The very first time that the Perseverance rover wanted to drill into the soil of Mars, in 2021, everything went well, or almost. The instruments worked wonderfully, but the coveted sample during this “coring” vanished. It sank into the softer than expected ground of the Red Planet. Same disappointment, in 2020, for the sampling of a NASA probe on the small asteroid Bennu. Its soil dispersed like a liquid. Suffice to say that it is difficult to predict in advance the behavior of an extraterrestrial surface.
“We often have surprises, because the little data we have is scattered and our predictions often come from extrapolations of terrestrial physical laws,” explains Naomi Murdoch, physicist and planetary scientist at theISAE-SUPAERO From toulouse. So, to prevent probes, rovers and even humans from getting stuck in distant and unknown lands, the researcher imagined a “variable gravity machine” capable of recreating, without moving from the Pink City, the mechanical properties of the surface of ‘a celestial body. And Naomi Murdoch will be able to move from theory to practice. For her “Gravity” project, she has just obtained one of the most prestigious grants – 2.3 million euros over 5 years – from the European Research Council (ERC).
“Extraterrestrial Geotechnics”
So, what will this machine to “travel” throughout the solar system look like? “Imagine an elevator,” says the Scottish expatriate. We cut the cables, the cabin falls and abolishes the gravity felt inside.” This “drop tower” system applied to space already exists in Bremen, Germany. Except that the Toulouse tower – “five to eight meters high” and with a small basket to place the “boxes” containing the materials to be tested, such as sand for example – will be adjustable. It will be able to reproduce several gravities. That of the Moon, six times lower than that of the Earth, but also that of the surface of certain asteroids 1,000 times lower.
The idea is to “recreate environments to which we do not have access” to allow those involved in space exploration to take on board the right tools, adapted to “extraterrestrial geotechnics”.
Space “crime scene” and rover on a Mars moon
“We want to generate an experimental database with our machine and we hope that our results will be very useful to space agencies and scientists,” summarizes the planetary scientist. The Gravity project will really start in the summer of 2024, when it will have recruited its team of engineers, doctoral students and young researchers and the famous machine should be operational “early 2026”. In time to press the He missionra of the European Space Agency (ESA). The latter will return “to the scene of the crime”, on the small asteroid that NASA “hit” voluntarily last year, during the DART mission, to try to deflect it like Bruce Willis in Armageddon. Naomie Murdoch’s team at ISAE-SUPAERO is participating in preparations for the landing of two small satellites near the crater. It is also associated with the Franco-German rover Idéfix which is due to land in 2027 on Phobos, a rocky moon of Mars. Gravity there is 1,500 times weaker than on our soil. The mission of the people of Toulouse is to help Idéfix to move without flying away.