion. Exciting because we know that the mission has been a resounding success, not only in terms of the scientific advancements it has enabled but also because it has accumulated an enormous legacy dataset, whose analysis will be keeping future generations of scientists occupied for many years to come. Sad because it means saying goodbye to the project itself.

I am a science co-investigator with the Cassini Magnetometer Team, led by Principal Investigator Professor Michele Dougherty from Imperial College London. The magnetometer, or MAG, is an instrument whose sensors are perched on an 11-metre boom which extends out from the side of the spacecraft – this arrangement is necessary for us to minimise the ‘contamination’ of the magnetic field measurements by field from spacecraft electronics.

Artist’s impression of Cassini in orbit at Saturn, with the magnetometer boom extending to the left. Credit: NASA/JPL-Caltech

Since 2004, MAG scientists have been mapping the magnetic field which is generated inside Saturn itself, and the field due to external sources which we find in Saturn’s magnetosphere, an enormous region surrounding the planet where physics is strongly influenced by the planet’s own magnetic field. Saturn’s internal field is almost perfectly symmetric about the planet’s rotation axis – making it almost unique among the magnetised planets, of which the Earth is of course another example.

The spacecraft is currently executing its final ‘proximal orbits’, which bring it closer to the planet than it has ever been, and which are critical for MAG analysis. We are hoping to accurately determine the apparently very small non-symmetric part of the field – this is crucial not only because it will give us information about how the field is being produced by the ‘magnetic dynamo’ in Saturn’s interior, but also because it will finally allow us to unambiguously pin down the rotation period of Saturn itself – that is, the exact length of a ‘Saturn day’.

There are two other important discoveries associated with MAG. Firstly, Cassini confirmed the earlier discovery by Voyager of a periodic ‘signal’ in the magnetic field throughout the planet’s magnetosphere; we have good reason to believe that this signal is an indication of energy being transferred from flows in the planet’s atmosphere out to its magnetosphere. This energy is transported over distances of millions of kilometres, and the magnetic field acts as the ‘wire’ along which this energy is transported.

Secondly, MAG was the first instrument to report something unusual at the first flybys of Saturn’s tiny icy moon, Enceladus. The field measurements indicated that Enceladus seemed to have something like a very extended ‘atmosphere’ of sorts. These data were sufficient to convince mission control to fly even closer to Enceladus on the next flybys and, indeed, during those flybys we obtained images of the incredible water plumes, or geysers, which continually throw out water molecules and ice grains from cracks in the icy surface of Enceladus. We now know that this source of water is also the principal source of plasma (charged particles) in the planet’s magnetosphere – thus making the small moon Enceladus the ‘little, but powerful engine’ that drives the much more enormous magnetosphere of its parent planet.

This artist concept shows the detection of a dynamic atmosphere on Saturn’s icy moon Enceladus. The Cassini magnetometer instrument is designed to measure the magnitude and direction of the magnetic fields of Saturn and its moons. Credit: NASA/JPL-Caltech.

The Cassini mission has given me, and many others, the privilege of collaborating with many greatly talented scientists, engineers and mission planners. I have played the roles of mission planner, support scientist and now co-investigator. I have had the good fortune to work with very talented graduate students who have written theses about the MAG and other Cassini datasets, and it has been a great pleasure to watch them blossom into talented scientists. The Cassini community, I’m sure, will continue to collaborate together in different ways in the future. For now, the approaching end of mission should be viewed as a commemoration of an enormously successful international,  scientific project – and a timely reminder of what humans can achieve when we respect each others’ abilities and differences, so that we can work together towards a common goal.

Cornwall – Sea to Stars

Cornwall – Sea to Stars

Europlanet 2020 RI is a partner in a new project to bring astronomy and geology to one of the remotest parts of the UK. ‘Cornwall – Sea to Stars’ has been awarded a grant of £30,000 by the Royal Astronomical Society as part of the RAS200 Sky & Earth project to celebrate the Society’s 200th anniversary.

