Tracking Development
The Air Force is developing its missile tracking system, the Space-Based Infrared System, in three increments:
* Increment 1 was recently completed and consolidated three ground control systems into one.
* Increment 2, known as SBIRS-High and slated for 2003 funding, will add four satellites in geosynchronous Earth orbit and two sensors in highly elliptical orbit.
* Increment 3, known as SBIRS-Low, will add 20 to 30 satellites in low Earth orbit to provide midcourse missile tracking.