Minor Damage Found On Space Shuttle

The BBC is reporting on minor damage to the space shuttle Atlantis revealed by a 10-hour inspection in orbit. On the shuttle's right side, near where the wing joins the body, inspection revealed a 21" (53cm) line of chips in the tiles that make up the vehicle's heat shield. "...more analysis by engineers would determine whether a 'focused inspection' was needed in that specific area. If so, astronauts would use sensors to determine the exact depth of the damage to the heat shield tiles. NASA has placed the space shuttle Endeavour on stand-by to rescue the crew of Atlantis if they are endangered." The crew couldn't shelter on the ISS in case of trouble, because their orbit is higher and on a different inclination.

Comments

So what happens....

[zonky]

.. if they launch Endeavour to rescue Atlantis, and Endeavour suffers damage at launch?

Re:So what happens....

[Anonymous Coward]

I'm sure they could chuck a few spare panels in the back of the otherwise-empty Endeavour.

Getting to ISS

[biocute]

If something goes wrong on this mission, Atlantis's astronauts will not be able to shelter on the International Space Station (ISS). The station orbits at around 350km (220 miles) above Earth, while Hubble occupies an orbit about 560km (350 miles) up.

Can someone speculate the feasibility of "dropping" to meet ISS?

I mean, does NASA have equipments/knowledge/training to do such maneuver?

Re:Getting to ISS

[EvanED]

Don't know much about orbital mechanics, do you?

Changing Apollo 13's course from what it was originally to a free-return course requires the merest nudge compared with the fuel required to change orbital planes like what would be required here.

Also, consider that the LEM had enough fuel in its descent engine to slow its descent and keep from smashing into the moon and an ascent engine to get it back up (though I don't know if the ascent engine fuel is usable by the descent engine).

Re:Getting to ISS

[Anonymous Coward]

If the two orbits were in the same inclination it would not take that much fuel to drop down to a lower orbit, however the great difference in inclination would require a very large amount of fuel, much more than the shuttle carries once it is in orbit. I recommend to anyone who is interested in these questions to play with the free Orbiter simulation: http://orbit.medphys.ucl.ac.uk/orbit.html It teaches orbital mechanics in a very practical and hands-on way.

Re:Getting to ISS

[Suzuran]

The descent engine and ascent engine were entirely separate, since the entire descent stage of the LM was discarded on the moon for return. There were no interconnections between the two. That does not mean they couldn't have burned the DPS to exhaustion, staged, and then burned the APS for as long as required.

In any event, the shuttle cannot carry enough fuel to make the orbit change required in this instance simply because the tanks aren't big enough. You can't put 500 gallons of gas in a tank that only holds 300. This is not a simple matter of flying in a line from point A to point B. Go download Orbiter and educate yourself.

What would happen to Atlantis?

[yogibaer]

So in case of any real damage, Endeavor blasts off (piloted by a 2 Astronaut crew?), all the Astronauts on board Atlantis pack their bags and take a seat in the other shutlle and live happily ever after, which is most important of all. But what would happen to Atlantis in that case? You obviously can't tow it or land it by remote, but leaving such a large object in a (decaying) orbit could cause a lot of trouble. So what would they do? Send it to the moon à la "Space Cowboys" or give it a gentle but controlled kick, letting it crash and burn up in the atmosphere?

What I wonder...

[Angstroem]

Is this really a new development that the Shuttle gets increasingly fragile or is it just the fact that since Columbia it gets checked extra carefully and therefore revealing what before just went unnoticed?

Speculation

[MichaelSmith]

Maybe NASA could build a capsule small enough to put into the shuttle through the side hatch. One crew member initiates re-entry then rides out aero braking inside the capsule. If the spacecraft burns up the capsule falls into the air. Parachutes open automatically.

As far as I know the pilot is only needed to manually deploy landing gear. Everything else can be automatic or remotely operated.

Rescue Logic

[Anonymous Coward]

Can someone explain the logic of a hypothetical rescue mission to me?

The reason a rescue mission is on standby is there are "higher amounts of space debris in Hubble's orbit". Of course in the articles I could find there are not specifics and I don't know if it was the language used by NASA or something that's been dumbed down. So the logic of sending another shuttle into the same orbital debris environment is far from apparent to me.

