CHALET / VORTEX / MERCURY
In the late 1970s, the NRO developed a successor to the CANYON COMINT (Communication Intelligence) satellite under Program 366, code-named CHALET. Like CANYON, the satellites were operated in near-geostationary 24h orbits. The program is still classified, and therefore no details about the satellites' characteristics are available. But they were almost certainly larger and heavier than CANYON, because they used the significantly more powerful Titan IIIC and Titan 34D launch vehicles.
The first CHALET launch occurred on 10 June 1978. Before the second launch in October 1979, the code name had changed to VORTEX. In 1987, the program's name was changed again, to MERCURY. The general "Mission 7500" designator of CANYON was taken over for the successor, so that CHALET/VORTEX/MERCURY mission numbers simply continued the series started by CANYON.
The last three MERCURY missions (the last of which failed on launch) used a larger satellite vehicle, informally known as "Advanced VORTEX". These satellites were launched by Titan IV launchers and placed in true geostationary orbits. Triangulation of signal source locations was possible by combining readings from two satellites at the same time.
There was no direct successor to MERCURY, becaue its COMINT mission has been incorporated into the "Mission 8300" versions of the ORION series of SIGINT (Signal Intelligence) satellites.
CHALET/VORTEX/MERCURY Launch List
- No.: Sequential flight number for the CHALET/VORTEX/MERCURY program. To follow most sources, the numbering follows up from the 7 CANYON flights.
- Name: Unclassified name of the satellite. The OPS number ("OPS" standing for "Operations") is a random number given to all military-related satellite launches between 1963 and May 1984. 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 serial number in the 75xx range, continuing the series of CANYON missions.
- COSPAR ID: International designation of the satellite; not applicable, if orbit was not reached
| No. | Name / NROL | Mission | COSPAR ID | Launch | Launch Vehicle |
|---|---|---|---|---|---|
| 8 | OPS 9454 | 7508 | 1978-058A | 10 Jun 1978 | SLV-5C Titan 3(23)C |
| 9 | OPS 1948 | 7509 | 1979-086A | 1 Oct 1979 | SLV-5C Titan 3(23)C |
| 10 | OPS 4029 | 7510 | 1981-107A | 31 Oct 1981 | SLV-5C Titan 3(23)C |
| 11 | OPS 0441 | 7511 | 1984-009A | 31 Jan 1984 | Titan 34D/Transtage |
| 12 | USA-31 | 7512 | 1988-077A | 2 Sep 1988 | Titan 34D/Transtage |
| 13 | USA-37 | 7513 | 1989-035A | 10 May 1989 | Titan 34D/Transtage |
| 14 | USA-105 | 7514 | 1994-054A | 27 Aug 1994 | SB-5A Titan 401A |
| 15 | USA-118 | 7515 | 1996-026A | 24 Apr 1996 | SB-5A Titan 401A |
| 16 | - / NROL-7 | 7516 | Launch failure | 12 Aug 1998 | SB-5A Titan 401A |
CHALET/VORTEX/MERCURY launches
Main Sources
[1] Jeffrey T. Richelson: Eavesdroppers
in Disguise, Air Force Magazine, August 2012
[2] Gunter Krebs: Gunter's Space Page (for launch lists)
Back to Directory of U.S. Military Rockets and Missiles, Appendix 3
Last Updated: 27 June 2025