Press Release

RHESSI Satellite Completes Successful Second Year of Solar Flare Observation

By SpaceRef Editor
February 15, 2004
Filed under ,

The Reuven Ramaty High Energy
Solar Spectroscopic Imager (RHESSI) satellite has completed its second
successful year of on-orbit operations as one of NASA’s Sun-Earth Connection
missions. Since its launch on February 5, 2002, RHESSI has observed over
8,000 solar activity events. Spectrum Astro built the RHESSI spacecraft and
provided instrument integration support for the NASA Small Explorer Mission
managed by the NASA Goddard Spaceflight Center and the University of
California, Berkeley. Since its on-orbit checkout, the RHESSI Spacecraft
Availability for the support of its payload operations is 99.4%.

“RHESSI is a great example of how a relatively low-cost satellite can
achieve world-class science,” said W. David Thompson, Spectrum Astro President
and CEO. “We are very proud to have been involved with this very successful

In August 2003, RHESSI received the NASA Senior Review Panel’s highest
rating of any of the 14 Sun-Earth Connection (SEC) missions. The panel rated
the RHESSI program as “clearly superior” with “compelling science and
relevance to the SEC mission.”

RHESSI’s primary mission is to explore the basic physics of particle
acceleration and the explosive energy release in solar flares. RHESSI has
obtained many “first time” observations of solar processes. Some of its
important results include the first imaging of a flare in gamma-rays, the
discovery of strong polarization in a cosmic gamma-ray burst; the first
detection of continuous glow from the sun at 3-15 KeV energies; and the first
hard X-ray imaging spectroscopy of flares from thermal to non-thermal

RHESSI is the sixth Small Explorer (SMEX) mission and the first to be
managed in the “principal investigator” mode. Professor Robert P. Lin of the
University of California, Berkeley is the principal investigator for RHESSI,
responsible for instrument and spacecraft development, mission operations, and
data analysis. The Explorer Program Office at NASA’s Goddard Space Flight
Center in Greenbelt, MD provides program management and technical oversight
for the mission for NASA’s Office of Space Science in Washington.

Total mission cost for RHESSI is about $85 million, which includes the
spacecraft, science payload, launch vehicle, mission operations, and data

The RHESSI scientific payload is a collaborative effort among the
University of California, Berkeley; Goddard; the Paul Scherrer Institute in
Switzerland; and the Lawrence Berkeley National Laboratory in Berkeley. The
mission also involves additional scientific participation from France, Japan,
The Netherlands, Scotland, and Switzerland.

SpaceRef staff editor.