- Jonathan Amos
- Science Correspondent, BBC
“We are definitely in the right place.”
There is a sense of relief in the science team in charge of the Perseverance rover (Perseverance, in Spanish) that the US space agency, NASA, has on Mars.
Investigators are now confident that they have sent the vehicle to the place that offers the best possible chance of finding traces of life. on the red planet.
“Percy,” as the robot is affectionately called, landed in Jezero Crater in February and has since been taking thousands of photographs of the surrounding area.
The interpretation of these images is the basis of the first scientific article based on these discoveries, published this week in the journal Science.
Analysis has confirmed that Perseverance is now settling at the bottom of what once was a great lake on the Martian surface, which was fed by a sinuous river that reached the depression in the west. We talked about something that happened more than 3.5 billion years ago, when the climate of Mars was much more benign.
From Perseverance’s observations, it has been possible to conclude that the river connected with the lake, the flow suddenly slowed down and the suspended sediments ended up precipitating to form a delta, that wedge-shaped formation that one can see in many places. from the earth.
It was in that environment where some microorganisms could have proliferated and perhaps to have left remains still preserved today.
Professor Sanjeev Gupta from Imperial College London, co-author of the Science paper, comments: “Some people have said to me: ‘What’s new in this? Didn’t we already know that there was a delta in Jezero crater? ‘ Well, actually, we didn’t know. We had inferred from orbital images that Jezero contained a delta but until you’re on the ground you can’t be totally sure. It could be that we were looking at an alluvial fan. ”
An alluvial fan or dejection cone is a geological formation in which, in general, the fan of materials is deposited in an environment of much more energy, such as a tide or flood.
Martian microbes, if they existed, would have preferred the calmer, more permanent waters of a delta.
Perseverance landed about two kilometers from the main delta, but the images captured by its telescope are most attractive, especially when it is located on an isolated mound that scientists have dubbed the Kodiak.
“It is possible to see in these remains some of the stratification that would typically produce a developing delta.”
There are horizontal bottoms formed by fine granulated sediments that the river threw from its entrance to the lake into the crater. Above these, sediments that slid down the slope through the most advanced lobes of the delta appear. And higher still are the sediments that were deposited by the river after the edges of the delta expanded beyond.
In addition to Kodiak and the main delta formation, at Jezero there are lots of big boulders. This indicates the existence of floods in later times in the crater’s history.
“Something changed in hydrology. We don’t know if it was a climate-related event, we don’t know,” says Professor Gupta. “To move such large rocks, you need something like a flood. Maybe there were glacial lakes in the local basin that sent these streams of water towards Jezero.”
“We see lake overflows on Earth, in places like the Himalayas. In the Ganges basin, you have these big rocks mixed in normal river sand and that’s where there has been a flash flood from a glacial lake,” Gupta told BBC News.
The Perseverance science team will send you to the base of the main delta formation to drill through the terrain in search of the small clay stones that are expected to be found. They will also focus on a ring of calcareous rocks around the edge of Jezero that possibly represents the shores of crater lake in its deepest age.
The robot is on a mission to collect and store more than two dozen rock samples from different locations. These samples will be brought from returned to Earth in the early 2030s to be examined in laboratories capable of determining if there were ever microscopic life forms on the face of Mars.
Plans for this are well advanced and will involve the dispatch of another robot from NASA and its partners from the European Space Agency to retrieve the samples from the crater point where Perseverance stores them.
It will be a British-made vehicle. It will collect the rocks and transfer them to a rocket that will launch them towards a point in the orbit of Mars where a satellite will be waiting that will finally transport them to Earth.
“We are about to enter the most exciting time of exploring Mars”says Sue Horne, Head of Space Exploration at the UK Space Agency.
“With the sampling vehicle’s propulsion system being tested next month, the dream of examining specimens from the red planet will soon be a reality.”
Now you can receive notifications from BBC Mundo. Download the new version of our app and activate them so you don’t miss out on our best content.
Eddie is an Australian news reporter with over 9 years in the industry and has published on Forbes and tech crunch.