By Ann Roosevelt

The Missile Defense Agency’s (MDA) two Space Tracking and Surveillance System (STSS) demonstration tracking satellites are at the launch site at Cape Canaveral, Fla., awaiting a fall launch, officials said.

The Low Earth Orbit satellites are to "explore the capability of concepts for viewing missiles after their powered flight," Army Lt. Gen. Patrick O’Reilly, the MDA director, said at a Defense Writers Group breakfast last week. "[Missiles are] very bright during powered flight but afterwards when they’re coasting, they cool down to a point that you need specific sensors to watch and track a missile while it’s coasting throughout its whole flight."

MDA requested $180 million for the program in the fiscal year 2010 budget.

The two satellites, delivered by Northrop Grumman [NOC] to the Cape in late April and early July, will work in tandem, viewing the same target to provide 3-D stereo tracking capability. The on-board infrared sensors are designed to track missiles through all phases of flight–boost, midcourse and terminal–and perform hit assessments after engagement

The STSS demonstration program was developed as part of the Space based Infrared System (SBIRS) Low program in the 1990s.

"It’s literally the same hardware," O’Reilly said. "It’s been somewhat difficult to develop and complete the work on it because a lot of the manufacturers have gone on to do other things and the components are obsolete in a lot of cases and the software."

Gabe Watson, vice president and program manager of STSS for Northrop Grumman Aerospace Systems, told Defense Daily in a recent interview, "One of the key things about STSS is it’s able to do cold body tracking and that’s different than the missile warning satellites like [Space Based Infrared System] SBIRS High, or [Defense Support Satellite] DSP. STSS, even though hardware was designed and in some cases built in the ’90s,…will still provide a unique capability for the country."

In 2002, Northrop Grumman received an $868 million cost-plus award fee contract for STSS to complete flight development, integration hardware into the two satellites and subjecting both to testing, Watson said.

The team continues its work.

In Florida, the Northrop Grumman team is involved with final testing of the satellites and tandem configuration assembly for launch, both on a single Delta II [rocket], he said. STSS is on NASA’s launch schedule for Sept. 15.

The team also developed the already operational STSS ground control system and will be responsible for operating the satellites at MDA’s Integration and Operations Center at Schriever AFB, Colo.

On orbit, MDA’s testing will include both aircraft and missile targets.

MDA’s ballistic missile defense system (BMDS) must be able to detect an enemy missile launch and be able to form a track of that missile through its boost phase, and then to be able to continue to track it through its ballistic phase where it’s a cold body. Then, it needs to be able to support the discrimination between what is a real reentry vehicle and what isn’t. The STSS sensors will be capable to conduct that discrimination function and combined with other sensing information, such as radar data, will be combined to pass missile-tracking data to missile defense interceptors with the accuracy and timeliness required to successfully intercept missile targets.

There are inherent limits to how well some sensors, such as radars, can discriminate, Watson said. Discrimination is an overall ballistic missile defense problem, and what the BMDS does is integrate information from all these sensing elements.

"With STSS, we’ll be able to accurately track from the very birth to the death and that’s what allows the interceptors to have accurate information for targeting," Watson said. "We call that closing the fire control loop."

Northrop Grumman will continue to be involved once the satellites are on orbit.

"We have a test plan that’s fairly well defined. We’re working jointly with MDA and we, Northrop, operate the satellite as well as participate in the test planning and test execution," he said.

Before the test program begins, there will be several months of tests to ensure the satellites are operating as expected. For example, that solar arrays are correctly deployed. Then, the payload is tested to ensure it’s operating correctly and that the acquisition and tracking sensors are properly calibrated. Then, as the pair of satellites fly in formation, actual testing begins.

O’Reilly said in the next two years interceptors will be launched on satellite data. "It’s never been done before."

Northrop Grumman is on contract for the first year of STSS operations and then there’s an option for a second year. The STSS satellites have a four-year design life.

O’Reilly said what MDA learns from the demonstrations will guide decisions on the development of an operational precision tracking space sensor constellation.

That constellation will not be called STSS, O’Reilly said. There are only two STSS satellites–"the only ones that exist and we have no intent of building further any like that. But we want to use them up there for the next several years, and it’s to inform us in procuring the Precision Tracking And Surveillance System."