Wing Leading-Edge Sensors: Although it was not required, NASA has added 88 accelerometer sensors behind the wing leading-edge panels, which, added to the existing temperature sensors, make a total of 176 sensors. Acceleration and temperature data will be combined with voltage data to detect debris impacts and their locations. The data is transmitted to both a cockpit laptop and Mission Control.
According to Sauser, accelerometers had been used elsewhere on the Shuttle, but not on the wings. Detecting impacts would be guesswork, Sauser says, without new software that improves data reduction. “We’ve been working hard on using the software to determine what is noise and what is critical data.”
Ground Monitoring: There are now 107 cameras, both ground-based and on the aircraft, in place to monitor lift-off, ascent, and re-entry. Improvements include better film cameras that run at higher frame rates (100 fps), the addition of HDTV cameras, and more widespread locations designed for triangulating different events from multiple angles. Film, video, and stills are integrated with radar, with mirrored servers added for faster communication between ground teams. HDTV results will be available for review within a few hours, and film will be compiled over one to two days. The combined system can detect debris objects as small as one inch in diameter up to 30 seconds from launch, and up to 15 inches at booster separation.
Air Monitoring: An experimental air monitoring system will augment ground views with HDTV and infrared imaging cameras mounted on the ball-turret systems of the last two active WB-57 high-altitude weather reconnaissance aircraft. Two aircraft flying at up to 6,000 feet on either side of launch will track the ascent until eight minutes and thirty seconds after launch.
Radar Monitoring: New Wideband Coherent C-Band Radar and Weibel Continuous Pulse Doppler X-Band radar tracking systems will be used to improve tracking of falling debris. The C-Band system provides high spatial resolution, and the Doppler system tracks debris velocity and differential motion. Data from both systems will be correlated from three different angles, with the C-Band data available in near real time.
Shuttle-Based Cameras and Radar: An Enhanced Launch Vehicle Imaging System (ELVIS) incorporates additional “lipstick” cameras located on the surfaces of the Orbiter, its rockets, and the external tank, to improve views of damage during ascent. Cameras are positioned to focus on potential problem areas and new equipment. Also, crew handheld digital cameras have been improved, and there’s a new high-resolution camera designed for spacewalks.
External Tank: Dwarfing the Shuttle orbiter, the 15-story external tank dispenses 535,000 gallons of liquid hydrogen and oxygen during the first two minutes of ascent. The foam shielding that damaged Columbia’s wing likely broke off from the tank’s “bipod” fitting – an area that also produced debris falling during the October 2002 launch of Atlantis. The existing tanks have been retrofitted, and the bipod shielding replaced with electric heaters to avoid the buildup of ice.