Earth Orbiter-1, Incorporating New Technology Advanced Sensors and Instruments

Earth Orbiter-1 (EO-1) is a flight segment of the New Millennium Program, which evaluates new technologies for future space missions. Although EO-1' s most important new technologies are part of the Advanced Land Imager (ALI) instrument - which contains several technologies that will be evaluated for use in the follow-on to Landsat 7 - many un-proven technologies are incorporated into the spacecraft. Systems engineers are challenged to incorporate as many new and innovative technologies as possible, but still minimize the risk to the primary goal of the mission: to evaluate the ALI performance. Following a short overview of the EO-1 mission, this paper describes the EO-1 spacecraft bus with an emphasis on the technical solutions required to minimize the risk of incorporating new technologies. New spacecraft technologies are separated into two categories: those that replace a spacecraft component, and those that are standalone and treated like a separate payload. EO-1 weighs 529 kg and will launch in late 1999 into an orbit near Landsat-7: 705 km, sun-synchronized, with a 10:00 AM descending node. The spacecraft is three-axis stabilized, nadir pointing, with advanced avionics, articulating 600-watt Silicon solar arrays, passive thermal control, and a hydrazine propulsion system for correcting insertion errors and orbit maintenance.