Nasa finds Mars rock that may have hosted tiny lifeforms
A rock on Mars may have hosted microscopic life billions of years ago, Nasa believes.
The arrowhead-shaped rock – nicknamed Cheyava Falls – was found to contain carbon-based molecules and tiny structures and may once have been a home for tiny alien lifeforms.
The rock, which measures around 3.2ft by 2ft, was spotted by Nasa’s Perseverance rover, which is exploring the northern edge of Neretva Vallism – an ancient river valley that was carved by water rushing into Jezero crater.
It stood out because it contained strange marks, resembling leopard spots, which when scanned by the rover contained organic compounds.
Prof Ken Farley, a Perseverance project scientist of Caltech in Pasadena, said: “Cheyava Falls is the most puzzling, complex, and potentially important rock yet investigated by Perseverance.
“On the one hand, we have our first compelling detection of organic material, distinctive colourful spots indicative of chemical reactions that microbial life could use as an energy source, and clear evidence that water – necessary for life – once passed through the rock.
“On the other hand, we have been unable to determine exactly how the rock formed and to what extent nearby rocks may have heated Cheyava Falls and contributed to these features.”
The Perseverance mission is looking for signs of alien life and so has focused on rocks that look like they have been created or modified by water.
Cheyava Falls was found to contain large white calcium sulfate veins, clear evidence that water once ran through the rock.
Between those veins are bands of material whose reddish colour suggests the presence of hematite, one of the minerals that gives Mars its distinctive rusty tone, and it is here that the rover picked up traces of organic compounds.
When Perseverance peered more closely closer at the red regions, it found dozens of irregularly shaped, millimetre-size off-white splotches, each ringed with black material, akin to leopard spots.
The black halos contain both iron and phosphate and on Earth indicate that microbial life once lived beneath the surface.
Spotting such as seen on the rock, can occur when chemical reactions involving hematite turn the rock from red to white, releasing iron and phosphate, and causing the black halos to form and providing an energy source for microbes.
David Flannery, an astrobiologist and member of the Perseverance science team from the Queensland University of Technology in Australia, said: “These spots are a big surprise. On Earth, these types of features in rocks are often associated with the fossilised record of microbes living in the subsurface.”
Nasa has hypothesised that the rock may have started as mud with organic compounds mixed in that eventually cemented into rock.
Later, water penetrated fissures in the rock, enabling mineral deposits that created the large white calcium sulphate veins seen today.
Morgan Cable, a Nasa scientist on the Perseverance mission, said: “We’ve never seen these three things together on Mars before.”
Nasa says that although the rock does seem to hold promise for ancient microbial life, it is impossible to know for sure without bringing samples back to Earth.
“We have zapped that rock with lasers and X-rays and imaged it literally day and night from just about every angle imaginable,” added Prof Farley.
“Scientifically, Perseverance has nothing more to give. To fully understand what really happened in that Martian river valley at Jezero Crater billions of years ago, we’d want to bring the Cheyava Falls sample back to Earth, so it can be studied with the powerful instruments available in laboratories.”
Perseverance has taken a sample of Cheyava Falls which will be collected and brought back to Earth for analysis under Nasa’s and the European Space Agency’s Mars Sample Return mission.
“We have designed the route for Perseverance to ensure that it goes to areas with the potential for interesting scientific samples,” said Nicola Fox, associate administrator for Nasa’s Science Mission Directorate in Washington DC.
“This trip through the Neretva Vallis riverbed paid off as we found something we’ve never seen before, which will give our scientists so much to study.”