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STSS Demonstrator Mission

Tyneside, UK
2024 May 20
Monday, Day 141

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STSS Demonstrator:


Description of missile detection and interception system

STSS Demonstrator home page

The Space Tracking and Surveillance System (STSS) Demonstrator mission was launched 2009 September 25 at 12:20 UTC from the Cape Canaveral Air force Station This was twenty minutes into a one hour launch window. Lift off followed several delays over the preceding days and hours through a combination of technical and weather issues.
STSS Demo Patch
The purpose of the satellite pair is to demonstrate the use of sensors in LEO to detect and monitor missile launches.

The Press Kit issued by United Launch Alliance described the Delta launch vehicle as destined for a circular orbit at 1350 km with inclination 58 degrees. After that, the payloads were to be released.

Transmission frequencies

2009 September 25, 14:33:45 UTC a new transmission was detected here at 2247.5 MHz (SGLS Channel 10). The STSS Demonstrator satellites had completed their first orbit of the Earth and were starting on the second. The Doppler curve of the 2247.5 MHz signal as it passed by indicated that the satellite was in an orbit very close to a pre-launch estimate made by Ted Molczan of Canada.

A 2272.5 MHz (SGLS Channel 15) transmission logged from South Africa on rev 2 also proved to be coming from the STSS Demonstrator pair.

Components of the Launch

Catalogue Designation Name NORAD Name Frequency
359372009-052ASTSS Demonstrator SV1STSS DEMO 1 (USA 208)2247.5
359382009-052BSTSS Demonstrator SV2STSS DEMO 2 (USA 209)2272.5

Ongoing Tracking

In subsequent days, the two satellites were tracked closely as they separated towards their operational locations and it very soon became apparent that the two transmissions each represented one of the satellites. Details of ongoing tracking of the mission can be found under "Radio Monitoring....." in the left hand menu.

For several weeks, the two satellites drifted apart until they lay on each others' horizons. They then reversed their drift and moved closer together until reaching the operational separation around the end of 2010 January.

Missile Detection Tests

2010 June saw the mission move into a new phase. Three missile launches from a combination of Vandenberg and Hawaii were used to test the vehicles' abilities and prove the technology.

See the notes on the Ground Based Interceptor test of June 6, the Vandenberg Minuteman III test of June 16, and the Scud launch and interception test of June 29.

A further Minuteman III missile test 2010 September 17 was also a target for the STSS Demonstrator satellites.
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