| Mission type | Satellite inspection |
|---|---|
| Operator | US NRO |
| COSPAR ID | N/A |
| SATCATno. | N/A |
| Spacecraft properties | |
| Bus | HS-376 |
| Manufacturer | Hughes |
| Launch mass | 1,300 kilograms (2,900 lb) |
| Start of mission | |
| Launch date | 15 November 1990, 23:48:13 (1990-11-15UTC23:48:13Z) UTC |
| Rocket | Space Shuttle Atlantis STS-38 /PAM-D |
| Launch site | KennedyLC-39A |
| Orbital parameters | |
| Reference system | Geocentric |
| Regime | Near-geosynchronous |
Prowler was an American reconnaissance satellite launched aboardSpace Shuttle Atlantis in 1990 to studySoviet satellites ingeosynchronous orbit. The government of the United States has never acknowledged its existence, however it has been identified byamateur observers and through leaked information.[1]
Prowler was based on theHS-376satellite bus, developed byHughes. It had a mass of around 1,300 kilograms (2,900 lb) and carried modifications to reduce its visibility to ground-based observers and to radar.[2] Following the satellite's retirement these modifications ceased to be effective, allowing it to be found by amateur observers.[3]
Prowler was designed to maneuver to within a few meters of satellites ingeosynchronous orbit. Its purpose was either to monitor them and return data about them,[4] or to perform asignals intelligence mission such as intercepting communications between those satellites and the ground.[2][3]
It seems that Prowler was deployed from Space ShuttleAtlantis during theSTS-38 mission. STS-38 was launched fromLaunch Complex 39A at theKennedy Space Center at 23:48:13 UTC on 15 November 1990.[5] The mission was officially acknowledged to have deployed a single satellite, USA-67, which observers have since identified as part of theSatellite Data System.[6] Prowler was deployed fromAtlantis at around 04:37 UTC on 17 November 1990, and boosted intogeosynchronous transfer orbit by aPAM-Dupper stage.[6] A second patch produced for the STS-38 mission showed a Shuttle orbiter in shadows above an illuminated orbiter; reversing the official mission patch; symbolizing the covert nature of the mission.[7]
The nature of STS-38's payload was classified, but observers attempted to identify it. Since Prowler is by nature stealthy, USA-67 was initially believed to be the only satellite deployed. Thus, because of the single payload and two upper stages, USA-67 was believed to be aMagnum satellite, deployed via a two-stageInertial Upper Stage (IUS). Photographs released from later in the STS-38 mission have shown thatAtlantis was not carrying the adaptor necessary to deploy an IUS during STS-38.[1]
In July 1998, amateur observers in Texas observed an unidentified object flashing in geosynchronous orbit.[8] The object was subsequently lost, then was rediscovered in June 2000 when its flashes became brighter,[9][10] some even visible with the naked eye. Following the 2000 observations amateur observers were still unable to identify the satellite, so began referring to it by the pseudoInternational Designator 2000-653A and pseudoSatellite Catalog Number 90007.[11]
In 2004 NBC published an article containing details about Prowler and its mission.[1][4]
In January 2010, amateur observerTed Molczan cross-referenced data from theEuropean Space Agency's Classification of Geosynchronous Objects survey with amateur observations of classified spacecraft, noting that an unidentified object designated UI.139 by the survey corresponded with observations of 2000-653A, and that its orbit was close to that of USA-67 - speculating that they may have been from the same launch.[12] Based on this, Molczan conducted a more detailed investigation, and in 2011 published a paper identifying 2000-653A as Prowler.[1]
