A critical space-based capability was added to America's ballistic missile defenses Sept. 25 when two U.S. Missile Defense Agency (MDA) Space Tracking and Surveillance System (STSS) Demonstrator satellites built by Northrop Grumman were launched aboard a Delta II rocket.

"This demonstration will show the inherent advantages space sensors bring to persistent missile tracking and engagement," said Gabe Watson, vice president and STSS program manager for Northrop Grumman's Aerospace Systems sector. "Space-based sensors will augment existing radar to enable missile tracking through all phases of flight from boost through intercept."

The United Launch Alliance Delta II rocket, with the tandem-stacked STSS demonstration satellites secured in its nose cone or fairing, lifted off from Cape Canaveral at 8:20 a.m. EDT. Within the first hour after lift-off, the two satellites began separating from the launch vehicle, as well as each other, in a sequence of automated maneuvers that inserted them into low-earth orbit.

During the next several months, the STSS Demonstrator satellites will undergo an early on-orbit test phase involving checkout of all space vehicle subsystems, ending with payload sensor calibration.

Lessons learned from the demonstration will be used by MDA to guide decisions about the development of an affordable, continuously available, operational, precision track space sensor constellation.