January 21, 2019

FTV: Columbia

Astronauts John Young and Robert Crippen stared out the aft window of the Space Shuttle Columbia as Crippen opened the two 60-foot-long payload doors.  This was a necessary step designed to expose the aluminum honeycomb radiator panels that would help regulate the spacecraft’s temperature. Beyond the open doors they could see some dark areas on the engine pod cowlings that should have been white.  While they did not recycle Jim Lovell’s famous radio message from Apollo 13 (“Houston, we have a problem”), they most certainly could have. Columbia definitely had a problem.

    Young and Crippen had ridden this new bird to orbit only hours earlier and even they were surprised by the power of the three main engines and the two solid fuel boosters that had lifted them into orbit.  No manned craft had ever been man-rated without an unmanned test run of the whole system, so they were making history at every turn. To say the astronauts had a great deal of faith in the team that had developed and assembled this remarkable machine would be an understatement of huge proportions.  The process of assembling the space shuttle amounted to solving one impossible problem after another. The shuttle was to be our reusable space truck that would transport materials into earth orbit like a rocket and return the orbiter portion of the craft as an unpowered glider. The shuttle never lived up to the promise that was envisioned during the development phase of the craft, but that is a thirty year long story for another day.  At this moment, Crippen and Young were more concerned about surviving the maiden flight of the Space Shuttle Columbia.

    Looking at the missing tiles on the aft engine pods, there were a host of safety questions that now confronted Columbia’s crew.  These tiles were their only protection against the searing heat that would be generated as the craft re-entered the earth’s atmosphere and returned to Earth.  They could see that a few of these tiles went missing during their bumpy ride to orbit, but they could only see the top surface of the shuttle. The bigger question was, “Are there any missing on the underside of the craft?”   This would be the area subjected to the highest temperatures at re-entry. An hour and fifty-three minutes into their flight, they were beaming real-time video of the damage back to Houston via the Madrid, Spain tracking station.  Fellow shuttle astronaut Dick Truly looked at the images coming in and thought “Holy Mackerel” as he pondered what the bottom of the shuttle looked like,  “If it’s been stripped of tiles, then these guys are in deep trouble.”

    During all of the earlier manned space flights (Mercury, Gemini, and Apollo), the astronauts rode to space in a capsule.  The blunt end was covered with what is known as an ‘ablative heat shield’. The spacecraft came through the atmosphere with this blunt end facing the earth.  The extreme temperature caused by friction with the atmosphere was dissipated to tolerable levels as the heat shield burned away, layer by layer. When the craft reached the lower atmosphere, the final descent was made by parachute.  

    The shuttle orbiter was covered, not by an ablative heat shield, but by thousands of lightweight blocks of insulation.  These compacted silica fiber blocks were light and their porous nature (they were described as ‘90%’ porous) kept heat transfer low, thus protecting the aluminum airframe of the vehicle.  When Ralph Winrich made his first visit to Ontonagon representing the NASA Education office back in the mid-1980s, he had a block of the shuttle thermal protection system with him. He heated it with a propane torch until it was glowing red.  He demonstrated the low heat transfer properties by picking up the still glowing tile (with his bare hands) by the edges. The areas on the vehicle that would be subjected to the highest temperatures (like the leading edges of the wings) would be covered with  a graphite and carbon composite called carbon-carbon. This material not only protected the shuttle’s airframe, but it became stronger as it got hotter. Having tiles missing on the orbiter put everyone on high alert. NASA would need to find a way to check out if there were damaged tiles on the belly of the shuttle.  The engineering team would then need to figure out how much leeway they would have to land the orbiter if there were missing tiles on the belly of the spacecraft.

      How potentially serious was Columbia’s problem?  In 2003, twenty two years after its maiden flight, Columbia was fatally damaged by a piece of insulating foam that had broken off its external fuel tank 82 seconds after launch.  Later tests revealed that this lightweight material packed enough punch that when it struck the leading edge of the orbiter’s wing at Mach 2.2 (2.2 times the speed of sound), it caused a breach that wouldn’t be noticed until the reentry phase of the mission.  This breach allowed the hot plasma to enter the wing during descent which caused the vehicle to tumble and disintegrate 200,000 feet over Texas and Louisiana. The crew was lost and the shuttle program was idled during the crash investigation just as it had been after the Challenger disaster.  Only after the loss of Columbia were steps taken to ensure that the crew would be able to examine the whole orbiter for damage before the re-entry phase. In 1984, Crippen and Young had no way to examine the underside of their craft while in orbit or to fix any tiles that were missing.

    The Air Force and the Department of Defense were enlisted to try and get images of the orbiter to better assess the shuttle’s heat shield.  The Air Force operated a couple of high resolution ground based telescopes but none of these were able to get a clear view of Columbia as it sped past 147 miles up.  The four classified surveillance satellites circling the Earth were designed to take pictures of ground sites and not objects traveling at 17,500 miles per hour. The security level needed to even discuss these satellites made it even more difficult for NASA to request help from the Air Force.  In the end, only one of the satellites was in a favorable position to get the images NASA needed to check the craft for further damage. The choreography needed to position both the surveillance sat and Columbia to obtain the imagery needed would have made Bob Fosse proud, but they were able to pull it off.

