When I was a young man
with less than 500 million years ago, Mars suffered a catastrophe that hung its
magnetic field, leave it exposed to strong solar winds and caused him to lose
most of its atmosphere. This is the most plausible story for children on the
planet, according to the latest findings of the rover Curiosity.
The conclusion is in
two studies published today in the journal "Science" that reveal with
unprecedented precision the composition of air on Mars.
Already suspected that
the planet had lost air in the past, but by analyzing in detail the composition
of different gases, scientists realized that the initial atmospheric erosion
was much more abrupt than previously thought, and then it subsided.
After being born with a
thick atmosphere with pressure hundreds of times larger than Earth, Mars
quickly lost almost all its air and became, perhaps, like our planet. The
erosion continued, however, and today the Martian air is so thin that its pressure
is less than one hundredth of that on Earth's surface.
Scientists were able to
deduct this loss history of atmosphere because the lighter atoms of a gas are
concentrated at the top of the atmosphere, and the solar wind pushes them off
the planet with greater ease. The proportion of argon gas to atomic weight 36
to 40 atomic weight of argon with, for example, was greater before the air
erode.
Scientists still debate
what may have caused this loss of atmosphere so sudden, and this must have to
do with the planet's magnetic field, which depended on a flow of magma inside.
If this magma has solidified, magnetism faded and left the planet exposed to
the solar wind, which was strong at that time. Another possibility is to have a
large impact destabilized the flow of magma.
For Paul Mahaffy,
leader of one of the studies, impacts with asteroids and comets may have
realized narrow down old Martian atmosphere.
Curiosity's mission is
to investigate the possibility of Mars has had conditions favorable to life in
the past, but it is not yet clear whether the history of early loss of the
planet's atmosphere is good news or bad for it.
Certainly, it is not an
obstacle, because at least for a while the atmospheric pressure of the planet
was adequate to maintain liquid water, whose flow left signs on rocks.
"The question is how long this lasted water," said Mahaffy Folha.
"It is plausible that it has persisted a long time under an atmosphere not
as heavy as the original."
Chris Webster, head of
NASA's another study out today, was optimistic. Even the atmosphere of Mars has
been reduced to one tenth of its original size at the beginning, says she would
still have a reasonable value, and only over time have been shortened to the
current value.
"There was a period
in which the atmosphere of Mars was similar to ours, and there was liquid
water," he says. "You have to take into account, of course, that the
surface of Mars is very cruel, very ultraviolet radiation, but below the
surface there is the possibility that there was a lot of ingredients necessary
for life."
These mild conditions,
however, would be with the days since the end of the magnetic field of Mars
would continue to lose atmosphere and pressure.
In November, NASA will
send a probe to Mars Maven, which will investigate the current rate of
atmospheric loss.
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