The Perseverance rover from NASA is nearing the end of its first set of objectives on Mars.
The Nasa robot has gathered a diverse collection of rock samples, which it will soon deposit on the surface, awaiting transport to Earth by subsequent missions.
It’s been 17 months since the vehicle arrived in Jezero Crater, slung beneath a rocket crane.
Everything “Percy” has seen since confirms to scientists that the rover is in the ideal location to search for life.
It is not looking for living organisms; the harsh environment on Mars makes their presence highly unlikely. Instead, the robot is looking for signs of biology that may have existed billions of years ago when a lake covered Jezero.
Scientists hope that the “amazing” rock samples that will be laid down in “a depot” in the coming months will record this ancient history.
“I think it’s safe to say, or at least assume, that biology would have done its thing and left its mark in these rocks for us to observe if [Jezero’s ancient] conditions existed pretty much anywhere on Earth at any point in time over the last 3.5 billion years,” said David Shuster, a Perseverance mission scientist from the University of California, Berkeley.
Nasa and the European Space Agency are devising a strategy to recover the rock cache. It’s a risky plan that will entail another landing system, helicopters, a Martian rocket, and an interplanetary freighter.
The samples are expected to be returned to Earth in 2033.
The shipment will contain some igneous, or volcanic, rocks that Perseverance drilled out on the crater floor. These will primarily tell the story of Jezero before it was filled with lake water.
Importantly, the samples are of a rock type that can be precisely dated. At the moment, ages on Mars can only be deduced indirectly.
The cache will also contain sedimentary-type rocks that Perseverance has been collecting in recent months from the delta deposits in the western sector of the 45km-wide crater.
A delta is a structure formed by the silt and sand deposited by a river as it slows its entry into a larger body of water.
It’s the type of geological feature that could have trapped traces of previous microbial life.
One of the sedimentary samples, from a rock known as “Wildcat Ridge,” was formed when mud settled in the evaporating Jezero lake. It’s loaded with salts. However, the rover’s instrumentation reveals that Wildcat Ridge is also rich in organic, or carbon-rich, compounds.
This is an intriguing observation, but there are some important caveats.
“Organics make up all of life as we know it. However, organic matter can also be formed through chemical processes that are unrelated to life, such as water-rock interactions. Organics can also be found in interstellar dust, “Sunanda Sharma, a mission instrument scientist at NASA’s Jet Propulsion Laboratory, confirmed this (JPL).
Perseverance has been working on the 40m-high scarp that represents the delta’s edge for the last four months.
The robot will soon drive off this slope to a nearby flat area of the crater floor where the rock samples can be deposited on the ground in their protective titanium tubes.
“We’re looking at putting down 10 to 11 sample tubes here on the surface,” said Rick Welch, project systems engineer at JPL.
“It would probably take about two months to put those samples down and carefully document where they are so that a future mission could find them.”
Nasa engineers have been practicing how the tubes currently in Perseverance’s belly will be ejected. JPL has a full-sized replica of the rover on which to simulate maneuvers before sending commands to Mars to carry out the actions in real-time.
Nasa is expected to make a yes/no decision following a meeting on October 19.
Perseverance’s first depot may serve as an insurance backup, to be collected and returned to Earth only if the rover suffers a catastrophic failure during the remainder of its mission.
Scientists want to collect many more samples, so the retrieval strategy may be based on where the robot goes in the future.
The events on Mars will determine the final outcome.
Lori Glaze, director of Nasa’s planetary science division, praised the mission’s “incredible Perseverance team” for their efforts thus far.
“Not only did we go to the right place, but we also sent the right spacecraft equipped with the right science instruments to explore this amazing ancient environment on Mars,” she told reporters.
