New Shuttle Fuel Tanks Ready

confusion writes "NASA has completed the redesigned fuel tanks for the Shuttle scheduled to for launch in May or June of this year. "On the new tank, NASA has reconfigured the struts and fittings where foam was prone to peeling off, and installed heaters to prevent ice from forming. The new tank has cameras that will allow ground workers to monitor for damage as the shuttle ascends.""

Comments

Re:They're still not solving the problem

[squidguy]

They're so soft you could problably crush a piece with your hands, which means they're easily damaged during flight (and we've seen the fatal results of that) Errr...it was an impact against the leading edge of the wing -- which is covered by reinforced carbon-carbon -- not the ceramic thermal tiles.

Re:I know how NASA could fix the shuttle

[Ironsides]

We have put nuclear reactors into orbit before. On one of the missions, the rocket even blew up. The net gain in radioactivity? ZERO. The casing around the material was designed to be able to tolerate a rocket explosion. They recovered the material (every last gram) and reused it on a later mission. The problem is not garunteeing a 100% success rate, the problem is making sure that if something does occur, that the material doesn't get spewed all over the contry side. And that is orders of magnitude easier.

Re:They're still not solving the problem

[AC-x]

That's funny, because I seem to remember the most likely theory on the disaster was the foam hit and punctured the leading edge of the wing which is made of reinforced carbon-carbon (RCC), and not the heat resistant tiles (which are designed so a few can be lost during normal flights anyway).

Re:They're still not solving the problem

[Rei]

Irrelevant.

Troy's bear suit uses FSA 333 ("Fire Suppression Agent 333"). Which he blames for the FBI harassing him and instigating his divorce (no, I'm not kidding - he claims that it is the secret to making extraction of Canadian tar sands cheap, and the US government is after it). It is a fire retardant, heat resistant material.

This is *NOT* what you want on a reentry craft.

You can't just insulate your way to a safe landing; you have to *dissipate* the heat. That is what the tiles are for; they have a huge surface area, and even non-fibrous ceramics are good at radiating heat. As a consequence, you can stick the titles under a blowtorch for an hour if you wanted, take them out, and a couple second later they'll be completely cool to the touch. They dissipate heat that fast. *That* is what you need for reentry; not some "fire suppression agent".

The other major in-use option is ablatatives (again, not what troy invented). Albatives "ablate" (i.e., steadily erode off) as they heat up. As they do so, they take the heat that they absorbed with them. There are also other theoretical or in-testing options being looked at

Re:I know how NASA could fix the shuttle

[Waffle Iron]

There basically are three major cases of nuclear-power on spacecraft: nuclear-powered liftoff stages, nuclear reactor powered deep space drives, and radioisotope thermal generators (RTGs) for electrical power. I'm not sure which incident you're referring to, but it's probably an RTG (which are very common, and which is not a nuclear fission reactor). The Soviet Union put a few dozen actual fission reactors in orbit. (A couple of these accidently reentered, and the are still in orbits that will decay within a few hundred years). The US has only put up one or two test fission reactors.

RTGs are potentially worrisome, but the fuel can be heavily protected as you mention. However, they are most often used as electrical power generators, not propulsion systems. RTG fuel is nasty stuff even before the RTG is put in use.

Fission reactors (not RTGs) that are not activated until orbit really aren't that much of a big deal on launch because they can be fueled with fresh U-235 which really isn't very radioactive or dangerous until you switch the reactor on and start generating fission products. The only issue is if they don't make it out of earth orbit and eventually the orbit decays. Powering an ion drive with one of these to do missions to the outer planets might make a lot of sense.

The scariest nuclear propulsion case a the high-thrust rocket used for the first or second stage liftoff. These have been successfully tested on the ground but never flown. They basically pack all of the power of a large commercial nuclear plant into a package only a few feet in diameter. They run full blast with little or no shielding. There is no way to heavily shield or isolate the fuel without impeding the huge heat transfer rate that is necessary to propel the massive amounts of propellant gas out the rocket.

These high-thrust rockets operate at the very fringes of material strength capabilities and probably have a high probability of disintegrating, spewing partially spent fuel and waste into the atmosphere. That's one reason that they've never been actually used.