HST repair mission "What if" poll

[llivinglarge]

By all means, if Discovery gets too ****ed up for reentry. I expect the astronauts to at the very least finish the mission to the best of their ability.

 

[Leovinus]

I think you meant "messed" up. <div class="Discussion_UserSignature"> </div>

 

[trailrider]

Base SOLELY on the premise stated, I voted, "YES!" <br /><br />However....what I would expect would actually happen is that NASA with the help of other agencies, and even other NATIONS, would exert every possible effort to rescue stranded astronauts, even if the standby Shuttle was unable to launch for the rescue attempt. <br /><br />This might include the launch of EELV's with spare oxygen to extend the time available for a rescue mission to be launched, or perhaps even arranging some means of adapting Soyuz-TM spacecraft to U.S. launch vehicles for launch from the Cape. (I don't believe you can reach a 28 degree inclination orbit from Baikonur, but I may be wrong! Once in a 28 degree orbit, the Shuttle doesn't possess enough delta-V to reach the ISS' orbit.)<br /><br />I suspect that Mission Control would NOT have the capability to handle both a resuce attempt and the very complicated tasks required to fix the Hubble, nor would the astronauts be able to do the Hubble mods without support from the ground simultaneously.<br /><br />I would expect Mission Control, et al, to be working with the stranded crew to effect whatever repairs MIGHT be possible on the stranded OV, no matter how slim the chances of effective repair might be. (For example, "Shove whatever spare stuff you have in the hole and then apply the repair material over it!") Once all steps possible had been done, (and I think it would take whatever time was available before the consumables were to run out) then the crew would try to bring the beast home...or would be rescued. There is an old story among test pilots (true or apocriphal, I don't know) that a pilot was in a plane spinning out of control. There was no ejection seat in the plane, or else he was simply trying to save the aircraft. He radioed in, "I've tried A! That didn't work. I've tried B! That didn't work. I've tried...(static...end of transmission)" Point is, you don't just sit there and take it! You keep trying...something, anything

 

[Leovinus]

I think I read the "A B C" story in "Lost Moon" by Jim Lovell, renamed "Apollo 13" for the movie. <div class="Discussion_UserSignature"> </div>

 

[Leovinus]

Are you saying the LEM would not fit in the cargo bay with the legs folded? Is that because it was square instead of round? <div class="Discussion_UserSignature"> </div>

 

[mrmorris]

Well -- the combined length of the CSM and LM would be over 17 meters. The spec I have for the payload bay says that it's 18m. However, SG has indicated that the addition of the external airlock changed the dimensions of the payload bay and I don't know how much. Certainly it would be a tight fit even at 18m -- likely close enough that it would be invalidated by safety standards even if it could squeak in.<br /><br />In any event -- the LM wouldn't be needed for such a mission and a functional CSM doesn't exist. Ergo, the point is moot.

 

[Leovinus]

The SM wouldn't be needed either. One assumes that the orbital maneuvering engines would do the de-orbit. <div class="Discussion_UserSignature"> </div>

 

[mrmorris]

<font color="yellow">"One assumes that the orbital maneuvering engines would do the de-orbit. "</font><br /><br />One would be spending a long cold time in LEO. The RCS on the CM was designed just for re-entry maneuvering and had only 257 kg-sec of impulse. This isn't enough to get home from a 700km orbit. Certainly the SM would be horrendously massive overkill for the stated purpose, but the CM alone wouldn't cut the mustard.

 

[futurexboy]

Actually they plan on using the Space Shuttle Rockets to boost the Hubble into a higher orbit on this coming Repair Mission, so the guy who said they are barely able to reach the Hubble has a lot to learn. As for the original poster's question, well they plan on having a second space shuttle and crew ready to fly in case of any kind of problem...if you ask me its safer to go to space than it is to take a dive in the ocean, at least in Space you don't have sharks or any other crazy crap like Sting Rays....I don't understand one thing, why can't they fly the space shuttle from the Hubble to the Space Station if there's a problem like the poster described?

 

[futurexboy]

BarryKirk, hahahaha, LOLROF!!

 

[scottb50]

so the guy who said they are barely able to reach the Hubble has a lot to learn....<br /><br />I would think after working on Apollo and having been involved with the Shuttle from it's inception SG would have learned quite a bit.<br /><br />I don't understand one thing, why can't they fly the space shuttle from the Hubble to the Space Station if there's a problem like the poster described? />>><br /><br />Maybe you should actually read some of the posts here and you might get to understand. It takes a lot of energy to go from one orbit to another. That's why they launch into specific orbits to begin with rather than the same initial orbit every time and move to the one they want. <div class="Discussion_UserSignature"> </div>

 

[MeteorWayne]

As explained elsewhere, it takes a huge amount of energy to shift the orbital inclinations. The ISS is in an orbit of 52 degrees, the HST's is 28 degrees. It takes more energy to change that orbit than the Shuttle has available once on orbit. <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[MeteorWayne]

And listening to me, you hear only what I've learned from shuttle_guy and some of the others here who are involved in the programs.<br /><br />Thanx again, S_G <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[mrmorris]

