STS-107: Space Shuttle Columbia Breakup ( Aerospace - Space Shuttle )

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    The Space Shuttle Columbia, flying a mission titled STS-107, broke up while re-entering the Earth's atmosphere on February 1, 2003. Columbia was at an altitude of about 39 miles, and traveling at about 12,500 miles per hour (mach 18.3) when the breakup occurred. Superheated air had entered a hole in the leading edge RCC (reinforced carbon-carbon) caps on the left wing, burning and melting internal structures until the vehicle came apart. All seven crewmembers perished: Commander Rick Husband, Pilot William McCool, Payload Commander Michael Anderson, Mission Specialists David Brown, Kalpana Chawla, & Laurel Clark, and Payload Specialist Ilan Ramon. No Space Shuttle flew again until July, 2005.

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    (Aug 9, 2005) The Space Shuttle Discovery was successfully launched on "Return to Flight" mission STS-114 on Tuesday, July 26, and reached orbit without any difficulties.
    Photo analysis of the Discovery showed that a large piece of spray-on foam insulation again broke off the External Tank during the launch, although there was no indication that it damaged the orbiter vehicle.
ET photos showing missing foam - NASA Return to Flight

    A similar piece of falling insulation has been blamed for putting a hole in the leading edge of the shuttle Columbia's wing in 2003, leading to the destruction of that vehicle and the loss of seven lives on reentry.
    Discovery landed safely on August 9, 2005. STS-114 was the first Space Shuttle flight since the STS-107 Columbia breakup.

    In the Spring and Summer of 2003, the cause of the breach in the leading edge of the Space Shuttle Columbia's wing on the STS-107 mission was attributed to the impact of foam insulation from the shuttle's external tank on the wing. On the basis of video that showed a chunk of insulation apparently impacting the wing, plus calculations indicating that ET insulation could have been the cause of the hole in the leading edge of the wing, the board flatly declared that ET insulation was the cause of the Columbia breakup.

The Columbia Accident Investigation Board said:
    Eighty-two seconds into STS 107, a sizeable piece of debris struck the left wing of the Columbia... At this time Columbia was traveling at a speed of about 2300 feet/second (fps) through an altitude of about 65,900 feet. Based on a combination of image analysis and advanced computational methods, the Board determined that a foam projectile with a total weight of 1.67 lb and impact velocity of 775 fps [about 530 mph] would best represent the debris strike...

    The visual evidence shows that the debris impacted the wing approximately 0.161 seconds after separating from the ET. In that time, the debris slowed down from 2300 fps to about 1500 fps, so it hit the orbiter with a relative velocity of about 800 fps. In essence, the debris slowed down and the Orbiter did not, so that the Orbiter ran into the debris...

    The CAIB's conclusions led to redesign of the Space Shuttle External Tank, to avoid foam insulation breaking off during flight. The redesign and its implementation have taken almost 2 years.

    (Feb. 15, 2003) The space shuttle wing leading edge and nose cap are composed of a carbon/carbon composite called reinforced carbon-carbon (RCC). RCC will not melt or decompose at reentry temperatures, but will oxidize at temps above 800° F. (427° C.). To prevent oxidation the RCC is covered with a silicon carbide oxygen-barrier coating.

    A NASA document from April, 2000 shows that: "Small pinholes roughly 0.1 mm in diameter have been observed on these materials [the silicon carbide, not the RCC] after 12 or more flights. These pinholes have been investigated by researchers... to determine the possible sources and the extent of damage."

    NASA engineer Dr. Nathan S. Jacobson goes on to say that "Our concern was that if a pinhole went through the silicon carbide to the carbon/carbon substrate, oxygen would have a clear path to oxidize the carbon at high temperatures." Studies of possible damage indicated "a strong dependence on pinhole diameter. For smaller diameters and short times, the oxidation of carbon is very limited."

    Although NASA officials are no doubt aware of this situation, and some form of impact damage is the leading suspect for causing the Columbia left wing breach, RCC burn-through resulting from pinholes or other damage to the silicon carbide coating should be specifically eliminated as a possibility.

    1998 Tech Report: Space Shuttle Pinhole Formation Mechanism Studies, .pdf.


Lockheed Martin photo shows the 22 U-shaped
RCC "caps" over a Shuttle wing leading edge.

