Jan 26th, Day of Remembrance
"Today we pause to remember the loss of all of our employees, including our Apollo 1, Challenger and Columbia astronauts, and to honor their legacy. Nearly 50 years into the space age, spaceflight remains the pinnacle of human challenge, an endeavor just barely possible with today’s technology. We at NASA are privileged to be in the business of learning how to do it, to extend the frontier of the possible, and, ultimately, to make space travel routine. It is an enormously difficult enterprise. The losses we commemorate today are a strong and poignant reminder of the sternness of the challenge."
NASA Administrator Michael Griffin
In honour of those NASA astronauts lost in ‘the line of duty’, the agency designates January 26th as a day to remember the ones that had gave their lives in the pursuit of exploration and discovery, most prominently the fallen heroes of 3 different missions (click on images to enlarge), the crew of Apollo 1, January 27, 1967, lost in a fire on the launch pad during a test,
The crew of space shuttle Challenger, lost during takeoff, January 28, 1986 and,
The crew of space shuttle Columbia, lost during re-entry, February 1, 2003.
Copyright Time Magazine
So, it seems that the ‘last frontier’ is still a forbidding place for us humans to go to right? But spacecrafts are designed to be highly survivable, reliable and have multiple redundancies. So how did it happen? Well, apparently the answer goes like this. They are complex systems, having up to millions of individual components in them. If any one of these parts fails, lives wouldn’t be at stake. But history has shown that the weakest link in the chain is us fallible humans. The events leading to these disasters take time to unfold (the saying ‘a nail in time saves nine, a tile in time saves a hundred’ is probably the most useful one to remember here), and they happen because nobody manages to catch them and add two and two together. Or sometimes, the engineers submit to the decisions of the mission managers although they have misgivings.
The Apollo 1 crew was killed when a spark ignited the materials in the cabin filled with 16++ psi pure oxygen. They were killed within 17 seconds of the first cry of ‘Fire!’ from the command module. The cause: Smoke inhalation.
"In space, the cabin would be filled with pure oxygen, but at 5.2 to 5.6 psi, not at 16+ psi. Outside the cabin the pressure was zero-the vacuum of space. The command module was designed to handle a positive pressure differential of about 8psi from inside to outside, but only a 1 or 2 psi negative differential from outside to inside. If the outside pressure was 2 psi higher than inside the cabin, the pressure hull could implode."
Chris Kraft, from his book ‘Flight’
Later, in tests, it was found that even a solid bar of aluminium burst into flame when ignited in a 16psi pure oxygen atmosphere. At 6 psi, the fires can easily be contained but at 16 psi, it is like a bomb waiting to go off. All it takes is a spark from an exposed wire (of which the command module have miles of wiring) and…
For Challenger, short story is the launch managers decided to launch when the temperatures are below the recommended operating temperatures of some shuttle components, as the launch was behind schedule. In this case, the ‘O-ring’ seal on the solid rocket booster sealing a joint failed. Fire leaked from the seal during ascent, and damaged the main external tank. The shuttle and tank rapidly disintegrated, and the cabin containing the crew fell down while the boosters continue to fly upwards before being self-destructed. The crew did not die then. The shuttle was not destroyed in the explosion of the external tank, but the crew was most likely rendered unconscious. They died when the shuttle impacted the sea, but it might be possible that some was conscious until then as some of them are ex USAF pilots, so they would have higher thresholds for the changes in acceleration than civilian astronauts (more Challenger myth busted here. Lesson for all: If the manufacturer says it’s not safe to use it under these conditions, listen!
Columbia? They saw the foam, larger than any ever seen before, hitting the wing of the shuttle, reasoned that it’s nothing unusual, and did nothing beyond doing some computer modelling, of which the model is unsuitable for foam (this is no spongy or squishy foam, but hard rigid foam) of such a size. And so, the crew came back in, and never touched ground again. If they have made real life tests, the outcome might have been very much different, because here are the results.
This was only a glancing blow…
But it left an 18-inch gaping hole in the wing.
P.S. I’m terribly sorry for multiple edits, but the HTML coding was faulty this time round, so I have to manually recode some sections of this blog.
