ExoMars Mission: If there is life on Mars, we will know for sure in 2023!
Establishing whether life ever existed on Mars is one of the outstanding scientific questions of our
time. To address this important goal, the European Space Agency (ESA) is preparing together with the
Russian space agency Roscosmos the ExoMars 2022 mission, whose rover will leave equipped with
a real laboratory for biological analysis. ExoMars 2022, in fact, will deliver a rover,
named Rosalind Franklin, and a Russian surface platform, named Kazachok, to the surface of Mars.
A Proton rocket will be used to launch the mission, which will arrive at Mars after a
nine-month journey. The ExoMars rover will travel across the Martian surface to search for signs of
life. It will collect samples with a drill and analyze them with next-generation instruments.
ExoMars will be the first mission to combine the capability to move across the
surface and to study Mars at depth of two meters. And perhaps it will be the mission of redemption
for Europe, which so far has never managed to bring down one of its rovers or landers on the
Martian surface. Or at least, that's what we all hope, because the Rosalind Franklin rover - more
than all others sent so far - is the one with the best chance of finding life on Mars (if any).
It's been almost half a century since the European Space Agency was born in Paris.
It was May 30, 1975. Ten countries of the
"old continent" met in the name of science to create an Agency that could keep up with the
two superpowers that then dominated the space sector: the Soviet Union and the United States.
And in all these years, ESA has certainly succeeded in achieving the goal it had set itself,
becoming a space exploration power and supporting a market, that of the new space economy, which
in recent years has seen unprecedented growth. The first great successes of ESA began in 1986,
with the probe Giotto, sent to meet Halley and to photograph for the first time
ever the nucleus of a comet. Then many other missions,
such as the Hipparcos in 1989 to measure the real distance of tens of thousands of stars,
and the Ulysses probe sent to the Sun in 1990... Not to mention the Huygens probe,
sent to land on Titan in 2005, and which is still the spacecraft that made the soft landing farthest
from Earth. And all while the mother probe Cassini, the result of collaboration with NASA,
explored the Saturn system, making us participants in extraordinary scientific discoveries.
But there is much more: spacecraft sent to Venus and Mercury, or space telescopes sent to search
for data on the cosmic background radiation, like Planck in 2009 or like Herschel in the same year,
who flew to the second Lagrangian point of the Earth to hunt for extrasolar planets.
And in 2014 the exciting adventure given to us by the Rosetta probe, which you will all
remember for the extraordinary photos taken of the comet Churyumov-Gerasimenko and for
the first landing on a cometary nucleus ... But that's not enough ... around our planet,
there are dozens of satellites put into orbit by the Old Continent.
Some of them are telescopes and probes that scan the cosmos (one of them is Hubble,
realized in partnership with NASA). Others instead observe us. They are the guardians of our Planet.
They allow us to keep an eye on the effects of climate change, prevent the consequences,
act in case of emergencies and keep our infrastructure under control.
The ESA has also signed a large part of the International Space Station itself,
and also has its own spaceport in South America: the one in Kourou, in French Guyana.
In short, decades of great successes, with a single worry ...
That of not having yet been able to land its own lander or rover on the surface of Mars.
It has tried twice, and both attempts have resulted in failure.
The first time happened with the mission that brought then in Mars orbit the probe Mars Express,
but that also had to bring down on the sands of Isidis planitia the small lander Beagle 2,
built by the British space agency. The lander separated from the probe on
December 19, 2003, and after six days should have landed on Mars, braked by a series of
parachutes and protected by some airbags at the time of impact with the ground. It was
photographed by the mother-probe on Christmas day of 2003 while it was preparing to descend,
then nothing more was known. It was speculated that it had missed the planet completely,
or that it had crashed. Then, in 2015 it was discovered that it had managed to land, but that
the solar panels had not opened properly, thus depriving it of the possibility of communication.
The one who really crashed was the Schiaparelli lander during ESA's second attempt to land on
Mars. This time the mission, carried out in collaboration with the Russian space agency,
was ExoMars 2016, also composed of a probe, the Trace Gas Orbiter, which managed to regularly
enter Martian orbit, and the lander dedicated to the memory of the Italian astronomer.
However, the communication with the lander stopped about 50 seconds before the expected
ground contact, just after the parachute and the heat shield had been released from the lander.
Further analysis of telemetry data transmitted in real time by the lander allowed ESA
engineers to discover that the retrorockets were turned off by the onboard computer
after only 3 seconds instead of the expected 30. According to ESA estimates, the lander has
traveled in free fall about 3 km and impacted with the Martian soil at a speed of 300 km / h,
spreading its wreckage among the sands of Meridiani Planum.
In short, apart from the orbiters, regularly entered in service, from Mars,
ESA has so far received only great disappointments, minimally mitigated by
the objective difficulty that all space agencies of the Earth have found in making a soft landing.
But woe betide giving up. The ExoMars 2016 mission was in fact only the first phase
of a more articulated mission, which later included the launch of ExoMars 2018,
intended to bring to Mars the first European rover.