‘Cornwall – Sea to Stars’ will create an interactive, mobile science outreach unit showcasing the best of Cornwall’s geology and astronomy. It will use both existing and new networks of community groups and trained volunteers to roll out a program of events. The unit will travel to many remote locations in the county to engage Cornwall’s varied and often disparate communities with astronomy and geophysics. The unit will be equipped with themed and interchangeable ‘modules’ that will allow community groups and trained volunteers to present topics in a fun but professional manner.

Europlanet will be providing planetary science resources and science communication training. We look congratulate all the winners of the RAS200 awards and look forward to working with the ‘Cornwall – Sea to Stars’ team!

Mars 2020 – stepping up the search for life on Mars

ken_farleyDuring a press tour of JPL, we were given an overview of the Mars 2020 mission by its Principal Investigator, Ken Farley.

Mars 2020 is NASA’s next flagship mission to the Red Planet. It has four main objectives: to determine whether life ever arose on Mars; to characterise the climate of Mars; to characterise the geology of Mars; and to prepare for human exploration.

The Mars 2020 mission re-uses much of the technology developed for Mars Science Laboratory and the Curiosity rover, with some added features in the Entry, Descent and Landing (EDL) system and some new instrumentation, including:

  • Mastcam-Z, a stereoscopic camera system that will have a zoom capacity that should make for some make amazing panoramas.
  • MEDA, a suite of weather sensors
  • MOXIE, a technology tester experiment to produce oxygen from Martian atmospheric carbon dioxide
  • PIXL, an X-ray fluorescence spectrometer to provide detailed chemical analysis
  • RIMFAX, a radar for sub surface sounding
  • Sherloc, a spectrometer and camera that will map the elemental composition of the Martian surface using a UV laser
  • SuperCam, an upgrade of Curiosity’s ChemCam instrument, that will allow researchers to sample the chemistry and mineralogy of rocks and other targets from a distance using a laser.

Mars 2020 has significant European involvement, with the MEDA wind sensors led by CAB-INTA in Spain, the RIMFAX radar led by the Forsvarets Forskningsinstitutt in Norway, the SuperCam Mast led by CNES and CNRS/IRAP in France, and European co-investigators on the Mastcam-Z, MOXIE and SHERLOC instruments.

Today, Mars is cold and dry, with high radiation levels and is generally inhospitable. However, around 3.6 billion years ago, the climate of Mars is thought to have been warm enough to support liquid water and an atmosphere, which raises the possibility that there was once life on Mars. Any life that did arise is likely to have been in very simple form — for billions of years, life on Earth was microbial and we only find complex fossils on Earth dating back 540 million years. Thus, Mars 2020 is not looking for current life on Mars but for evidence of microbial life from when the Red Planet was only about one billion years old.

The choice of sites for the Mars 2020 mission to explore has been narrowed down to eight potential locations that are either near ancient deltas in lakes or near ancient hydrothermal systems. NASA will down-select the final landing site within the next couple of years.

The eight potential landing sites for Mars 2020. NASA/JPL-Caltech

For the Curiosity rover, NASA restricted the choice of landing sites away from lumpy, bumpy geological hazards. This reduced significantly the risks on landing but had the drawback that flat areas are not of particular geological interest. Curiosity landed within Gale Crater – a 154km wide impact crater dating back 3.5-3.8 billion years containing sedimentary deposits. However, the landing site was on a flat patch well inside the crater rim and to the north of Mount Sharp, the central mound.  To reach the foot of Mount Sharp, the real area of interest, Curiosity first had to travel several miles. With a top speed on hard-packed flat ground of just 0.14 kilometres per hour, it took a few months before the rover was able to start its main scientific investigations.

Route driven by NASA’s Curiosity Mars rover from the location where it landed in August 2012 to its location in September 2016 at “Murray Buttes” on lower Mount Sharp. Credit: NASA/JPL-Caltech

For Mars 2020, NASA has updated the EDL system to include Terrain Relative Navigation, which means that – actually during the landing — the spacecraft will identify hazards and deflect its trajectory to the surface. This means that Mars 2020 will arrive at the site of interest and can start collecting scientifically valid samples more-or-less straight away.

