[meteorite-list] NASA's MAVEN Mission Identifies Links in Chain Leading to Atmospheric Loss

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Wed, 17 Dec 2014 10:47:05 -0800 (PST)
Message-ID: <201412171847.sBHIl5rN003024_at_zagami.jpl.nasa.gov>

http://www.nasa.gov/press/goddard/2014/december/nasa-s-maven-mission-identifies-links-in-chain-leading-to-atmospheric-loss/

December 15, 2014
RELEASE 14-042

NASA's MAVEN Mission Identifies Links in Chain Leading to Atmospheric Loss

Early discoveries by NASA's newest Mars orbiter are starting to reveal
key features about the loss of the planet's atmosphere to space over time.
The findings are among the first returns from NASA's Mars Atmosphere and
Volatile Evolution (MAVEN) mission, which entered its science phase on
Nov. 16. The observations reveal a new process by which the solar wind
can penetrate deep into a planetary atmosphere. They include the first
comprehensive measurements of the composition of Mars' upper atmosphere
and electrically charged ionosphere. The results also offer an unprecedented
view of ions as they gain the energy that will lead to their to escape
from the atmosphere.

"We are beginning to see the links in a chain that begins with solar-driven
processes acting on gas in the upper atmosphere and leads to atmospheric
loss," said Bruce Jakosky, MAVEN principal investigator with the Laboratory
for Atmospheric and Space Physics at the University of Colorado, Boulder.
"Over the course of the full mission, we'll be able to fill in this picture
and really understand the processes by which the atmosphere changed over
time."

On each orbit around Mars, MAVEN dips into the ionosphere - the layer
of ions and electrons extending from about 75 to 300 miles above the surface.
This layer serves as a kind of shield around the planet, deflecting the
solar wind, an intense stream of hot, high-energy particles from the sun.

Scientists have long thought that measurements of the solar wind could
be made only before these particles hit the invisible boundary of the
ionosphere. MAVEN's Solar Wind Ion Analyzer, however, has discovered a
stream of solar-wind particles that are not deflected but penetrate deep
into Mars' upper atmosphere and ionosphere.

Interactions in the upper atmosphere appear to transform this stream of
ions into a neutral form that can penetrate to surprisingly low altitudes.
Deep in the ionosphere, the stream emerges, almost Houdini-like, in ion
form again. The reappearance of these ions, which retain characteristics
of the pristine solar wind, provides a new way to track the properties
of the solar wind and may make it easier to link drivers of atmospheric
loss directly to activity in the upper atmosphere and ionosphere.

MAVEN's Neutral Gas and Ion Mass Spectrometer is exploring the nature
of the reservoir from which gases are escaping by conducting the first
comprehensive analysis of the composition of the upper atmosphere and
 ionosphere. These studies will help researchers make connections between
the lower atmosphere, which controls climate, and the upper atmosphere,
where the loss is occurring.

The instrument has measured the abundances of many gases in ion and neutral
forms, revealing well-defined structure in the upper atmosphere and ionosphere,
in contrast to the lower atmosphere, where gases are well-mixed. The variations
in these abundances over time will provide new insights into the physics
and chemistry of this region and have already provided evidence of significant
upper-atmospheric "weather" that has not been measured in detail before.

New insight into how gases leave the atmosphere is being provided by the
spacecraft's Suprathermal and Thermal Ion Composition (STATIC) instrument.
Within hours after being turned on at Mars, STATIC detected the "polar
plume" of ions escaping from Mars. This measurement is important in determining
the rate of atmospheric loss.

As the satellite dips down into the atmosphere, STATIC identifies the
cold ionosphere at closest approach and subsequently measures the heating
of this charged gas to escape velocities as MAVEN rises in altitude. The
energized ions ultimately break free of the planet's gravity as they move
along a plume that extends behind Mars.

The MAVEN spacecraft and its instruments have the full technical capability
proposed in 2007 and are on track to carry out the primary science mission.
The MAVEN team delivered the spacecraft to Mars on schedule, launching
on the very day in 2013 projected by the team 5 years earlier. MAVEN was
also delivered well under the confirmed budget established by NASA in
2010.

The team's success can be attributed to a focused science mission that
matched the available funding and diligent management of resources. There
were also minimal changes in requirements on the hardware or science capabilities
that could have driven costs. It also reflects good coordination between
the principal investigator; the project management at NASA's Goddard Space
Flight Center; the Mars Program Office at NASA's Jet Propulsion Laboratory
in Pasadena, California; and the Mars Exploration Program at NASA Headquarters.

The entire project team contributed to MAVEN's success to date, including
the management team, the spacecraft and science-instrument institutions,
and the launch-services provider.

"The MAVEN spacecraft and its instruments are fully operational and well
on their way to carrying out the primary science mission," said Jim Green,
director of NASA's Planetary Science Division at NASA Headquarters in
Washington. "The management team's outstanding work enabled the project
to be delivered on schedule and under budget."

MAVEN's principal investigator is based at the University of Colorado's
Laboratory for Atmospheric and Space Physics in Boulder, and NASA's Goddard
Space Flight Center in Greenbelt, Maryland, manages the mission.

For more information about NASA's MAVEN mission, visit: http://www.nasa.gov/maven

Nancy Neal-Jones
NASA's Goddard Space Flight Center, Greenbelt, Maryland
301-286-0039
nancy.n.jones at nasa.gov

Elizabeth Zubritsky
NASA's Goddard Space Flight Center, Greenbelt, Maryland
301-614-5438
elizabeth.a.zubritsky at nasa.gov
Received on Wed 17 Dec 2014 01:47:05 PM PST