ExoMars: All you need to know about the mission that ESA postponed in support of Ukraine

• The ExoMars mission was a joint astrobiology program between the ESA and Russian Federation's space corporation Roscosmos.
• It aims to find out whether life ever existed on Mars or not.
• Due to Russia's invasion of Ukraine, however, the ESA decided to cut ties with Russian Federation's space corporation Roscosmos.

The Russian invasion of Ukraine had a number of repercussions in areas outside the battlefield. Prices for gas and a number of staple foods shot up, hundreds of international companies have curtailed operations in the Russian market, FIFA suspended Russia’s national football team from the men's World Cup in Qatar, and retailers stopped selling all kinds of Russian-made products in their shops. 

The war also affected space exploration. On March 17, 2022, almost one month after the invasion, the European Space Agency (ESA) decided to cut ties with Russian Federation's space corporation Roscosmos. This led to the immediate suspension of their most important joint project, the ExoMars mission, which is now postponed until at least 2028.

What is the ExoMars mission?

The ExoMars mission is an astrobiology program of the ESA that is intended to find out whether life ever existed on Mars. To accomplish that, one strategy is based on atmospheric research on the Red Planet, and the other is based on geological research.

In fact, the program is divided into two missions. The first one launched in 2016 and put an atmospheric research orbiter into Mars orbit, the Trace Gas Orbiter, which is meant to search for methane and other trace gasses in the Martian atmosphere that could reveal an active biological or geological process on the Red Planet. 

The second part of the project will consist of the delivery of the Rosalind Franklin rover, originally by the Russian robotic Mars lander Kazachok (Little Cossack). At first, this mission was planned to launch in 2020, but due to technical problems with the lander’s parachutes, the launch was rescheduled to September 2022. 

Of course, this didn’t happen as Russia invaded Ukraine in February 2022, and the ESA officially terminated its cooperation with Roscosmos in July.

Currently, the ESA is looking for a non-Russian landing platform to restart the mission.

Who made the ExoMars rover?

The ExoMars rover, named after Rosalind Franklin (1920-1958), the British chemist whose work was vital to unraveling the molecular structures of DNA, is an autonomous six-wheeled vehicle designed to search for signs of past life on Mars. 

It weighs around 660 lb (300 kg) and contains, among some 18 different instruments, a drill created to penetrate the harsh Martian surface to a depth of 6 ft 7 in (2 meters) in order to collect samples.

According to the ESA, underground samples are more likely to include biological molecules than those retrieved from the surface of Mars. This is because the Martian surface receives a lot of radiation due to the Red Planet’s thin atmosphere (it is 100 times thinner than Earth’s). 

The rover will also carry an onboard laboratory, the Analytical Laboratory Drawer (ALD), containing nine next-generation science instruments designed to study the retrieved samples on site.

The Rosalind Franklin rover was mostly built by the British division of Airbus Defense and Space in the United Kingdom. Due to funding constraints, though, the wheels and suspension of the vehicle were financed by the Canadian Space Agency and manufactured by Canadian space technology company MDA Corporation.

What did ExoMars find?

The second part of the ExoMars mission has been postponed due to the diplomatic crisis over the Russian invasion of Ukraine, but the first part of the mission, which sent the Trace Gas Orbiter to Mars, took place in 2016 and was partially successful.

The Trace Gas Orbiter was meant to deliver the Schiaparelli lander upon its arrival on Mars, but due to a premature release of the parachutes, the lander crashed on the Martian surface. The Trace Gas Orbiter, however, is operational and conducting science activities in the Martian atmosphere. 

The Trace Gas Orbiter has four suites of science instruments: 

• ACS (Atmospheric Chemistry Suite) and NOMAD (Nadir and Occultation for Mars Discovery) focus on the detection and registration of atmospheric trace gasses on Mars.

• CaSSIS (Colour and Stereo Surface Imaging System) takes high-resolution images of the Martian surface to find volcanoes and other possible sources of trace gasses.

  

• FREND (Fine Resolution Epithermal Neutron Detector) maps subsurface hydrogen levels at a depth of 3 ft 3 in (1 meter) below the Martian soil with the objective of revealing water-ice deposits (one of the crucial components for life).

  

So far, the main findings of the Trace Gas Orbiter and its instruments include the following:

• Significant amounts of subsurface hydrogen in Valles Marineris, a system of canyons along the equator of Mars. This reveals Mars’ Grand Canyon as a potentially water-rich area, most likely in the form of sub-surface ice. 

  Another hypothesis is that the hydrogen content belongs to water chemically bound to other minerals in the Martian soil, but evidence shows that minerals in this part of Mars have much less water than what was observed by the Trace Gas Orbiter.

  The conclusion that Valles Marineris is a water-rich area was also possible thanks to the Trace Gas Orbiter’s FREND neutron telescope. On Mars, neutrons are generated by galactic cosmic rays and emitted through the planet’s dry soil. The drier the soil, the more neutrons it emits, so the number of neutrons that FREND detected over the course of two years (from 2018 to 2021) helped scientists calculate how much water the Martian soil potentially contains. 

  While this is not the first time that water was found on Mars, ESA's ExoMars Trace Gas Orbiter project scientist Colin Wilson explained that “knowing more about how and where water exists on present-day Mars is essential to understand what happened to Mars’ once-abundant water, and helps our search for habitable environments, possible signs of past life, and organic materials from Mars’ earliest days.”

• The presence of hydrogen chloride, a halogen gas, in the atmosphere of Mars. 

  Chlorine-based gasses can be explained by volcanic activity, but not when they are found in distant places and in the absence of other gasses related to volcanism, like in this case.

  Therefore, scientists hypothesize that the hydrogen chloride gas could be due to a surface-atmosphere interaction driven by dust seasons on Mars.

  

  “We observe a correlation to dust: we see more hydrogen chloride when dust activity ramps up, a process linked to the seasonal heating of the southern hemisphere,” explained Kevin Olsen from the University of Oxford at the time of the discovery.

  But overall, this finding could point to a new chemical cycle or previously unseen chemical reaction that we don’t fully understand yet.

  However, “you need water vapor to free chlorine, and you need the by-products of water – hydrogen ­– to form hydrogen chloride,” added Kevin Olsen. “Water is critical in this chemistry.”

The Trace Gas Orbiter will also work as a relay satellite for future landed missions.