NASA finds diverse organics on Mars: What it means for the search for life beyond Earth

NASA’s Jet Propulsion Laboratory (JPL), which manages the mission, said the discovery of these organics “reinforces evidence that ancient Mars had the right chemistry to support life”. It added that the molecules join a growing list of compounds preserved in rocks despite billions of years of exposure to radiation on Mars, which can break them down over time.

According to a study published in Nature Communications on April 21, there are 21 carbon-containing molecules in the sample, including nitrogen heterocycles and benzothiophene, which are key compounds in prebiotic chemistry.

Soon after, the sample got the nickname ‘Mary Anning 3’, inspired by the English palaeontologist who discovered the first fossil ichthyosaur and plesiosaur. The fossils discovered by Anning in the 19th century were found in aquatic environments. Similarly, the molecules were found on the rocky surface of Mars, where lakes and streams could have existed a billion years ago. JPL officials, in a written statement, confirmed, “This oasis surged and dried up multiple times in the planet’s ancient past, eventually enriching the area with clay minerals, which are especially good at preserving organic compounds.”

Curiosity had earlier detected long-chain hydrocarbons, such as decane, undecane, and dodecane, adding to evidence of complex organic chemistry on Mars. These findings were made using the rover’s Sample Analysis at Mars (SAM) instrument.

The rover drills into rocks to collect powdered samples, which are then heated inside SAM’s onboard laboratory. The process releases gases that are analysed to determine their chemical composition.

SAM is equipped to conduct a “wet chemistry” analysis of the solvent in small cups. This method was deduced from the sample, Mary Anning 3. The substance was used to break apart the organic molecule. Since the molecule was valuable, Curiosity carried two cups. Mary Anning 3 was the first sample tested by the application of tetramethylammonium hydroxide (TMAH).

The verification of the molecule was confirmed on Earth by the use of a space rock, which is four billion years old and contains organic molecules, named the Murchison meteorite.

“A Murchison sample exposed to TMAH was found to break much larger molecules into some of the ones seen in Mary Anning 3, including benzothiophene. That result verifies that the Martian molecules found in Mary Anning 3 could have been generated from the breakdown of even more complex compounds relevant to life.” JPL explained and stated in a statement.

The last TMH cup was used on weblike boxwork ridges, whose formation was a result of ancient underground water. 2012 was the year when Curiosity landed on Mars and will provide a detailed analysis to substantiate the evidence that can prove life on Mars through further studies.

(This article has been curated by Salonee Kulkarni, who is an intern with The Indian Express)