The Mars 2020 rover’s mast. Credit: NASA/JPL-Caltech

Scientists can’t be sure how much the radiation levels on Mars might affect and degrade evidence of ancient biological activity. Thus, a good strategy for finding preserved biomarkers is to collect samples from rocks that have only been recently exposed e.g. scarp areas where wind erosion grinds away at the surface.

The ambition is that Mars 2020 will be the first step in a sample return programme to bring rocks back to Earth for scientific analysis. The rover will carry out “depot caching”, in which it will collect 30-40 cores (cylindrical samples about the size of a piece of chalk), store each core in a capped tube, and lay them down on the ground for future collection. Rather than just grabbing and laying down samples as the rover goes along, Mars 2020 will first make a survey of the area and prioritise the samples from the most interesting geological areas.

The samples may need to sit on Mars for a decade or more before being collected by a robotic mission (currently planned by NASA for the late 2020s), so the storage tubes will need to protect this valuable scientific cargo from long-term UV exposure and heat degradation. Even at chilly Martian temperatures, thermal effects inside the storage tubes could cause heating of samples to damaging temperatures where biological evidence could be lost. To mitigate this, tubes will be painted with bright white aluminium oxide to keep samples at no more than 10 degrees above surface temperature.

Though films like ‘The Martian’ might lead you to believe everything on Mars gets quickly buried by dust devils, the cores will be deposited in bare, hard-packed areas and are unlikely to experience more than a very light surface dusting of particles. In addition, NASA will take coordinates of the cache and photo document the surrounding area. Detailed images and measurements from the rovers instrumentation of the environment surrounding each core extraction site will be vital during analysis back on Earth to get a thorough understanding of the geology and context for the samples.

Mars 2020 is due for launch in July or August 2020 when Earth and Mars well aligned in their orbits for a short transit time to Mars. For more information on the mission, see:

Many thanks to Ken Farley for speaking to us about the mission and the AAS press officer, Rick Feinberg, and Jia-Rui Cook at JPL for organizing the tour of JPL for the DPS-EPSC Joint Meeting media attendees.

Anita Heward, EPSC-DPS Press Officer

DPS-EPSC 2016: Press tour of JPL

Anita Heward is the press officer for Europlanet 2020 RI and the joint DPS-EPSC meeting.

The highlight of my trip last month to Pasadena for the Joint DPS-EPSC Meeting 2016 was a tour of the legendary Jet Propulsion Laboratory (JPL), which celebrated its 80th anniversary on Halloween this year.

The tour kicked off in the Spacecraft Assembly Facility. From a viewing gallery, we could see into the facility’s Class 10,000 cleanroom. The engineers working in this environment wear full protective gear and take air showers before entry to remove particles that might contaminate spacecraft.

The high bay clean room in JPL’s Spacecraft Assembly Facility

One of the pieces of hardware under construction in the cleanroom was the enormous heat-shield that will protect NASA’s Mars 2020 mission during its initial plunge through the Martian atmosphere. We were given an overview of the science that Mars 2020 will carry out on Mars by the mission’s Principal Investigator, Ken Farley. You can read more about that here.

The heatshield for the Mars 2020 mission

Next up came a visit to the Earth Science facilities, where we viewed a 3D film and were given a demonstration of visualisation of multiple types of Earth observation data. If you want to keep track of sea surface temperature, CO2 concentrations, the Earth’s changing gravity, or have your picture taken with one of NASA’s fleet of satellites, you can download ‘Earth Now’ and ‘Spacecraft 3D’ Apps.

