CLASSIFIED
SDS-4
Classified Satellite Data Relay (Molniya Orbit) · NRO (US)
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SDS-4, part of the US Satellite Data System — a classified constellation flying in highly elliptical Molniya-type orbits specifically to relay data from polar-orbiting reconnaissance satellites down to ground stations, solving the problem of getting spy-satellite imagery to analysts before a spacecraft passes back over friendly territory. The SDS program has operated since the 1970s with minimal public disclosure.
Its orbit
- Orbit
- Low Earth Orbitcan appear as a fast-moving star at dawn or dusk
- Altitude
- 399–405 mi (642–651 km)
- Inclination
- 98.1°
- One orbit
- 97.5 minutes14.8 orbits a day
- NORAD ID
- 38339
- Int’l designator
- 2012-025C
- Launched
- 2012
Orbital elements from CelesTrak, as of 22 Sep 2026.
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