In 2014, NASA’s Curiosity rover found evidence of organic matter in rock-powder samples from Gale crater, and NASA’s Perseverance rover has detected organics in Jezero crater before. But unlike that previous discovery, this latest detection was made in an area where, in the distant past, sediment and salts were deposited into a lake under conditions in which life could potentially have existed.
This image shows a rocky outcrop called Wildcat Ridge, where NASA’s Perseverance rover extracted two rock cores and abraded a circular patch to investigate the rock’s composition. Image credit: NASA / JPL-Caltech / ASU / MSSS.
Jezero crater is a 45-km-wide crater in the Syrtis Major quadrangle on Mars.
It hosts a delta — an ancient fan-shaped feature that formed about 3.5 billion years ago at the convergence of a river and a lake.
Perseverance is currently investigating the delta’s sedimentary rocks, formed when particles of various sizes settled in the once-watery environment.
“We picked the Jezero crater for Perseverance to explore because we thought it had the best chance of providing scientifically excellent samples — and now we know we sent the rover to the right location,” said Dr. Thomas Zurbuchen, NASA’s associate administrator for science.
“The first two science campaigns have yielded an amazing diversity of samples to bring back to Earth by the Mars Sample Return campaign.”
“The delta, with its diverse sedimentary rocks, contrasts beautifully with the igneous rocks — formed from crystallization of magma — discovered on the crater floor,” said Perseverance project scientist Dr. Ken Farley, a researcher at Caltech.
“This juxtaposition provides us with a rich understanding of the geologic history after the crater formed and a diverse sample suite.”
“For example, we found a sandstone that carries grains and rock fragments created far from Jezero crater — and a mudstone that includes intriguing organic compounds.”
On July 20, 2022, Perseverance abraded some of the surface of ‘Wildcat Ridge’ — a rock about 3 feet (1 meter) wide that likely formed billions of years ago as mud and fine sand settled in an evaporating saltwater lake — so it could analyze the area with the SHERLOC instrument.
The analysis indicated the samples feature a class of organic molecules that are spatially correlated with those of sulfate minerals.
Sulfate minerals found in layers of sedimentary rock can yield significant information about the aqueous environments in which they formed.
“In the distant past, the sand, mud, and salts that now make up the Wildcat Ridge sample were deposited under conditions where life could potentially have thrived,” Dr. Farley said.
“The fact the organic matter was found in such a sedimentary rock — known for preserving fossils of ancient life here on Earth — is important.”
“However, as capable as our instruments aboard Perseverance are, further conclusions regarding what is contained in the Wildcat Ridge sample will have to wait until it’s returned to Earth for in-depth study as part of the agency’s Mars Sample Return campaign.”