TRW ES-4 DSCS II
The second generation of operational communications satellites for the US military services, was named Defense Satellite Communications System (DSCS) II. Designated ES-4A, the satellites provided communication services from geostationary orbits. The 521 kg satellites were built by TRW, were fitted with two transponders operating in the 7/8 GHz band although later satellites carried six transponders. The satellites were launched in pairs and the operational constellation consisted of four satellites placed at 60°E, 175°E, 12°W and 135°W, as well as two in-orbit back-ups.
 |
| Image: Author's collection |
| ES-4A DSCS II-1 (1971-095A) |
| Name | Intl. Designation | Launch | Re-entry | Notes |
|---|---|---|---|---|
| DSCS II-1 | 1971-095A | 3-Nov-1971 | Also known as Ops-9431 | |
| DSCS II-2 | 1971-095B | 3-Nov-1971 | Also known as Ops-9432 | |
| DSCS II-3 | 1973-100A | 13-Dec-1973 | Also known as Ops-9433 | |
| DSCS II-4 | 1973-100B | 13-Dec-1973 | Also known as Ops-9434 | |
| DSCS II-5 | 1975-040A | 20-May-1975 | 26-May-1975 | Also known as Ops-9435; failed to achieve correct orbit |
| DSCS II-6 | 1975-040B | 20-May-1975 | 26-May-1975 | Also known as Ops-9436; failed to achieve correct orbit |
| DSCS II-7 | 1977-034A | 12-May-1977 | Also known as Ops-9437 | |
| DSCS II-8 | 1977-034B | 12-May-1977 | Also known as Ops-9438 | |
| DSCS II-9 | --- | 25-Mar-1978 | --- | Also known as Ops-9439; failed to orbit |
| DSCS II-10 | --- | 25-Mar-1978 | --- | Also known as Ops-9440; failed to orbit |
| DSCS II-11 | 1978-113A | 14-Dec-1978 | Also known as Ops-9441 | |
| DSCS II-12 | 1978-113B | 14-Dec-1978 | Also known as Ops-9442 | |
| DSCS II-13 | 1979-098A | 21-Nov-1979 | Also known as Ops-9443 | |
| DSCS II-14 | 1979-098B | 21-Nov-1979 | Also known as Ops-9444 | |
| DSCS II-15 | 1982-106A | 30-Oct-1982 | ||
| DSCS II-16 | 1989-069A | 4-Sep-1989 | Also known as USA-43 |
Launch dates of the DSCS II series
The next generation of DSCS satellites has been designated as ES-5A.
Background History
IDSCS
The first operational military communications satellite system was the Initial Defense Satellite Communications System (IDSCS) which commenced as a research and development project but was converted into a global operational network for high volume communications in 1968. It was initially known as the Initial Defense Communications Satellite Program (IDCSP).
The system consisted of a string of satellites which were in an orbit which was 90 minutes short of a geostationary orbit, drifting each day from west to east by 27.8° at altitudes of approximately 33,800 km. Built by Philco, each satellite, which had a mass of 45 kg, carried a single transponder operating at 7/8 Mhz.
 |
| Photo: Author's collection |
| IDSCS-1 (1966-053B) |
| Name | Intl. Designation | Launch | Re-entry | Notes |
|---|---|---|---|---|
| IDSCS-1 | 1966-053B | 16-Jun-1966 | Also known as Ops-9311 | |
| IDSCS-2 | 1966-053C | 16-Jun-1966 | Also known as Ops-9312 | |
| IDSCS-3 | 1966-053D | 16-Jun-1966 | Also known as Ops-9313 | |
| IDSCS-4 | 1966-053E | 16-Jun-1966 | Also known as Ops-9314 | |
| IDSCS-5 | 1966-053F | 16-Jun-1966 | Also known as Ops-9315 | |
| IDSCS-6 | 1966-053G | 16-Jun-1966 | Also known as Ops-9316 | |
| IDSCS-7 | 1966-053H | 16-Jun-1966 | Also known as Ops-9317 | |
| IDSCS | --- | 26-Aug-1966 | --- | Eight satellites failed to orbit |
| IDSCS-8 | 1967-003A | 18-Jan-1967 | Also known as Ops-9321 | |
| IDSCS-9 | 1967-003B | 18-Jan-1967 | Also known as Ops-9322 | |
| IDSCS-10 | 1967-003C | 18-Jan-1967 | Also known as Ops-9323 | |
| IDSCS-11 | 1967-003D | 18-Jan-1967 | Also known as Ops-9324 | |
| IDSCS-12 | 1967-003E | 18-Jan-1967 | Also known as Ops-9325 | |
| IDSCS-13 | 1967-003F | 18-Jan-1967 | Also known as Ops-9326 | |
| IDSCS-14 | 1967-003G | 18-Jan-1967 | Also known as Ops-9327 | |
| IDSCS-15 | 1967-003H | 18-Jan-1967 | Also known as Ops-9328 | |
| IDSCS-16 | 1967-066A | 1-Jul-1967 | Also known as Ops-9331 | |
| IDSCS-17 | 1967-066B | 1-Jul-1967 | Also known as Ops-9332 | |
| IDSCS-18 | 1967-066C | 1-Jul-1967 | Also known as Ops-9333 | |
| IDSCS-19 | 1968-050A | 13-Jun-1968 | Also known as Ops-9341 | |
| IDSCS-20 | 1968-050B | 13-Jun-1968 | Also known as Ops-9342 | |
| IDSCS-21 | 1968-050C | 13-Jun-1968 | Also known as Ops-9343 | |
| IDSCS-22 | 1968-050D | 13-Jun-1968 | Also known as Ops-9344 | |
| IDSCS-23 | 1968-050E | 13-Jun-1968 | Also known as Ops-9345 | |
| IDSCS-24 | 1968-050F | 13-Jun-1968 | Also known as Ops-9346 | |
| IDSCS-25 | 1968-050G | 13-Jun-1968 | Also known as Ops-9347 | |
| IDSCS-26 | 1968-050H | 13-Jun-1968 | Also known as Ops-9348 |
Launch dates of the IDSCS series
Back to Directory of U.S. Military Rockets and Missiles, Appendix 3
Last Updated: 22 February 2003