Editing Space Shuttle Columbia disaster (section)

=== Debris strike concerns ===
[[File:Left bipod foam ramp.jpg|thumb|alt=Zoomed in image with arrows that label the bipod foam on the external tank.|Close-up of the left bipod foam ramp that broke off and damaged the orbiter wing]]

During the design process of the Space Shuttle, a requirement of the ET was that it would not release any debris that could potentially damage the orbiter and its TPS. The integrity of the TPS components was necessary for the survival of the crew during reentry, and the tiles and panels were only built to withstand relatively minor impacts. On STS-1, the first flight of the Space Shuttle, the orbiter ''Columbia'' was damaged during its launch from a foam strike. Foam strikes occurred regularly during Space Shuttle launches; of the 79 missions with available imagery during launch, foam strikes occurred on 65.{{r|caib_report}}{{Reference page|pages=121–122}}

The bipod connected the ET near the top to the front underside of the orbiter via two struts with a ramp at the tank end of each strut; the ramps were covered in foam to prevent ice from forming that could damage the orbiter. The foam on each bipod ramp was approximately {{convert|30|by|14|by|12|in|cm}}, and was carved by hand from the original foam application.<ref name="bipod">{{cite web|url=https://www.nasa.gov/pdf/63908main_Bipod_Fact_Sheet.pdf|title=External Tank Return to Flight Focus Area:Forward Bipod Fitting|publisher=NASA|date=August 2004|access-date=January 19, 2022|archive-date=November 4, 2021|archive-url=https://web.archive.org/web/20211104234744/https://www.nasa.gov/pdf/63908main_Bipod_Fact_Sheet.pdf|url-status=live}}</ref> Bipod ramp foam from the left strut had been observed falling off the ET on six flights prior to [[STS-107]], and had created some of the largest foam strikes that the orbiter experienced.{{NoteTag|No foam shedding was ever observed from the right bipod ramp. In its report, the CAIB hypothesized that this is because of the ET's liquid oxygen line, which partially shielded the right strut from aerodynamic forces.}} The first bipod ramp foam strike occurred during [[STS-7]]; the orbiter's TPS was repaired after the mission but no changes were made to address the cause of the bipod foam loss.{{r|caib_report}}{{Reference page|page=123}} After bipod foam loss on [[STS-32]], NASA engineers, under the assumption that the foam loss was due to pressure buildup within the insulation, added vent holes to the foam to allow gas to escape. After a bipod foam strike damaged the TPS on [[STS-50]], internal NASA investigations concluded it was an "accepted flight risk" and that it should not be treated as a flight safety issue. Bipod foam loss occurred on [[STS-52]] and [[STS-62]], but neither event was noticed until the investigation following ''Columbia'''s destruction.{{r|caib_report}}{{Reference page|page=124}}

During [[STS-112]], which flew in October 2002, a {{convert|4|by|5|by|12|in|cm|adj=on}} chunk of bipod ramp foam broke away from the ET bipod ramp and hit the SRB-ET attachment ring near the bottom of the left SRB, creating a dent {{convert|4|in|cm|sigfig=1}} wide and {{convert|3|in|cm|sigfig=1}} deep.{{r|caib_report}}{{Reference page|page=124}} Following the mission, the Program Requirements Control Board declined to categorize the bipod ramp foam loss as an in-flight anomaly. The foam loss was briefed at the [[STS-113]] Flight Readiness Brief, but the Program Requirements Control Board decided that the ET was safe to fly.{{r|caib_report}}{{Reference page|page=125}}

A debris strike from the [[ablative material]] on the right SRB caused significant damage to{{OV|104|full=no}} during the [[STS-27]] launch on December 2, 1988. On the second day of the flight the crew inspected the damage using a camera on the [[remote manipulator system]]. The debris strike had removed a tile; the exposed orbiter skin was a reinforced section, and a burn-through might have occurred had the damage been in a different location. After the mission, the NASA Program Requirements Control Board designated the issue as an in-flight anomaly that was corrected with the planned improvement for the SRB ablator.{{r|caib_report}}{{Reference page|page=127}}