But even with ExoMars 2018 considerable difficulties arose. Initially, the whole mission
was supposed to be an ESA-NASA collaboration, but then, when by then the European agency had already
started the plans for its realization, NASA withdrew from the agreement for budgetary reasons.
So ESA turned to Roscosmos, which was desperately trying to get back on track
after previous failures, in particular that of the Phobos-Grunt mission,
which was supposed to bring back to Earth samples of the Martian moon Phobos, but for a malfunction
of the last stage of the carrier fell back into the Earth's atmosphere burning completely.
The change of partner was not painless: less money, many technologies to be replaced,
much time lost. The second mission, initially scheduled for 2018, has slipped by two years,
thus becoming ExoMars 2020, and then by another two for problems encountered in the parachute
tests and for the slowdown due to the pandemic. So, now we are talking about ExoMars 2022,
a mission that if all goes well will be launched on a Proton-M rocket from Baikonur, Kazakhstan,
in the 20 September - 1 October 2022 launch window. It is planned to land on Mars
in the Oxia Planum region on June 10, 2023. During launch and cruise phase, a carrier module
(provided by ESA) will transport the surface platform and the rover within a single aeroshell.
A descent module (provided by Roscosmos) will separate from the carrier shortly before reaching
the Martian atmosphere. During the descent phase, a heat shield will protect the payload from the
severe heat flux. Parachutes, thrusters, and damping systems will reduce the speed,
allowing a controlled landing on the surface of Mars.
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After landing, the rover (recently named in honor of scientist Rosalind Franklin,
who made key contributions to the understanding of the molecular structures of DNA)
will egress from the platform to start its science mission. The primary objective is to
land the rover at a site with high potential for finding well-preserved organic material,
particularly from the very early history of the planet. The rover will establish
the physical and chemical properties of Martian samples, mainly from the subsurface.
Underground samples are more likely to include biomarkers, since the tenuous
Martian atmosphere offers little protection from radiation and photochemistry at the surface.
The drill is designed to extract samples from various depths, down to a maximum of
two meters. It includes an infrared spectrometer to characterize the mineralogy in the borehole.
Once collected, a sample is delivered to the rover's analytical laboratory,
which will perform mineralogical and chemistry determination investigations.
Of special interest is the identification of organic substances. The rover is expected to
travel several kilometers during its mission. The ExoMars Rover provides key mission
capabilities: surface mobility, subsurface drilling, and automatic sample collection,
processing, and distribution to instruments. It hosts a suite of analytical instruments
dedicated to exobiology and geochemistry research: this is the Pasteur payload.
The Rover uses solar panels to generate the required electrical power,
and is designed to survive the cold Martian nights with the help of novel batteries and heater units.
Due to the infrequent communication opportunities, only one or two short sessions per day,
Rosalind Franklin is highly autonomous. Scientists on Earth will designate target destinations on the
basis of compressed stereo images acquired by the cameras mounted on the Rover mast.
Rosalind Franklin must then calculate navigation solutions and safely travel approximately 100
meters per day. To achieve this, it creates digital maps from navigation stereo cameras and
computes a suitable trajectory. Close-up collision avoidance cameras are used to ensure safety.
The locomotion is achieved through six wheels. Each wheel pair is suspended on an independently
pivoted bogie (the articulated assembly holding the wheel drives), and each wheel can
be independently steered and driven. All wheels can be individually pivoted to adjust Rosalind
Franklin's height and angle with respect to the local surface, and to create a sort of walking
ability, particularly useful in soft, non-cohesive soils like dunes. In addition, inclinometers and
gyroscopes are used to enhance the motion control robustness. Finally, Sun sensors are utilised to
determine the rover’s absolute attitude on the Martian surface and the direction to Earth.
The camera system's images, combined with ground penetrating radar data collected while travelling,
will allow scientists on-ground to define suitable drilling locations.
Rosalind Franklin's subsurface sampling device will then autonomously drill to the required
depth while investigating the borehole wall mineralogy, and collect a small sample.
This sample will be delivered to the analytical laboratory in the heart of the vehicle.
The laboratory hosts four different instruments and several support mechanisms. The sample will
be crushed into a fine powder. By means of a dosing station the powder will then be presented
to other instruments for performing a detailed chemistry, physical, and spectral analyses.
The chosen landing site, Oxia Planum, is a 200 km-wide clay-bearing plain located inside the
Oxia Palus quadrangle on the eastern boarder of Chryse Planitia. The plain lies between the Mawrth
Vallis outflow channel to the north-east and the Ares Vallis outflow channel to the south-west.
Oxia Planum contains one of the largest exposures of rocks on Mars that are
around 3.9 billion years old and clay-rich, indicating that water once played a role here.
The site sits in a wide catchment area of valley systems with the exposed rocks
exhibiting different compositions, indicating a variety of deposition and wetting environments.
A period of volcanic activity may have covered early clays and other aqueous deposits,
offering preservation for biosignatures against the planet's harsh radiation and oxidation
environment, and have only been exposed by erosion within the last few hundred million years.
Well, that's it! We are still two years away from the arrival of the rover on Mars.
Let's cross our fingers and hope that Rosalind Franklin will be able to find
on the red planet the most important thing in the universe: LIFE, in whatever form it is.