The current AW&ST article says:

    The U-shaped RCC sections are attached to the wing "with a series of floating joints to reduce loading on the panels due to wing deflections," according to Boeing data on the attachment mechanism.
    "The [critical heat protection] seal between each wing leading-edge panel is referred to as a 'tee' seal," according to Boeing, and is also made of a carbon material.
    The tee seals allow lateral motion and thermal expansion differences between the carbon sections and sections of the orbiter wing that remain much cooler during reentry.

    In addition to debris impact issues, investigators will likely examine whether any structural bending between the cooler wing structure and the more-than-2,000F leading edge sections could have played a role in the accident. There is insulation packed between the cooler wing structure and the bowl-shaped cavity formed by the carbon leading-edge sections.
    The RCC leading-edge structures are bolted to the wing using Inconel fittings that attach to aluminum flanges on the front of the wing.
 


Columbia's underside shortly before breakup, from a 3½" consumer telescope.

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 STS-107 Columbia:

STS-107 Investigation Reference Page
NASA: Return to Flight Pages
CAIB Report, .pdf:
low-res 10MB - 28MB - 175MB hi-res
Columbia Accident Invest. Board
NASA: Columbia Home
NASA History: Columbia Home
NASA: Ground Track w/ Data, .pdf

Space.com: Columbia Tragedy
AviationNow: Columbia Disintegrates
CNN Special: Columbia Lost

NASA: Shuttle Thermal Protect. Sys.
Space Shuttle Orbiter Structures
 

 See also:

Space.com: Columbia FAQs
NASA Ref.: Space Shuttle Structure
AW&ST: USAF Images: Wing Damage
SS Pinhole Form. Mech. Studies
(.pdf of NASA 1988 tech paper)
Thermal Resp. of SS Wing in Reentry
(.pdf of NASA 1984 tech paper)
Risk Mgmt for Space Shuttle Tiles
(.pdf of paper by CMU's P. Fischbeck)
MSNBC: Wing Corrosion a Factor?
Encyclopedia Astronautica: Columbia
Shuttle Mission Events Summary
NASA Shuttle Crew Operations Manual
NASA Press Releases
US News Columbia Links

NASA STS-107 Shuttle Mission Archive from NASA's pages with concise but complete descriptions of each of the 100+ Space Shuttle missions thus far, from STS-1, launched on April 12, 1981, right up to the present.

KSC STS-107 Shuttle Mission Info

STS-51L Challenger:
STS-51L Challenger Resources

STS-51L Challenger Rogers Commission Report (1986)

Personal Observations on the Reliability of the Shuttle is the full text of Richard Feynman's addendum to the STS-51L Challenger Commission report on the catastrophic loss of a Shuttle and seven lives on January 28, 1986.

Apollo 13:
Apollo 13 Review Board Report
(Cortright Commission) 36 .pdf files, also see restored version

cover

The Space Shuttle Operators Manual,
1982 ed., p. 7.16:


EXTERNAL INSULATION
    ...the thermal protection system, or TPS, keeps... the Orbiter structure below 175°C (350°F) during entry. Several different materials make up the TPS. A high-temperature, high-strength material called reinforced carbon-carbon (RCC) is used on the nosecap and leading edges of the wings. This gray substance can withstand temperatures of 1,650°C (3,000°F).

    The black areas on the Orbiter are covered with blocks or tiles of varying size and thickness. These are the high-temperature reusable surface insulation, or HRSI. HRSI tiles protect areas where temperatures are between 650°C (1,200°F) and 1,275°C (2,300°F).

    On Orbiter 102, Columbia, white tiles cover the forward fuselage, outer wing areas, pods, and the stabilizer. Called low-temperature reusable surface insulation, or LRSI, these tiles are used where temperatures are between 370°C (700°F) and 650°C (1,200°F).

    Columbia's cargo-bay doors, fuselage sides, upper wing surfaces, and aft areas of the OMS pods are covered with a Nomex felt material. These areas remain below 370°C (700°F) during flight.

    Altogether, nearly 32,000 HRSI and LRSI tiles cover Columbia. No two tiles are exactly alike and each must be installed by hand...

