UPDATE - February
05, 2002
HESSI SPACECRAFT SAFELY REACHES ORBITNASA'S
High Energy Solar Spectroscopic Imager, or HESSI, lifted off this afternoon from
Cape Canaveral Air Force Station, Fla. at 2:29 p.m. EST.
During its planned two-year
mission HESSI will study the secrets of how solar flares are produced in the Sun's
atmosphere.
Tucked
inside a Pegasus XL rocket, attached to the under belly of the Orbital Stargazer
L-1011 aircraft, the spacecraft was carried approximately 113 nautical miles east-southeast
of the Cape to an altitude of about 39,000 feet. The Pegasus drop occurred at
3:58 p.m. EST, and after a short powered sequence, delivered the 645-pound HESSI
spacecraft into a circular orbit 373 miles above the Earth, inclined at 38 degrees
to the equator. "We're
extremely thrilled to report the Pegasus drop went without a hitch," said
Frank Snow, HESSI Project Manager at NASA's Goddard Space Flight Center, Greenbelt,
Md. Controllers
at the University of California, Berkeley, made initial contact with the spacecraft
at 5:33 p.m. EST. HESSI
will help unlock some of the secrets of these gigantic explosions in the Sun's
atmosphere, providing scientists with the first high-fidelity color movies of
solar flares in X-rays and gamma rays, which is their highest energy emissions.
Scientists hope to capture hundreds of X-ray and gamma ray flares during the spacecraft's
planned two-year mission. Science
operations should begin in about three weeks, after germanium detectors inside
the X-ray/gamma-ray imaging spectrometer are cooled to their operating temperature
of minus 320 degrees Fahrenheit, turned on and checked out. HESSI
is the first NASA Small Explorer mission being managed in the 'principal investigator'
mode. Professor Robert Lin of the University of California, Berkeley, is responsible
for many aspects of the mission, including the science instrument, spacecraft
integration and environmental testing, and spacecraft operations and data analysis. The
HESSI scientific payload is a collaborative effort between the University of California,
Berkeley, NASA's Goddard Space Flight Center, the Paul Scherrer Institut in Switzerland,
and the Lawrence Berkeley National Laboratory in Berkeley. The mission also involves
scientific participation from France, Japan, The Netherlands, Scotland, and Switzerland. The
Explorers Program Office at Goddard manages the HESSI mission for NASA's Office
of Space Science in Washington, D.C. Spectrum Astro, Inc. of Gilbert, Ariz., constructed
the HESSI spacecraft and provided integration support. The
HESSI mission cost, including the spacecraft, science instrument, launch vehicle,
and mission operations and data analysis, is approximately $85 million.
HESSI
Spacecraft to Study Solar Flares NASA's
High Energy Solar Spectroscopic Imager (HESSI) is the sixth Small Explorers (SMEX)
mission, and the first one dedicated to studying the most powerful explosions
in our solar system - solar flares. These explosions fire solar gas, which gets
heated to tens of millions of degrees, causing it to sizzle with high-energy radiation
in the form of X-rays and gamma rays. HESSI
will be tucked inside a Pegasus XL rocket under the belly of Orbital Science's
Corporation's Stargazer L-1011 aircraft. The L-1011, scheduled to depart in the
afternoon of Feb. 5 from Cape Canaveral Air Force Station, Fla. will release the
Pegasus rocket carrying HESSI at about 3:26 p.m. EST. Once
spacecraft and instrument checkout is complete, HESSI will use its sole instrument
- an imaging spectrometer - to generate high-resolution spectrographic movies
of each flare's rapidly changing features as seen in X-rays and gamma rays. Detectors
aboard the spacecraft will count the number of X-ray and gamma ray photons passing
through pairs of grids, measuring their energies with exceptional precision. HESSI
is expected to provide scientists with the finest images and spectra ever made
using the gamma rays and the highest energy X-rays emitted by solar flares.
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| Image
1 | | Artist
concept of HESSI spacecraft with the Sun in background | The
HESSI mission falls under NASA's Sun-Earth Connection theme. Missions under this
theme focus on the physical processes that link the Sun and Earth. The
Explorers Program Office at NASA's Goddard Space Flight Center provides overall
management for the HESSI mission for NASA's Office of Space Science in Washington,
D.C. Dr.
Robert Lin of the University of California, Berkeley, is the Principal Investigator
for HESSI and is responsible for most aspects of the mission, including the instrument
and spacecraft, integration and testing, and operations and data analysis after
launch. Back
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