DSCS 3-10

USA

Spacecraft n°:

USA satellite n°:

Defense Satellite Communications System
Also called USA 135 (code B13)

Launch data:

Designation	25019 / 97065A
Launch date	25 Oct 1997
Launch site	CC, LC-36A
Launch vehicle	Atlas-2A (AC-131 #111 + IABS)
Mission	Military: Communications
Geostationary orbit:
Perigee / Apogee	35757 x 35817 km
Eccentricity	7.12E-04
Inclination	2.54 deg
Period	1436.1 min

Spacecraft data:

Prime contractor	Lockheed Martin (former GE Astro Space)
Platform
Operator	US Air Force
Mass at launch	1156 kg
Mass in orbit	884 kg
Basic shape
Dimension (m)	2.07 x 1.93 x 1.96m (LxWxD)
Solar array	11.4m
Stabilization	3 axis
DC power	BOL: 1240 W EOL; 837 W three 35 AH NiCd batteries
Telemetry	S- and X-band
Beacon	7600.0 and 7604.7 MHz
Design lifetime	10 yrs - still active

Location:

Date	Position	Remarks
April 2010	130.05° W

Features fixed (multiple-beam) antennas and a steerable high power antenna.

X-band:

Main transponders	6
Backup	two 40 W and two 10 W amplifiers
Power	channels 1 & 2: 40 W (TWTA) channels 3 to 6: 10 W (SSPA)
Coverage and EIRP max	2 Global beams: 29 dBW 2 Spot beams: 34 dBW Gimballed dish: 44 dBW

Transponder frequency chart (GHz)

Channel	Bandwidth (MHz)	Frequency
1	50	?
2	75	?
3	85	?
4	85	?
5	60	?
6	50	?

Frequencies are probably in 250 MHz, S-band and X-band range. In X-band, uplink in the 7.9-8.025 GHz, 8.025-8.400 GHz, downlink in 7.250-7.750 GHz
Super High Frequency (SHF) for U.S. government and military; sophisticated survivability enhancement; worldwide, longhaul coverage; X-band.

Description:

Defense Satellite Communications System (DSCS III-B13) was part of a US military satellite constellation place in geosynchronous orbit to provide high-volume, secure voice and data communications. Phase II was a successor to the IDSCS (Initial Defense Satellite Communications System) program which began in 1966 with the launch of the first 8 satellites of this constellation. The DSCS III system was used for high priority communications such as the exchange of wartime information between defense officials and battlefield commanders. The military also used DSCS to transmit space operations and early warning data to various systems and users.
Each satellite orbits the earth at an altitude of more than 23,000 miles. They carried a single channel transponder used for disseminating emergency action and force direction messages to nuclear capable forces. Each satellite utilized six super high frequency transponder channels capable of providing worldwide secure voice and high rate data communications.

Ref: #6, #15, #226 - update: 19.05.10