NASA's THEMIS Mission Launches to Study Geomagnetic Substorms (Forwarded)

Dwayne Brown/Tabatha Thompson
Headquarters, Washington Feb. 17, 2007
202-358-1726/3895

George H. Diller
Kennedy Space Center, Fla.
321-867-2468

RELEASE: 07-47

NASA'S THEMIS MISSION LAUNCHES TO STUDY GEOMAGNETIC SUBSTORMS

CAPE CANAVERAL, Fla. -- NASA's THEMIS mission successfully launched
Saturday, Feb. 17, at 6:01 p.m. EST from Pad 17-B at Cape Canaveral
Air Force Station, Fla.

THEMIS stands for the Time History of Events and Macroscale
Interactions during Substorms. It is NASA's first five-satellite
mission launched aboard a single rocket. The spacecraft separated
from the launch vehicle approximately 73 minutes after liftoff. By
8:07 p.m. EST, mission operators at the University of California,
Berkeley, commanded and received signals from all five spacecraft,
confirming nominal separation status.

The mission will help resolve the mystery of what triggers geomagnetic
substorms. Substorms are atmospheric events visible in the Northern
Hemisphere as a sudden brightening of the Northern Lights, or aurora
borealis. The findings from the mission may help protect commercial
satellites and humans in space from the adverse effects of particle
radiation.

THEMIS' satellite constellation will line up along the Sun-Earth line,
collect coordinated measurements, and observe substorms during the
two-year mission. Data collected from the five identical probes will
help pinpoint where and when substorms begin, a feat impossible with
any previous single-satellite mission.

"The THEMIS mission will make a breakthrough in our understanding of
how Earth's magnetosphere stores and releases energy from the sun and
also will demonstrate the tremendous potential that constellation
missions have for space exploration," said Vassilis Angelopoulos,
THEMIS principal investigator at the University of California,
Berkeley. "THEMIS' unique alignments also will answer how the
sun-Earth interaction is affected by Earth's bow shock, and how
'killer electrons' at Earth's radiation belts are accelerated."

The Mission Operations Center at the University of California,
Berkeley, will monitor the health and status of the five satellites.
Instrument scientists will turn on and characterize the instruments
during the next 30 days. The center will then assign each spacecraft
a target orbit within the THEMIS constellation based on its
performance. Mission operators will direct the spacecraft to their
final orbits in mid-September.

During the mission the five THEMIS satellites will observe an
estimated 30 substorms in process. At the same time, 20 ground
observatories in Alaska and Canada will time the aurora and space
currents. The relative timing between the five spacecraft and ground
observations underneath them will help scientists determine the
elusive substorm trigger mechanism.

"I am proud to manage the fifth medium class mission of the Explorer
Program," said Willis S. Jenkins, the THEMIS program executive. "As
we seek the answer to a compelling scientific question in geospace
physics, we are keeping up the tradition that began with Explorer I."

NASA's Launch Services Program at the Kennedy Space Center was
responsible for the launch of THEMIS aboard a Delta II rocket. The
United Launch Alliance, Denver, provided launch service.

For additional information about THEMIS, news media should contact
Cynthia O'Carroll, Goddard Space Flight Center, Md., at 301-286-4647
or Robert Sanders, University of California, Berkeley, at
510-643-6998.

The Explorer Program Office at Goddard manages the NASA-funded THEMIS
mission. The Space Sciences Laboratory at the University of
California, Berkeley, is responsible for project management, space
and ground-based instruments, mission integration, mission operations
and science. Swales Aerospace, Beltsville, Md., built the THEMIS
probes. THEMIS is an international project conducted in partnership
with Germany, France, Austria and Canada.

For more information about the THEMIS mission and imagery on the Web,
visit:

http://www.nasa.gov/themis