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OPS 5111

American navigation satellite used for GPS

Field	Value
name	OPS 5111
names_list	Navstar 1
NDS-1
GPS I-1
GPS SVN-1
image	GPS Block 1 satellite.jpg
image_caption	A Block I GPS satellite (Navstar 1)
image_size	290px
mission_type	Navigation
Technology
operator	U.S. Air Force
COSPAR_ID	1978-020A
SATCAT	10684
mission_duration	5 years (planned)
7.25 years (achieved)
spacecraft	Navstar
spacecraft_type	GPS Block I
manufacturer	Rockwell Space Systems
launch_mass	758 kg
dimensions	Solar panel span: 5.3 m (17.4 ft)
power	400 watts
launch_date	22 February 1978, 23:44:00 UTC
launch_rocket	Atlas F / SGS-1
(Atlas-64F)
launch_site	Vandenberg, SLC-3E
launch_contractor	Convair
General Dynamics
entered_service	29 March 1978
deactivated	17 July 1985
orbit_reference	Geocentric orbit
orbit_regime	Medium Earth orbit
(Semi-synchronous)
orbit_periapsis	20095 km
orbit_apoapsis	20308 km
orbit_inclination	63.3°
orbit_period	718.70 minutes
apsis	gee
programme	Global Positioning System
next_mission	OPS 5112 (Navstar 2)

NDS-1 GPS I-1 GPS SVN-1 Technology 7.25 years (achieved) (Atlas-64F) General Dynamics (Semi-synchronous)

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.

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.

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°.

Launch

OPS 5111 was launched at 23:44 UTC on 22 February 1978, atop an Atlas F launch vehicle with an SGS-1 upper stage. The Atlas used had the serial number 64F, and was originally built as an Atlas F. The launch took place from Vandenberg Space Launch Complex 3 (SLC-3E) at Vandenberg Air Force Base, and placed OPS 5111 into a transfer orbit. The satellite raised itself into medium Earth orbit using a Star-27 apogee motor.

Mission

By 29 March 1978, OPS 5111 was in an orbit with a perigee of 20095 km, an apogee of 20308 km, a period of 718.70 minutes, and 63.3° of inclination to the equator. The satellite had a design life of 5 years and a mass of 758 kg. It broadcast the PRN 04 signal in the GPS demonstration constellation, and was retired from service on 17 July 1985.

References

(14 May 2020). "Trajectory: Navstar 1 1978-020A". NASA.
(14 May 2020). "Display: Navstar 1 1978-020A". NASA.
McDowell, Jonathan. "Launch Log". Jonathan's Space Report.
McDowell, Jonathan. "Launch List". Jonathan's Space Report.
Krebs, Gunter. "GPS (Navstar)". Gunter's Space Page.
McDowell, Jonathan. "Satellite Catalog". Jonathan's Space Report.

Info: Wikipedia Source

This article was imported from Wikipedia and is available under the Creative Commons Attribution-ShareAlike 4.0 License. Content has been adapted to SurfDoc format. Original contributors can be found on the article history page.

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