S-55 Satellite Bus
Data current as of 2026-07-20.
The S-55 bus accounts for 3 cataloged objects, of which 1 are in orbit and 0 are active. 2 have reentered. Most are built by LARCN. The largest operator on this bus is NASA. The first launched in 1961, the most recent in 1964.
1
In orbit
0
Active
3
Total launched
2
Reentered
S-55 launched per year
Still in orbit Since reentered Click a year to list its satellites.
Typical specifications
Most common values across cataloged S-55 satellites.
| Manufacturer | LARCN |
|---|---|
| Launch mass | 62 kg |
| Dry mass | 62 kg |
| Length | 2.2 m |
| Diameter | 0.6 m |
| Span | 2.2 m |
| Shape | Cyl |
| Typical orbit | 104 min period, 52° inclination |
Top operators
Top countries
US 3
S-55 satellites
Track any of them live in KeepTrack.
| Name | NORAD | COSPAR | Owner | Launched | Orbit | Status | Track |
|---|---|---|---|---|---|---|---|
| EXPLORER 23 Explorer 23 | 00924 | 1964-074A | LARCN | Nov 6, 1964 | 88 min, 51.9° | Reentered | ◉ |
| EXPLORER 16 Explorer 16 | 00506 | 1962-070A | LARCN | Dec 16, 1962 | 104 min, 52.0° | Inactive | ◉ |
| EXPLORER 13 Explorer 13 | 00180 | 1961-022A | LARCN | Aug 25, 1961 | 96 min, 36.4° | Reentered | ◉ |
Frequently asked questions
How many S-55 satellites are there?
The catalog lists 3 objects built on the S-55 bus. 1 are in orbit and 2 have reentered.
How many S-55 satellites are in orbit?
1 S-55 objects are currently in orbit, of which 0 carry an active status.
Who builds the S-55 bus?
The S-55 bus is most commonly built by LARCN.
When did the first S-55 satellite launch?
The first cataloged S-55 satellite launched in 1961, and the most recent in 1964.