Mars, organic molecules found at the bottom of an ancient lake: proof of life?

Credits: NASA/JPL-Caltech/MSSS

The discovery of organic molecules is mentioned in a new article published on the NASA site a few hours ago, in connection with the discoveries made thanks to the Perseverance rover. The latter, which landed on the red planet on July 30, 2020, is indeed collecting several rock samples during what is its second scientific campaign.

Jezero Crater

Sample collection takes place in an area within Jezero Crater. This is an ancient river delta and one of the most interesting areas that NASA scientists themselves have carefully chosen because it offers the best chance of finding “scientifically excellent samples”, as Thomas Zurbuchen, one of the NASA officials in Washington, calls them.
According to Zurbuchen, Perseverance’s first two science campaigns produced an incredible variety of samples, some of which could then be returned to Earth via another mission called Mars Sample Return (in which the European Space Agency will also participate).

Samples taken by Perseverance

The Jezero crater, which has a diameter of about 45 km, contains the presence of an ancient fan-shaped river delta formed about 3.5 billion years ago. In this region, in very ancient times, there was a river that flowed into a lake. The samples taken from Perseverance were formed in this aquatic environment from sedimentary igneous rocks that formed at shallow depths as a result of surface volcanic activity.

Presence of organic molecules

These days, Perseverance is particularly interested in a rock about a meter wide that was formed billions of years ago when sand and mud settled on the bottom of a salt lake. under the effect of water evaporation. Using an instrument called Scanning Habitable Environments with Raman & Luminescence for Organics & Chemicals, or SHERLOC, researchers found that some of the samples analyzed are characterized by the presence of organic molecules. These are molecules inside which there are various compounds consisting mainly of carbon, hydrogen and oxygen. The presence of these organic molecules can be considered as a “biosignature”, that is to say a possible trace of past life.

Difference with previous results

This isn’t the first time organic matter has been found in samples of Martian dust and rock. The Curiosity rover had already found such traces in 2013. However, this time the discovery was made at the bottom of an ancient lake, that is, in a place where there was a lot of water. And we know that water is essential to life. Is the presence of organic molecules, which can anyway be formed by non-biological activities, in this precise place a mere coincidence? It is only when the samples arrive on Earth that in-depth studies can be carried out, which will probably allow this doubt to be dispelled. So we just have to wait.

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