SDS Satellite Bus
Data current as of 2026-07-20.
The SDS bus accounts for 7 cataloged objects, of which 5 are in orbit and 0 are active. 2 have reentered. Most are built by HSES. The largest operator on this bus is National Reconnaissance Office. The first launched in 1976, the most recent in 1987.
5
In orbit
0
Active
7
Total launched
2
Reentered
SDS launched per year
Still in orbit Since reentered Click a year to list its satellites.
Typical specifications
Most common values across cataloged SDS satellites.
| Manufacturer | HSES |
|---|---|
| Purpose | Communication |
| Launch mass | 800 kg |
| Dry mass | 650 kg |
| Length | 7 m |
| Diameter | 2.4 m |
| Span | 7 m |
| Shape | Cyl + 2 Dish |
| Power | Solar cells (body mounted), batteries |
| Propulsion | ? |
| Equipment | ? |
| Typical orbit | 715 min period, 63° inclination |
Top operators
Top countries
US 7
SDS satellites
Track any of them live in KeepTrack.
| Name | NORAD | COSPAR | Owner | Launched | Orbit | Status | Track |
|---|---|---|---|---|---|---|---|
| USA 21 USA 21 | 17506 | 1987-015A | NRO/SAFSP | Feb 12, 1987 | 715 min, 63.0° | Inactive | ◉ |
| USA 9 USA 9 | 15546 | 1985-014A | NRO/SAFSP | Feb 8, 1985 | · | Inactive | ◉ |
| USA 4 USA 4 | 15226 | 1984-091A | NRO/SAFSP | Aug 28, 1984 | 718 min, 63.1° | Inactive | ◉ |
| OPS 5805 OPS 5805 | 12093 | 1980-100A | NRO/SAFSP | Dec 13, 1980 | 719 min, 63.9° | Inactive | ◉ |
| OPS 7310 OPS 7310 | 10993 | · | NRO/SAFSP | Aug 5, 1978 | · | Reentered | ◉ |
| OPS 7940 OPS 7940 | 09270 | 1976-080A | NRO/SAFSP | Aug 6, 1976 | 94 min, 61.8° | Reentered | ◉ |
| OPS 7837 OPS 7837 | 08871 | · | NRO/SAFSP | Jun 2, 1976 | · | Inactive | ◉ |
Frequently asked questions
How many SDS satellites are there?
The catalog lists 7 objects built on the SDS bus. 5 are in orbit and 2 have reentered.
How many SDS satellites are in orbit?
5 SDS objects are currently in orbit, of which 0 carry an active status.
Who builds the SDS bus?
The SDS bus is most commonly built by HSES.
When did the first SDS satellite launch?
The first cataloged SDS satellite launched in 1976, and the most recent in 1987.