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NASA Optimistic About Fuel Tank Repairs
DarkNemesis618 writes "NASA is now optimistic Atlantis' fuel tank will be able to be repaired in Florida. Due to a freak hail storm February 26 that had golf-sized hail chunks raining down on the launchpad put several thousand dings in the foam covering the external fuel tank as well as damaging 28 tiles on Atlantis' wing. 20 of the 28 tiles have been repaired and workers have started sanding down the damaged area of the tank itself. After it was decided that Atlantis needed to return to the VAB, NASA was unsure as to whether or not the tank could be repaired. But after bringing it back and doing more extensive inspections, the tank appeared to be in good enough shape that repairs could be done on the spot and a replacement was not necessary. This will allow for Atlantis to be launched late April for its construction mission to the ISS as well as not interfering with the remaining 4 launches planned this year. If the tank needed to be replaced, Atlantis would not have launched until June at the earliest."
"Just park the damn thing under a roof for once."
Is this a joke or does this person not know not know about the Vehicle Assembly Building (VAB)?
Of course they keep it indoors. But of course they take it outside before they light off the big rockets and launch it into space. Makes a mess of the building if you try doing the inside. What happened was they chaecked the weather, it looked good so they took the think outdoors and then unexpectedly they got hailed on.
The VAB is quite famous. It was built in the 1960's and was and still is the largest enclosed space in the world. It was designed to house a fully assembled Appolo era moon rockets, (A Saturn V with all the upper stages)
See here for more info on the VAB
http://science.ksc.nasa.gov/facilities/vab.html
compared to what?
Oh.. an 86 Ford Econoline van I guess.
Good thing those 30 year old 747's and DC-10's don't have to carry large fragile payloads into low Earth orbit. Funny though, they are built by the same companies that build the shuttle. And the shuttle was probably constructed with a lot more care attention and diligence the the jumbo jet they built in march of 1993. Maybe the application is just slightly different.
Yea, the shuttle is far from perfect. It is expensive and more complex then it should be. It's also constrained to a small very un-glamorous space application. But it's the first vehicle of it's type humans built. And it's the only vehicle we have that can do what it does. The fact that it's still in service after 25 years doing amazing things is a testament to it's design. And I have confidence that NASA could do a whole lot better given more funding and a vision they are allowed to follow through with.
Enough with the bandwagon, whiney, pessimistic idiotic shuttle bashing. Do some research, and post objectively. Yes, it's time to move on and yes I'd like to see a new space vehicle. Really though, these let's slam the POS shuttle trolls are wearing me the hell out.
Wonder no more, there is a possible explanation. Adding armour to a shuttle would make it heavier, and heavier things have a hard time flying, especially into space. It's not the foam by itself that is so damaging, it is the foam moving at high velocity that is so damaging. If you have better solutions, (and a demonstation of your solution) I'm sure NASA would like to hear you out. They do, after all, need some fresh new ideas when it comes to human spaceflight.
Let's see... ESA, RFSA... I'm sure there are others. I'm not saying NASA hasn't done a lot of good work. They have. They aren't by a long shot the only space agency that has done a lot of good work, though.
The ISS was developed jointly by all of those organizations and others, and was built jointly as well. The shuttle's remote manipulator arm was built by the Canadian Space Sgency, IIRC. As for shuttles, the Russian (nay, Soviet) space agency studied the concept of building a reusable space plane, built one, and scrapped it after only a single flight. I suspect that they realized how poor the reusability of the design was, then concluded that it wasn't worth the trouble.
The shuttle was a classic example of "too many cooks" syndrome. The military's insistence on carrying home satellites (AFAIK, never used during reentry for anything other than Spacelab, which, BTW, was designed by the ESA), coupled with NASA's insistence on maximum reusability resulted in a shuttle in which the orbiter main engines still require a complete tear down between launches, the heat tiles require massive service for every launch, and the external tank still burns up. If someone were designing the shuttle today, it would look very different. It would be at the top of the stack, the orbiter would have no main engines internally, and would be orders of magnitude safer as a result of either one of those changes.
A shuttle designed today would not be built using steel frames, but would instead be built using more modern materials like carbon-fiber-reinforced plastic, polycarbonate, etc. except for the portions that get to extreme temperatures during reentry. A shuttle today would ideally not use liquid fuel. That stuff is a nightmare, both in terms of safety and in terms of the required facilities to maintain its temperature. Instead, it would solely use solid rockets (or a single solid rocket) with adjustable nozzles. This part would be disposable.
