The United States Missile Defense Agency (MDA) is developing a Space Tracking and Surveillance System (STSS) which it will use to research the space-based detection and tracking of ballistic missiles. Data from STSS satellites could allow interceptors to engage incoming missiles earlier in flight than would be possible with other missile detection systems. The STSS program began in 2001, when the "SBIRS Low" program was transferred to MDA from the United States Air Force.
Two demonstration satellites were launched together on a single Delta II launch vehicle. Launch took place September 25, 2009, from Cape Canaveral Air Force Station Space Launch Complex 17. One of the two satellites had been shipped to Cape Canaveral May 4, 2009; the second satellite arrived at the launch site on June 25, 2009. It was reported that several items of debris, identified by amateur satellite watchers as remnants of the Delta-2 launch vehicle, had crashed in a field in Mongolia on the February 19, 2010.
The perceived advantage of STSS is that its satellites, by operating at a lower altitude and by using long- and short-wave infrared sensors, will be able to acquire and track missiles in midcourse and during the boost phase.
STSS is designed to be the low earth orbiter within the layered Ballistic Missile Defense System. It complements the geosynchronous Defense Support Program, the Space-Based Infrared System, and other Overhead Non-Imaging Infrared systems (ONIR) and provides tracking cues to systems on the surface. The STSS program is developed in phases, the first of which is the launch of two demonstrator satellites. The demonstrators will perform experiments and prove out systems and processes to establish a knowledge base for future operational designs. The demonstration satellites, built by Northrop Grumman and Raytheon detected and tracked a two-stage Ground-Based Interceptor (GBI) during a U.S. Missile Defense Agency flight test on June 6, 2010.
According to Congressional testimony, military officials believe that STSS has the potential to bolster the nation’s missile defense system. “Two recent flight tests demonstrated that STSS dramatically improved the precision of threat missile attacks and provided more accurate fire control quality data to the Aegis ships several minutes earlier than less accurate data provided by organic radars in the Aegis or THAAD (Theater High Altitude Area Defense) systems,” U.S. Army Lt. General Patrick J. O’Reilly, Director of the U.S. Missile Defense Agency, told the U.S. Senate Appropriations Committee’s Defense subcommittee in prepared testimony on May 25, 2011.
According to Global Newswire (sourced by Northrop Grumman) press releases, the following is a summary of the STSS Demonstration program satellites' on-orbit performance.
Ground-Based Interceptor test launch – 06.06.2010
First STSS Object Sighting Messages (OSM) of a missile
First on-board missile track formed
ICBM Minuteman III test launch – 16.06.2010
First dual satellite collect of target, and
First target acquisition from a target launched beyond the horizon
Terminal High Altitude Area Defense system test – 28.06.2010
First OSMs sent to Enterprise Sensors Laboratory at Schriever Air Force Base, Colo., for data fusion with other sensors in real time
First track of a dim theater missile
First track of a resident space object – 19.07.2010
Tracked a NOAA weather satellite 19.07.2010 for several minutes (externally queued)
First autonomous acquisition sensor to track sensor handover of a target – 23.07.2010
Hand-off demonstration occurred when STSS acquired a ground laser source operated by U.S. Air Force Research Laboratory from the Starfire Optical Range at Kirtland Air Force Base, NM
First track of an aircraft
Precision track sensor operation below the horizon during daylight – 05.08.2010
First autonomous acquisition sensor to track sensor handover of an aircraft
Airborne Laser Test Bed Exercise – 01.09.2010
First autonomous acquisition sensor to track sensor handover of a boosted target
ICBM Minuteman III test launch – 17.09.2010
First post boost track continuation of a target with track sensor
First demonstration of track sensor generating multiple tracks for separating objects
Aegis Launch on Remote Campaign
First Track sensor stereo track of a dim boosted target
First stereo post boost tracking of midcourse target
Second Aegis Readiness Assessment Vehicle Targeting – 09.03.2011
STSS satellites acquired and tracked its target until re-entry
Second full-course tracking during U.S. Missile Defense Agency's (MDA) Aegis launch – 15.03.2011
Successful production of "stereo" 3-D tracking software to follow the target missile's flight path to predict its impact point
Sea-based missile defense test – 15.04.2011
STSS satellites target and help to intercept an intermediate range ballistic missile (IRBM); destruction of the IRBM on impact
STSS test on short-range, air-launched target (SRALT) – 08.07.2011
This test proved the STSS's ability to track dim objects that have extremely short flight timelines