NASA scientists said in a press release that the PERSEVERANCE rover has uncovered several rock samples containing puzzling organic material from an ancient river delta on Mars.
Scientists at the Mars Exploration Project explained that "the rocks contain the highest concentration of organic matter found so far, and those first samples collected and returned can answer a key question: Was life on Mars before?"
Analysis of the samples indicates that they feature a class of organic molecules associated with those of sulfate minerals (NASA)
Samples from the Martian delta
The NASA statement says that core rock samples have been collected from features within an area that scientists have long considered one of the best potential areas for finding signs of ancient microbial life.
The spacecraft collected 4 samples from an ancient river delta in Jezero crater, on the Red Planet, bringing the total number of scientifically significant rock samples collected to 12.
According to the statement, the "Presence" spacecraft is currently examining the sedimentary rocks of the delta, which were formed when particles of various sizes settled in an aquatic environment one day.
During its first scientific expedition, the spacecraft explored the crater floor, and found igneous rocks, which form in the depths of the earth from magma or during volcanic activity on the surface.
"The delta, with its various sedimentary rocks, differs from the igneous rocks that formed from the crystallization of magma discovered in the crater floor, and this juxtaposition provides us with a rich understanding of the geological history after the crater was formed," says Ken Farley of the California Institute of Technology (Caltech).
On the other hand, the NASA statement says that analysis of the samples indicates that they feature a class of organic molecules associated with those in sulfate minerals, and sulfate minerals found in sedimentary rock layers can give important information about the aquatic environments in which they formed.
Organic molecules consist of a variety of compounds composed primarily of carbon and other elements (NASA)
What is organic matter?
The NASA statement says that organic molecules are made up of a variety of compounds made up of carbon and usually include hydrogen and oxygen atoms, and can also contain other elements, such as nitrogen, phosphorous and sulfur.
While there are chemical processes that produce these molecules that do not require life, some of these compounds are the basic chemical building blocks of life, and their presence is a potential biosignature, and thus could be evidence of past life but may also have been produced without life.
On previous discoveries of the presence of organic matter on Mars, the NASA statement says that in 2013, the Curiosity rover found evidence of organic matter in rock powder samples.
But unlike the previous discovery, this latest discovery was made in an area where in the distant past sediments and salts were deposited in a lake under conditions in which life would have existed, the latest discovery has shown that organic matter is more abundant so far.
"The fact that organic matter has been found in such sedimentary rocks - which are known to preserve fossils of ancient life here on Earth - is important," Farley says. "However, we will have to wait until the sample is returned to Earth for an in-depth study."