Behind the Scenes: Real-Time Shuttle Debris Analysis
07.25.11
NAS researcher Stuart Rogers gives an insider's glimpse of debris-related support work for all shuttle missions over the past 8 years.
From the moment each Space Shuttle mission begins fueling, various teams at NASA's Johnson Space Center in Houston and Kennedy Space Center in Florida go into action to monitor the mission. On hand are computational fluid dynamics (CFD) experts from the NASA Advanced Supercomputing (NAS) Division at Ames Research Center, who identify, analyze and help make decisions about potential debris hits and any resulting damage to the shuttle (see the article, "The Right Stuff at the Right Time").
Capturing the vehicle from all angles using both ground-based and onboard cameras, debris team members look for anything unusual such as ice formation or cracks in the insulating foam on the shuttle's external tank. Anything spotted during these inspections must be acceptable under NASA's launch commit criteria, which define what constitutes a vehicle that is ready to fly and the conditions under which it is permissible to launch, or a waiver must be written certifying that the vehicle is safe to fly. This sometimes requires real-time debris analysis, where the worst-case debris impacts from the suspect foam or ice must be analyzed and cleared within the span of an hour.
After a successful launch, the debris and imagery analysis teams spend the first several flight days scrutinizing videos frame by frame to look for any debris events and any evidence of damage to the orbiter.
Being this close, and affecting the safety of missions and astronauts for remaining shuttle flights makes me proud to work for NASA.
Stuart Rogers
Two years ago, after the successful launch of Space Shuttle Endeavor (STS-126), post-launch videos showed something that initially looked like a piece of white insulation material falling off the shuttle's aft fuselage during ascent. On day 2 of the mission, NAS Division CFD researcher Stuart Rogers and the debris-assessment team monitored the on-orbit inspections from the Mission Evaluation Room in Houston. These regular inspections use a boom sensor system to assess the shuttle's thermal protection systems.
The debris team asked the astronauts to zoom in on the area of the fuselage in question, which revealed that the insulation material was completely intact. By communicating directly with the astronauts in orbit, they were able to determine that the debris was ice that formed next to the T0 umbilical plate while still on the ground.
"Everything on the vehicle looked perfect," said Rogers. "The ice didn't hit any part of the vehicle, but it could happen in the future, so we've continued to run lots of detailed simulations and tracked the problem since then."
Another example of real-time analysis comes from the pre-launch countdown for the shuttle Discovery (STS-119), when a bat landed on and attached itself to the external tank. Debris transport analysis was performed to see if the bat could have damaged the orbiter during ascent. Fortunately, the unexpected "hitchhiker" was settled on a part of the tank where it could not have caused damage, so an official written waiver was processed and the launch occurred without incident.
"Being part of the team doing real-time analysis during missions is really cool and exciting," Rogers said. "Most of us on the NAS CFD team started our careers as research engineers developing new tools, algorithms, or software, and applying to them to test problems and some flight vehicles. Being this close, and affecting the safety of missions and astronauts for remaining shuttle flights makes me proud to work for NASA."
– Jill Dunbar
