Is there life on Mars?(11)
2023-05-30 来源:百合文库
Previous attempts to study organic molecules on Mars have been plagued by the presence of chemicals called perchlorates. These were first seen in 2008, by NASA’s Phoenix lander, and were confirmed by Curiosity half a decade later. Those missions baked their Martian samples in ovens, to release the organics. That also released chlorine and oxygen from the perchlorates, and these oxidised most of the organic molecules present. moma will circumvent this problem by using an ultraviolet laser that will knock organic molecules off rock samples so fast that any perchlorates present will not have time to decompose.
Rosalind Franklin’s most important tool, however, will be a drill that can collect samples from two metres below the surface. This is crucial for recovering material in which organic molecules can be found in a good state of preservation. The thin Martian atmosphere is easily penetrated by ionising radiation from space. This slams into the surface and even penetrates a little way beneath. As Jorge Vago, ExoMars’s lead scientist, observes, “Over many millions of years, this ionising radiation acts like gazillion little knives slowly cutting away the functional groups of the organic molecules you would like to hopefully discover.” Use a drill to go deep enough, though, and any material collected will have been protected from radiation by several metres of rock. ESA’s modelling suggests that samples from 1.5 metres down would be scientifically interesting. The deepest any mission has so far sampled under the surface of Mars is a few centimetres.
Rosalind Franklin’s most important tool, however, will be a drill that can collect samples from two metres below the surface. This is crucial for recovering material in which organic molecules can be found in a good state of preservation. The thin Martian atmosphere is easily penetrated by ionising radiation from space. This slams into the surface and even penetrates a little way beneath. As Jorge Vago, ExoMars’s lead scientist, observes, “Over many millions of years, this ionising radiation acts like gazillion little knives slowly cutting away the functional groups of the organic molecules you would like to hopefully discover.” Use a drill to go deep enough, though, and any material collected will have been protected from radiation by several metres of rock. ESA’s modelling suggests that samples from 1.5 metres down would be scientifically interesting. The deepest any mission has so far sampled under the surface of Mars is a few centimetres.
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