GILBERT, Ariz., Feb. 14 -- The high-energy solar spectroscopic imager (HESSI) spacecraft, a NASA Goddard Small Explorer mission, was launched last week to investigate the physics of particle acceleration and energy release in solar flares. The spin-stabilized spacecraft was designed and developed by Spectrum Astro. The University of California, Berkeley, the mission's prime contractor, developed the HESSI payload and led observatory integration and testing. HESSI is a sun-pointed, inertial spinner spacecraft that will orbit at an altitude of 600 km, inclined at 38 degrees. The UCB payload will observe x-ray and Gamma-ray emissions in solar flares with an unprecedented combination of high-resolution imaging and spectroscopy, Spectrum Astro said.