Navstar 7

Last updated

Navstar 7
NamesGPS I-7
GPS SVN-7
Mission type Navigation
Technology
Operator U.S. Air Force
Mission duration5 years (planned)
Launch failure
Spacecraft properties
Spacecraft Navstar
Spacecraft type GPS Block I
Manufacturer Rockwell Space Systems [1]
Launch mass758 kg (1,671 lb) [1]
Dimensions5.3 meters of long
Power400 watts
Start of mission
Launch date19 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)
Altitude20,200 km
Inclination 63.0°
Period 720 minutes
  OPS 5118 (Navstar 6)
OPS 9794 (Navstar 8) 

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]

Contents

Background

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]

Launch

Navstar 7 was launched at 01:10 UTC on 19 December 1981, atop an Atlas E launch vehicle with an SGS-1 upper stage. The Atlas used had the serial number 76E, and was originally built as an Atlas E. [2] The launch took place from Space Launch Complex 3E at Vandenberg Air Force Base. [4]

During preparations for launch, a seal on the number B2 engine of the MA-3 booster section of the Atlas was replaced. Sealant from this seeped into three coolant holes, plugging them. Four seconds after liftoff, the engine overheated and burned through its gas generator, severing an oxidiser line. Within seven and a half seconds of launch, the engine lost thrust, causing the rocket to pitch out of control. [5] It was destroyed by range safety officer, [6] with debris landing within 150 m (490 ft) of the launch pad, less than twenty seconds after liftoff. [5]

Mission

If the launch had been successful, it would have placed Navstar 7 into a transfer orbit, from which the satellite would have raised itself into medium Earth orbit by means of a Star-27 apogee motor. [1] The spacecraft had a design life of 5 years and a mass of 758 kg (1,671 lb). [1]

Related Research Articles

USA-87, also known as GPS IIA-8, GPS II-17 and GPS SVN-29, was an American navigation satellite which formed part of the Global Positioning System. It was the eighth of nineteen Block IIA GPS satellites to be launched.

USA-54, also known as GPS II-7 and GPS SVN-20, was an American navigation satellite which formed part of the Global Positioning System. It was the seventh of nine Block II GPS satellites to be launched, which were the first operational GPS satellites to fly.

USA-63, also known as GPS II-8 and GPS SVN-21, was an American navigation satellite which formed part of the Global Positioning System. It was the eighth of nine Block II GPS satellites to be launched, which were the first operational GPS satellites to fly.

USA-79, also known as GPS IIA-3, GPS II-12 and GPS SVN-25, was an American navigation satellite which formed part of the Global Positioning System. It was the third of nineteen Block IIA GPS satellites to be launched.

USA-80, also known as GPS IIA-4, GPS II-13 and GPS SVN-28, was an American navigation satellite which formed part of the Global Positioning System. It was the fourth of nineteen Block IIA GPS satellites to be launched.

USA-88, also known as GPS IIA-9, GPS II-18 and GPS SVN-22, was an American navigation satellite which formed part of the Global Positioning System. It was the ninth of nineteen Block IIA GPS satellites to be launched.

USA-90, also known as GPS IIA-10, GPS II-19 and GPS SVN-31, was an American navigation satellite which formed part of the Global Positioning System. It was the tenth of nineteen Block IIA GPS satellites to be launched.

USA-100, also known as GPS IIA-15, GPS II-24 and GPS SVN-36, is an American navigation satellite which forms part of the Global Positioning System. It was the fifteenth of nineteen Block IIA GPS satellites to be launched.

USA-128, also known as GPS IIA-18, GPS II-27 and GPS SVN-30, is an American navigation satellite which forms part of the Global Positioning System. It was the eighteenth of nineteen Block IIA GPS satellites to be launched.

USA-135, also known as GPS IIA-19, GPS II-28 and GPS SVN-38, is an American navigation satellite which forms part of the Global Positioning System. It was the last of nineteen Block IIA GPS satellites to be launched.

<span class="mw-page-title-main">OPS 5111</span> American navigation satellite used for GPS

OPS 5111, also known as Navstar 1, NDS-1, GPS I-1 and GPS SVN-1, was an American navigation satellite launched in 1978 as part of the Global Positioning System development program. It was the first GPS satellite to be launched, and one of eleven Block I demonstration satellites.

OPS 5112, also known as Navstar 2, NDS-2, GPS I-2 and GPS SVN-2, was an American navigation satellite launched in 1978 as part of the Global Positioning System development programme. It was the second of eleven Block I GPS satellites to be launched.

OPS 5113, also known as Navstar 3, GPS I-3 and GPS SVN-3, was an American navigation satellite launched in 1978 as part of the Global Positioning System development programme. It was the third of eleven Block I GPS satellites to be launched.

OPS 5114, also known as Navstar 4, GPS I-4 and GPS SVN-4, was an American navigation satellite launched in 1978 as part of the Global Positioning System development programme. It was the fourth of eleven Block I GPS satellites to be launched.

OPS 5117, also known as Navstar 5, GPS I-5 and GPS SVN-5, was an American navigation satellite launched in 1980 as part of the Global Positioning System development programme. It was the fifth of eleven Block I GPS satellites to be launched.

OPS 5118, also known as Navstar 6, GPS I-6 and GPS SVN-6, was an American navigation satellite launched in 1980 as part of the Global Positioning System development programme. It was the sixth of eleven Block I GPS satellites to be launched.

OPS 9794, also known as Navstar 8, GPS I-8 and GPS SVN-8, was an American navigation satellite launched in 1983 as part of the Global Positioning System development program. It was the eighth of eleven Block I GPS satellites to be launched.

USA-1, also known as Navstar 9, GPS I-9 and GPS SVN-9, was an American navigation satellite launched in 1984 as part of the Global Positioning System development programme. It was the ninth of eleven Block I GPS satellites to be launched, and the first satellite to receive a USA designation.

USA-5, also known as Navstar 10, GPS I-10 and GPS SVN-10, was an American navigation satellite launched in 1984 as part of the Global Positioning System (GPS) development programme. It was the tenth of eleven Block I GPS satellites to be launched.

USA-10, also known as Navstar 11, GPS I-11 and GPS SVN-11, was an American navigation satellite launched in 1985 as part of the Global Positioning System development programme. It was the last of eleven Block I GPS satellites to be launched.

References

  1. 1 2 3 4 5 Krebs, Gunter. "GPS (Navstar)". Gunter's Space Page. Retrieved 12 July 2012.
  2. 1 2 McDowell, Jonathan. "Launch Log". Jonathan's Space Report. Retrieved 12 July 2012.
  3. 1 2 "Display: Navstar 6 1980-032A". NASA. 14 May 2020. Retrieved 21 November 2020.PD-icon.svg This article incorporates text from this source, which is in the public domain .
  4. McDowell, Jonathan. "Launch List". Launch Vehicle Database. Jonathan's Space Report. Archived from the original on 15 August 2020. Retrieved 12 July 2012.
  5. 1 2 Eleazer, Wayne (31 January 2011). "Launch failures: the "Oops!" factor". The Space Review. Retrieved 12 July 2012.
  6. "Booster Destroyed on Liftoff". The Press-Courier. Vol. 45, no. 159. Oxnard, California. 19 December 1981. p. 3.