From the NASA STS-107 Briefing February 1, 2003 (15:31 ET)

MILT HEFLIN, CHIEF FLIGHT DIRECTOR:

    Around 7:53 a.m. central time... we saw indication of off-scale, low temperature measurements on the left inboard and outboard hydraulic systems. This is loss of the temperature measurement. It wasn't any indication that it was high or low. We just lost it [this is during the period of highest heating of the vehicle due to atmospheric friction].

    About three minutes later, around 7:56 a.m., in the left main gear tire wheel well brake line and tire temperatures, there we saw an increase.

    Now, I need to tell you that during this time the vehicle was performing fine. We had no indications of any problem.

    Around 7:58 a.m. central time... we have what we call bond (ph) line temperatures. These are temperature sensors that are embedded in the structure of the vehicle. We have them all over the orbiter.
    Three of these temperatures on, again, the left side of the vehicle, the left wing area, the off-scale low reading again. This was not high indication, low indication, but they were -- we lost measurements.
    Don't have the seconds here. Clearly seconds will play a part in our analysis, but I'm giving this to you at the nearest minute.

    Around 7:59... left inboard and outboard tire temperatures and pressures, off-scale low. About eight measurements total during that time. One of these -- one of these measurements sensed on board by the computers gave the crew a message, indication that they could look at on their displays. And they -- we think they were acknowledging that measurement that they saw.
    Again, the vehicle was flying with no problems at that time.

    And when things like this happen, when a crew gets an alert, you acknowledge it, they recognize they've seen it, and then we go and do what we might need to do with it.

    And as far as I know, that was the last transmission from the crew. I've asked a couple of people, I haven't heard the tapes myself. I'm not sure what they said at the time. But they were acknowledging, we believe, that indication that they'd seen.

    Then we lost all vehicle data. It looks like it was around -- and I apologize, it looks like my little cheat sheet here doesn't have the last central time on it and I'm not going to try to convert it to you at this point, but it was around 8 o'clock central standard time. Altitude was 207,135 feet, and traveling at a mach of about 18.3 [about 12,500 MPH].

    And the flight control team, during this time -- again, we lost the data, and that's when we clearly begin to know that we had a bad day.

    That's all I've got.

    (Feb. 14, 2003) From a Columbia Accident Investigation Board Statement:

    Preliminary analysis: temperatures show the presence of plasma in Columbia's left wheel well during entry (plasma means the super heated gas which surrounds the orbiter during re-entry).

    Heat transfer through the structure (as from a missing tile) would not be sufficient to cause the high temperatures seen in the last minutes of flight. An AW&ST story says: "a breach in the left wing-along its leading edge, its landing gear door or seals-would had to have occurred for temperatures in the left wheel well to rise as they did in the final seconds before breakup began, according to data developed by a NASA thermal analysis team...

    Sources outside the board noted that it is increasingly likely the breach in the wing structure was not specifically in the wheel well area..." A CNN story quotes a space shuttle program source as saying: "There is no question that wheel well was breached... But who knows how? Did it start there, or was this part of a domino effect?"

    The foam ET insulation that broke off during ascent is still a suspect for the cause of such a breach. Another possibility: orbital collision (CNN story).

    The board also released a detailed .pdf file showing the ground track of Columbia throughout the reentry, with sensor data from various points along the way.

    (Feb. 12, 2003) NASA has released a transcript of voice contact during Columbia's final moments before breakup. They have also released text of email exchanges on the ground during the mission, concerning possible effects on the landing gear door caused by the foam insulation that struck the wing during ascent.
    (Feb. 7-11, 2003) A portion of the left wing from the Space Shuttle Columbia has been found near Fort Worth, TX. Debris in this area is the furthest west of any that has been confirmed as coming from Columbia. The "large" wing segment includes leading edge carbon-carbon, and TPS tiles. Space Shuttle program manager Ron Dittemore said: "We have recovered a partial wing leading edge RCC panel, that's reinforced carbon carbon panel. It's 26 to 27 inches long with 18 inches of wing structure still attached." It was later confirmed that the segment is from the left wing. About 12,000 separate pieces of debris had been recovered as of Feb. 10.

    Aviation Week & Space Technology magazine reported that the US Air Force was photographing Columbia's descent through a ground-based telescope, and that photos from about 8:59AM ET (1 minute before breakup) show substantial structural damage on the left wing, on the leading edge near the fuselage. In this morning's press briefing, NASA Dep. Assoc. Admin. for ISS & Shuttle Michael Kostelnik confirmed that the photos do exist, but said they are low-resolution and had not yet been evaluated.

