The first really high-precision measurements of the composition of
Mars' atmosphere suggest that the Red planet's atmosphere was much
thicker than it is today, researchers, including an Indian origin
scientist, say.
New findings from NASA's Curiosity rover provide clues to how
Mars lost its original atmosphere, which scientists believe was much
thicker than the one left today.
"The beauty of these measurements lies in the fact that these are
the first really high-precision measurements of the composition of
Mars' atmosphere," said Sushil Atreya, professor of atmospheric, oceanic
and space sciences at the University of Michigan.
Atreya is co-author of two related papers published in the
journal Science, and co-investigator on Curiosity's Sample Analysis at
Mars (SAM) suite of instruments, considered the rover's cornerstone lab.
SAM measured the abundances of different gases and isotopes in samples of Martian air, according to NASA.
Isotopes are variations of the same chemical element that contain
different numbers of neutrons, such as the most common carbon isotope,
carbon-12, and a heavier stable isotope, carbon-13, which contains an
additional neutron.
SAM analysed the ratios of heavier to lighter isotopes of carbon
and oxygen in the carbon dioxide that makes up most of Mars' atmosphere
today.
Measurements showed that heavy isotopes of carbon and oxygen were
more abundant in today's thin atmosphere compared with the proportions
in the raw material that formed the planet (which scientists can deduce
from proportions in the Sun and other parts of the solar system).
This provides not only supportive evidence for the loss of much
of Mars' original atmosphere, but also gives clues to how the loss
occurred. It suggests that the planet's atmosphere escaped from the top,
rather than due to the lower atmosphere
interacting with the ground, NASA's said.
"The isotope data are unambiguous and robust, having been
independently confirmed by the quadrupole mass spectrometer and the
tunable laser spectrometer, two of the SAM suite instruments," Atreya
said.