NASA’s Eyes on the Earth interactive shows its fleet of Earth observation satellites. Credit: NASA

Our next stop was to find out about development of ion drive propulsion. Ion drives are particularly valuable for long-distance planetary missions, especially those visiting multiple targets, as they provide a highly efficient way of building up acceleration. An ion drive was first used on the Deep Space 1 mission, which launched in 1998 and had flyby encounters with asteroid 9969 Braille and comet 19P/Borrelly, and have since been used successfully on the Dawn mission to the dwarf planets Vesta and Ceres — as well as ESA’s SMART-1 mission to the moon.

The ion drive test facility

No tour of JPL would be complete without a visit to Mission Control — the scene of ‘Seven minutes of terror‘, while the Mars Science Laboratory team held their breath to find out whether the sky crane had successfully landed the spacecraft and Curiosity rover on the Red Planet.

Mission Control in the JPL Spacecraft Operations Facility

During our visit it was rather more serene.

Mission Control in the JPL Spacecraft Operations Facility

But I did get to sit in the ‘Curiosity Mission Ace’ chair, which made my Space Geek day 🙂


Our final stop was the Mars Yard, where we met the engineering model of Curiosity. Since landing on Mars in 2012, Curiosity has travelled nearly 15 km through the Gale Crater to the base of Mount Sharp.

Engineering model of the Curiosity rover

The engineering model is regularly active to help the Curosity team figure out how the rover on Mars can achieve maneouvres, such as climbing steep slopes or getting into position to drill samples, and the best way of minimising wear and tear on the spacecraft’s wheels.

JPL’s Mars Yard

Many thanks to the AAS press officer, Rick Fienberg, and Jia-Rui Cook and the press team at JPL for organizing the tour.

Calls for the EPN2020 Exchange Programme are now open

Calls for the EPN2020 Exchange Programme are now open.

This programme will provide funding for short visits to improve infrastructure facilities and services offered to the scientific community by the EPN2020 participant laboratories or institutes.

Its main objectives are:

  • Support the integration of the inclusiveness states with the European planetary community;
  • Support and engage young scientists with the European planetary science community;
  • Support exchange and foster cooperation between academia and industry (SMEs);
  • Support the inclusion of amateur communities in European planetary science campaigns;
  • Support the activities of EPN2020 with exchange of experts

Deadline for this call is 30th of September, 2016.

More information on the official website. Contact: Maria Genzer,

The Venus Twilight Experiment – what we learned from the last transit of Venus

Paolo_Tanga  In the run-up to the Transit of Mercury on 9th May, the Europlanet Outreach website is featuring a series of guest articles by European scientists that study the innermost planet or whose research relates to transits.  

Our second post is by Paolo Tanga, Senior Astronomer and planetary scientist at Observatoire de la Côte d’Azur, Nice, about the last transit of Venus in 2012. This article has been published to coincide with the premiere of a new film about the Venus Twilight Experiment by Lightcurve Films. 

The Venus Twilight Experiment – what we learned from the last transit of Venus

faintest aureole
Faint aureole at Venus’s south pole as the planet approaches the solar limb. Credit: Venus Twilight Experiment

In 2012, people on Earth had their last opportunity to view a transit of Venus for more than a century. Transits of Venus are even less frequent than transits of Mercury – the next time Venus passes directly between the Earth and the Sun will be in 2117. And unlike the atmosphere-free Mercury, the thick clouds surrounding Venus make its transits fascinating opportunities for science.

Venus transits usually occur in pairs, 8 years apart, once per century. These rare events have been historically important for astronomers in trying to determine the distance of the Sun from the Earth. In theory, this distance can be calculated by observing a transit from different locations around the globe and using the principal of parallax. By extrapolating this measurement to the other planets, transits could therefore be a tool in putting a distance scale on the Solar System as a whole.

This method was first suggested in 1677 by the English Astronomer Royal, Edmond Halley. For the next opportunity of observing a transit of Venus (in 1761, after Halley’s death), challenging overseas expeditions were organised. The same year, a thin arc of light – encircling the planet at the beginning and end of the transit, on the portion projected outside the Solar limb – was detected for the first time, and correctly interpreted as the presence of an atmosphere.

