A Summary of the NASA Glenn Ballistic Impact Lab Contributions to the Columbia Accident Investigation Matthew E. Melis, NASA Glenn Research Center Mike Pereira Ph.D, NASA Glenn Research Center Duane Revilock, NASA Glenn Research Center Kelly S. Carney, Ph.D, NASA Glenn Research Center Key Words: Columbia Accident, Impact, Testing, Impact Analysis SUMMARY On February 1, 2003, the Space Shuttle Columbia broke apart during reentry resulting in the loss of 7 crewmembers and craft. For the next several months an extensive investigation of the accident ensued involving a nationwide team of experts from NASA, industry, and academia, spanning dozens of technical disciplines. The Columbia Accident Investigation Board (CAIB), a group of experts assembled to conduct an investigation independent of NASA, concluded in August, 2003 that the cause of the loss of Columbia and its crew was a breach in the left wing leading edge Reinforced Carbon-Carbon (RCC) thermal protection system initiated by the impact of thermal insulating foam that had separated from the orbiter’s external fuel tank 81 seconds into that mission’s launch. During reentry, this breach allowed superheated air to penetrate behind the leading edge and erode the aluminum structure of left wing which ultimately led to the breakup of the orbiter. Supporting the findings of the CAIB numerous ballistic impact testing programs were conducted to investigate and quantify the physics of External Tank foam impact on the RCC wing leading edge material. These tests ranged from fundamental material characterization tests to full-scale Orbiter wing leading edge tests. Following the accident investigation, NASA turned its focus to returning the Shuttle safely to flight. Supporting this effort are many test programs to evaluate impact threats from various debris sources during ascent that must be completed for certifying the Shuttle system safe for flight. Researchers at the NASA Glenn Ballistic Impact Laboratory have conducted several of the impact test programs supporting the Accident Investigation and Return- to-Flight efforts. This paper summarizes those activities and highlights the significant accomplishments made by this group. 1. BACKGROUND On January 16, 2003, at 10:39 a.m. Eastern Standard Time, the Space Shuttle Columbia lifted off from Launch Complex 39-A at Kennedy Space Center in Florida. At approximately 82 seconds into launch, Columbia was traveling at Mach 2.46 (1,650 miles per hour) at an altitude of nearly 66,000 feet when it was struck by a large piece of foam that had separated from the shuttle’s external fuel tank. The foam, decelerated by the air flow past the Orbiter, struck the left wing leading edge of Columbia, at a relative speed of 416 to 573 miles per hour, causing the breach in the leading edge thermal protection system that ultimately led to the tragedy. Two ground movie cameras captured the event. Figure 1 is an image taken from one of the movies just before the event and depicts two foam pieces separating from the bipod ramp. Figure 1. Two Pieces of Foam Debris Separating from Bipod Ramp. Various types of insulating foam cover the majority of the External Fuel Tank (ET) to keep the propellants cold and prevent the formation of ice on the outside of the tank. The characteristic deep orange color of these foams is due to exposure to sunlight. Most areas on the ET require only an inch or so of foam which is typically sprayed on by machine. Some locations, however, require more substantial build-ups of foam and are applied by hand. The Bipod Attachment Struts connect the nose of the Orbiter to the ET. An additional foam buildup was required where the struts attach to the ET RAMS 2005 284 U.S. Government work not protected by U.S. copyright