Shuttle Reviews: Debris Assessment Activity
NASA engineer Justin Kerr (left) and Boeing engineer Jorge Zapata inspect a Reinforced Carbon-Carbon panel following foam impact test at the Southwest Research Institute (SWRI), San Antonio, Texas. RCC Panel 9, located at the heat critical region of the Shuttle's wing as shown here, is one of 22 panels on each wing-leading edge that protect the Space Shuttle from temperatures as high as 3,000 degrees Fahrenheit during reentry into the earth's atmosphere. Panel 9 was the focus of impact tests at SWRI to finalize validation of the damage prediction models being developed by Boeing. (Boeing Photo by Tony Romero)
One of the recommendations of the Columbia Accident Investigation Board (CAIB) investigation was to improve the capability to assess what damage debris such as ice or insulating foam from the ET could inflict on the orbiter. Boeing has been heavily involved in debris assessment activity where the different elements define what type of debris could come off.
Boeing' s shuttle Integration team performed various debris transport analysis, using complicated Computational Fluid Dynamics modeling. The debris activity proved to be challenging and a tough physics problem, but over the past two years since the Columbia accident there was enough time to create new models and run enough tests to solve the problem.
NASA, USA and Boeing conducted debris impact tests at White Sands, Southwest Research Center in San Antonio, Kennedy Space Center and Glenn Research Center for orbiter materials and tiles, RCC material and even shuttle windows.
Boeing has relied upon an analytical tool called LS-DYNA to model RCC and tile reaction to foam and ice impact. It is a finite element model that physically models what is being hit, the material itself and the physical interaction between the two. LS-DYNA allows one to do individual properties on the foam, RCC/tile and develop the models.
Phase II impact testing for RCC, conducted at Glenn Research Center, was used to calibrate and correlate the LS-DYNA models that the Boeing Philadelphia employees worked on.
Boeing and NASA conducted enough tests to bound the possible cases to cover pre-flight and actual flight of possible debris.