U.S. Air Force Space Command, led by Gen. William Shelton, last month declared the first Space-Based Infrared System (Sbirs-1) satellite designed for use in geosynchronous orbit (GEO) operational and recommended to U.S. Strategic Command, which will operate the missile-warning spacecraft, that it begin accepting missile attack messages from it. Sbirs GEO-1 was launched in May 2011.

Sbirs, built by Lockheed Martin, is an $18 billion program to field new space-based infrared missile warning sensors. They are used to tip off U.S. missile defenses with the Integrated Threat Warning and Attack Assessment (ITW/AA) system.

Each Sbirs satellite in geosynchronous orbit includes older infrared scanners as well as newer staring sensors. After many technical challenges crafting the first satellites — the price to develop the system went from $4.5 billion in 1996 to $11.6 billion in 2012 — the Pentagon opted to take a methodical approach toward certifying the system in space.

Sbirs GEO-2 was launched March 19, and Jeff Smith, Lockheed Martin’s vice president for Sbirs, said then that this satellite’s scanner will be certified for ITW/AA use by year’s end.

These two spacecraft are augmenting legacy Defense Support Program spacecraft that have been in orbit conducting this mission for decades.

The company has already begun construction of the third satellite after a production gap, and negotiations are under way for a contract to fabricate two more satellites.

The first of two Sbirs scanners — one each on separate classified host satellites — was put in highly elliptical orbit (HEO) in 2006. The HEO-3 sensor is nearly ready for delivery and integration onto its host satellite.