several meters of the planet’s surface would be killed by lethal doses of cosmic radiation. In
2007, it was calculated that DNA and RNA damage by cosmic radiation would limit life on Mars
to depths greater than 7.5 metres below the planet’s surface. Therefore, the best potential
locations for discovering life on Mars may be at subsurface environments that have not been
studied yet. Disappearance of the magnetic field may played an significant role in the process
of Martian climate change. According to the valuation of the scientists, the climate of Mars
gradually transits from warm and wet to cold and dry after magnetic field vanished.
F. NASA’s recent missions have focused on another question: whether Mars held lakes or
oceans of liquid water on its surface in the ancient past. Scientists have found hematite, a
mineral that forms in the presence of water. Thus, the mission of the Mars Exploration Rovers
of 2004 was not to look for present or past life, but for evidence of liquid water on the surface
of Mars in the planet’s ancient past. Liquid water, necessary for Earth life and for metabolism as
generally conducted by species on Earth, cannot exist on the surface of Mars under its present
low atmospheric pressure and temperature, except at the lowest shaded elevations for short
periods and liquid water does not appear at the surface itself. In March 2004, NASA announced
that its rover Opportunity had discovered evidence that Mars was, in the ancient past, a wet
planet. This had raised hopes that evidence of past life might be found on the planet today. ESA
confirmed that the Mars Express orbiter had directly detected huge reserves of water ice at
Mars’ south pole in January 2004.
G. Researchers from the Center of Astrobiology (Spain) and the Catholic University of the North
in Chile have found an ‘oasis’ of microorganisms two meters below the surface of the Atacama
Desert, SOLID, a detector for signs of life which could be used in environments similar to
subsoil on Mars. “We have named it a ‘microbial oasis’ because we found microorganisms
developing in a habitat that was rich in rock salt and other highly hygroscopic compounds that
absorb water” explained Victor Parro, researcher from the Center of Astrobiology in Spain. “If
there are similar microbes on Mars or remains in similar conditions to the ones we have found
in Atacama, we could detect them with instruments like SOLID” Parro highlighted.
H. Even more intriguing, however, is the alternative scenario by Spanish scientists: If those
samples could be found to that use DNA, as Earthly life does, as their genetic code. It is
extremely unlikely that such a highly specialised, complex molecule like DNA could have
evolved separately on the two planets, indicating that there must be a common origin for
Martian and Earthly life. Life based on DNA first appeared on Mars and then spread to Earth,
where it then evolved into the myriad forms of plants and creatures that exist today. If this was
found to be the case, we would have to face the logical conclusion: we are all Martian. If not, we
would continue to search the life of signs.
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