USA-1, also known as Navstar 9, GPS I-9 and GPS SVN-9, was an American

navigation satellite A satellite navigation or satnav system is a system that uses satellites to provide autonomous geo-spatial positioning. It allows satellite navigation devices to determine their location (longitude, latitude, and altitude/elevation) to high pre ...

launched in 1984 as part of the

Global Positioning System The Global Positioning System (GPS), originally Navstar GPS, is a satellite-based radionavigation system owned by the United States government and operated by the United States Space Force. It is one of the global navigation satellite sy ...

development programme. It was the ninth of eleven Block I GPS satellites to be launched, and the first satellite to receive a USA designation.

Background

Global Positioning System (GPS) was developed by the

U.S. Department of Defense The United States Department of Defense (DoD, USDOD or DOD) is an executive branch department of the federal government charged with coordinating and supervising all agencies and functions of the government directly related to national secur ...

to provide all-weather round-the-clock

navigation Navigation is a field of study that focuses on the process of monitoring and controlling the movement of a craft or vehicle from one place to another.Bowditch, 2003:799. The field of navigation includes four general categories: land 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 The Global Positioning System (GPS), originally Navstar GPS, is a satellite-based radionavigation system owned by the United States government and operated by the United States Space Force. It is one of the global navigation satellite sy ...

. 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 Telemetry is the in situ collection of measurements or other data at remote points and their automatic transmission to receiving equipment (telecommunication) for monitoring. The word is derived from the Greek roots ''tele'', "remote", an ...

and

Ultra high frequency Ultra high frequency (UHF) is the ITU designation for radio frequencies in the range between 300 megahertz (MHz) and 3 gigahertz (GHz), also known as the decimetre band as the wavelengths range from one meter to one tenth of a meter ( ...

(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

USA-1 was launched at 11:37 UTC on 13 June 1984, atop an

Atlas E The SM-65 Atlas was the first operational intercontinental ballistic missile (ICBM) developed by the United States and the first member of the Atlas rocket family. It was built for the U.S. Air Force by the Convair Division of General Dyna ...

launch vehicle A launch vehicle or carrier rocket is a rocket designed to carry a payload ( spacecraft or satellites) from the Earth's surface to outer space. Most launch vehicles operate from a launch pads, supported by a launch control center and ...

with an SGS-2

upper stage A multistage rocket or step rocket is a launch vehicle that uses two or more rocket ''stages'', each of which contains its own engines and propellant. A ''tandem'' or ''serial'' stage is mounted on top of another stage; a ''parallel'' stage is ...

. The Atlas used had the serial number 42E, and was originally built as an Atlas E. The launch took place from Space Launch Complex 3W at

Vandenberg Air Force Base Vandenberg may refer to: * Vandenberg (surname), including a list of people with the name * USNS ''General Hoyt S. Vandenberg'' (T-AGM-10), transport ship in the United States Navy, sank as an artificial reef in Key West, Florida * Vandenberg Sp ...

, and placed USA-1 into a transfer orbit. The satellite raised itself into

medium Earth orbit A medium Earth orbit (MEO) is an Earth-centered orbit with an altitude above a low Earth orbit (LEO) and below a high Earth orbit (HEO) – between above sea level.

(MEO) using a Star-27

apogee motor An apogee kick motor (AKM) is a rocket motor that is regularly employed on artificial satellites to provide the final impulse to change the trajectory from the transfer orbit into its final (most commonly circular) orbit. For a satellite laun ...

Mission

By 19 July 1984, USA-1 had been raised to an orbit with a

perigee An apsis (; ) is the farthest or nearest point in the orbit of a planetary body about its primary body. For example, the apsides of the Earth are called the aphelion and perihelion. General description There are two apsides in any ell ...

of , an

apogee An apsis (; ) is the farthest or nearest point in the orbit of a planetary body about its primary body. For example, the apsides of the Earth are called the aphelion and perihelion. General description There are two apsides in any ell ...

of , a

period Period may refer to: Common uses * Era, a length or span of time * Full stop (or period), a punctuation mark Arts, entertainment, and media * Period (music), a concept in musical composition * Periodic sentence (or rhetorical period), a concept ...

of 718.00 minutes, and 62.80° of

inclination Orbital inclination measures the tilt of an object's orbit around a celestial body. It is expressed as the angle between a reference plane and the orbital plane or axis of direction of the orbiting object. For a satellite orbiting the Eart ...

to the equator. The satellite had a design life of 5 years and a mass of . It broadcast the PRN 13 signal in the GPS demonstration constellation, and was retired from service on 20 June 1994.

References

{{Orbital launches in 1984 1984 in spaceflight GPS satellites USA satellites Spacecraft launched in 1984