High Energy Transient Explorer 1 (HETE-1) was a NASA astronomical satellite with international participation (mainly Japan and France). History The concept of a satellite capable of multi-wavelength observations of gamma-ray bursts (GRB) was discussed at the Santa Cruz, California meeting on GRBs in 1981. In 1986, the first realistic implementation of the HETE concept by a Massachusetts Institute of Technology MIT-led International Team was proposed. This concept, which was adopted, emphasized accurate locations and multi-wavelength coverage as the primary scientific goals for a sharply-focused small satellite mission which would ultimately solve the gamma-ray burst mystery. In 1989, NASA approved funding for a low-cost "University Class" explorer satellite to search for GRBs. In 1992, the HETE-1 program was funded, and the design and construction of HETE-1 began. The original spacecraft contractor for HETE-1 was AeroAstro, Inc., of Herndon, Virginia. AeroAstro was responsible for the spacecraft bus, including power, communications, attitude control, and computers. The instrument complement for HETE-1 consisted of four wide-field gamma-ray detectors, supplied by the CESR of Toulouse, France. A wide-field coded-aperture X-ray imager, supplied by a collaboration of Los Alamos National Laboratory (LANL) and the Institute of Chemistry and Physics (RIKEN) of Tokyo, Japan. Four wide-field near-UV CCD cameras, supplied by the Center for Space Research at the Massachusetts Institute of Techology. Due to the tragic fate of HETE-1 and the continuing timeliness of GRB science, NASA agreed to a reflight of the HETE-1 satellite, using flight spare hardware from the first satellite. In July 1997, funding for a second HETE satellite was granted, with a target launch date early 2000. Mission The prime objective of HETE-1 was to carry out the first multi-wavelength study of GRBs with ultraviolet (UV), X-ray, and gamma-ray instruments mounted on a single, compact spacecraft. A unique feature of the HETE-1 mission was its capability to localize GRBs with ~10 arcseconds accuracy in near real time aboard the spacecraft, and to transmit these positions directly to a network of receivers at existing ground-based observatories enabling rapid, sensitive follow-up studies in the radio, infrared (IR), and visible light bands. Spacecraft The satellite bus for the HETE-1 satellite was designed and built by AeroAstro, Inc. (USA) of Herndon, Virginia. The HETE-1 spacecraft was Sun-pointing with four solar panels connected to the bottom of the spacecraft bus. Spacecraft attitude was to be controlled by magnetic torque coils and a momentum wheel. Experiments Omnidirectional Gamma-Ray Spectrometer The