<font color="yellow">"That requires a change in velocity of about 24,000 ft/sec. Since the velocity the Orbiter must obtain to get to orbite is around 25,000 ft. sec"</font><br /><br />That make no sense, SG. Plane changes are expensive, but there's simply no way that a 24-degree plane change could require as much energy as that used to get into orbit. Also -- the orbital velocity at 400km is 7.67 km/s -- which equates to 25,164,042 ft/s.<br /><br />The Apollo MODAP document I've used for info on my G-X3 and Dragon threads puts plane change dv at 100 m/s per degree of change. Since the plane change from the Hublle to ISS is 24 degrees, that would come to 2400 m/s (7,874 ft/s). However, since that MODAP figure appears to be a simplistic rule of thumb -- I searched for a specific plane change formula. I found one in some course documents for a Navy class on Astrodynamics for the Navy Postgraduate School in Monterey, California. Working out the dv from Hubble's orbit at 700km using that formula, I get:<br /><br />dv = 2 * sin [ di / 2] * Vc<br />dv = 2 * sin [ 24 / 2 ] * 7500 m/sec<br />dv = 15000 m/s * sin [12]<br />dv = 3118.6 m/s<br /><br />If we assume the plane change occurs after the drop from 700km to 400 km -- the equation becomes:<br /><br />dv = 2 * sin [ di / 2] * Vc<br />dv = 2 * sin [ 24 / 2 ] * 7670 m/sec<br />dv = 15340 m/s * sin [12]<br />dv = 3189.4 m/s<br /><br />Not that this changes the overall issue, of course. The orbiters only have about 700m/s tops -- much of which would have been used getting to Hubble, and almost all of the remainder is needed for de-orbit.

 

[spacester]

Deja Vu.<br /><br />I'm guessing that SG was recalling the number for the max plane change one could contemplate: 90 deg; IOW changing from equatorial to polar. I've seen this done by others as well. I think it's a matter of not being too worried about the number because it ain't happening no matter what nohow.<br /><br />Congrats on finding that formula, it's been elusive for years. Note that the dV required can be reduced by reducing the Vc (Circular Velocity) which is what you get when you increase the orbital radius. For example, plane changes for trips to the moon can be done relatively cheaply by waiting until you're more than halfway there. There is another version of the formula for eccentric orbits. <div class="Discussion_UserSignature"> </div>

 

[scottb50]

At one point we were also discussing a highly elliptical orbit with a plane change at the apogee of the orbit. Sort of a turn about a point at the smallest radius of a cone. Still, with the propellant carried by Shuttle any meaningful plane change is pretty much out of the picture. <div class="Discussion_UserSignature"> </div>

 

[llivinglarge]

It doesn't matter whether fitting an escape pod/module in the Shuttle payload bay is feasible. Of course it could be done, but you must remember that you need to save 7 astronauts, not 3 or 4. It's all or none. I don't think human sacrifice is an option for NASA besides as an absolute and extreme last resort.

 

[llivinglarge]

(Nice job mrmorris...)<br /><br />SG, I know you've been working for NASA for at least 30 years (correct me if I am mistaken) and I am inclined to believe your statements, a little math to support your claim wouldn't hurt.

 

[gunsandrockets]

"One assumes that the orbital maneuvering engines would do the de-orbit."<br /><br />Obviously he meant the OMS of the Shuttle, not the RCS of the CM. <br />

 

[gunsandrockets]

"but you must remember that you need to save 7 astronauts, not 3 or 4."<br /><br />There have been plans for a Shuttle rescue module based on the Apollo CM which could hold the entire crew of the Shuttle. Crowded, but better than dying.

 

[llivinglarge]

Pure curiosity, but can Hubble be packed up into the shuttle and brought back to Earth?

 

[mrmorris]

<font color="yellow">"SG, I know you've been working for NASA..."</font><br /><br />My post was <b>not</b> intended to be a slam at SG, and anyone that does so better eat their Wheaties that morning. He provides a *huge* amount of valuable experience to this forum and to me personally on multiple occasions. He remembers more about the shuttle program than I will ever be able to research. If he sometimes slips a decimal point or a unit when reporting data on the forum -- that's just the price of doing business. <br /><br />As far as SG adding more math to his posts -- my posts tend to be math-intensive for several reasons. First -- I tend to think in mathematical terms. Second -- I'm on this forum because I like learning about space and what is/isn't possible. Generally it's math that determines that -- so I find the formula(s) involved and work them out -- and once I've done that, it only makes sense to post my results. Finally -- I like posting <i>facts</i> whenever possible. The vast majority of the posts on this board are composed of <i>opinions</i> or <i>wishes/dreams</i>. Generally when I post something that involves a statement, I like to either provide the math that backs it up or a link to my source that backs it up. SG, by contrast, is his *own* source and his facts & figures generally come from his memory or from NASA documentation that we don't have access to (if it weren't for SG being here). He's said on multiple occasions that he welcomes corrections. If you find a post of his that you think is wrong, then post a correction of your own... preferably with the math to prove it.

 

[mrmorris]

<font color="yellow">"Obviously he meant the OMS of the Shuttle, not the RCS of the CM. "</font><br /><br />More likely possible -- but quite dicey. You'd need to use the shuttle OMS to get the shuttle *close* to re-entry, but not all the way there because the CM would still be in the payload pay. Getting it out of the bay would be a reasonably lengthy operation. Someone would have to be in the shuttle to use the RMS to pull the CM out of the payload bay -- then EVA over to the CM. The CM's RCS would then have to have enough dv to complete the DO burn. I still doubt that enough dv would be available, but it's certainly closer.

 

[rocketman5000]

I got it chop some peices off the shuttle so you can strech more delta V out of the engines....<br /><br />maybe remove an engine and some tanks and ride the engine over to the station like that in that movie "Mission to Mars" where he road a russian lander back to orbit

 

[Leovinus]

I don't buy it. You wouldn't have to use the arm to get the escape pod out. Let it depart on remote control spring ejectors. Controllers then fire jets on the shuttle to move it the heck out of the entry path so that there is no collision on re-entry. <div class="Discussion_UserSignature"> </div>