NASA’s Mars rover should not expect to detect biomarkers on the Red Planet’s surface, according to a new study based on an experiment aboard the International Space Station (ISS) that suggests ultraviolet radiation will break up these molecules after just a year or two.
Both Curiosity of And the perseverance Use of a Raman spectrometer for Identification of organic compounds And maybe biological molecules? MarsSurface. Raman spectroscopy uses lasers to excite the particles, and then the way these particles scatter light tells scientists what kind of particles they are. In particular, it is sensitive to organic compounds, which is why it is a key tool for both roving compounds.
However, new research in International Space Station Led by Mickael Baqué of the German Aerospace Center (DLR), he questioned the usefulness of these instruments on Mars. Due to the thin atmosphere and lack of magnetic protection, Mars is bathed in a torrent of ultraviolet light coming from the sunwhich can be harmful to biological cells.
Baqué’s team exposed a sample of seven different types of biomolecule to Mars-like conditions for a 469-day Biology and Mars Experiment (BIOMEX), which was installed on the Expose-R2 platform outside the International Space Station. The temperature, daily light cycles, and levels of ionizing radiation were designed to mimic Mars, and the sample was placed among the simulated Martian regolith.
All the biomolecules involved in the experiment were commonly present in living organisms: carotene (an antioxidant and a pigment that responds to light), chlorophyllin (a derivative of chlorophyll plants used to process sunlight), naringin (a common antioxidant), quercetin (an antioxidant Other common ones), melanin (a pigment that provides protection from UV rays), cellulose (a component of the cell walls of plants) and chitin (found in the skeletons of insects).
Normally, a Raman spectrometer 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 signals were weakened by 30% to 50%. The ultraviolet light to which the molecules were exposed degraded them to such an extent that the Raman spectrometer was unable to identify them.
Importantly, this technique was still able to detect biomolecules from a control sample that was shielded from radiation by deeper layers of the regolith. These discoveries indicate that persistence or future rover missions can still identify biomarkers buried in the surface.
“ultraviolet [radiation] It only penetrates the first few micrometers to millimeters of the surface of Mars, so organic compounds and potential biomolecules must be shielded outside these depths.” Smaller than a grain of sand.) Dig a little deeper, and the Martian regolith should provide an adequate shield from radiation.
Meanwhile, ESA Rosalind Franklin ExoMars The rover will take a robotic drill to Mars capable of drilling 6.6 feet (2 meters) into the surface. The launch of this rover was postponed because a Russian lander was to deposit it on the surface, and Europe will no longer cooperate with Russia because of its invasion of Ukraine. Even in the face of launch no later than 2028, the rover Rosalind Franklin advances Best chance to find life on Mars Ago Vikings missionsScientists say.
If you find Rosalind Franklin’s cart proof of that microbial lifethose microbes would have evolved in a very harsh environment.
The surface of Mars appears to be very harmful to organic compounds due to ultraviolet radiation, but also [because of] Oxidizing materials and finally – but most importantly for long-term preservation across billions of years – ionizing radiation,” Paquet said.
Interestingly, the results differ from those of similar BIOMEX experiments that exposed healthy organisms, both live and dead, to similar conditions bathed in ultraviolet light. Those experiments found that biomolecules inside an organism remain intact. Paquet said he attributes this discrepancy to life’s ability to protect its own cells.
“Just as the regolith can protect directly exposed molecules from UV-induced photolysis, other cellular components can play the same role in living organisms,” he said.
However, the results mean that the Raman spectrometer may play a lesser role in the search for Martian life, in part or present, than scientists expected. Baqué’s team concluded that any biomarkers on the surface would decay within a few years at most, meaning that unless Mars was teeming with enough life to constantly replenish these biomarkers, the surface would appear dead – which may or may not be the real picture.
The research was published on Wednesday (September 7) in science progress.