ECS Satellite Bus
Data current as of 2026-07-20.
The ECS bus accounts for 15 cataloged objects, of which 15 are in orbit and 1 are active. Most are built by BAES. The largest operator on this bus is MOD. The first launched in 1983, the most recent in 2001.
15
In orbit
1
Active
15
Total launched
0
Reentered
ECS launched per year
Still in orbit Click a year to list its satellites.
Typical specifications
Most common values across cataloged ECS satellites.
| Manufacturer | BAES |
|---|---|
| Purpose | Military communication |
| Launch mass | 1430 kg |
| Dry mass | 525 kg |
| Length | 2.1 m |
| Diameter | 1.9 m |
| Span | 16 m |
| Shape | Box + 2 Pan |
| Power | 2 deployable solar arrays, batteries |
| Propulsion | Mage 2 |
| Design life | 7 years |
| Equipment | 4 SHF transponders (all), 2 UHF transponders (all), 2 C-band transponders (#D-F) |
| Typical orbit | 1452 min period, 13° inclination |
Top operators
Top countries
UK 6 F 3 I-EUT 3 I-NATO 2 I-ESA 1
ECS satellites
Track any of them live in KeepTrack.
| Name | NORAD | COSPAR | Owner | Launched | Orbit | Status | Track |
|---|---|---|---|---|---|---|---|
| SKYNET 4F Skynet 4F | 26695 | 2001-005B | MOD | Feb 7, 2001 | 1452 min, 12.2° | Inactive | ◉ |
| SKYNET 4E Skynet 4E | 25639 | 1999-009B | MOD | Feb 26, 1999 | 1454 min, 12.1° | Inactive | ◉ |
| SKYNET 4D Skynet 4D | 25134 | 1998-002A | MOD | Jan 10, 1998 | 1452 min, 12.8° | Inactive | ◉ |
| NATO 4B NATO IVB | 22921 | 1993-076A | NATO | Dec 8, 1993 | 1462 min, 13.0° | Inactive | ◉ |
| NATO 4A NATO IVA | 21047 | 1991-001A | NATO | Jan 8, 1991 | 1465 min, 13.0° | Inactive | ◉ |
| SKYNET 4C Skynet 4C | 20776 | 1990-079A | MOD | Aug 30, 1990 | 1461 min, 13.3° | Active | ◉ |
| SKYNET 4A Skynet 4A | 20401 | 1990-001A | MOD | Jan 1, 1990 | 1455 min, 12.5° | Inactive | ◉ |
| SKYNET 4B Skynet 4B | 19687 | 1988-109A | MOD | Dec 11, 1988 | 1445 min, 13.1° | Inactive | ◉ |
| EUTELSAT 1-F5 (ECS 5) Eutelsat I F-5 | 19331 | 1988-063B | EUTEL | Jul 21, 1988 | 1467 min, 14.5° | Inactive | ◉ |
| TELECOM 1C Telecom 1C | 18952 | 1988-018B | FTEL | Mar 11, 1988 | 1470 min, 15.1° | Inactive | ◉ |
| EUTELSAT 1-F4 (ECS 4) Eutelsat I F-4 | 18351 | 1987-078B | EUTEL | Sep 16, 1987 | 1459 min, 13.8° | Inactive | ◉ |
| TELECOM 1B Telecom 1B | 15678 | 1985-035B | FTEL | May 8, 1985 | 1435 min, 10.1° | Inactive | ◉ |
| TELECOM 1A Telecom 1A | 15159 | 1984-081B | FTEL | Aug 4, 1984 | 1463 min, 12.7° | Inactive | ◉ |
| EUTELSAT 1-F2 (ECS 2) ECS 2 | 15158 | 1984-081A | EUTEL | Aug 4, 1984 | 1458 min, 12.5° | Inactive | ◉ |
| EUTELSAT 1-F1 (ECS 1) ECS 1 | 14128 | 1983-058A | ESA | Jun 16, 1983 | 1456 min, 11.8° | Inactive | ◉ |
Frequently asked questions
How many ECS satellites are there?
The catalog lists 15 objects built on the ECS bus. 15 are in orbit and 0 have reentered.
How many ECS satellites are in orbit?
15 ECS objects are currently in orbit, of which 1 carry an active status.
Who builds the ECS bus?
The ECS bus is most commonly built by BAES.
When did the first ECS satellite launch?
The first cataloged ECS satellite launched in 1983, and the most recent in 2001.