    The photos were shown at the afternoon press conference, and only a fuzzy-edged shilouette can be seen. Ron Dittemore said: "The nature of the photograph shows some choppiness to the wing leading edge... It is not clear to me that it reveals anything significant at the moment... It does look like there's something just a little different about the left-hand side behind the wing than the right-hand side." It is not likely that any higher-resolution photos of Columbia during reentry exist.

    Amateur video taken from Reno, Nevada apparently shows a large fragment breaking off of Columbia as it was in the area of the Arizona-Nevada border. The moon is visible in the video, this + where the video was shot from should allow fairly precise determination of where Columbia was when the piece broke off.

    AW&ST says: "The abnormal events seen on orbiter telemetry in Houston indicate a slow penetration of reentry heat into the orbiter and damage on the wing, overpowering the flight control system."

Timeline (primarily from the excellent AW&ST article):

    7:52 a.m. CST: Abnormal telemetry events began. Columbia was crossing the west coast N. of San Francisco at 43 mi. alt., about Mach 20.
    At this time Columbia was in a 43° right bank completing its first "roll reversal", an S-turn maneuver to lose speed.
    That initial bank had been as steep as about 80 deg. between Hawaii and the California coast. This is a normal part of reentry.

    7:52 a.m.: 3 left main landing gear brakeline temps show an unusual rise. It appears that hot gases had a flow path within the wing to reach the wheel well.

    7:53 a.m.: A 4th left brakeline strut temperature measurement rose significantly--about 30-40 deg. in 5 min.

    7:54 a.m.: Columbia was now over E. California-W. Nevada. The left wing root/leading edge area showed an unusual temperature rise of 60° F over 5 min. Something was heating the wing fuselage interface area. Wing leading edge and belly temperatures were over 2,000° F. The outside layer of the double fuselage wall was heating, but the inside wall remained cool.

    7:55 a.m.: A 5th left main gear temperature sensor showed an unusual rise.

    7:57 a.m.: Columbia was passing over Arizona and New Mexico. The upper and lower left wing temperature sensors failed, probably indicating their lines had been cut. The orbiter was rolling back to the left into about a 75° left bank angle, again to dissipate energy and for navigation and guidance toward Runway 33 at Kennedy, then about 1,800 mi. away.

    7:58 a.m.: Still over New Mexico, the elevons began to move to adjust orbiter roll axis trim, indicating an increase in drag on the Columbia's left side of the vehicle. That could indicate a "rough tile or missing tile but we are not sure," Ron Dittemore said. At the same time, the elevons were reacting to increased drag on the left side of the vehicle, the left main landing gear tire pressure and wheel temp measurements failed. This probably indicated a loss of the sensor, not the explosion or failure of the left main gear tires.

    7:59 a.m.: Additional elevon motion was commanded by the flight control system to counteract left side drag. The drag was trying to roll the vehicle to the left, while the flight control system was commanding the elevons to roll it back to the right.
    But the rate of left roll was beginning to overpower the elevons, so the control system fired two 870-lb.-thrust right yaw RCS thrusters to help maintain the proper flight path angle. The firing lasted 1.5 sec. and, along with the tire pressure data and elevon data, would have been noted by the pilots.
    The USAF telephoto imagery from about this time is said (not yet officially) show substantial damage to the left wing root/leading edge area.

    8:00 a.m.: Final contact: CAPCOM Lt. Col. Charles Hobaugh, radioed "Columbia, we see your tire pressure [telemetry] messages and we did not copy your last transmission." On Columbia, CMDR Col. Rick Husband began to reply, "Roger, buh--" and then contact was lost, and the vehicle broke up.
    Alt.: 207,135 feet (about 39.23 mi.)
    Speed: Mach 18.3 (about 12,500 mph)
    Reentry flight director: Leroy Cain

TIME Magazine, February 3, 1967, p. 13:

