Space Tracking and Surveillance System
The Missile Defense Agency (MDA) operates the Space Tracking and Surveillance SystemDemonstrators (STSS-D). STSS-D constellation consists of two satellites orbiting at 1350 km,
58 degree inclination, with 120 minute orbital period. Using sensors capable of detecting visible
and infrared light, STSS-D serves as the experimental space layer of the Ballistic Missile Defense System (BMDS).
Mission Objective: Provide Accurate Tracks of Midcourse Re-entry Vehicles to the Shooter.
Boosting targets detected by acquisition sensor – continuously scans visible Earth in ShortWave
Targets autonomously handed-off to track sensor – Sensitivity/Wavebands enable midcourse
Target 2-D Line-of-Sight reported to ground via Object Sighting Messages.
Ground forms high accuracy 3-D track from stereo Object Sighting Messages.
3-D tracks reported to the BMDS.
On Sept. 25, 2009, MDA, NASA, and U.S. Air Force team successfully launched two STSS-D
satellites in tandem into low earth orbit on a NASA Delta II launch vehicle from Cape Canaveral, Fla.
Both satellites are operating nominally on-orbit under the control of the Missile Defense Space
Development Center (MDSDC).
STSS-D is participating in integrated BMDS testing and providing significant risk reduction in
support of the development and fielding of a future missile defense operational satellite constellation.
Program Update and Accomplishments
STSS-D satellites completed an Early On-orbit Test series of 127 System Functionality Tests and
achieved a critical milestone of demonstrating full calibrated performance of both satellites, their
crosslink systems, and the acquisition and track sensor payloads.
First stereo collection on birth-to-death missile flight and provided the missile tracking data to the
BMDS in near real-time.
First on-orbit demonstration of receipt of an external cue and the use of the STSS-D crosslink to
transmit that cue to the out-of-view satellite, resulting in stereo midcourse tracking and first
observation of missile intercept from low earth orbit.
First simulated Aegis remote engagement authorization based on STSS-D tracking data.
Transferred STSS-D Program Office Responsibility from Los Angeles AFB, Calif. to
MDSDC, Colorado Springs, Colo.
Validate remote sensor and fire control integration to inform the design and operations of the next
generation space tracking system, to characterize the contribution of space data into the BMDS
architecture, and to provide sensor measurements and background data supporting trade studies
and analysis for BMDS systems.
Integrate space capabilities into the BMDS architecture and collaborate with Air Force Space
Command on studies and experiments to optimize next generation tracking satellites support for
Space Situational Awareness functionality.
Continue to participate in MDA scheduled test events and track available targets and missiles in all
phases of flight and provide track data to the integrated BMDS.
Provide invaluable engineering and integration data for development of a follow-on operational
BMDS Space Layer for accurate and timely object tracking and reporting of missile attacks against
U.S., its allies, and deployed forces.