An Earth satellite that is in (a prograde) subsynchronous orbit will appear to drift eastward as seen from the Earth's surface.
Economic importance in commercial spaceflight
The Geosynchronous-belt subsynchronous orbital regime is regularly used in spaceflight. This orbit is typically used to house working communication satellites that have not yet been deactivated, and may be still be used again in geostationary service if the need arises.
- Maral, Gérard; Michel Bousquet; Zhili Sun (2009). Satellite communications systems : systems, techniques and technology. Wiley. OCLC 701718866.
- Kumar, Krishna (March 1993). "Geosynchronous satellites at sub-synchronous altitudes". Acta Astronautica. 29 (3): 149–151. Bibcode:1993AcAau..29..149K. doi:10.1016/0094-5765(93)90043-V.