Re:Why can't you land it by remote/autopilot?

[dpilot]

Last I heard, the shuttles had full autolanding capability, with one exception. There is no computer control for lowering the landing gear - the controls for that are fully and only manual. That dates back to way-back-when days, when they didn't fully trust the computers. There are no provisions inside the shuttle whatsoever for raising the landing gear, that can only be one at the processing facilities on the ground. Therefore they wanted no chance whatsoever that the landing gear could be accidentally deployed, because if that happened, there would be 3 giant holes in the heat shield, and nothing they could do about it.

So everything from de-orbit through final approach and landing could be done automatically, they'd just have to do it on the belly.

This isn't necessarily bad, either. One of the big fears right now is that there is more space junk in the higher orbit where Atlantis and Hubble currently are. Even if Atlantis is damaged, we want it to come down, so it doesn't add to the space junk problem, itself. For the current situation, self-destruct is a really bad option, unless carried out during reentry. Short of complete success, I would think that a belly landing at Edwards would be the best option, since it would likely yield a whole bunch of either spare parts or museum fodder.

Re:I have the fail-safe solution to these problems

[JWSmythe]

    No, I really meant down into a geosynchronous orbit. :)

    At a low orbit with 0 ground speed, the orbit will decay fast, which is what you'd want. If it went up to where it could maintain that orbit, well, it wouldn't come down very easily.

    Basically, do a burn similar to their deorbit burn. Spin it around backwards, fire the main engines for about 4 minutes, flip back around, and fly home. :)

    When they do the deorbit burn, they slow down by about 150mph, and the orbit decays rapidly.

    They don't carry enough fuel to bring that down to 0 though.

    I went looking around, and found that there was a proposal a long time ago for basically a bean bag that an astronaut could climb into. More like a big foam filled sleeping bag. It had minimal heat shielding, but if they were dropped geosynchronous, they could make it back. It'd take about 4 hours or so, trapped inside a little bag, with no light, no communications, nothing. They'd just lay in it and wonder if they were going to survive. It was dropped because of the potential psychological effects, and they never tested it from a real altitude. The only "test" was throwing a crash dummy in the bag from a bridge.

   

Re:I have the fail-safe solution to these problems

[AeroIllini]

I don't know that there's enough fuel on the shuttle to bring it down to a geosynchronous orbit. They have oms thrusters, good for changing altitude on a mission and maintaining their orbit, but not dropping so much speed.

Low Earth Orbit velocity is approximately 7.8 km/s. The Hubble's orbit is slightly higher, with a slower velocity of 7.5 km/s.

The delta-v capability of a space shuttle after successfully completing a launch is approximately 600 mph (0.27 km/s), depending on the weight of the payload it's carrying. Dumping all their non-essential items out the airlock before the burn might gain them something, but not nearly enough. Remember that it takes two extra rockets and a full bolt-on fuel tank to achieve that 7.8 km/s in the first place (actually 9.3 km/s with atmospheric effects).

Even if a second rocket with a payload of nothing but fuel was launched to rendezvous with the shuttle, it would still not be enough to slow down the shuttle to zero tangential velocity. Nothing as big as the Stage 1 tank has ever been boosted into orbit in a single launch. It would take many launches and lots of complicated orbital rendezvous maneuvers to refuel the shuttle enough on-orbit to achieve a 7.5 km/s burn.

And even then, Main Engine Cutoff (MECO) during launch is at T+8 minutes; the shuttle engines can't burn a full tank of fuel much faster than that (they throttle down right at the end to keep the acceleration to 3g or less, but before that it's balls-to-the-wall). I'm not sure how long it would take the orbiter to reach the atmosphere during the deorbit maneuver--the shuttle would start to fall to the Earth immediately, in an arc that would end up perfectly vertical with respect to the ground--but 8 minutes seems like a long time. If the shuttle hit the atmosphere before the full 7.5 km/s delta-v was achieved, it would still have some tangential velocity, making for a bumpy ride, and the possibility of heating effects on unprotected surfaces.

In any case, there isn't nearly enough fuel up there to do this, and any secondary launch to bring them fuel may as well just bring a rescue capsule for the astronauts.

Thanks for the fun thought experiment, though.