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For NASA's Mars 2020 rover, which is currently assembled at the agency's Jet Propulsion Laboratory for launch in July 2020, the stakes could not be much bigger. The $ 2.4 billion nuclear-powered mobile is the most complex machine to ever have been a ballistic asset to the red planet. And after landing in February 2021, the completion of a prominent goal – the collection of rock samples for possible transport to Earth – would ensure that the rover set the path to follow for the future exploration of Mars for the coming decades. But first, mission planners have to decide where this ambitious machine should go on Mars.
Last week at a conference in North Los Angeles, an international group of more than 150 scientists met for two and a half days to deliberate on this topic – their debates sometimes seeming less like a conversation scientific in depth only as a geological and geological discussion. astrobiological food fight. This controversial meeting is the fourth and final such workshop to be held since 2014 and examined four potentially life – friendly candidates for the coveted Mars 2020 landing site:
- Columbia Hills / Gusev Crater, a site previously studied by the now deceased NASA rover Spirit. It is teeming with hot spring deposits that on Earth would provide a comfortable home for microbial life.
- Jezero Crater, a site with dry lakes and deltas that could have harbored – and subsequently preserved – a multitude of microbial martians.
- Syrtis Major Northeast, Giant volcano shield adjoining a huge impact crater, which houses some of the oldest rocks on the planet, was built while Mars was a warmer and wetter place.
- Half-way, another destination dotted with ancient rocks, appropriately named, between the landing sites of Jezero and Northeast Syrtis.
"The amount of information we have to study another planet is mind-boggling," said Michael Meyer, chief scientist of NASA's exploration program for the planet Mars. The workshop differentiated potential landing sites "based on what we know, what we do not know and what we want to know," he said. American scientist, "But we only have one shot."
Matthew Golombek, a geologist who co-chairs the March 2020 Landing Site Steering Committee, said the four finalist nominees were now the most studied sites on the planet Mars. Each has been saturated by numerous remote observations by orbits surrounding the planet above his head. These gave researchers new torrents of information on geological history, rock composition, surface conditions, and so on. Based on all of this data, workshop participants eventually had to vote for their preferred landing site, the location they thought had the best chance of success in March 2020.
At the conclusion of the workshop, the combined tables suggested a consensual preference for a hybrid approach – an approach in which the Mars 2020 rover would visit and explore the lake bottoms and dry deltas of the Jezero crater, as well as ancient rocks. from the Midway site, which is only about 28 kilometers away. It's not very far, bird-flying, but remains a potentially gigantic command for a robotic rover flying over rugged foreign terrain. Trekking would be a more difficult goal for the rover, as crossing could easily take longer than his main mission of 2.35 years. Moreover, even if this two-for-one approach is scientifically convincing, it is not fixed in stone: the decision to send exactly Mars 2020 is the responsibility of Thomas Zurbuchen, NASA's senior scientist, who is to examine results of the workshop and announce its results. his choice of here the end of the year. His report will then go to NASA's management channel for a final announcement.
The preference for two sites was influenced by the richness of the extended mission, said David Des Marais, an astrobiologist and workshop participant from NASA's Ames Research Center. "It really made the difference, a lot more than in previous missions." In particular, Mars 2020 will take advantage of several new technologies – such as better terrain mapping and more accurate and responsive triggering of its parachute during the descent – that should allow: the rover to achieve a precise landing surpassing those of all his robotic predecessors. "These technologies have opened the door to sites that people would have loved to visit earlier, but they would not have been able to," says Des Marais.
It remains to be determined when and how to recover the samples from March 2020, as well as the order in which the rover will recognize the preferred exploration sites of the workshop. Like many workshop attendees, Des Marais is personally supportive of the March 2020 Jezero landing, using a fraction of its 42 pencil-sized test tubes to collect stones, then going to the Midway site for a new performance. "The workshop rating reflected a fairly symmetrical view of the starting point and the end of the work," says Des Marais, adding that the landing site of Syrtis Northeast also showed strong performance.
John Mustard, a world scientist at Brown University in Providence, Rhode Island, was the main advocate for Jezero Crater at the workshop. "Jezero has had the best results in primary rover search, and Northeast Syrtis has a higher value than returned samples. The real winner was Midway's extended mission to Jezero, which enjoyed broad support in terms of scientific value, "he said.
As for Jezero and Midway, Mustard says, "It's the best of both worlds. If we can sample both sites, we are more advanced and able to explore a more diverse range of Mars science than we would otherwise. "
Importantly, the March 2020 mission will involve a repeat landing of the NASA Curiosity rover in August 2012. This means that mission scientists and an enthusiastic audience back on Earth must endure a breathtaking recovery of the So called Curiosity's "Seven Minutes of Terror" entry, its descent and landing on Mars in 2012. To close the process, the celestial crane robot hovers over the rockets and then lowers the rover on a link with the surface. The Sky Curiosity crane worked perfectly. It remains to be seen whether this approach will be repeated in 2020.
Despite these operational uncertainties, mission scientists are optimistic. Rover assembly and testing is proceeding as planned at JPL, and no obstacles are in sight, "said Matt Wallace, Assistant Project Manager, March 2020.
Even though, against all odds, the Mars rover's high-voltage landing failed, "the Mars program will go forward," said Ray Arvidson of Washington University in St. Louis, veteran of several missions on the Red Planet. "[Mars] is the long-term goal of NASA. Whether Mars 2020 works or not, exploration will continue. "
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