Proves Wide-Band Doppler Can Track Debris

Radar tracking data gathered during the Delta II launch of the MESSENGER spacecraft earlier this month has provided promising results that may benefit NASA's Space Shuttle Program and Discovery's Return to Flight.

A pair of radars installed at NASA's Kennedy Space Center (FL) at a site north of Haulover Canal tracked the launch phase of the Delta II, including separation of the nine solid rocket boosters and jettison of the first stage and the payload fairing, the "nose" of the rocket that protected the MESSENGER spacecraft during launch.

"This test was quite successful for us in proving a concept," said NASA project manager Tony Griffith. "The use of high-resolution wide band and Doppler radars allows us to observe almost any possible debris during ascent and means we can observe the Space Shuttle without regard to limitations of visibility, cloud cover and darkness."

More importantly, the tandem radars "saw" -- in significant detail -- ice shedding from the Delta first stage, ejection of the solid rocket booster nozzle throat plugs, and contents of their exhaust. These are normal Delta launch events. For the Space Shuttle Program, the test showed that the radars, working together, were effective in visualizing the vehicle elements in high resolution and the ability to attain speedy interpretation of the images for initial data analysis after a Shuttle launch.

The antennas have been on loan to NASA from the USNS Pathfinder, a US Navy instrumentation ship. The 30-foot-diameter C-band wideband radar antenna and the smaller X-band Doppler radar worked together to image the Delta in flight. The Navy operated the radars for NASA during the MESSENGER launch. NASA was responsible for analyzing the imagery.

"This turned out to be a successful and mutually beneficial partnership with the Navy that we will pursue," Griffith said.

Later this fall, a 50-foot-diameter C-band wide band radar will be installed on this site for a similar Return to Flight application and for use by the Navy. The radar is being relocated to KSC from the Roosevelt Roads Naval Station in Puerto Rico.

The radars used for the test are being returned to the USNS Pathfinder, though the C-band radar used in this test could return as a backup for Return to Flight, if available from the Navy. NASA is evaluating the procurement of two X-band Doppler radars for use on ships downrange, including one of the solid rocket booster retrieval ships.

FMI: www.returntoflight.org