RG828 From Brazil, joined Jan 2004, 558 posts, RR: 1 Posted (3 months 3 days 14 hours ago) and read 4156 times:
Just throwing out a silly idea here, be nice!
Could a Space Shuttle make a trip to the moon, orbit the moon, and return? No landing of course, just something like say .... what Apollo 8 did. Nothing fancy at all.
I wouldnt know the dynamics of a moon mission, but in theory you would need a big thruster to get off earth orbit and head to the moon, to correct your course, then to slow you down for Moon orbit, possibly play around moon orbit like descend to lower orbits, then do the same to get back to Earth. I dont know, maybe put a fuel tank in the cargo bay to supply a TLI rocket?
I´m just fantasizing here guys, is it possible?
Thanks
Cowboys should not fly, they should take care of horses not horse power.
DfwRevolution From United States, joined Mar 2004, 7691 posts, RR: 55 Reply 1, posted (3 months 3 days 14 hours ago) and read 4154 times:
Quoting RG828 (Thread starter): Could a Space Shuttle make a trip to the moon, orbit the moon, and return? No landing of course, just something like say .... what Apollo 8 did. Nothing fancy at all.
Completely impossible, and not just from a cost standpoint. The Shuttle is designed to operate in low Earth orbit, and the trans-lunar space is a very different environment. The thermal and radiation environments would likely render the Shuttle crippled.
Quoting RG828 (Thread starter):
I wouldnt know the dynamics of a moon mission, but in theory you would need a big thruster to get off earth orbit and head to the moon, to correct your course, then to slow you down for Moon orbit, possibly play around moon orbit like descend to lower orbits, then do the same to get back to Earth. I dont know, maybe put a fuel tank in the cargo bay to supply a TLI rocket?
The delta-V requirements to get the Shuttle from LEO to Trans-Lunar Injection (TLI) are tremendous. The Shuttle weights about twice the combine Apollo CSM/LM.
RG828 From Brazil, joined Jan 2004, 558 posts, RR: 1 Reply 2, posted (3 months 3 days 13 hours ago) and read 4140 times:
Quoting DfwRevolution (Reply 1): The Shuttle is designed to operate in low Earth orbit, and the trans-lunar space is a very different environment. The thermal and radiation environments would likely render the Shuttle crippled.
How is trans-lunar space different? Does radiation increase and temperature decrease(more?)
Quoting DfwRevolution (Reply 1): The delta-V requirements to get the Shuttle from LEO to Trans-Lunar Injection (TLI) are tremendous. The Shuttle weights about twice the combine Apollo CSM/LM.
Fascinating stuff. So the shuttle is´nt structurally ... 'sound´ for a TLI burn? What kind of dynamics are involved? I mean, the shuttle has to deal with a re-entry, and that seems like a violent event in itself. Why could´nt it take a LEO-TLI burn?
Other than that, I guess it can orbit the moon all right then, correct?
Thanks for your input Dfw!
Cowboys should not fly, they should take care of horses not horse power.
WingedMigrator From United States, joined Oct 2005, 1507 posts, RR: 27 Reply 3, posted (3 months 3 days 12 hours ago) and read 4124 times:
Quoting DfwRevolution (Reply 1): The delta-V requirements to get the Shuttle from LEO to Trans-Lunar Injection (TLI) are tremendous.
No more tremendous than any other vehicle, since delta-V is independent of vehicle mass. But yes it's a bunch... couple of miles per second, something the shuttle definitely couldn't do.
Quoting RG828 (Reply 2): How is trans-lunar space different?
Here there be dragons
Quoting RG828 (Reply 2): Does radiation increase and temperature decrease(more?)
Radiation is more benign after you exit the belts, unless you get a solar event. I doubt the shuttle's ancient computers would hiccup at all in the trans-lunar environment. Temperature would be OK too: LEO eclipse is a far harsher thermal environment than a cruise to the moon.
Quoting RG828 (Reply 2): the shuttle has to deal with a re-entry
That is the biggest show stopper. The thermal protection system on the shuttle orbiter isn't sized for that kind of heating rate or total heat load. The kinetic energy of the vehicle would more than double.
Thorny From United States, joined Jul 2005, 1449 posts, RR: 10 Reply 4, posted (3 months 3 days 3 hours ago) and read 3987 times:
Quoting WingedMigrator (Reply 3): LEO eclipse is a far harsher thermal environment than a cruise to the moon.
No it isn't. The Earth is warm and keeps nearby space warm, too. The temperature variations in cislunar space are much more severe.
Quoting WingedMigrator (Reply 3): No more tremendous than any other vehicle, since delta-V is independent of vehicle mass. But yes it's a bunch... couple of miles per second, something the shuttle definitely couldn't do.
The Shuttle with payload (say, a LM) is ~220,000 lbs. Apollo 17's CSM/LM were ~110,000 lbs. Apollo 17 required an S-IVB upper stage weighing around 200,000 lbs. to launch it from LEO to the moon. We'd probably need about 400,000 lbs of fuel to launch a Shuttle to the moon (all other concerns notwithstanding.) That's eight Shuttle missions, or about two years of Shuttle flights at current rates, worth of fuel.
