Durable spacecraft marks 10 years exploring processes that createthe aurora (Forwarded)

Bill Steigerwald / Ed Campion
NASA Goddard Space Flight Center, Greenbelt, Md Sept. 12, 2006
301 286 5017 / 0697

Release 06-74

DURABLE SPACECRAFT MARKS 10 YEARS EXPLORING PROCESSES THAT CREATE THE
AURORA

After more than 10 years and 40,000 orbits, a resilient NASA satellite
continues to unveil the mysteries of the Earth's aurora borealis and
australis, also known as the northern and southern lights.

The Fast Auroral SnapshoT (FAST) satellite was launched from Vandenberg
Air Force Base in California, on August 21, 1996, into a near polar
orbit. "In many aspects, the FAST mission has revolutionized our view
of the aurora," said Dr. Charles W. Carlson, FAST Principal
Investigator, University of California, Berkeley.

The energy source that creates the aurora originates from the solar
wind, an electrically charged gas (plasma) released by the sun that
impacts the Earth's magnetic field. This energy ultimately sets up
electric fields in space that accelerate electrically charged particles
trapped in the Earth's magnetic field. The particles slam into the
upper atmosphere above the polar regions, generating the dynamic and
beautiful glow we know as the aurora.

The solar wind can do more than put on a pretty light show. The
brightest aurora are a manifestation of solar storms that disrupt
satellites, radio communication, and power plants. Understanding the
aurora and other effects of solar storms will help people mitigate these
disruptions.

Important discoveries by the FAST team include identification of an
"invisible" aurora, not detectable with previous instrumentation, in the
form of upward-moving electron beams. These beams explain how the
auroral electrical current "returns" to space. This invisible aurora is
not detectable on the ground, and systematic detection by FAST
established it as a fundamental feature of the aurora. FAST also
detected electron solitary waves within these upward-moving electron
beams, a discovery that motivated an intense theoretical effort to
explain this new phenomena. Solitary waves are low-density bubbles in
the charged gas that form due to intense instabilities caused by the
beams.

The FAST team was able to solve a long-standing problem of what produces
the intense radio emissions from Earth known as Auroral Kilometric
Radiation. These are the most powerful naturally-occurring radio waves
beamed into space by our planet. Since similar radiation is observed
from Jupiter, this discovery also provides the observational evidence to
understand Jupiter's aurora.

A third achievement of the FAST team was the discovery of a new type of
aurora powered by intense plasma waves. These waves occur at the most
poleward boundaries of the auroral regions and produce some of the most
intense auroral displays. This wave-powered aurora also produces the
most intense outflows of positively charged atoms (mostly hydrogen and
oxygen), and the highest flows of counter-streaming electrons observed
near the Earth.

The spacecraft was designed, built, and tested at NASA's Goddard Space
Flight Center in Greenbelt, Md. Instruments were provided by the
University of California, Berkeley, with contributions from the
University of California, Los Angeles, the University of New Hampshire,
and Lockheed Martin, Palo Alto, California. "FAST was designed for a
one-year lifetime," said Dr. Robert Pfaff, FAST Project Scientist at
NASA Goddard. "Because of anticipated radiation damage, the satellite
was not expected to last more than a few years. FAST's longevity is a
credit to the scientists and engineers who built the satellite, and to
the operations team that has kept the satellite running."

The FAST satellite has collected over five terabytes of data. Its
observations have demonstrated the ubiquitous role of particle
acceleration by parallel electric fields in nature, with important
consequences for planetary, solar, and astrophysical bodies. "Due to its
scientific productivity and key role in NASA's current "Great
Observatory" program of satellite platforms in the solar system, NASA
has recently extended the operations of the FAST mission to 2008," said
Pfaff. FAST is funded by NASA Headquarters and is administered by the
Explorer Satellite program at Goddard. For images, refer to:
http://www.nasa.gov/vision/universe/...fast_10yr.html