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The missile defense community got a unique, close-up view of yesterday's successful Aegis Ballistic Missile Defense (BMD) intercept test thanks to APL-developed sensors placed onboard the target missile.

A team from The Johns Hopkins University Applied Physics Laboratory (APL), in Laurel, Md., developed a multi-purpose sensor payload that was integrated with the target missile to collect video and infrared imagery of the target's boost and post-boost phases of flight; video coverage of the target's reentry vehicle separation event; and spectral, radiometric and video coverage of the intercept by a Standard Missile-3 (SM-3).

"This provided scientists with the closest and clearest view of the intercept," says Joseph Mulé, APL's project manager for Aegis BMD Test and Evaluation. "It will also enable scientists to better understand the phenomenon of post-burnout motor debris associated with solid-fueled boosters."

The payload takes advantage of the target booster's attitude control and guidance and navigation systems, which enable very accurate pointing of the separated booster section towards the reentry vehicle to ensure the intercept takes place within the forward looking sensors' fields of view. The payload consists of three fundamental parts — forward- and aft-looking sensors, and an electronics box.

The forward-looking sensor package consists of a radiometer, spectrometer, debris impact sensor and a visible-light camera to collect, for the first time, in situ measurements of an Aegis BMD intercept viewed from the target's separated booster section. The target-based sensors provide closer, clearer observations acquired at a different angle than those obtained by airborne- and ground-based platforms, which are often subject to transmission losses.

The forward-looking sensors, used to view the reentry vehicle separating from the booster, are placed inside a hinged cover with sapphire windows to protect them from contamination. After separation, the hinged cover opens so the sensors can directly view the intercept.

The aft-looking package consists of an infrared camera to collect data on the booster's post-burnout debris efflux, and a visible-light camera to obtain "departing Earth" video footage as the target's booster flies into space. The APL team designed and built pods, placed on the outside of the booster, to house each of the aft-looking sensors and protect them from aerothermal heating.

The APL team also oversaw the development of an electronics box to switch between instruments and cameras during the mission, and encode and format data and video for telemetry transmission.

"We're very excited to provide the Aegis BMD community with this unique capability," Mulé says. " Data collected during this flight test will add to the understanding of the intercept, as well as post-burnout solid rocket motor debris phenomena."

The APL team built and tested, in house, two payloads — one for the November 17 flight test and another for the next test scheduled for early 2006. They're currently fabricating two additional payloads for future tests, and developing the next-generation payload concept that would fly on much longer-range targets used to support Aegis BMD flight tests.

"It was rewarding for our team to build off of the Lab's legacy in both air and missile defense and space applications, and develop and test the payloads within APL facilities," Mulé says. "We envision continuing our efforts to evolve the payload and transitioning the technology to industry."

APL is the technical direction agent for the Aegis BMD program, which includes SM-3. The Missile Defense Agency and the Navy manage the Aegis BMD program.