U.S. Water News Online
KIRUNA, Sweden (EUROPEAN SPACE AGENCY) -- Recent results
from the ASPERA-3 instrument on board Mars Express confirm that a
very efficient process is at work in the Martian atmosphere which
could explain the loss of water. Water is believed to have once been
abundant on the Red Planet. Professor Rickard Lundin, leader of the
ASPERA-3 team, describes these findings in a paper published in the
latest issue of 'Science.'
Mars is bombarded by a flood of charged particles from the Sun,
commonly called the 'solar wind' and consisting of electrons and
alpha particles. The solar wind erodes the atmosphere of Mars, and is
believed to have stripped away a large amount of water that was
present on the planet about 3.8 billion years ago. Geological
evidence, as recently confirmed by images from the High Resolution
Stereo Camera (HRSC) onboard Mars Express, indicates that water flows
and even an ocean in the Northern hemisphere shaped the surface of
Today, water still exists on the Red Planet, but less than in the
past. Observations made earlier this year by the OMEGA instrument on
Mars Express showed that Mars has vast fields of perennial water ice,
stretching out from its south pole.
The ASPERA-3 instrument on board Mars Express aims to answer the
question of whether the solar wind interaction with the upper
atmosphere of Mars contributes to the depletion of water. It is
measuring a process called 'solar wind scavenging', or the slow
'invisible' escape of volatile gases and liquid compounds which make
up the atmosphere and hydrosphere of a planet.
Using plasma spectrometers and a special imager to detect
energetic neutral atoms, ASPERA-3 is making global and simultaneous
measurements of the solar wind, the inflow of energetic particles,
and also the 'planetary wind,' which is the outflow of particles from
the Martian atmosphere and ionosphere.
Aspera 3 has established that the solar wind penetrates through
the ionosphere and very deeply into the Martian atmosphere down to an
altitude of 270 kilometers. This seems to be the reason for the
acceleration processes that cause the loss of atmosphere on Mars.
A paper describing the results, by Professor Rickard Lundin and
his collaborators has published in 'Science.' Professor Rickard
Lundin and Dr Stas Barabash from the Swedish Institute for Space
Physics in Kiruna, Sweden, are the leading scientists responsible for
the ASPERA-3 instrument, which results from collaboration with 15
other research groups in ten different countries.
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