The NASA rover Perseverance has drilled its sixteenth sample. Extracted from an interesting rock, it marks the beginning of its latest mission, which sees it exploring the top of the delta of an ancient river.
The newly collected sample, the size of a piece of chalk, is safely hidden in the storage compartment of the Perseverance rover, as announced by NASA on Friday, March 31st in an article (ref.). It was extracted from a rock that could plausibly host evidence of ancient microbial life on Mars, said members of the mission team.
Perseverance, the size of a car, has been collecting samples and searching for signs of life on Mars. Since landing inside the Jezero crater of the Red Planet in February 2021, rover has explored various terrains as planned in the scientific campaigns. Its latest mission has brought the six-wheeled robot to the top of the ancient delta of the Jezero river.
On March 30th, Perseverance’s 749th Martian day on the Red Planet, the rover used the drill at the end of its 2-meter-long robotic arm to make a hole in a rock nicknamed “Berea”. Within 30 minutes, the rover had a cylindrical fragment of Martian rock stored in one of its 43 titanium sample tubes. To date, the rover has collected 19 of the planned 38 samples (ref.), 16 of which have been collected by drilling Martian rocks.
Scientists believe that the recently sampled Berea rock may have formed when an ancient river transported its constituent elements, various sediments and minerals that make up the rock, downstream of Jezero outside the crater.
The latest sample aboard Perseverance is an exciting victory for scientists. The Berea rock is rich in carbonate minerals, which can be created as a byproduct of life (ref.). “If the biological signatures were present in this part of the Jezero crater, a rock like this that could well guard their secrets” said Katie Morgan, deputy project scientist for Perseverance at NASA’s Jet Propulsion Laboratory (JPL) in California.
Analysis of carbonate minerals
Carbonate rocks materialize when carbon dioxide and water react with the minerals usually present in volcanic rocks, such as calcium and iron. The fact that the Berea rock is rich in carbonates could confirm that rivers flowed on the Martian surface 3.5 billion years ago. Additionally, these bodies of water could have hosted life, whose evidence scientists hope to find in the samples just collected by the rover on Mars.
On Earth, details of the evolution of ancient microbial life are protected for billions of years in the form of fossils rich in carbonates. Shells, for example, are made of calcium carbonate, which helps them become hard enough to resist until today. These structures become guardians of information about ancient life. They often change in size and thickness in response to the growth of animals living inside them, as well as to the temperatures of the surrounding environment. In this way, the history of these life forms is stored in the intricate patterns of the shells.
Similarly, Perseverance scientists hope to reveal valuable information about Mars’ past. Did life exist on the Red Planet? How and why did Mars’ environment change over time? Answers to these questions will come from studying the samples stored in the rover in detail. This work will mainly be done on Earth. If everything goes according to plan, a joint NASA-ESA mission, Mars Sample Return, will transport the samples collected by Perseverance to our planet in 2033.