Initial on-orbit checkout of the first Space-Based Infrared System (SBIRS) early-warning payload has been completed, says the US Air Force. No launch was announced, but the timing makes it likely the host satellite was carried on the 27 June Boeing Delta IV launch from Vandenberg AFB in California. That launch, designated NROL-22, was the first of a Delta IV from Vandenberg and carried a classified US National Reconnaissance Office satellite into a highly elliptical orbit (HEO).
Being developed by Lockheed Martin, with Northrop Grumman as payload supplier, the SBIRS constellation will eventually consist of two HEO payloads and at least two geosynchronous-orbit (GEO) satellites. Operating in a highly inclined elliptical orbit, the HEO-1 first payload is designed to detect ballistic-missile launches from northern polar regions, says Lockheed.
SBIRS Increment 1, which became operational in 2001, involves a consolidated ground architecture that processes data from existing Defense Support Programme (DSP) early-warning satellites. HEO-1 is the first part of the Increment 2 constellation replacing the GEO DSPs, the last of which was launched in May 2005.
Orbital checkout of HEO-1 is focusing on calibration of the infrared sensors and performance is "meeting or exceeding" requirements, says the USAF. The payload is scheduled to be fully operational by the third quarter of 2008, and the first GEO satellite is on target for launch in late 2008, says Lockheed. Plagued by cost growth and schedule slippage, the programme was split into two: SBIRS-High to replace the DSPs and SBIRS-Low - later renamed the Space Tracking and Surveillance System - using low-Earth-orbit satellites to track missiles in their boost, mid-course and terminal phases.
Source: Flight International
