Biodiversity, space, artificial intelligence, education… Spotlight on the conferences and meetings organized at the Cité des Sciences et de l'Industrie. Today, March, returns from missions, Saturday November 23 at 4 p.m.
New course for a new life on Mars! It's time for Curiosity to change regions, NASA announced this week. “He will soon leave the furrow of Gediz Vallis behind him” pour “preparing for the next stage of his journey, which will be a month-long expedition to a formation called the Boxwork, a set of spider-web-like patterns that stretches several kilometers across the surface of Mars. »
Give up everything for a rock
After twelve years spent surveying the red planet on its increasingly damaged wheels, the American rover has already traveled 33 kilometers and visited several Martian areas, according to a route concocted gradually by the scientists who follow it from Earth . The choice of destinations and detours imposed on Curiosity depends mainly on the geological interest of its environment: it can leave everything behind to spend two weeks driving towards a rock that seems promising, spotted in a photo in the depths of the landscape.
Its landing site was chosen at the bottom of Gale Crater, formed by an asteroid impact about 3.5 billion years ago. Planetologists strongly suspected that this 150 kilometer wide crater was the bed of a lake at the beginning of its history, and therefore that it retained traces of sediments deposited at this ancient time, with, why not, chemical compounds organics showing that life could have developed in this humidity.
Unexpected sulfur
Curiosity began by driving 9 kilometers relatively flat at the bottom of Gale Crater, between 2012 and 2014, to extract itself from its landing zone, studying four interesting nooks and crannies in detail along the way. The second phase of his trip was more sporty. The NASA rover skirted then began the ascent of Mount Sharp, which occupies the center of the crater. An increasingly technical route on increasingly steep slopes, always dotted with interesting finds (nitrogen, organic molecules, etc.) as the rocks are photographed, drilled and analyzed.
Since the summer of 2023, Curiosity has been diving into the Gediz valley, a sort of canyon on the slopes of Mount Sharp, and notably discovered there (by chance by crushing a rock) bright yellow sulfur in its pure state, for first time. A total surprise. “We have no explanation for the presence of this sulfur herenotes the NASA press release. On Earth, sulfur is associated with volcanoes and hot springs, and neither of these causes exists on Mount Sharp that we know of.” Ashwin Vasavada, geophysicist at NASA's Jet Propulsion Laboratory, says he “inspected this sulfur from all angles, from above and from the sides […]. We've accumulated a ton of data, and now we have a cool puzzle to solve.”
A valley in a too dry climate
The Gediz valley is “a region shrouded in mystery”summarizes NASA today, as it leaves the region. “How this furrow formed so late, during a transition to a drier climate, is a big question for the scientific team.” From what planetary scientists have understood so far, “the older strata of the mountain had already formed in a dry climate”and secondly, despite this ambient aridity, “water leaked occasionally” by digging this valley.
Using cameras mounted on the end of its robotic arm, Curiosity took a 360-degree panorama of its surroundings in the Gediz Valley. The image was published this Monday on YouTube. The enlightened eye of geologists can see that “rivers, wet debris flows and dry avalanches have all left their mark. The scientific team is now working to reconstruct a timeline of events in the region based on Curiosity's observations.
Cobwebs “where salt water flowed”
Curiosity is now expected to take a month to reach its next destination, the place of interest nicknamed “Boxwork” by mission scientists. For English-speaking geologists, a boxwork is a calcite stringer in relief: a small vein of limestone rock, which has acquired a characteristic spider's web shape through erosion. We know them well on Earth, and we have spotted beautiful specimens on Mars too, notably in photos taken by the American Mars Reconnaissance Orbiter probe, which has been circling the red planet since 2005.
These calcite webs in Gale Crater are thought to have formed “when the minerals carried by the last water currents on Mount Sharp seeped into fractures in the rocks on the surface”explains NASA. The rest of the rock has eroded, but not these minerals, which have remained in relief, keeping the trace of the network of cracks. On Earth, these geological curiosities are found in caves and on cliffs. On Mars, those that Curiosity will visit are remarkable for their extent: 10 to 20 kilometers wide.
They keep track of the past climate “warmer, where salty liquid water flowed”judge Kirsten Siebach, professor at Rice University in Houston, and planetologist for the Curiosity mission. “Terrestrial microbes could have survived in a similar environment. This makes it a fascinating target for exploration.”
