Columbia, What Might Have Happened
A Tribute to Heroes Why We Fly It's Not Face Mountain, It's the Slag Pile 12 Miles From Face Mountain
Or go to mars.jpl.nasa.gov/mgs/msss/camera/images/01_31_01_releases/cydonia/ and download Photo M18-00606 and look at the Slag Pile. Look at the ground immediately to the east of the Slag Pile. We better find out what that is.
I was a student at the University of Washington when the Columbia first went up. At that time, I had been accepted into the engineering program and most of my schedule was in engineering classes. One of the professors apparently performed consulting work for NASA or for Rockwell International, the contractor who built the Shuttles. During Columbia's first flight, he brought a prop to class. It was a slab of aluminum, about a square foot, upon which was glued a layer of insulation and a ceramic tile. We discussed the technical problems faced with trying to keep such tiles from falling off the shuttle during the ascent, when the giant Morton-Thiokol solid fuel boosters would shake the ship with extreme vibrations.
In spite of the absence of some of the tiles, the Columbia came down and safely landed at Edwards Air Force Base in California. Because of this experience with the tiles, many people believe that a massive loss of tiles is what doomed the ship. They have never solved the problem of the tiles. Every time the Columbia was launched, tiles fell off. If you wander the fields and marshes of Cape Canaveral and manage to avoid the security guards and police, you might find Columbia tiles in the grass and the reeds. This one was there since 1984, that one has been there since 1996. Because of the problems with the tiles, the newer Shuttles such as Atlantis and Endeavour are made with a different heat shield system, involving large pieces of ceramic covering large areas of the ship.
What would have happened if there was a substantial area of the ship exposed to a loss of tiles, perhaps near the wheel wells and the wire bundles leading to the sensors on the left wing, can be deduced from the design of the ship. The basic structure of the Shuttles is essentially the same as the basic structure of most aircraft built since B-17 days: 7075 aluminum alloy structural members tied together with steel fasteners. When I worked for The Boeing Company, that is part of what I worked with. The frame of the Shuttle, its body, the wings, the vertical fin, and the large hinged doors, are made of 7075 aluminum and steel fasteners. Over the frame is the aluminum skin to which the tiles are fastened. This aluminum skin is made of 1/10 inch thick sheet, chem milled down to a few hundredths of an inch away from the fastener locations to save weight. The passenger cabin up front is made of 6061 aluminum which is welded. 7075 cannot be welded, 6061 is the alloy of choice when welded seals are desired. Thus the passenger cabin can contain air at 14 psi while in space.
In the event of direct exposure to the high atmosphere between 100,000 and 400,000 feet at over 20,000 feet per second, the aluminum skin would warm up to melting temperature in only a few seconds. This heat would transfer rapidly to the structure. Aluminum and steel transfer heat rapidly. Everything attached to the aluminum structure would immediately feel the heat. Thus the reports of tires in the landing gear losing pressure, they ruptured. Temperature probes would report the increasing temperature and then go silent as either they or the wire bundles leading to them would fail.
Aluminum melts at 1,220 Fahrenheit. The structural members are like soft clay at temperatures below that. The wings and other parts would fall off when the structure was soft enough to no longer hold against the stresses and loads of re-entry. Once the parts fall off, the big gaping wounds in the ship would be exposed to the thin air moving past at over 20,000 feet per second. The heat would quickly transfer to the passenger cabin and turn it into an oven. I like to believe that the cabin ruptured exposing the astronauts to the extremely low pressure of 207,000 feet. That way they suffered as little as possible under the circumstances.
The astronauts and mission controllers should have seen such a massive loss of tiles sufficient to cause the break-up we observed. I am disturbed by the report that they sent them up without the Canadian arm. The double jointed 50 foot Canadian arm with its camera has been used to inspect for tile damage. They did not and we had the glowing reports of another successful mission. We should have had an Apollo 13 scenario, NASA and Russia's space agency working to bring the astronauts back alive. If they could get to the International Space Station, a re-entry need not be attempted to save the astronauts from starvation. I am disturbed by the report that they sent them into an orbit where getting to the ISS is difficult or impossible. A reasonable contingency to plan considering we spent the money to have it up there. Too bad the Russians could not have kept Mir in orbit, it could have served as a second emergency stop for damaged Shuttles. Two or three of the astronauts could drop down to Kazakhstan in the Soyuz capsule. Soyuz ships and other Shuttles could rise to relieve the crew and carry parts such as replacement tiles to repair a damaged Shuttle.
Discovery went up and appears to be intact. It has successfully docked with the International Space Station and appears safe for re-entry.
However, foam still keeps falling off the external fuel tank. I suspect that this has happened with every Shuttle launch since the first Columbia launch in 1980. It was only in 2003 we had the bad luck of a piece of foam hitting the shuttle and damaging the tiles. Some people have commented that the Shuttles are obsolete and should be replaced.
I agree that new Shuttles should be built, for very many reasons. However, I disagree that the existing three Shuttles are obsolete. It was a brand new and redesigned fuel tank attached to Discovery that proved to still have the problem. Columbia's fuel tank was also brand new. The problem is that we place the insulating foam OUTSIDE the surface of the tank and expect it to remain intact during the vibrations and wind drag of launch and flight through atmosphere with several G's of acceleration.
Apparently that does not work very well.
The fuel tank thus needs to be redesigned, with insulation on the INSIDE of the external metal skin. Or we will have to bite the weight bullet and place a second metal skin on the outside of the foam layer. The reason for the insulation, of course, is because the fuel is liquid hydrogen and liquid oxygen which need to be kept liquid before and during launch.
Such a new fuel tank will solve any problem with obsolescence of the existing Shuttles and make safe the launch of new Shuttles.
Or at least remove one source of potential disaster.