Home - Search - Browse - Alphabetic Index: 0- 1- 2- 3- 4- 5- 6- 7- 8- 9
A- B- C- D- E- F- G- H- I- J- K- L- M- N- O- P- Q- R- S- T- U- V- W- X- Y- Z
HS 381
HS-381 / Syncom 4
HS-381 / Syncom 4
Credit: Hughes
American military communications satellite. The Leasat HS 381 series was developed as a commercial venture to provide dedicated communications services to the U. S. military.

Status: Operational 1984. First Launch: 1984-08-30. Last Launch: 1985-08-27. Number: 4 . Gross mass: 1,330 kg (2,930 lb). Height: 2.70 m (8.80 ft).

Owned by Hughes Communications, the satellites were designed to provide global UHF communications to military air, sea, and ground forces.

The Leasat program was initiated as a result of Congressional reviews in 1976 and 1977 which advised increased use of leased commercial facilities. The system's primary user was the US Navy, with some support also provided to the Air Force and ground mobile forces (using FLTSATCOM terminals). Hughes was paid $ 84M per year for each operational satellite. At the end of each satellites' designed 7 year life, the Navy had the option of purchasing the satellite for $15M. The Leasats, along with the Navy's FLTSATCOM spacecraft, were later replaced by the UFO (UHF Follow-on) spacecraft. The spacecraft used a Hughes HS-381 bus, spin stabilized at 30 rpm with despun communications and antenna section. Body mounted solar cells provided 1500 W BOL and NiCd batteries provided power in eclipse. A solid rocket motor was used for perigee burn, and a bipropellant system for apogee burn. A hydrazine system was used for station-keeping. The design was optimized for Shuttle launch and deployment. The payload included five antennas on the despun platform, which provided full Earth coverage. These included two UHF helices (30 cm diameter, 3.8 m long) were fitted, one for one transmit, one for receive; two X-Band horns (one beacon, one receive); and one omni TT&C antenna. Channel 1 was used for X-Band uplink, UHF downlink, 25 kHz bandwidth for fleet broadcast using spread-spectrum anti-jamming protection. Channel 2 was UHF, with 500 kHz bandwidth. Channels 3 to 8 were UHF, 25 kHz bandwidth. Channels 9 to 13 were UHF, 5 kHz bandwidth.



Subtopics

Leasat 1, 2, 3, 4, 5 (Syncom-4 1, 2, 3, 4, 5) Null

Family: Communications, Geosynchronous orbit, Military communications sat. Country: USA. Engines: R-4D. Launch Vehicles: Space Shuttle. Launch Sites: Cape Canaveral, Cape Canaveral LC39A. Agency: USN, USAF, Hughes. Bibliography: 2, 279, 6.
Photo Gallery

Leasat 1Leasat 1
Credit: Manufacturer Image



1984 August 30 - . 12:41 GMT - . Launch Site: Cape Canaveral. Launch Complex: Cape Canaveral LC39A. Launch Platform: MLP2. LV Family: Shuttle. Launch Vehicle: Space Shuttle.
1984 November 8 - . 12:15 GMT - . Launch Site: Cape Canaveral. Launch Complex: Cape Canaveral LC39A. Launch Platform: MLP2. LV Family: Shuttle. Launch Vehicle: Space Shuttle.
1985 April 12 - . 13:59 GMT - . Launch Site: Cape Canaveral. Launch Complex: Cape Canaveral LC39A. Launch Platform: MLP1. LV Family: Shuttle. Launch Vehicle: Space Shuttle.
1985 August 27 - . 10:58 GMT - . Launch Site: Cape Canaveral. Launch Complex: Cape Canaveral LC39A. Launch Platform: MLP1. LV Family: Shuttle. Launch Vehicle: Space Shuttle.

Back to top of page
Home - Search - Browse - Alphabetic Index: 0- 1- 2- 3- 4- 5- 6- 7- 8- 9
A- B- C- D- E- F- G- H- I- J- K- L- M- N- O- P- Q- R- S- T- U- V- W- X- Y- Z
© 1997-2019 Mark Wade - Contact
© / Conditions for Use