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."

Comments

I'm Like NASA!

[Anonymous Coward]

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.

Just like my chevy!

I wonder if they're having problems getting the smell of stale McDonald's & whiskey out of their vehicle too.

Obviously

[Rob T Firefly]

NASA is not a golfer.

Re:Obviously

[CrackedButter]

Woo, isn't NASA supposed to be a millionaire?

Re:Obviously

[aadvancedGIR]

That foam really tied the fuel tank together, did it not?

Re:Obviously

[saboola]

What they need is The Ding King!. (As Seen On TV!)

Re:Obviously

[Rob T Firefly]

You want foam? I can get you foam. Believe me, there are ways, dude..

Re:Obviously

[ajlitt]

Also, foam is not the preferred nomenclature. Insulation, please.

Re:Obviously

[racermd]

Maybe it's just me, and I don't claim to be a super-smrt - sorry, smart - rocket-scientist (because I'm not), but why don't they put the foam insulation on the inside of the fuel tank shell?

I'm sure there are reasons why they don't, but can those reasons out-weigh the problems it's causing with the foam on the outside?

Does anyone know if this has been considered? If so, why hasn't it been done, yet? Please be as specific as you can. I'm really interested in this.

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:Obviously

[KoshClassic]

One possible reason - save weight. Metal is heavier than foam. Imagine a tank similar to the current one in shape, size, and internal volume. Move the metal to the outside of the foam, you need more metal to cover the greater surface area on the outside of the resulting shape than it does on the inside of the current tank, hence more weight.

re: the liner idea - yeah, the tank was painted white for the first two or three launches. They got rid of the paint to save weight - apparently covering the foam with something relatively as light weight as paint, given the surface area involved, still added up to enough weight to make a difference. And, apparently it didn't really help keep the foam in place.

Heh, apparently hail ain't their only problem

[bad_fx]

[quote]NASA has had less serious problems with fuel tank foam as well. In 1995, a shuttle on the launch pad had to be returned to its hangar for repairs after woodpeckers punched about a dozen small holes in the tank's insulation.[/quote]

That got a bit of a chuckle; It's in the article linked from TFA.

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

[saboola]

Here ya go, right from the pedia:

Cape Canaveral

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.

Paradigm shift

[TWX]

Maybe there really is something to all of those science fiction movies that show space ports opening like a clamshell a few minutes before the spacecraft lifts off, especially if the air inside was temperature and humidity controlled. That kind of thing might have prevented Challenger's destruction and would keep any craft free from weather-related damage before takeoff...

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:Paradigm shift

[Mercano]

How about, say, something like this? Though I don't know how early in the countdown then need to roll back the building.

Rain

[saskboy]

So Columbia survived a half a ton of rain in its fragile shield, but was brought down by scarring foam. How odd space flight can be...

Re:Rain

[Anonymous Coward]

What is more shocking is the fact that they deliberately took up half a ton of water up into space.

I wonder how much such a worthless payload costs in terms of fuel needs.

Would it not have been cheaper to dry the shuttle while on earth? and spare a couple of hundred liters of fuel?

Re:Rain

[maxume]

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

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).

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:Exactly how hard...

[SydBarrett]

Uh oh, NASA forgot to put the shuttle in the garage after they got back from the mall. Their dad is gonna be SO pissed.

hang on...

[symes]

Golf balls have bumps and divots over the surface to enable longer flight times. Surely these additional bumps will also aid the shuttle's aerodynamics?

That is what you get having it in Florida

[DaveV1.0]

All those damned retirees and there golf. Worse than kids, I tell ya!

Re:I do the same

[DeeVeeAnt]

So, how do you expect it to survive re-entry then?

Re:I do the same

[daeg]

Better to have it burn up in re-entry than have your wife get your truck in the divorce.

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:Face the sun to dry out?

[imsabbel]

Evaporation enthalpy.

At 80 Kelvin, ice will be fine even in ultrahigh vacuum. So energy has to come from somewhere to allow the ice to evaporate. Those headshields are very good insulators, which leaves the sun as energy source.

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.