NASA Finds 4-5" Crack in Shuttle Insulation

PresidentKang writes "Spaceflight Now is reporting that a large crack has been found in an external tank foam of Space Shuttle Discovery on the launch pad. According to the article: "Engineers inspecting the shuttle Discovery's external tank following Sunday's launch scrub found a crack in the tank's foam insulation near a bracket holding a 17-inch oxygen feed line in place. Some engineers believe the crack must be repaired but senior managers say a variety of options are on the table, from fly as is to making repairs.""

Comments

And what about the pilots?

[DHalcyon]

"...but senior managers say a variety of options are on the table, from fly as is to making repairs."

I wonder what those managers would say if they had to fly the shuttle.

DNF, Vista, or Shuttle

[Belgarion89]

So now the real question becomes, which will launch first, DNF, Windows Vista, or the Shuttle? I say the Shuttle, it's cracks aren't nearly as big as Vista's (an M$ product) will be.

How can they fix this

[DeviceDriver]

I know the shuttle is at the end of life, but the follow on will still need insulated tanks. The early Atlas had no insulation and needed to be fueled in the final minutes of the countdown. Clearly a problem. But any means of making the insulation crack free, thus flexable, and still able to withstand the launch, thus stiff, would require significent added mass. Mayby an outer shell of carbon composite.

Re:How can they fix this

[sparky555]

The only reason why the foam is a problem is because the orbiter hangs from the side of the tank and can be hit by the foam when it falls off. In future generations of manned spacecraft, the crew vehicle will be on the top again, like in Apollo, Gemini and Mercury. In that case, it really doesn't matter what falls off.

Re:How can they fix this

[Nimey]

But if NASA does the sensible thing and mounts the Shuttle's replacement on top of the stack like they did for Apollo, you don't have to worry about ice falling and hitting heat-resistant tiles, because all that's mounted above the fuel tank.

I wouldn't be suprised if the external tank is insulated just because of how the shuttle is mounted on the assembly.

Re:How can they fix this

[0123456]

"I wouldn't be suprised if the external tank is insulated just because of how the shuttle is mounted on the assembly."

It's more complicated than that. It is needed to stop ice forming that would trash the shuttle, but it also reduces fuel boiloff, protects the tank from aerodynamic heating, and keeps the metal cold... the metal in the tank gets stronger as it cools down, and that means they've been able to cut back on the amount they use. Since the tank goes most of the way to orbit, saving a pound of mass in the tank gives you close to a pound of extra payload in the shuttle.

Now what?

[Billosaur]

On the one hand, shuttles flew forever shedding foam and it only became a real problem when a large enough piece tore off to actually damage the shuttle in flight significantly. Engineers accepted the risks with many reservations, because damage was never really that severe. Of course hindsight is 20-20 and this problem could have been rectified if the foam was located interior to the tank as opposed to externally. I think they were worried that if they tried that, there would be voids in the insulation that would allow heat to enter and cause problems, but that was a manufacturing issue which probably could have been resolved with a little ingenuity.

On the other hand, a 4-5 inch crack is nothing to sneeze at and with the aerodynamic forces that batter a shuttle on its way into LEO, any number of things could cause that crack to widen and eventually spilt, teraing off a really large section of foam. It has to be repaired; I don't see how NASA management can ignore this. If they do, and the shuttle is damaged or heaven forbid, destroyed, that's the end of the space program. And probably rightly so. Like to many things, NASA was created due to Cold War concerns, namely that the Russians were going to grab the "high ground" of space and show us up in technical endeavors, weakening our position on the world stage. Like other Cold War relics, it too either needs to change or be dismantled.

I'm a NASA booster (forgive the pun) -- my dream from childhood was to walk on the Moon. But I can say that I find it hard to trust the NASA I see now; it has become hamstrung by indecision, beaureaucracy, and lack of imaginative leadership (with apologies to Dan Goldin, Sean O'Keffe, and Mike Griffin). I wanted John Young to become NASA Administrator -- tough talking, smart, no-nonsense, and imaginative. He might have (and still could if he wanted the job) lit a fire under NASA and got them thinking straight. The problem is, NASA was not prepared for life after Apollo and it shows. The STS was a compromise (no engineer in the early 70's thought solid rocket boosters were a good idea) and a poor one at that.

I think a) NASA needs to be saved from itself and b) the American people have to learn what a truly great resource they have in their space program. Barring either of those, it will be up to private industry to carry the torch.

Shouldn't Fuel under uncertain Weather conditions

[DumbSwede]

Well they've fueled the Shuttle twice already, Tuesday will be the third. Thermal stress was indicted as a contributing factor in foam detaching. Everything probably would have been fine if they had launched the first time, I suspect their cloud distance tolerances are too tight these days compared to thermal stress from fuel cycling on the parts for later lift off.

I'm not saying NASA should have launched the first time, but with only a 30% chance of launch due to weather, why did they even fuel the bird up? Weather should have a least an 80% chance window I would think think to decrease the likelihood of one fueled up scrub after another leading to excessive thermal stress on tank components.

Also while many may see July 4th as a feel-good day to launch (National pride and all that) if anything goes wrong there are religious types both Christian and Muslim that will see it as a sign validating whatever their view of the world is.