Session
Technical Session XII: Smart Mission Design and Risk Mitigation
Abstract
The designers of ELLIPSO have intentionally driven the design of their satellites towards simplicity, and thus lower cost. The service link antennas are state of the art fixed planar arrays mounted on a nadir pointing plane that is always oriented towards the center of the earth. The communications payload uses simple, bent-pipe transponders to avoid the necessity of extensive onboard digital processing. The level of major component redundancy in each satellite is much less than in their more expensive GEO comsat cousins. The effect of a satellite failure is not so severe for ELLIPSO as for a typical GEO satellite for two reasons. First, failure of one satellite out of a system of 17 (the total in the ELLIPSO system) is much less percentage-wise, than the failure of a single GEO that may represent the entire system, or one in a group of two or three satellites. Second, the planned lifetime of the less expensive ELLIPSO satellites is shorter than that typical of GEO satellites. Scheduled launches for system replacement will occur earlier and more often than for GEO systems. Also, replacement of a single ELLIPSO satellite requires a much smaller launch vehicle than a GEO (due to its lower elliptic orbit). In short, the ELLIPSO satellites bear a closer resemblance to their smallsat cousins than they do to the conventional, larger and more complex GEO communications satellites.
The ELLIPSO™ Satellite - Application of Small Satellite Principles to the Space Segment of a Global Mobile Personal Communications System
The designers of ELLIPSO have intentionally driven the design of their satellites towards simplicity, and thus lower cost. The service link antennas are state of the art fixed planar arrays mounted on a nadir pointing plane that is always oriented towards the center of the earth. The communications payload uses simple, bent-pipe transponders to avoid the necessity of extensive onboard digital processing. The level of major component redundancy in each satellite is much less than in their more expensive GEO comsat cousins. The effect of a satellite failure is not so severe for ELLIPSO as for a typical GEO satellite for two reasons. First, failure of one satellite out of a system of 17 (the total in the ELLIPSO system) is much less percentage-wise, than the failure of a single GEO that may represent the entire system, or one in a group of two or three satellites. Second, the planned lifetime of the less expensive ELLIPSO satellites is shorter than that typical of GEO satellites. Scheduled launches for system replacement will occur earlier and more often than for GEO systems. Also, replacement of a single ELLIPSO satellite requires a much smaller launch vehicle than a GEO (due to its lower elliptic orbit). In short, the ELLIPSO satellites bear a closer resemblance to their smallsat cousins than they do to the conventional, larger and more complex GEO communications satellites.
