He hasn’t even been on Mars for a whole year, and NASA’s Perseverance rover makes some wonderfully surprising discoveries.
Amid a number of findings announced this week at the American Geophysical Union Fall Meeting, scientists have revealed that Jezero Crater was formed from molten volcanic magma — and that organic molecules have been discovered in rocks and dust on the crater floor.
This is by no means evidence of life on Mars. Organic compounds are simply compounds containing carbon-hydrogen bonds and they can be formed by a number of non-biological processes. Indeed, organic compounds have been discovered on Mars before, both by the Curiosity rover and the Mars Express orbiter.
But the finding does suggest that Mars rocks can preserve these compounds well, which in turn suggests that biological organic matter can also be preserved. And that’s pretty exciting.
“Curiosity also detected organics at the landing site in Gale Crater,” said planetary scientist Luther Beegle of NASA’s Jet Propulsion Laboratory in Southern California. The detection was done using a new tool on Perseverance called the Scanning Habitable Environments with Raman & Luminescence for Organics & Chemicals, or SHERLOC for short.
“What SHERLOC adds to the story is its ability to map the spatial distribution of organics in rocks and relate those organics to minerals found there,” explains Beegle. “This helps us understand the environment in which the organics formed. More analysis is needed to determine the method of production for the identified organics.”
Perseverance landed on the red planet in February, in an area called Jezero Crater. This site is believed to have once been flooded with water and is rich in clay minerals – features vital to Perseverance’s mission. That’s because, in a first for a Mars expedition, the rover is tasked with looking for signs of ancient life; in our terrestrial experience, that probably happens near water.
In another first, the rover is equipped with 43 canisters in which it will deposit geological samples from Mars, which will be picked up and returned to Earth in a future mission called Mars Sample Return. Of course, those samples will be limited, so Perseverance is also equipped with a range of scientific instruments to perform in situ analyses.
For example, the SHERLOC instrument was able to detect a combination of organic minerals in the Jezero crater. These were not just in rocks the rover scoured to study their internal contents, but in dust covering the crater floor.
Another Perseverance tool, the Planetary Instrument for X-ray Lithochemistry (PIXL), also enabled scientists here on Earth to learn the source of the rock in Jezero Crater. After taking a core sample in a region nicknamed “Brac,” PIXL’s data clearly showed the presence of olivine crystals embedded in pyroxene crystals.
Here on Earth, such a mineral configuration is igneous in origin, suggesting that the bottom of Jezero Crater was formed from hot magma.
“A good geology student will tell you that such a texture indicates the rock that was formed when crystals grew and settled in a slowly cooling magma — say, a thick lava flow, lava lake, or magma chamber,” says geochemist Ken Farley of the California Institute of Technology .
“The rock was subsequently altered by water several times, turning it into a treasure trove that will enable future scientists to date the events at Jezero, the period when water was more prevalent on the surface, and better understand the planet’s early history. Mars Sample Return has great stuff to choose from!”
We may have to wait a while for that; there’s currently no set launch date for Mars Sample Return, and it’s at least a year-long round trip to Mars, assuming everything goes smoothly, not counting the time Mars spends picking up Perseverance’s sample tubes.
Even with limited instruments, however, the data Perseverance sends home is invaluable to Mars scientists both now and for planning future missions. And scientists are eager to get their hands on real Mars rock, harvested relatively fresh, to complement studies of Mars meteorites that may have changed during their journey to Earth.
“When these samples are returned to Earth, they will be a source of scientific research and discovery for years to come,” Beegle says.