A shuttle designed today, since it would not have to carry the weight of main engines during reentry, could safely handle the weight of an ablative heat shield under the thermal tiles to ensure a safe return. Fewer thermal tiles (say a fourth as many, but 4x as large) would be a big win in terms of complexity and propensity for failure. Use a more flexible binder so that they don't fall off so often, or better yet, hold them in place with a replaceable steel lattice with pins that stick into the edges of the tiles to anchor them even more securely than any glue (or run pins into them from the back or... fill in the blank.
A shuttle designed today might even have a rear ablative shield and a switch wing design, falling back-end-first through the upper layers of atmosphere, using the ablative heat shield to handle the heat, then at some known altitude, would use the partially deployed wings to reverse its direction and use a chute to slow its descent. Once its descent slowed to a reasonable level, the chute would be detached (with the ablative shield in tow), and the shuttle would continue to fall nose down, at which point the switch wings would be deployed fully and the shuttle would glide in for a landing. You could even put in some small, in-air-safe engines under the heat shield, with a few minutes of fuel to make landing more manageable.
Anyway, I could rant for hours about all the things NASA (and the military) did wrong in designing and maintaining the shuttle program, but I won't because I'm really glad to see that the current head of NASA doesn't share the rose colored glasses of previous administrators and sees the shuttle for what it is---a good first prototype, but a bad final design. I'm hopeful that eventually we will see something like the shuttle in concept, but radically improved in implementation, even if we do end up stuck with plain old rockets for a while in the interim.
Check out my sci-fi/humor trilogy at PatriotsBooks.
Don't get defensive. He wasn't trash talking the ESA or any other space agency. ESA in particular has performed well lately. He was trash talking the people who trash talk NASA without having a freaking clue what they're talking about.
Part of the reason a shuttle designed today would look very different is because of what we learned from the shuttle. Of course, partially due to limited budgets, we're moving away from the shuttle concept (google CEV if you're unfamiliar).
That said, I think there's some parts where you're flat out wrong. Rather than deal with the variety of architectures that are possible for a shuttle, I'm going to address them in the context of the shuttle we now have and why it is the way it is.
The orbiter is not made from steel, it's made from aluminum and titanium. Of course, CF was just budding at the time it was built and was not a feasible technology. It's only now becoming mainstream in planes, but you can expect to see significant amounts of it on future spacecraft, I will grant you that. It will not, however, offer any magical advantages. Merely a little weight-savings.
The shuttle main engines are liquid fueled because they are significantly more efficient than solid fueled boosters (ISP of about 420 compared to 250 for the SRB's). The solid rocket boosters are desirable because of their extremely high thrust for getting off the ground, but most of the delta V comes from the cryogenic liquid fuels. The wisdom of this choice is reflected in the fact that almost every commercial launcher uses liquid fuel for its core and upper stages, and I think most use LOX (but with kerosene instead of H2). Solid fuels are not without their faults. In addition to low efficiency, their throttling ability is fixed, they can't do a live abort (stop launch once ignition begins), and the fuel can be damaged by excess handling, meaning it needs replacing or the booster may fail.
The engines are mounted on the orbiter instead of the external tank (as per the Russian Buran shuttle) because NASA was counting on reusing them. At $50 million dollars each x 3 engines (~2005 dollars), reusing them saves $150 million per flight (The Russian engines were cheaper, slightly less efficient).
There's a lot of room for criticism of the heat shield, but for a winged re-entry vehicle, there wasn't much flexibility for achieving a light weight shield over such a large area. I believe quite a few alternative mounting methods were considered but found infeasible or higher risk, including mounting pins. The size of the tiles was largely affected by the need to flex in flight.
The Russian space shuttle was scrapped due to lack of money. Given the state of the Soviet Union at the time of its completion and the direction of their space program, it wasn't even worth making do with it after all the money they spent developing it. I don't understand your proposal for a rearward entry or desire for the addition of engines. A rearward entry would not address any of the lessons learned from the shuttle and would only complicate aerodynamics and heat issues. The swing wing would increase mechanical complexity and be difficult to implement for a blunt body re-entry design. No landing attempt has ever come up short, and the size of engines required to enable a fly around would be a significant weight penalty.
I maintain the view that others have offered. While the shuttle was overly ambitious, represented a needlessly challenging architecture, and did not fit the needs of the space program well as it developed (the shuttle was never meant to be our only manned vehicle), it is an astounding marvel of technology and a fine piece of engineering.
We may someday see another vehicle like the shuttle, but probably smaller...designed for crew shuttling and maybe as a work platform only. Not for cargo. It will definitely not use the side stack configuration that places the re-entry vehicle at risk from launch damage. That's probably the biggest lesson of the shuttle program.