NASA’s Curiosity and Perseverance rovers will have to dig a little deeper on Mars to unearth signs of ancient life, researchers have found. Rovers designed to explore Mars have previously detected organic matter, but these were not sufficient evidence that life once thrived on the Red Planet. The discovery of traces of amino acids on Mars could be a potential sign of ancient life that may have existed on Earth billions of years ago, researchers believe.
Two rovers NASA has sent to explore Mars have been able to detect organic matter, but it has not been seen as concrete evidence that life once flourished on Earth. Scientists note that while amino acids can be produced by life and abiotic chemistry, finding traces of it on Mars could be a potential sign of ancient life. Terrestrial organisms use amino acids to build proteins, which are needed to make enzymes. These enzymes in turn regulate or speed up chemical reactions and make structures.
Now, using a NASA laboratory experiment, researchers have concluded that rovers may need to dig deeper to unearth evidence of possible past life on Mars.
Alexander Pavlov of NASA’s Goddard Space Flight Center in Greenbelt, Maryland, and the study’s lead author, said: “Our results show that amino acids are present in Martian surface rocks and regolith (loose solids). cosmic ray-damaged material above the planetary bedrock) at a much faster rate than previously thought.”
Pavlov added that the current Mars rover mission is to drill to about 5 centimeters below the Earth’s surface. At that depth, amino acids can be completely destroyed in as little as 20 million years, he said. This period is relatively small, as scientists are looking for traces of life that existed billions of years ago.
The research, published in the journal Astrobiology, suggests a new approach to mining tasks at shallow depths. “Shallow drill sampling missions have to look for recently exposed outcrops — such as recent microcraters less than 10 million years old or material ejected from them,” Pavlov said.
Organic molecules are destroyed by cosmic rays, high-energy particles produced by the sun or by powerful events in deep space. While Earth is protected from these rays due to its thick atmosphere and magnetic field, the same is not true of Mars. The Red Planet has a similar “shield,” but as the planet ages, it eventually loses its protection.
In the experiments, the team mixed certain types of amino acids, such as hydrated silica and perchlorate, and tried to mimic the conditions in Martian soil. The samples were sealed in test tubes under conditions similar to those on Mars. These samples were then exposed to gamma radiation to replicate the effects of cosmic rays.
“Our work is the first comprehensive study to investigate the destruction (radiolysis) of a broad range of amino acids under various Mars-related factors (temperature, water content, perchlorate abundance) and to compare radiolysis rates,” Said Pavlov.
Adding silicates, especially silicates and perchlorates, led to an increased rate of amino acid destruction, he added.