Curiosity Mars rover hands in homework and gets top marks
On 6 August 2012, the most
technically advanced geochemistry
laboratory ever sent to the surface of
another planet arrived at Mars. The
audacity of the landing, which
involved using a hovering 'sky-crane'
to lower the car-sized Mars rover to
the ground, captured the world's
attention.
After 100 Martian days, each of
which lasts approximately 24 hours
40 minutes, all of Curiosity's ten
instruments had been tested and
calibrated. Then the real work began.
It included firing Curiosity's unique
laser system more than 10,000 times.
Each blast* vaporises a small layer of
rock or soil that the ChemCam
instrument can then analyse.
Typically, the laser is fired 30 to 50
times for each spot. This allows
deeper and deeper portions of the
surface to be unveiled and measured.
In soils it can be to depths of a few
millimetres; in rocks, the depth
reached is shallower at just a few tens
of micrometres.
During its first year, Curiosity has
been busy driving around inside Gale
Crater, the large 154 kilometres-wide
impact crater where it was placed. It
has concentrated on analysing
materials that look as if they were
laid down in an aqueous
environment, long ago in Mars's
history.
Two notable locations that Curiosity
stopped to analyse were a rock called
Jake_M that was simply lying on the
plain, and a wind-blown
accumulation of sand and silt dubbed
Rocknest. But the most intriguing part
of Curiosity's first year is the one
involving the search for organic
molecules.
In November last year, the media
exploded with speculation about a
'historic' detection . It turned out to
revolve around the possible detection
of 'organic' molecules.
In this case, organic means chemical
compounds made from carbon
bonded to hydrogen. They are
essential for life, but not necessarily
evidence of life because such
molecules can be built from simple
chemical reactions.
Organic compounds are widespread
throughout the cosmos but as yet
there has not been a definitive
detection of them on Mars. This could
be because the chemical environment
on Mars is so hostile towards these
fragile molecules.
As these official results make clear,
Curiosity has indeed detected some
evidence of organic molecules on
Mars. But - and it is a big but – no
one can yet be sure whether it is
contamination brought from Earth
aboard the spacecraft, the result of
meteorites containing organic
compounds falling to Mars, or the
genuine detection of long-lived
organics in the Martian soil.
Only time and the testing of more
samples will allow such a
determination to be made.
In the meantime, Curiosity is driving
towards Mt Sharp in the middle of
Gale crater. Once there, it will begin
to climb the shallow slopes, analysing
the various rock layers on its way.
The scientists hope that the variation
of composition with altitude will tell
them the climate history of Mars and
show whether or not it was once a
world on which life may have
thrived.
All in all, the mission could not have
had a better first year. The five
papers that detail the results are
published online in Science
magazine.
