NASA’s Curiosity Mars rover Spending more than 13 years exploring the 3.5-billion-year-old Gale Crater, he slowly climbed the central hill known as Mount Sharp. Satellite data suggests that this formation may contain evidence of an ancient Martian ocean, and life where water once existed.
“We’re learning more about the recipe for what’s on Mars and whether it’s the right recipe for life,” Amy Williams, an astrobiologist, geobiologist and associate professor at the University of Florida, told Gizmodo. “We don’t know yet, but we’re building this story with that kind of information.”
Discovery of ancient organic chemistry on Mars
Based on orbital data, Williams and his colleagues knew that parts of Mount Sharp that preserved water evidence also contained clay minerals. This helped them find places to look for organic molecules, because clay is made up of charged particles that easily bind to organic matter and protect it.
“The goal was to find a place with enough clay minerals to do this experiment because we only had two opportunities to experiment on the rover, so we were trying to get it as right as possible,” Williams said.
That experiment used a chemical called tetramethylammonium hydroxide (TMAH) to break down larger, more complex organic molecules inside rocks collected by Curiosity. The rover usually doesn’t even analyze geological samples. Normally, he drills into the rock, puts the drill bits into a cup and heats them until they turn into gases. This technique, called advanced gas analysis, allows researchers must identify different materials in a sample based on the temperature at which they turn into a gas.
According to Williams, using TMAH instead could be beneficial. This chemical can break down larger, more complex molecules, which may be too large for Curiosity’s instruments to detect. However, only rover takes two cups of the TMAH chemical, so Williams’ team had to plan and carefully select the most convenient location. Their study area was located in the Glen Torridon region of Gale Crater.
Fortunately, the experiment was successful. Among the 20 different organic molecules they discovered was benzothiophene, a large, two-ring, sulfur-containing chemical that originated in the interstellar medium of the infant solar system, according to Williams. His team was the first to confirm that it was on Mars. Interestingly, benzothiophene is often delivered to the planets by meteorites Earth probably received life-giving molecules.
Curiosity discovered a nitrogen-carrying molecule that resembles indole, one of the many precursor molecules involved in making DNA. Although Williams and his colleagues did not get perfect confirmation of this, it was an interesting discovery.
“We don’t have DNA, we don’t have nucleobases, but this is the first time we’ve seen a nitrogen heterocycle like this on Mars, and it’s exciting to see the (precursor) component building blocks for life as we know it,” Williams said.
Deepening the search for extraterrestrial life
The in-situ detection of these organic molecules is promising, but more evidence will be needed to confirm whether life actually exists on Mars.
“If you want to be really confident in the detection of life beyond Earth, I think you need a lot of relevant evidence to come together to support that interpretation,” Williams said.
Mars samples would be returned to Earth give permission researchers must perform analyzes that NASA’s rovers cannot do, helping to confirm the true nature and origin of these organic molecules. Samples collected by NASA’s Perseverance rover were originally supposed to return to Earth in the early 2030s, but the mission effectively canceled due to schedule and cost overruns.
Williams and his colleagues still have a lot to learn as they sift through the mountain of data they collected with Curiosity. Now that they have validated the TMAH analysis technique, it will play an important role in future missions, including European Space Agency’s Rosalind Franklin Mars rover and NASA’s Dragonfly missionA moon of Saturn will send a rotor to explore Titan. Both missions are now set for to turn on In 2028.
“It’s exciting to perform the first experiment that will hopefully pave the way for incredible discoveries,” Williams said. “And who knows what next-generation tools and experiments will help us delve deeper into the history of these planets.”