Yes. Neck-and-neck with being able to restart a Main Engine in space for the trans-lunar injection. Once upon a time, we thought that would be an easy upgrade. Constellation has now proven differently. So we'd need to add an entirely new thermal protection system, replace at least one Main Engine with a new design, update the Shuttle's guidance, control and communications systems for cislunar flight, and find a way to launch 400,000 lbs of propellant in a reasonably short time to make it work.
KBFIspotter From United States, joined May 2005, 716 posts, RR: 1 Reply 5, posted (3 months 3 days ago) and read 3885 times:
While purely a work of fiction, Homer Hickam tackled this subject in his book "Return to the Moon". Like I said, the book is purely fiction, but it gives a basic idea of what would be required to fly the shuttle to the moon, such as adding new engines, and upgrading the avionics.
RG828 From Brazil, joined Jan 2004, 558 posts, RR: 1 Reply 6, posted (3 months 2 days 21 hours ago) and read 3825 times:
Quoting Thorny (Reply 4): Once upon a time, we thought that would be an easy upgrade.
Oh, so the idea was brought up before?
Quoting WingedMigrator (Reply 3): The thermal protection system on the shuttle orbiter isn't sized for that kind of heating rate or total heat load. The kinetic energy of the vehicle would more than double.
Quoting Thorny (Reply 4): So we'd need to add an entirely new thermal protection system
I dont get it - Fo what phase of flight would the thermal protection system need to be adapted? I´m guessing the requirements for an Earth re-entry would remain the same, either after a LEO mission or a moon mission.
Is it because the Shuttle would need to get heavier?
Thanks for the replies guys!
Cowboys should not fly, they should take care of horses not horse power.
Thorny From United States, joined Jul 2005, 1449 posts, RR: 10 Reply 7, posted (3 months 2 days 21 hours ago) and read 3812 times:
Quoting RG828 (Reply 6): Oh, so the idea was brought up before?
Many times. But most recently, the Space Shuttle Main Engine was to power the upperstage of the new Ares I rocket which will launch the Orion manned spacecraft. NASA eventually abandoned that concept when the cost and complexity of making the Main Engine air-startable (more or less the same as re-startable in space) grew too high. It was essentially the same as an all-new engine development effort, and that wasn't in the budget.
Quoting RG828 (Reply 6): I dont get it - Fo what phase of flight would the thermal protection system need to be adapted?
Re-entry. Entry from LEO is about 17,500 mph. Entry from lunar return is about 25,000 mph and is over a shorter period of time, making for much high peak heating loads. The existing tile/RCC/blanket TPS cannot handle those loads.
There would be secondary issues of making things like the inside of the payload bay able to handle the wide temperature swings of cislunar space, but those wouldn't be as difficult to solve.
PITIngres From United States, joined Dec 2007, 194 posts, RR: 2 Reply 8, posted (3 months 2 days 21 hours ago) and read 3809 times:
Quoting RG828 (Reply 6): Fo what phase of flight would the thermal protection system need to be adapted? I´m guessing the requirements for an Earth re-entry would remain the same, either after a LEO mission or a moon mission.
Probably both transit and re-entry, but mostly the latter. As Thorny pointed out, the shuttle "sees" more of the warm Earth in LEO, and hence the thermal fluctuations in LEO are smaller. I'm sure that the orbiter cooling systems would have to be spiffed up to deal with transit extremes.
But the big noise is re-entry. Your guess about re-entry is unfortunately not correct. An easy way to think of it is to consider how much energy you put into the outbound trip; to a very rough approximation, you have to dispose of about that much energy upon re-entry. You have to boost the vehicle out of LEO to the moon, so you have to dispose of that extra energy coming back. Upon returning from the Moon, the vehicle is going at least 2X faster than it goes in LEO. (I forget the exact multiplier.) So you either have to dissipate 2X more heat in the TPS, or you have to carry MORE fuel to first slow the orbiter into LEO, then re-enter normally. And of course, the latter option makes the initial boost and trans-lunar injection just that much harder because you have to fly the necessary fuel out and back.
WingedMigrator From United States, joined Oct 2005, 1507 posts, RR: 27 Reply 9, posted (3 months 2 days 20 hours ago) and read 3792 times:
Quoting Thorny (Reply 4): The Earth is warm and keeps nearby space warm, too.
Nearby space, whatever that is, has no intrinsic temperature. It is a vacuum.
Quoting Thorny (Reply 4): The temperature variations in cislunar space are much more severe.
Nonsense. The cislunar environment is thermally similar to GEO and has no temporal variations.
Quoting PITIngres (Reply 8): the shuttle "sees" more of the warm Earth in LEO, and hence the thermal fluctuations in LEO are smaller.
The temperature swings (dT/dt) are far larger in LEO because of eclipses. In GEO or on a trip to the moon or anywhere near 1 AU from the sun, the thermal environment does not vary appreciably with time. The temperature differential between the hot side and the cold side of the vehicle may be a bit larger than LEO, but that can be solved easily by turning the vehicle. All other things being equal, the vehicle will run hotter than LEO since there is no eclipse.