    The highly classified joint mission to take high resolution photos of the shuttle from space was, to say the least, a complicated affair.  Members of the press corps who had covered previous NASA missions pressed (pun intended) director of Flight Operations Gene Kranz for more information about the efforts to capture the photos of the orbiting shuttle.  This was the same Gene Kranz who uttered the iconic “failure is not an option” line in the movie Apollo 13 (which he also used as the title of his autobiography).  Kranz answered questions with ”It’s classified” and “Shall I read the statement again” more times than would seem to be necessary to satisfy the press pool, but these were savvy reporters who had covered enough NASA flights to read between the lines.  Kranz was not free to divulge exactly how they were trying to obtain the images beyond using nondescript phrases such as, “special assets”, “national technological assets”, “DOD assets”, or “ground-based telescopes.” There were very few people in the loop who knew that it was the classified satellites of the National Reconnaissance Office that were being pressed into service and Kranz was not about to be the one to break the news.

    Robert Crippen and Dick Truly were two of the Air Force astronauts who got into the space program training to man the USAF Manned Orbiting Laboratory that was under development in the mid-1960s.   MOL was basically a manned spy satellite, but the program was cancelled when technological advances made it possible to do the same work from space from an unmanned platform. Some of the MOL astronauts were able to transition into the NASA astronaut corps meaning the likes of Truly and Crippen had inside knowledge of the steps being taken to get images of the shuttle using the NRO’s classified Keyhole satellites.  If one can imagine using the Hubble Space Telescope to peer down at the Earth instead of into deep space, then one has a pretty good idea of how advanced these satellites were. The HST was a direct descendant of the Keyhole satellite technology yet using a space born telescope to take images of objects light years away from the Earth is much easier than taking pictures of one orbiting object from another.

    Imagine travelling down the highway at 60 MPH and trying to hit a road sign with an apple thrown from your speeding car (and no, I am not suggesting that you need to actually try this).  The velocity of the car added to the velocity of the thrown apple would make it hard to hit the target. Now imagine that the sign is painted on the side of another vehicle traveling at the same speed but across your path of travel.  Obviously, this would make the task even more difficult to execute. Lastly, imagine that both vehicles are traveling at the speed needed to maintain Earth orbit (17,500 MPH). The shuttle’s first flight was scheduled for a little over two days, meaning all the navigational details needed to put the shuttle in the right attitude at the right time and the program needed to point the Keyhole satellite in the right direction had to be engineered in a very short period of time.  Of the five satellites available, only one, NRO’s KENNEN 5502 (also known as KH-11 ), was in the correct position to get the shot on orbit #20. A couple of hours later, Kranz had the sheaf of photos in his possession and they showed that the tiles on the shuttle’s belly were undamaged. No one could be told where the images had been attained, but the feeling of relief quietly spread throughout the Houston control room that ‘the shuttle would be fine’. The final re-entry and landing phase provided some surprising handling data that just could not have been simulated with scale models in wind tunnels.  Mission commander Young was ecstatic about how well the ship flew and the entire design team celebrated this triumphant first for the manned space program.

    Rowland White’s book Into the Black (Touchstone 2016) is a fascinating, detailed account about the extraordinary story that went on behind the scenes of Shuttle Columbia’s first flight.  I shared the title with Craig Linde when he sent me his monthly installment of The Night Sky that is reprinted in the Ontonagon Herald each month.  Interestingly enough, he wrote back that not only was he aware of the MOL program and the NRO satellite program, he had actually worked with various Keyhole satellites during his time in the Air Force.  He sent me some fascinating background material and a uniform patch from his old Air Force outfit. With his insider’s view, I believe he will find White’s story even more interesting that I did.

    After Columbia’s fatal wounding in 2002, NASA took two important steps to help prevent future catastrophes.  The first was to use a camera on the shuttle’s payload bay arm (and later direct observation by astronauts on the International Space Shuttle) to scan all surfaces of the spacecraft for damage once it was in orbit.  The second step was to develop a way for astronauts to repair missing tiles. Though the shuttle was thoroughly examined during each subsequent flight, they never needed to resort to the ‘repair tiles in orbit’ scenario.  Standing beneath the retired Shuttle Atlantis at the Los Angeles Science Center a few years ago, I was awestruck by the complex mosaic of tiles that had done the job so well. In my mind’s eye, I could still see Ralph standing in front of my JH students holding one of these red hot tiles as he demonstrated the unique heat dissipating properties that would someday protect the returning shuttles.

Top Piece Video – Canadian astronaut Chris Hadfield does his Bowie thing aboard ISS.