In fact, it turned out that using transits of Venus for distance determination was not to be as precise as expected. Subsequent transits were approached with curiosity, rather than with a real scientific interest.


Aureole at Ingress
Aureole at ingress during the transit of Venus on 5 June 2012. Credit: P Tanga, Venus Twilight Experiment

However, for the first “modern” event in 2004, planetary scientists realised that the “aureole” created by the halo of atmosphere around Venus was a good target for astronomical cameras and that its brightness could be accurately measured. What’s more, the brightness of the aureole, and its evolution over time while Venus was entering and leaving the solar disk, could be reproduced by modeling the refraction (bending) of light in the planet’s atmosphere. This refraction is directly related to the physical properties of the upper atmospheric layers (the mesosphere at more than 80 km of altitude above the planet’s surface), and above the thick cloud deck that surrounds Venus.

Thus, interest in a transit of Venus revived from two new angles. Firstly, it provided an opportunity to increase our understanding of Venus. The European Space Agency’s Venus Express satellite was orbiting around the planet (from 2006-2014), collecting close-up data. However, it was clear that the transit gave us the opportunity to study Venus from a wider perspective and probe the whole planet (all latitudes) at the same time.

Secondly, the Venus transits enabled us to collect detailed data on planetary transits and use them as an analogue for exoplanets transiting distant stars. We have discovered more than 2000 exoplanets to date, but too far away to see any detail. The events in 2004 and 2012 represented a lifetime’s opportunity to study a planet’s atmosphere during a transit in our own Solar System.


Wideman constructing coronograph
Thomas Widemann constructing a corongraph for the Venus Twilight Experiment. Credit: Venus Twilight Experiment

For this reason, Thomas Widemann (of LESIA, Paris Observatory, France) and I, with the participation of an international group of astronomers, set up the “Venus Twilight Experiment” to try and obtain useful data.

This “modern” expedition covered half of the Earth’s globe and used instruments designed and built especially for the 2012 event. Technically, it was very challenging – from the observer’s perspective, probing the aureole of Venus is like looking toward a sunset or sunrise sky.

The instruments used to make the observations were small portable telescopes, equipped with a “coronagraph”, i.e. a device that hides the solar disk to enhance the contrast of the faint aureole. I should say, to us on Earth, the aureole looked faint, since it is thin and far away. But for an observer close to the planet it would have the same surface brightness as the Sun – a glorious sight!

A film about the adventures of our team of observers, who travelled halfway around the world to observe the transit, has been produced by Lightcurve Films and is going to be premiered at the International Venus Conference 2016 in Oxford on 5th April. You can watch the film here:



The eve of the transit
Setting up equipment on the eve of the 2012 Transit of Venus. Credit: Venus Twilight Experiment

We collected a huge volume of data during the Venus Twilight Experiment, including hundreds of gigabytes of movies, and the analysis is still underway. Some results will be presented at the conference in Oxford this week, showing that our coronographs (which were never tested in real “transit” conditions before the actual event) performed well, even beyond our expectations. In some images, Venus and its aureole are even seen before the beginning of the transit, with the Venus disk silhouetted against a faint background of solar corona.

Also, our measurements complement other data, such as a vertical temperature profile obtained by Venus Express when performing a similar “solar sunset” measurement (by using the spacecraft’s SOIR experiment) at the transit time – but for a single latitude. This Venus Express/SOIR data demonstrates that the detailed structure of the mesosphere matches our observations of the aureole. We were able to extend the measurements to all other latitudes, as expected. Some known features, such as lower-altitude cloud at Venus’s poles, show up nicely in our data as brighter aureole regions.

