The SNOE Spacecraft: Integration, Test, Launch, Operation, and On-orbit Performance

The Student Nitric Oxide Explorer (SNOE) was launched on 26 February 1998. Its objectives are to measure nitric oxide density in the lower thermosphere, to analyze the solar and auroral fluxes that create it and cause its variation, and to demonstrate the feasibility of low-cost, University-based missions that include a high degree of student participation. The SNOE spacecraft and instruments were designed and built at the University of Colorado Laboratory for Atmospheric and Space Physics (CU/LASP). It travels in a 580 x 550 km, sunsynchronous orbit with a 10:30 AM ascending node. It spins at 5 rpm with the spin axis normal to the orbit plane. It carries three instruments: An ultraviolet spectrometer to measure nitric oxide altitude profiles on the limb, a two-channel ultraviolet photometer to measure auroral emissions in the nadir, and a five-channel solar soft X-ray photometer. An experimental GPS receiver is also included for orbit determination. This paper describes completion of the SNOE project through integration and test, launch site operations at Vandenberg AFB, the early-orbit campaign, and routine mission and science operations. The on-orbit performance of the spacecraft subsystems is assessed, including the passive thermal regulation system as well as the electrical and computer systems. SNOE is in good health and appears to be headed for a long and successful mission.