Mars was habitable 4.6 million years ago. Today, it isn’t. Véronique Dehant, department head at the Royal Observatory of Belgium and a part-time professor at UCLouvain, tries to understand how the red planet has evolved, by studying the inside of it. She tells us about two upcoming missions that should deliver some answers.
Mars formed 4.6 billion years ago. For a few hundred million years, the planet was covered with water. Its magnetic field disappeared and its atmosphere escaped 4.1 billion years ago, preventing water from remaining liquid on its surface. Since then Mars has hardly changed, with the exception of rarely surfacing lava that liquefies residual ice trapped underground. The thin atmosphere slowly oxidises the planet’s soil, which is currently very red. For many years, Véronique Dehant, department head at the Royal Observatory of Belgium and part-time professor at UCL, has been passionate about Mars and its habitability. Recently, as part of several international missions, Dr Dehant has asked herself why Mars is no longer habitable. She and her Observatory-UCLouvain team intend to find the answer by analysing the planet’s interior.
Mars is a fascinating and interesting object of study. ‘The whole history of Mars is written on its surface. There is no plate tectonics or resurfacing, unlike Earth, whose continents plunge into its mantle, where everything is recycled’, says Dr Dehant, who leads two projects to understand the red planet’s evolution: RISE (Rotation and Interior Structure Experiment) and LaRa (Lander Radioscience). The former is aboard the InSight mission of the American space agency (NASA) and the latter is aboard the ExoMars mission of the European (ESA) and Russian (Roscosmos) space agencies.
InSight: the first mission to study the interior of Mars
InSight is an American mission that was launched by NASA on 5 May 2018 and is expected to land on Mars on 26 November. As its name suggests, InSight will target the interior of Mars. ‘This is the first mission that will study the deep interior of Mars, to gain a better understanding of its evolution and that of other terrestrial (or rocky) planets like Earth’, Dr Dehant says. Three experiments using three instruments will measure Mars’s vital signs:
- Its pulse (seismology): a mainly French team has built a seismometer adapted to Mars that will listen to its vibrations and thus give us information on its internal structure and materials.
- Its temperature (heat flow): a German team has set up ‘HP3’, an instrument that will drill down one or two meters and take temperatures to determine the heat flow and therefore the energy which emanates from Mars.
- Its reflexes (radio-science): an American team has built ‘RISE’, an instrument for studying a radio signal sent to Mars from Earth via huge antennas (70 meters in diameter) and RISE sends back. Thanks to the Doppler effect, it will be possible to determine the relative speed of Mars with respect to Earth and thus the rotation and position of Mars in space. The rotation measurement will give us information about the planet’s deep interior (for example, a cooked egg rotates differently than an uncooked egg does). The study will determine whether the core of Mars is liquid or solid, its dimensions and content. All the data collected by RISE will be studied by the Belgians (Dr Dehant's team) and the Americans.
InSight is more than a mission on Mars. By studying the red planet’s interior, all participating international teams want to learn more about its habitability and evolution compared to those of other terrestrial (rocky) planets, that is, Mercury, Venus and Earth. Our planet and Mars were formed from the same primordial elements, yet they evolved differently. Why did they have different fates? That’s one of the questions Dr Dehant and her team are posing.
LaRa: a 100% Belgian first on Mars
The other project Dr Dehant is working on is ‘LaRa’ (‘Lander Radioscience’). This instrument, currently under construction at UCL, will be 100% Belgian. It will be aboard the ExoMars mission in 2020. ‘It will be the first time that a totally Belgian instrument will land on the red planet’, she says. The antennas are built by UCL engineers including Prof. Christophe Craeye. The transponder is designed by Antwerp Space, a Flemish company specialising in the construction of telecommunication transponders. LaRa is miniaturised relative to RISE but works in the same way: it will listen for the radio signal from Earth and send it back directly. ‘We hope RISE will still be in place when LaRa lands, which would mean two surface points for studying Mars, and we’ll provide unprecedented precision for collecting information about the core of Mars.’ The goal will be to refine information concerning the interior of Mars, particularly its core.
Today, Dr Dehant’s team is preparing for the landing of RISE and to analyse precious data. In the meantime, asking her for current explanations of how Mars became uninhabitable leads to questions about what caused the atmosphere loss: Was it the impact of meteorites? Degassing from within Mars via volcanoes or surface fractures? The vanished magnetic field? The Sun, which at the time differed from its current state? A blend of all of the above? ‘What is certain is that by analysing the interior of Mars, we will have more answers, that is, about 26 months after RISE lands. That’s fundamental science: when you answer one question, ten more pop up.’
EOS: pooling research
Largely thanks to these two missions, Dr Dehant participates in an EOS (Excellence of Science) project promoting fundamental joint research between researchers from several French and Dutch-speaking Belgian universities as well as (to a lesser extent) several federal institutes across scientific disciplines. The question of the habitability of Mars is put to multiple teams who try to answer in their own way: VUB is interested in the effect of craters on the evolution of Mars; ULB specialises in meteorites; the IASB focuses on the red planet’s atmosphere; and UCLouvain delves into its interior. With this EOS project, teams will find more complete answers together.
Louvain4Space: bringing together scientists and attracting the young
At UCL, outer space is an interdisciplinary field. Indeed, space projects involve many institutes that we don’t necessarily think about when thinking about space. Louvain4Space was created in October 2017 to allow scientists from distinct fields to interact. It’s a platform for sharing calls for tender, best practices, knowledge, contacts, etc. Louvain4Space also addresses the future scarcity of researchers. ‘In this area,’ Dr Dehant says, ‘the age pyramid is reversed. Yet in ten years space-related skills will be in great demand. Too few students know that researchers at UCL work in the field of outer space. The Louvain4Space platform was launched particularly to inform and attract them.’
Discover the video of Insight's landing on Mars!
A glance at Véronique Dehant's bio
Véronique Dehant, obtained a master's degree in mathematics in 1981, a master's degree in physics in 1982, and a PhD in science and her accreditation in 1986 and 1992, respectively – all from UCLouvain. During her PhD she studied Earth’s rotation and interior. In 1981-92, she was a researcher at the National Fund for Scientific Research (FNRS). She then worked as a researcher at the Royal Observatory of Belgium (1993-present) and became, in 1994, head of the ‘Time, Earth Rotation and Space Geodesy’, now called ‘Reference Systems and Planetology’, Section, which she currently directs and which contains about 40 people.
In 2006, she became principal investigator of the LaRa Experiment (Lander Radioscience Experience) as part of the 2015 ExoMars mission and whose launch is scheduled for 2020. Currently Dr Dehant is also co-investigator in the InSight (interior exploration using seismic investigations, geodesy, and heat transport) mission to Mars, which was successfully launched and is scheduled to land on Mars in November 2018.
Dr Dehant has also won several awards including the European Union’s Descartes Prize. In 2014, she was named honorary doctor of the Paris Observatory. In 2015, she obtained a prestigious European Research Council (ERC) Advanced Grant with the RotaNut (rotation and nutation of a wobbly earth) project.
She is also a part-time professor at UCL. She is currently (July 2018) author of 480 publications, including 165 in peer-reviewed journals, and has written more than 1,085 scientific papers. Her main current scientific interest is comparative planetology, particularly planet interior, rotation, evolution and habitability.