Golf-Ball Sized Hail Damages Shuttle

MattSparkes writes "The Shuttles March launch has been delayed to late April after golf-ball sized hail caused 7000 pits and divots in the foam that shields the fuel tank. NASA say it's the worst damage of its kind that they have ever seen, but hail is not a new problem for the agency. In 1982, a hailstorm damaged the sensitive heat shield tiles on the Columbia's wings. The damaged tiles then absorbed about 540 kilograms of rain. Once in space, the orbiter faced the Sun to allow the tiles to dry out."

Exactly how hard...

[joshetc]

Exactly how hard is it to just cover the damn thing? I would think after spending so much money on something NASA would want to take care of it...

Re:Paradigm shift

[hcdejong]

The only problem with that is keeping the clamshell (and the whole building) from being blasted to smithereens during takeoff. The noise level alone is enough to crumble concrete, add to that the temperature and pressure, and you see why rockets are usually launched in the open. True, missiles are often launched from canisters or silos, but:

1. Smaller missiles often use a cold-gas ejection system. The motor doesn't ignite until the missile is out of the canister. Some systems (e.g. Mk 41 VLS) ignite the missile in the canister. In this case, the canister consists of an inner tube that contains the missile, and a fixed outer tube. When reloading, the inner tube is replaced. This is doable for a missile, not so much for a Shuttle-sized rocket.

2. For larger missiles (ICBMs), a reusable launch site isn't the top priority. Damage to the silo is more acceptable here than for a NASA launch facility.

Re:Paradigm shift

[140Mandak262Jamuna]

ISRO has fixed launch pads and the Vehicle assembly building moves on rails out of the way for launch. NASA has a fixed Vehicle assembly building and the rocket moves on very complex tracked vehicle a few miles to the launch site. So far ISRO has not launched anything the size NASA has. The largest payload by ISRO, a six ton Low earth orbit, 1 ton Geostationery payload (quoting from memory, pardon errors) is very small compared to what NASA has done. So the building capable of assembling something the size of space shuttle cant easily move out of the way. But the could try to create a simpler building mainly to protect the vehicle without all that expensive jigs and assembly equipment that moves out of the way on the day of launch. They would not really like to have a fueled vehicle inside a building.

Re:Rain

[maxume]

http://en.wikipedia.org/wiki/Space_Shuttle [wikipedia.org]
http://en.wikipedia.org/wiki/Space_Shuttle_Orbiter [wikipedia.org]

The whole thing apparently weighs more than 4 million pounds at launch, with the orbiter being about 150,000 pounds and the payload being more than 50,000 pounds(there are 35,000 pounds that look like they are fuel). 1,000 pounds doesn't really seem like that big a deal, and probably needs to be factored into their payload mass tracking anyway(it seems like it would vary with humidity, etc).

Re:540 kilograms of rain...

[Rakishi]

It's unlikely that they knew the volume but this being a rocket the mass was measurable. While you can calculate the volume from the mass, due to the rain not being perfectly pure and the temperature not being 4C the volume will not be exactly 540 liters even if the mass is exactly 540 kg (at room temp it'd be ~537 by my calculations).

Re:Heh, apparently hail ain't their only problem

[saboola]

Here ya go, right from the pedia:

Cape Canaveral [wikipedia.org]

Cape Canaveral was chosen for rocket launches to take advantage of the earth's rotation. The centrifugal force of this rotation is greatest at the equator, and to take advantage of it, rockets are launched eastward, in the same direction of the earth's rotation. It is also highly desirable to have the downrange area sparsely populated, in case of accidents; an ocean is ideal for this. Although the United States has sites closer to the equator with expanses of ocean to the east of them (e.g. Hawaii, Puerto Rico), the east coast of Florida has substantial logistical advantages over these island locations. The tip of the cape is at LC-46 in Cape Canaveral Air Force Station.

Re:Obviously

[Rei]

It's not just insulation to stop the hydrogen from boiling off; it's also an ablative TPS (Thermal Protection System) for liftoff. You'd melt the aluminium. Furthermore, I would wager that having liquid hydrogen seeping through the insulation would ruin its R-value, if the material is compatable with LH at all (I'd have to check). Plus it'd be harder (read: more expensive, slower) to apply internally. Plus it would take a redesign and recertification of the craft.

Re:Hanger Queen

[Rei]

No, it just goes to show how easily people ignorant of the difficulties of getting to orbit can make fun of those who actually have to deal with them. Rockets must be built incredibly light. Unfortunately, for the time being, this means flimsy. Even an extra coating of paint could kill the amount of payload they could take up.

Also, in constant dollars, the Apollo Saturn V stack was probably more expensive; it depends on how you do your accounting. And it, too, was vulnerable to weather. NASA was simply braver (perhaps crazier) back then. They even launched once during a thunderstorm -- Apollo 12. I love the logic of that one. There's a thunderstorm, and we have a gigantic vehicle full of explosive fuel, made of highly conductive metal. Lets have it launch so that it gets up to the charge layer, with a trail of ionized exhaust gas leading straight to the ground. ;) When it was struck by lightning, it nearly caused the termination of the mission -- knocked the fuel cells offline and scrambled the data from the navigational computer. Thankfully, the computer damage could be worked around due to an electrical engineer in Mission Control who knew a workaround.