The expedition was an exciting challenge, involving several teams and observing sites, but the rewards have been huge. The Venus Twilight Experiment will remain a heritage that we hope will assist future transits observers, in a little more than a century from now…



The Venus Twilight Experiment would like to thank:

Optical design: Sylvain and Alain Rondi (Societé Astronomique de France)
Coronagraph realization: Alain Roussel, Christian Baccelli, Serge Bonhomme – S2M Observatoire de la Côte d’Azur (mechanical workshop)

Venus Twilight Experiment Teams
   Mobile Station, Svalbard, Norway : Thomas Widemann, Jérôme Berthier
   Lowell Observatory, Flagstaff, USA: Paolo Tanga, Klaus Brasch, William Sheehan
   Mees Solar Observatory, Haleakala, Hawai’i, USA: Jay Pasachoff, Bryce Babcock
   Mobile station, Hokkaido, Japan: Tetsuya Fukuhara, Nicolas Thouvenin
   Mobile station, Taiohae, Marqueses Islands: Christian Veillet
   Moondara Observatory, Mount-Isa, Australia: Felipe Braga Ribas, Len & Sandra Fulham
   Udaipur Solar Observatory, Udaipur, India: Pedro Machado, Ashok Ambastha, João Retrê
   Tein Shan Observatory, Kazakhstan: François Colas, Frédéric Vachier

Paolo Tanga is Senior Astronomer and planetary scientist at Observatoire de la Côte d’Azur, Nice.
Follow Paolo on Twitter: @ziggypao

The Venus Twilight Experiment film was co-funded by Europlanet RI under FP7.

Mercury: the planet, the missions and the transit – by Prof Dave Rothery

Prof David Rothery

In the run-up to the Transit of Mercury on 9th May, the Europlanet Outreach website is featuring a series of guest articles by European scientists that study the innermost planet or whose research relates to transits.  

Our first post is by David Rothery, Professor of Planetary Geosciences at the Open University. 


Introduction to the Transit of Mercury
Mercury will pass across the face of the Sun on 9 May 2016 and again on 11 November 2019, both at excellent times of day for viewing the phenomenon from Europe. I’m involved in the European Space Agency’s upcoming mission to Mercury, BepiColombo, so I’m keen to see this event for myself, to share it with others, and to use the opportunity explain what a fascinating planet Mercury is.

If you plan to watch the transit, Mercury will appear as a black dot about 1/150th of the Sun’s diameter. This is too small to see without magnification. See this video for advice on how to watch safely, or look for webstreamed live images via this ESA website.

Missions to Mercury

Only two spacecraft have visited Mercury so far: NASA’s Mariner 10 made three flybys in 1974-5, and NASA’s MESSENGER orbited Mercury from March 2011 until April 2015. BepiColombo, a mission led by ESA in collaboration with the Japanese Space Agency (JAXA), is due to launch in in 2018 and to arrive in 2024. During its journey to the inner Solar System, BepiColombo will be propelled by an ion-drive housed in the Mercury Transfer Module (MTM). On arrival, the JAXA-led Mercury Magnetospheric Orbiter (MMO) will be placed in an eccentric orbit, and the sunshield that protected  it during the cruise phase will be jettisoned. The ESA-led Mercury Planetary Orbiter (MPO) will be nudged into a lower, relatively circular orbit.

ESA's BepiColombo mission
Artist’s impression of BepiColombo (shown during its cruise to Mercury). The inset (lower left) shows an exploded view with extendable components stowed.  Credit: ESA

The planet

Mercury is the smallest terrestrial planet, and the closest to the Sun. As Mercury is at one end of the planetary chain, we need to determine its nature and origin if we wish to understand our Solar System. It has a more eccentric (non-circular) orbit than any other planet, being 46 million kilometres from the Sun at the closest point in its orbit (perihelion) but 70 million kilometres away at its furthest point (aphelion). The planet rotates slowly, exactly three time for every two orbits round the Sun. To see how this results in Mercury’s day being twice as long as its year (which lasts 88 Earth-days), see this animation.

This slow rotation results in surface temperatures rising in excess of 400 °C in the daytime and dropping below -170 °C before dawn. However, because Mercury spins vertically on its axis, with no tilt relative to its orbit, the floors of some craters near the poles are in permanent shadow. This means that they are permanently cold and can shelter ice derived from comets impacting the surface.

