The US Air Force has accepted modifications to the second highly elliptical orbit (HEO-2) spacecraft and ground systems of the Space Based Infrared System (SBIRS) for operations.

The SBIRS will offer early warning of missile launches, while supporting other missions including missile defence, technical intelligence and battle space awareness.

The acceptance follows an operational utility evaluation and trial period where live HEO-2 data was used over a variety of intelligence networks.

US Air Force SBIRS Wing Commander Colonel Roger Teague said this asset provides outstanding capabilities to combatant commanders and the excellent performance of this second HEO system is a true testament to the teamwork and dedication by the government and industry team.

The US Strategic Command will give the final certification for the HEO-2 system in August 2009 when the sensor and its data is certified for use as part of the US strategic missile warning system.

The USAF has awarded contracts to Lockheed Martin for three HEO payloads and geosynchronous orbit satellites each along with ground systems.