According to a new study based on an experiment aboard the International Space Station (ISS), NASA’s Mars rovers shouldn’t expect to spot biomarkers on the red planet’s surface that suggest ultraviolet radiation can destroy such molecules after only a year or less will degrade two.
Both curiosity and persistence To do this, use Raman spectrometers identify organic compounds and possibly biological molecules Mars‘ Pop up. A Raman spectrometer uses a laser to excite molecules, and then the way those excited molecules scatter light tells scientists what kind of molecules they are. In particular, they are sensitive to organic compounds, making them an important tool for both rovers.
However, new research International Space Station led by Mickael Baqué from the German Aerospace Center (DLR) doubts how useful the instruments could be on Mars. Due to its thin atmosphere and lack of magnetic shielding, Mars is inundated with a barrage of ultraviolet light The sunwhich can be harmful to biological cells.
Related: 12 amazing photos from the Perseverance rover’s first year on Mars
Baqué’s team exposed a sample of seven different types of biomolecules to Martian conditions for 469 days in the Biology and Mars Experiment (BIOMEX), installed on the Expose-R2 platform outside the ISS. Temperature, daily light cycles and ionizing radiation were adjusted to mimic Mars and the sample was placed between simulated Mars regolith.
The biomolecules involved in the experiment were all commonly found in organisms: 𝛃-carotene (which is an antioxidant and a pigment that responds to light), chlorophyllin (derived from the chlorophyll that plants use to process sunlight), naringenin (a common antioxidant). , quercetin (another common antioxidant), melanin (a pigment that provides protection from ultraviolet light), cellulose (a component of plant cell walls), and chitin (found in beetle skeletons).
Normally, Raman spectroscopy can detect all seven of these biomolecules. However, at the end of the experiment, Baqué’s team discovered that only three – chlorophyllin, quercetin and melanin – remained detectable and even their signal was attenuated by 30% to 50%. The ultraviolet light the molecules were exposed to had degraded them to the point that Raman spectroscopy could no longer detect them.
Importantly, the technique was still able to detect the biomolecules from a control sample that was shielded from radiation by deeper layers of regolith. These discoveries imply that Perseverance or future rover missions could still identify biomarkers buried in the surface.
“Ultraviolet [radiation] penetrates only the first few microns to millimeters of the Martian surface, so organic compounds and potential biomolecules should be protected beyond those depths,” Baqué told Space.com. (A micron is about 1% the width of a strand of hair; 1 millimeter is smaller than a grain of sand.) If you dig a little deeper, the Martian regolith should provide a decent shield from the radiation.
Meanwhile that of the European Space Agency Rosalind Franklin ExoMars Rover will bring a robotic drill to Mars that will be able to dig 6.6 feet (2 meters) deep into the surface. The launch of this rover was delayed because a Russian lander was scheduled to land it on the surface, and Europe will no longer cooperate with Russia because of his invasion of Ukraine. Even before a launch no earlier than 2028, the Rover Rosalind Franklin offers our best chance of finding life on Mars since the Viking missionssay scientists.
If the Rover Rosalind Franklin finds evidence of it microbial lifethen these microbes have evolved in a very harsh environment.
“The surface of Mars appears to be very harmful to organic compounds because of ultraviolet radiation, but also [because of] oxidative substances, and finally—but most importantly for long-term conservation over billions of years—ionizing radiation,” Baqué said.
Interestingly, the results differ from those of similar BIOMEX experiments in which intact organisms, both living and dead, were exposed to similar ultraviolet radiation conditions. These experiments revealed that biomolecules remain intact within the organism. Baqué said he attributed this discrepancy to life’s ability to protect its own cells.
“Just as regolith can protect directly exposed molecules from photodegradation by UV radiation, other cellular components in organisms can play the same role,” he said.
However, the results mean that Raman spectroscopy may play a smaller role in the search for Martian life, either partial or present, than scientists had anticipated. Baqué’s team concludes that all biomarkers on the surface would deplete within a few years, meaning that unless Mars is teeming with enough life to constantly replenish such biomarkers, the surface will appear dead — which is the true image may or may not be.
The research was published in Wednesday (September 7). scientific advances.
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