Navstar 7
From Wikipedia, the free encyclopedia
GPS SVN-7
Technology
Launch failure
| Names | GPS I-7 GPS SVN-7 |
|---|---|
| Mission type | Navigation Technology |
| Operator | U.S. Air Force |
| Mission duration | 5 years (planned) Launch failure |
| Spacecraft properties | |
| Spacecraft | Navstar |
| Spacecraft type | GPS Block I |
| Manufacturer | Rockwell Space Systems[1] |
| Launch mass | 758 kg (1,671 lb)[1] |
| Dimensions | 5.3 meters of long |
| Power | 400 watts |
| Start of mission | |
| Launch date | 19 December 1981, 01:10:00 UTC |
| Rocket | Atlas E / SGS-1 (Atlas-76E)[2] |
| Launch site | Vandenberg, SLC-3E |
| Contractor | Convair General Dynamics |
| Entered service | Launch failure |
| Orbital parameters | |
| Reference system | Geocentric orbit (planned) |
| Regime | Medium Earth orbit (Semi-synchronous) |
| Altitude | 20,200 km |
| Inclination | 63.0° |
| Period | 720 minutes |
Navstar 7, also known as GPS I-7 and GPS SVN-7, was an American navigation satellite which was lost in a launch failure in 1981. It was intended to be used in the Global Positioning System development program. It was the seventh of eleven Block I GPS satellites to be launched, and the only one to fail to achieve orbit.[1]
Global Positioning System (GPS) was developed by the U.S. Department of Defense to provide all-weather round-the-clock navigation capabilities for military ground, sea, and air forces. Since its implementation, GPS has also become an integral asset in numerous civilian applications and industries around the globe, including recreational used (e.g., boating, aircraft, hiking), corporate vehicle fleet tracking, and surveying. GPS employs 24 spacecraft in 20,200 km circular orbits inclined at 55°. These vehicles are placed in 6 orbit planes with four operational satellites in each plane.[3]
Spacecraft
The first eleven spacecraft (GPS Block 1) were used to demonstrate the feasibility of the GPS system. They were 3-axis stabilized, nadir pointing using reaction wheels. Dual solar arrays supplied over 400 watts. They had S-band communications for control and telemetry and Ultra high frequency (UHF) cross-link between spacecraft. They were manufactured by Rockwell Space Systems, were 5.3 meters across with solar panels deployed, and had a design life expectancy of 5 years. Unlike the later operational satellites, GPS Block 1 spacecraft were inclined at 63°.[3]