SPACE: "To Strive, To Seek, To Find, And Not To Yield..."
    Death could have come in any number of bizarre ways. In the explosion of an errant rocket in the view of millions on TV; in the instant incineration of a capsule out of control during the treacherous re-entry into the earth's atmosphere; in the coffin of a malfunctioning craft unable to descend that orbits, orbits, orbits in the spatial void while power ebbs and life leaks away in slow suffocation.
    But the first three U.S. astronauts to die on duty were motionless and earthbound when they were killed last week. With helmet faceplates closed and suits pressurized, they reclined in a row on padded couches in their cylindrical Apollo capsule, running through the countdown of a simulated launch, a routine but rigorous rehearsal for the real thing. They had been there 5 hrs. 31 min. when fire exploded in the cabin. Within seconds, Lieut. Colonel Virgil Grissom, 40, Lieut. Colonel Edward White, 36, and Lieut. Commander Roger Chaffee, 31, lay dead in the charred cockpit of a vehicle that was built to hit the moon 239,000 miles away, but never got closer than the tip of a Saturn rocket, 218 ft. above Launching Pad 34 at Cape Kennedy...

    Open-End Mission. As it was planned, the flight of Apollo 204 [today more commonly called Apollo 1, sometimes called Apollo 6] would have tested both the mettle and the technology of the three astronauts beyond anything that men had yet experienced in space. On Feb. 21, the capsule was to be fired off the ground by a Saturn 1-B rocket to go into orbit for as long as Grissom, White and Chaffee could take it, an "open-end" mission that marked a bold departure from the rigidly limited flights of the past. It was to be essentially an engineering flight, a manned shakedown for the Apollo systems, which had already twice been fired aloft without anyone aboard. If things went well, Apollo 204 would lead to two other manned flights later this year, and then, possibly as early as 1968, to fullfillment of man's ancient vision of a landing on the moon.
    The Apollo, built by North American Aviation, is by far the biggest, most sophisticated space vehicle ever made. It is to the Gemini what a Boeing 747 is to a DC-6-- roomy enough for a man to stand erect amd move about, equipped with space luxuries such as hammock for stretched-out sleeping, hot and cold water, even a toilet...

    Countdown-Minus-10. At 1 p.m. on Friday last week, Grissom, White and Chaffee strolled casually into the gantry elevator on Pad 34, rose swiftly to a sterilized "white room," then ambled along the 20-ft. catwalk to the stainless-steel hull of the capsule, now secured to the Saturn rocket inside the launching complex. The craft was like an old friend, for they had spent hours in it during vacuum-chamber tests in the Houston Space Center, had run through identical launch-simulation procedures several times before.
    All spacecraft have their own personal quirks, and 204 had been balky from the start... The nozzle of its big engine shattered during one test. The heat shield of the command module split wide open and the ship sank like a stone when it was dropped at high speed into a water tank. Certain kinds of fuel caused ruptures in attitude-control fuel tanks. The cooling system failed, causing a two-month delay for redesign. But all the bugs were eventually ironed out, as far as the experts knew, after arduous testing under every conceivable circumstance.
    Last week's test was billed as the ship's first full "plugs-out" operation-- meaning that the craft was to rely solely on its own power system instead of using an exterior source... At 2:50 p.m., the airtight double hatch plates were sealed. And the familiar routine began, an infinitely detailed run-through that was scheduled to last slightly more than five hours.
    Things progressed smoothly enough; a few "glitches" (minor problems) stalled the operation. At countdown-minus-10-minutes, the procedure was stopped again because of static in the communications channels between the spacecraft and technicians at the operations center. It took 15 minutes to correct the problem, and the simulated count was ready to begin again. Then, at 6:31 p.m., a voice cried from inside the capsule: "Fire aboard the spacecraft!"

    No Random Failure. At the same instant, a couple of technicians standing on a level with the craft windows saw a blinding flash inside the ship. Heavy smoke began to seep from the capsule, filling the white room. A workman sprinted across the catwalk leading to the craft, tried desperately to loosen the hatch cover. He was driven back by the intense heat and smoke, but half a dozen other technicians, some wearing face masks and asbestos gloves, raced to help. One or two would try to wrench open the hatch, then fall bach again from the scorching heat while others struggled with it. Six minutes after the cry of alarm, the hatch sprung open. A blast of hot air shot out, followed by suffocating clouds of smoke.
    The rest was silence. The flames were apparently sucked into the astronauts space suits, killing them as soon as they noticed the fire. The three charred bodies were left strapped to their couches for more than seven hours while anguished experts sought to piece together the reasons for the accident...


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