http://www.jpl.nasa.gov/news/news.php?feature=4334
NASA Mission Provides Its First Look at Martian Upper Atmosphere
Jet Propulsion Laboratory
October 14, 2014
NASA's Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft has provided
scientists their first look at a storm of energetic solar particles at
Mars, produced unprecedented ultraviolet images of the tenuous oxygen,
hydrogen, and carbon coronas surrounding the Red Planet, and yielded a
comprehensive map of highly variable ozone in the atmosphere underlying
the coronas.
The spacecraft, which entered Mars' orbit Sept. 21, now is lowering its
orbit and testing its instruments. MAVEN was launched to Mars in November
2013, to help solve the mystery of how the Red Planet lost most of its
atmosphere.
All the instruments are showing data quality that is better than anticipated
at this early stage of the mission, said Bruce Jakosky, MAVEN principal
investigator at the University of Colorado, Boulder. All instruments
have now been turned on -- although not yet fully checked out -- and are
functioning nominally. It's turning out to be an easy and straightforward
spacecraft to fly, at least so far. It really looks as if we're headed
for an exciting science mission.
Solar energetic particles (SEPs) are streams of high-speed particles blasted
from the sun during explosive solar activity like flares or coronal mass
ejections (CMEs). Around Earth, SEP storms can damage the sensitive electronics
on satellites. At Mars, they are thought to be one possible mechanism
for driving atmospheric loss.
A solar flare on Sept. 26 produced a CME that was observed by NASA satellites
on both sides of the sun. Computer models of the CME propagation predicted
the disturbance and the accompanying SEPs would reach Mars on Sept. 29.
MAVEN's Solar Energetic Particle instrument was able to observe the onset
of the event that day.
After traveling through interplanetary space, these energetic particles
of mostly protons deposit their energy in the upper atmosphere of Mars,
said SEP instrument lead Davin Larson of the Space Sciences Laboratory
at the University of California, Berkeley. A SEP event like this typically
occurs every couple weeks. Once all the instruments are turned on, we
expect to also be able to track the response of the upper atmosphere to
them.
The hydrogen and oxygen coronas of Mars are the tenuous outer fringe of
the planet's upper atmosphere, where the edge of the atmosphere meets
space. In this region, atoms that were once a part of carbon dioxide or
water molecules near the surface can escape to space. These molecules
control the climate, so following them allows us to understand the history
of Mars over the last four billion years and to track the change from
a warm and wet climate to the cold, dry climate we see today. MAVEN observed
the edges of the Martian atmosphere using the Imaging Ultraviolet Spectrograph
(IUVS), which is sensitive to the sunlight reflected by these atoms.
With these observations, MAVEN's IUVS has obtained the most complete
picture of the extended Martian upper atmosphere ever made, said MAVEN
remote sensing team member Mike Chaffin of the University of Colorado,
Boulder. By measuring the extended upper atmosphere of the planet, MAVEN
directly probes how these atoms escape to space. The observations support
our current understanding that the upper atmosphere of Mars, when compared
to Venus and Earth, is only tenuously bound by the Red Planet's weak gravity.
IUVS also created a map of the atmospheric ozone on Mars by detecting
the absorption of ultraviolet sunlight by the molecule.
With these maps we have the kind of complete and simultaneous coverage
of Mars that is usually only possible for Earth, said MAVEN remote sensing
team member Justin Deighan of the University of Colorado, Boulder. On
Earth, ozone destruction by refrigerator CFCs is the cause of the polar
ozone hole. On Mars, ozone is just as easily destroyed by the byproducts
of water vapor breakdown by ultraviolet sunlight. Tracking the ozone lets
us track the photochemical processes taking place in the Martian atmosphere.
We'll be exploring this in more complete detail during MAVEN's primary
science mission.
There will be about two weeks of additional instrument calibration and
testing before MAVEN starts its primary science mission. This includes
an end-to-end test to transmit data between NASA's Curiosity rover on
the surface of Mars and Earth using the MAVEN mission's Electra
telecommunications
relay. The mission aims to start full science gathering in early to
mid-November.
MAVEN's principal investigator is based at the University of Colorado's
Laboratory for Atmospheric and Space Physics. The university provided
two science instruments and leads science operations, as well as education
and public outreach, for the mission. The University of California at
Berkeley's Space Sciences Laboratory also
