Orbital RHESSI - Manual

Mission Description
The Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) is a NASA Small Explorer
(SMEX) space observatory with a primary mission to explore the basic physics of particle acceleration
and explosive energy release in solar flares. RHESSI combines, for the first time, high-resolution imaging
in hard X-rays and gamma rays with high-resolution spectroscopy, allowing a detailed energy spectrum
to be obtained at each point of the image.
Orbital was responsible for the initial concept study, followed by the design and manufacture of the
spacecraft. Orbital also participated in the integration and test of the payload at the University of
California at Berkeley.
RHESSI was launched in February 2002 on an Orbital Pegasus ® XL rocket from Cape Canaveral
Air Force Station to begin a two-year mission. At the end of the two years, RHESSI’s net spacecraft
availability was 100 percent and the mission was extended. After more than ten years, RHESSI
continues to collect and download data.
Spacecraft
The spacecraft, derived from Orbital's LEOStar ™ -2 core design, provides a mature, reliable platform
with a VME-based modular architecture and a RAD6000 Central Processing Unit (CPU). The attitude
control functions include a spin control mode for adjustment of the vehicle spin rate to a commandable
value, and a normal mode to keep the spin axis pointed at the sun.
Placing the equipment deck, solar array wings, and the majority of the electronic components near the
spacecraft center of mass provides a symmetrically balanced, stable platform for the spin-stabilized
attitude control system.
• Launched February 5, 2002 on
an Orbital Pegasus XL from Cape
Canaveral Air Force Station, Florida
• 600 km circular, 38 ° inclination, Low
Earth Orbit mission
• RHESSI successfully completed its
two-year mission in March 2004 and
continues to collect on-orbit data
• The onboard instrument observes
and collects X-ray and gamma ray
emissions with an unprecedented
combination of high-resolution imaging
and spectroscopy
Customer:
University of California at Berkeley
FACTS AT A GLANCE
RHESSI
Space-based Solar Flare Observatory
Heliophysics
LEO
RHESSI in Orbital's Gilbert, Arizona satellite
manufacturing facility