TACOMSAT (also known as TACSAT 1, OPS 0757, or Tactical Communications Satellite) was a communications

satellite A satellite or an artificial satellite is an object, typically a spacecraft, placed into orbit around a celestial body. They have a variety of uses, including communication relay, weather forecasting, navigation ( GPS), broadcasting, scient ...

designed and built by

Hughes Aircraft Corporation The Hughes Aircraft Company was a major American aerospace company, aerospace and defense contractor founded on February 14, 1934 by Howard Hughes in Glendale, California, as a division of the Hughes Tool Company. The company produced the Hughes ...

under the direction of the

United States Air Force The United States Air Force (USAF) is the Air force, air service branch of the United States Department of Defense. It is one of the six United States Armed Forces and one of the eight uniformed services of the United States. Tracing its ori ...

Space and Missile Systems Organization Space Systems Command (SSC) is the United States Space Force's research and development, space development, Military acquisition, acquisition, space launch, launch, and Military logistics, logistics field command. It is headquartered at Los An ...

(SAMSO). TACOMSAT was used by the

United States Department of Defense The United States Department of Defense (DoD, USDOD, or DOD) is an United States federal executive departments, executive department of the federal government of the United States, U.S. federal government charged with coordinating and superv ...

to explore the feasibility of geostationary satellite communications between ground stations comprising fixed bases, military field units, aircraft, and ships.

Construction

At in length and in diameter, TACOMSAT was the largest and most powerful communications satellite at the time of its launch. The -long main cylinder of the HS-308 bus was spin-stabilized at 54 rpm with the antennas mounted to a despun platform in an early version of the Hughes Gyrostat design. The platform was equipped with a variety of antennas, including a five-element

UHF 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 ...

bifilar

helical antenna A helical antenna is an antenna consisting of one or more conducting wires wound in the form of a helix. A helical antenna made of one helical wire, the most common type, is called ''monofilar'', while antennas with two or four wires in a h ...

array, two

X band The X band is the designation for a band of frequencies in the microwave radio region of the electromagnetic spectrum. In some cases, such as in communication engineering, the frequency range of the X band is set at approximately 7.0–11.2&nbs ...

horn antenna A horn antenna or microwave horn is an antenna (radio), antenna that consists of a flaring metal waveguide shaped like a horn (acoustic), horn to direct radio waves in a beam. Horns are widely used as antennas at Ultrahigh frequency, UHF and m ...

s, and a

biconical antenna In radio systems, a biconical antenna is a broad-bandwidth antenna made of two roughly conical conductive objects, nearly touching at their points. Biconical antennas are broadband dipole antennas, typically exhibiting a bandwidth of three octaves ...

for telemetry and control. The UHF transponder could provide a maximum RF output of 230 watts over a 10 MHz bandwidth, while the X band transponder could provide 30 watts over 10 MHz of bandwidth. The two transponders could be interconnected, allowing all signals to be exchanged between bands with a reduced usable bandwidth of 425 kHz. The combination of high RF power and stable antenna platform resulted in strong signals that could be received by antennas as small as in diameter. This permitted remotely deployed field units to communicate with one another and with headquarters. High RF power also permitted simultaneous access by many users across the transponder bandwidth.

Mission

After a February 9, 1969 launch on a

Titan IIIC The Titan IIIC was an expendable launch system used by the United States Air Force from 1965 until 1982. It was the first Titan (rocket family), Titan booster to feature large solid rocket motors and was planned to be used as a launcher for the D ...

launch vehicle, TACOMSAT reached a geostationary transfer orbit over the Pacific Ocean. After more than three years of successful experiments by the

US Army The United States Army (USA) is the primary land service branch of the United States Department of Defense. It is designated as the Army of the United States in the United States Constitution.Article II, section 2, clause 1 of the United Stat ...

US Air Force The United States Air Force (USAF) is the Air force, air service branch of the United States Department of Defense. It is one of the six United States Armed Forces and one of the eight uniformed services of the United States. Tracing its ori ...

, and

US Navy The United States Navy (USN) is the naval warfare, maritime military branch, service branch of the United States Department of Defense. It is the world's most powerful navy with the largest Displacement (ship), displacement, at 4.5 millio ...

, TACSAT was decommissioned on December 16, 1972.

References

{{DEFAULTSORT:TACOMSAT Reconnaissance satellites of the United States Cancelled spacecraft