NASA’s Mars Perseverance rover has made some exciting new discoveries, offering even more clues to the red planet’s complex, watery past. Plus, mission scientists say, these new discoveries will help direct the planned Mars Sample Return (MSR) mission planned for the end of the decade to the most tantalizing targets in the space agency’s ongoing search for extraterrestrial life.
BACKGROUND: MARS WATERY PAST HINTS AT HABITABILITY
Numerous missions have confirmed that there was once water on Mars. This information has helped mission planners decide which areas of the red planet are the best places to search for signs of ancient (and maybe even current) microbial life.
Some of those follow-up missions have also shown the presence of organics within the Martian soil. Although such organics are not necessarily life-affirming biosignatures, they may indeed point to a biological origin.
Now, the folks at NASA’s Jet Propulsion Laboratory (JPL), who are in charge of the Perseverance rover’s daily operations, are revealing new details about the formation of Jezero crater, the rover’s current home, which they believe will provide future missions even more tantalizing targets to study and explore.
ANALYSIS: MARTIAN LAVA AND MORE ORGANICS
After using the drill at the end of Perseverance’s arm to abrade a tantalizing target within the crater’s rocky surface, the Planetary Instrument for X-ray Lithochemistry, or PIXL, was able to use something called X-ray fluorescence to map the elemental composition of the rocks. This analysis was designed to answer one of the mission’s key questions; was Jezero crater formed by sedimentary deposits like those found in a lake or river, or from the flow of lava.
“I was beginning to despair we would never find the answer,” said Perseverance Project Scientist Ken Farley at the American Geophysical Union’s fall meeting. “But then our PIXL instrument got a good look at the abraded patch of a rock from the area nicknamed ‘South Séítah,’ and it all became clear: The crystals within the rock provided the smoking gun.”
Specifically, the findings showed olivine crystals formed within pyroxene crystals, which mission scientists say is a dead giveaway that the crater was formed by lava.
“A good geology student will tell you that such a texture indicates the rock formed when crystals grew and settled in a slowly cooling magma – for example a thick lava flow, lava lake, or magma chamber,” explained Farley. “The rock was then altered by water several times, making it a treasure trove that will allow future scientists to date events in Jezero, better understand the period in which water was more common on its surface, and reveal the early history of the planet.”
“Mars Sample Return is going to have great stuff to choose from!” he added.
The other big news revealed by the Perseverance team is the discovery of even more organic molecules in the Martian rocks using the Scanning Habitable Environments with Raman & Luminescence for Organics & Chemicals, or SHERLOC, instrument.
“Confirmation of organics is not a confirmation that life once existed in Jezero and left telltale signs (biosignatures),” explains a post by the JPL team. “There are both biological and non-biological mechanisms that create organics.”
However, the same post notes, it is a tantalizing clue that ancient life may have once flourished in the watery environment that we now know existed within the lava-formed crater.
“Curiosity also discovered organics at its landing site within Gale Crater,” said Luther Beegle, SHERLOC’s principal investigator at JPL. “What SHERLOC adds to the story is its capability to map the spatial distribution of organics inside rocks and relate those organics to minerals found there.”
This process, says Beegle, should help researchers better understand the environment in which the organics formed. However, he notes, “more analysis needs to be done to determine the method of production for the identified organics.”
OUTLOOK: MARS SAMPLE RETURN FLUSH WITH TARGETS
In its conclusion, the JPL team’s post explains that “the preservation of organics inside ancient rocks – regardless of origin – at both Gale and Jezero Craters does mean that potential biosignatures (signs of life, whether past or present) could be preserved, too.” However, they note, the answer to that question may not be readily available until the planned Mars Sample Return (MSR) mission brings those examples home, hopefully sometime before the end of the decade.
“This is a question that may not be solved until the samples are returned to Earth,” said Beegle, “but the preservation of organics is very exciting. When these samples are returned to Earth, they will be a source of scientific inquiry and discovery for many years.”
Follow and connect with author Christopher Plain on Twitter:@plain_fiction