Blackbody radiation from the earth is quite small compared to solar radiation flux.
Quoting PITIngres (Reply 8): Upon returning from the Moon, the vehicle is going at least 2X faster than it goes in LEO. (I forget the exact multiplier.) So you either have to dissipate 2X more heat in the TPS
Worse: the energy to be dissipated goes as the square of entry velocity.
RG828 From Brazil, joined Jan 2004, 558 posts, RR: 1 Reply 11, posted (3 months 2 days 18 hours ago) and read 3717 times:
Quoting Thorny (Reply 7): Quoting RG828 (Reply 6):
I dont get it - Fo what phase of flight would the thermal protection system need to be adapted?
Re-entry. Entry from LEO is about 17,500 mph. Entry from lunar return is about 25,000 mph and is over a shorter period of time, making for much high peak heating loads. The existing tile/RCC/blanket TPS cannot handle those loads.
Quoting PITIngres (Reply 8): Upon returning from the Moon, the vehicle is going at least 2X faster than it goes in LEO.
That clears it up. I did´nt consider the fact that a spacecraft returning from the moon ( or beyond LEO?) would be coming in much much faster.
So I guess thats why NASA did´nt bother designing the Apollo CM with rockets to slow her down into earth orbit before reentry - just bring her in straight away. I can imagine the extra shielding a Shuttle would need. Would ablative material help some?
I havent seen the complete Constellation retrun-to-moon plan, is the setup similar to Apollo?
Thanks again
Cowboys should not fly, they should take care of horses not horse power.
WingedMigrator From United States, joined Oct 2005, 1507 posts, RR: 27 Reply 12, posted (3 months 2 days 17 hours ago) and read 3706 times:
Quoting RG828 (Reply 11): So I guess thats why NASA did´nt bother designing the Apollo CM with rockets to slow her down into earth orbit before reentry - just bring her in straight away
That's the most effective way of doing it, since there is no propellant mass to take there and back. Atmospheric braking is very effective. This also explains the somewhat surprising fact that it takes less fuel to land on Mars than it does to land on the Moon.
Quoting Thorny (Reply 10): the Shuttle does not fly in GEO
Who said it did? The original poster asked if it could, and my response was 'it isn't practical'. One reason (of many) is the much more severe environment of cislunar space compared to LEO in which the Shuttle was designed to operate. You then called this "nonsense" and cited GEO as being about the same as cislunar space, which is totally irrelevant.
WingedMigrator From United States, joined Oct 2005, 1507 posts, RR: 27 Reply 14, posted (3 months 2 days 14 hours ago) and read 3643 times:
Quoting Thorny (Reply 13): the much more severe environment of cislunar space compared to LEO
Much more severe?
You made the point that Earth somehow "warms" vehicles in LEO, which to me implied that they would "freeze" in cislunar space because the Earth wasn't there. That just isn't the case. Cislunar space, from a thermal standpoint, is
(1) hotter than LEO due to the lack of eclipse
(2) more stable than LEO due to the lack of eclipse
The idea that it would be colder or that there would be temperature extremes or variations or fluctuations worse than LEO is mistaken, and I simply used the GEO example to illustrate the point. Thermally, GEO and cislunar are for all practical purposes the same environment, and not a particularly harsh one compared to the enormous thermal swings experienced in LEO.
I'm sorry I called it nonsense, I should have been more gentle.
DfwRevolution From United States, joined Mar 2004, 7691 posts, RR: 55 Reply 15, posted (3 months 2 days 14 hours ago) and read 3641 times:
Quoting RG828 (Reply 11): I havent seen the complete Constellation retrun-to-moon plan, is the setup similar to Apollo?
Constellation will use the same configuration of a manned capsule and purpose-built lunar lander, but there are some notable operational changes from Apollo. A quick Google search to NASA's website or even Wikipedia could fill you in on many of these details as they are currently planned.
BHMBAGLOCK From United States, joined Jul 2005, 2672 posts, RR: 22 Reply 16, posted (3 months 2 days 13 hours ago) and read 3624 times:
Quoting RG828 (Thread starter): I wouldnt know the dynamics of a moon mission, but in theory you would need a big thruster to get off earth orbit and head to the moon, to correct your course, then to slow you down for Moon orbit, possibly play around moon orbit like descend to lower orbits, then do the same to get back to Earth. I dont know, maybe put a fuel tank in the cargo bay to supply a TLI rocket?
I'm not going to crunch numbers tonight as it's nearly midnight but IIRC the delta V required for a round trip moon mission well exceeds that required to escape from our solar system.
What about the half of the vehicle being eclipsed by the other half facing the sun? You could spin the vehicle but it makes it more difficult to keep antennas properly aimed and if there are windows the strobing of the sun would get damn annoying inside.
Curt22 From United States, joined Jul 2007, 282 posts, RR: 1 Reply 17, posted (3 months 1 day 18 hours ago) and read 3429 times:
Quoting BHMBAGLOCK (Reply 16): What about the half of the vehicle being eclipsed by the other half facing the sun? You could spin the vehicle but it makes it more difficult to keep antennas properly aimed and if there are windows the strobing of the sun would get damn annoying inside.
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