ONYX
Optical photo-reconnaissance satellites have the disadvantage, that they can only obtain images of the ground in daylight and without cloud cover. An alternative, which is independent from daylight and weather, is SAR (Synthetic Aperture Radar) imaging, where the surface is scanned with a strong radar emitter/receiver. The ground resolution will be not quite as high as for optical imaging, but still more than good enough for many purposes.
In the late 1970s, the CIA proposed to fit an SAR module to its new KENNEN series of electro-optical photo-reconnaissance satellites. The idea was that if the satellite encountered cloud cover over the intended target, it could switch to radar mode to get useful images. At the same time, the USAF favored a separate radar-imaging satellite system, named INDIGO, arguing that distributing capabilities over several systems would be more versatile and less risky. In the end, the Air Force's reasoning prevailed, and the NRO got approval to develop INDIGO. The name was soon changed to LACROS (mostly spelled as "Lacrosse" in open sources), and finally to ONYX before the launch of the system's first satellite.
LACROS/ONYX encountered some development problems, and it took until December 1988 that the first ONYX satellite was launched into space, by the Shuttle Atlantis. The other four ONYX launches in later years all used Titan IV launch vehicles. ONYX was also designated as Mission 3100 by the NRO. The satellites operated in low-earth orbit of about 450-720 km altitude, and delivered images with a ground resolution of 1 m (3 ft) or better. Each ONYX satellite had an operational lifetime of around 10 years.
ONYX has been succeeded by the FIA-R (Future Image Architecture - Radar) program.
ONYX Launch List
- No.: Sequential flight number for the ONYX program
- Name: Unclassified name of the satellite. Since June 1984, U.S. military satellites get a sequential "USA" number. "NROL" stands for National Reconnaissance Office Launch, a number assigned by the NRO to its satellite launches since 1996.
- Mission: Each mission had a unique NRO Mission number in the 31xx range.
- COSPAR ID: International designation of the satellite
| No. | Name / NROL | Mission | COSPAR ID | Launch | Launch Vehicle |
|---|---|---|---|---|---|
| 1 | USA 34 | 3101 | 1988-106B | 2 Dec 1988 | Space Shuttle Atlantis |
| 2 | USA 69 | 3102 | 1991-017A | 8 Mar 1991 | Titan-403A |
| 3 | USA 133 / NROL-3 | 3103 | 1997-064A | 24 Oct 1997 | Titan-403A |
| 4 | USA 152 / NROL-11 | 3104 | 2000-047A | 17 Aug 2000 | Titan-403B |
| 5 | USA 182 / NROL-16 | 3105 | 2005-016A | 30 Apr 2005 | Titan-405B |
ONYX launches
Main Sources
[1] Dwayne A. Day: Radar love: the tortured history of American space radar programs,
The Space Review, January 2007
[2] Jeffrey T. Richelson: Ups and Downs
of Space Radars, Air Force Magazine, January 2009
[3] Gunter Krebs: Gunter's Space Page (for launch lists)
Back to Directory of U.S. Military Rockets and Missiles, Appendix 3
Last Updated: 16 July 2025