What's Up With That? #51: A hole in the bucket

I'm no rocket scientist — the wags among you are shouting, "No [insert vulgar reference to excrement here], Sherlock!" even as I type — but here's what I don't understand about the current situation with Space Shuttle Endeavour.

First, let's set the scene. When Endeavour launched last week, a piece of debris from the main external fuel tank — either insulating foam, or ice, or a combination of the two — struck the underside of the shuttle, causing a small gouge (3.5 by 2 inches) in one of the orbiter's heat shield tiles. Similar damage, on a considerably larger scale, resulted in the post-reentry destruction of Space Shuttle Columbia five years ago.

Now to the source of my confusion. NASA knows all too well that debris flying off the fuel tank and striking the shuttle can cause damage that puts the orbiter and its crew at risk. And apparently, numerous post-Columbia attempts to eliminate this flying debris have proven unsuccessful. (It's my understanding that NASA has been able to minimize the castoff of foam and ice somewhat, but due to the nature of the fuel and equipment being used, can't curtail this entirely.)

So why doesn't NASA devise a shield of some sort to protect the underside of the shuttle from flying debris?

The first guy who drove any distance in a primitive automobile surely said to himself, "You know, I love this machine, but getting smacked in the face by bugs, raindrops, and other airborne junk really sucks." That's why we have windshields on our cars to this very day. How hard could it be to invent a lightweight panel that attaches to the base of the shuttle, between the orbiter and the fuel tank, that deflects hurtling detritus in the same way that a windshield does? The device could be jettisoned at the same time as the fuel tank, and the shuttle would speed on its merry way unharmed.

Surely I can't be the only person who's thought of this. I'm not even an engineer, but it seems perfectly obvious to me.

And since we're on the subject, NASA has expended beaucoup time and effort conducting model tests to determine whether the damage to Endeavour is significant enough to require repair before reentry. I don't get that. If you can fix the problem — and NASA says they can — why would you not? Why go through all of this exercise in "cautious optimism" that the damage won't endanger the shuttle and its crew, when you could eliminate the worry altogether by just sending an astronaut out with a repair kit to patch the hole? Who wants to be sitting at the Johnson Space Center witnessing another Columbia-like disaster and thinking, "Maybe we should have run that test one more time"?

I guess that's why I'm not a rocket scientist.