Mercury is a dense planet, with an iron core that occupies a greater portion of its interior than in the case of the Earth. We can tell that the outer part of this core must be molten like the Earth’s (and unlike the solid cores of Venus, Mars and the Moon), because motion of this electrically-conducting liquid generates a magnetic field. This was discovered by the first space mission to visit Mercury, Mariner 10. More recently, the MESSENGER orbiter found that Mercury’s magnetic poles align with its rotational poles, but that its magnetic equator is mysteriously displaced 480 km north of the geographic equator.


Interior of Mercury
Under its rocky crust and mantle, Mercury has an iron-dominated outer and inner core, and possibly an ‘anticrust’ of iron sulfide. Convection in the liquid outer core generates the magnetic field. (Credit: D. Rothery).

Because its core is so big, the rocky part of Mercury (its mantle and crust) is relatively thin. This may result from a giant collision that stripped off most of the original crust and mantle. However, one of the biggest surprises revealed by the MESSENGER mission is that Mercury’s surface is rich in elements such as sulfur, chlorine, sodium and potassium that we would expect to be easily lost in a hot or violent event. There are also patches of Mercury’s surface (called ‘hollows’) where the top ten metres or more of material has simply vanished, relatively recently. Maybe those patches have evaporated (more properly speaking, ‘sublimed’) away to space. We do not know the composition of this volatile and easily-lost material, and one of BepiColombo’s main goals is to find out.

Hollows on Mercury. Credit NASA-JHUAPL-CIW
18 km detail from a MESSENGER image (exaggerated colour) showing hollows on Mercury. Sunlight is coming from the left. (Image: NASA/JHUAPL/CIW)

Mercury’s diameter appears to have shrunk by about 14 km during the past 3 billion years or so, which is most simply explained by thermal contraction as the planet cooled. We see the evidence of contraction mostly in the form of giant thrust faults (breaks in Mercury’s crust that have been pushed upwards), known as lobate scarps, that cross the surface. Mapping of Mercury’s lobate scarps reveals that most examples in mid- and low-latitudes are orientated north-south, and these overlaps imply that most of the shrinking of the crust has been in the east-west direction around the planet’s equator (i.e. Mercury has got thinner around its middle).  This may be evidence of the slowing down of Mercury’s spin leading to the collapse of a former equatorial bulge that had previously been sustained as a result of more rapid spin.

This image taken by MESSENGER shows Unity Rupes, a lobate scarp (named after the ship that took Edmond Halley to St Helena to observe a transit of Mercury in 1677). The scarp cuts through, and so must be younger than the 30 km impact crater near its southwestern end. (Image: NASA/JHUAPL/CIW)
This image taken by MESSENGER shows a lobate scarp on the surface of Mercury called Unity Rupes (named after the ship that took Edmond Halley to the island of St Helena to observe a transit of Mercury in 1677). The scarp cuts through, and so must be younger than the 30 km impact crater near its southwestern end. (Image: NASA/JHUAPL/CIW)

Mercury’s surface was formed almost entirely through volcanic processes. Most of its crust was formed by lava flows more than 3 billion years ago, and there are many volcanic vents where explosive volcanic eruptions have occurred. At least one of these is probably less than a billion years old.

MESSENGER image of volcanic vent on Mercury. Credit: NASA/JHUAPL/CIW
The irregular-shaped pit near the centre of this MESSENGER image is nearly 2 km deep. It appears to be an ancient volcanic vent, the source of explosive eruptions that discoloured the surrounding surface. Below are two high-resolution views of the volcanic vent seen under different illuminations. (Images: NASA/JHUAPL/CIW)

Prof Rothery is funded by the UK Space Agency and the Science & Technology Facilities Council for research on Mercury and his work on the BepiColombo mission. His book, Planet Mercury: from Pale Pink Dot to Dynamic World, was published by Springer in 2015.