Fewer Heat Shield Dings on Shuttle Discovery

According to NASA, the amount of damage to thermal tiles noted on Discovery was significantly lower after the latest mission. According to the report, there was a 33% reduction in the number of dings on the belly of the orbiter and an almost 50% reduction in the number of hits greater than one inch. This would seem to indicate that the new foam is working better. "The vehicle looked very good," Thomas Ford, a member of NASA's ice-debris inspection team at Kennedy Space Center, said Wednesday. "It's definitely gratifying."

Comments

Re:A flight every 6 weeks

[Anonymous Coward]

Wouldn't that be great. I really like this new administrator.

Currently only Russians are able to do that. Shuttles' turn-around time is way too long and even though there's less damage it still takes one person a week per tile to repair.

Re:no liner?

[Jboost]

The heat shields are shaped so the hot regions of the gas are kept away from the shield.

The problem isn't the heat, but the pressure (that causes this heat as a side effect).
During re-entry, the shuttle travels supersonic thereby preventing the air to get out of the way fast enough.

Re:the only explanation

[njchick]

Actually, a female astronaut commanded the Return to Flight expedition, also aboard Discovery, which was also a very "clean" flight in terms of the tile damage.

Re:50% less bits of foam falling off!!!

[ToasterofDOOM]

Exactly. The more complex anything is, the more likely it is to be susceptible to many complex problems. We happen to have, for better or worse, a more complex space program than pretty much anyone else. Also, the more complex the support infrastructure that is needed, the more opportunities there are to screw up royally. While we should move on from the shuttle, It should by no means be dead yet. As the late Guss Grissom said, "If we die, do not mourn for us. This is a risky business we're in, and we accept those risks. The space program is too valuable to this country to be halted for too long if a disaster should ever happen." While this is adifferent time, his words still are as true and pertinent today as they were almost a half-century ago.

Re:no liner?

[evanbd]

That would be called an ablative heat shield. It's been done quite successfully -- Apollo, Soyuz, and almost every reentry vehicle except the shuttle.

That said, ablatives aren't easy, especially if you want aerodynamic control as you come in -- it's exceedingly difficult to get them to ablate evenly, which results in weird and unpredictable forces on the lifting and control surfaces.

If the shuttle had been a capsule reentry system, ablatives would have been fairly obvious. With wings, it's much less clear. What is clear is that it's cheaper to replace the damaged tiles than it would be to do the R&D to give the shuttle an ablative heat shield. And you can't just retrofit it on with an extra layer.

BTW, I think the choice of a winged orbiter was a mistake in the first place, and that a capsule and ablatives would have been better.

Re:How about they use the old coolant

[grozzie2]

Actually, this has been a problem since the first launch. Maybe you are to young to remember, but there was a lot of tension for the first shuttle re-entry, because there were tiles missing, apparently lost/damaged during launch. It all worked out ok, so, the attitude became 'oh, lose a few is no big deal'. Eventually it became a big deal.

Re:50% less bits of foam falling off!!!

[Anonymous Coward]

And then they lost the plans so they can't even build new ones.

Fortunately, the plans are not lost. Unfortunately, even with the plans, it's not possible to build new Saturn V rockets.

Here's what the SpaceFAQ (http://www.faqs.org/faqs/space/controversy/) has to say about the "lost" Saturn V plans.

From the FAQ:

WHAT HAPPENED TO THE SATURN V PLANS

Despite a widespread belief to the contrary, the Saturn V blueprints have not been lost. They are kept at Marshall Space Flight Center on microfilm. The Federal Archives in East Point, GA also has 2900 cubic feet of Saturn documents. Rocketdyne has in its archives dozens of volumes from its Knowledge Retention Program. This effort was initiated in the late '60s to document every facet of F-1 and J-2 engine production to assist in any future re-start.

The problem in re-creating the Saturn V is not finding the drawings, it is finding vendors who can supply mid-1960's vintage hardware (like guidance system components), and the fact that the launch pads and VAB have been converted to Space Shuttle use, so you have no place to launch from.

By the time you redesign to accommodate available hardware and re-modify the launch pads, you may as well have started from scratch with a clean sheet design.