User avatar
rg828
Posts: 568
Joined: Sun Jan 25, 2004 5:12 pm

Space Shuttle To Moon: Possible?

Tue Sep 02, 2008 3:46 am

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
I dont know the key to success, but the key to failure is trying to please everyone
 
DfwRevolution
Posts: 8588
Joined: Sat Jan 09, 2010 7:31 pm

RE: Space Shuttle To Moon: Possible?

Tue Sep 02, 2008 4:20 am



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.
 
User avatar
rg828
Posts: 568
Joined: Sun Jan 25, 2004 5:12 pm

RE: Space Shuttle To Moon: Possible?

Tue Sep 02, 2008 4:38 am



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!
I dont know the key to success, but the key to failure is trying to please everyone
 
WingedMigrator
Posts: 1769
Joined: Wed Oct 26, 2005 9:45 am

RE: Space Shuttle To Moon: Possible?

Tue Sep 02, 2008 5:30 am



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 Big grin

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
Posts: 1508
Joined: Thu Jul 07, 2005 8:44 am

RE: Space Shuttle To Moon: Possible?

Tue Sep 02, 2008 2:56 pm



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.

Quoting WingedMigrator (Reply 3):
That is the biggest show stopper.

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.

Impossible? No. Impractical? Impressively so.
 
kbfispotter
Posts: 658
Joined: Sat May 14, 2005 5:56 pm

RE: Space Shuttle To Moon: Possible?

Tue Sep 02, 2008 6:21 pm

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.

Kris
Proud to be an A&P!!!
 
User avatar
rg828
Posts: 568
Joined: Sun Jan 25, 2004 5:12 pm

RE: Space Shuttle To Moon: Possible?

Tue Sep 02, 2008 8:29 pm



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!
I dont know the key to success, but the key to failure is trying to please everyone
 
Thorny
Posts: 1508
Joined: Thu Jul 07, 2005 8:44 am

RE: Space Shuttle To Moon: Possible?

Tue Sep 02, 2008 8:49 pm



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
Posts: 997
Joined: Fri Dec 21, 2007 1:59 am

RE: Space Shuttle To Moon: Possible?

Tue Sep 02, 2008 8:55 pm



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.
Fly, you fools! Fly!
 
WingedMigrator
Posts: 1769
Joined: Wed Oct 26, 2005 9:45 am

RE: Space Shuttle To Moon: Possible?

Tue Sep 02, 2008 9:39 pm



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.
 
Thorny
Posts: 1508
Joined: Thu Jul 07, 2005 8:44 am

RE: Space Shuttle To Moon: Possible?

Tue Sep 02, 2008 11:29 pm



Quoting WingedMigrator (Reply 9):
Nonsense. The cislunar environment is thermally similar to GEO and has no temporal variations.

Of course, the Shuttle does not fly in GEO (22,300 miles), it flies in LEO (150-300 miles.)
 
User avatar
rg828
Posts: 568
Joined: Sun Jan 25, 2004 5:12 pm

RE: Space Shuttle To Moon: Possible?

Wed Sep 03, 2008 12:04 am



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
I dont know the key to success, but the key to failure is trying to please everyone
 
WingedMigrator
Posts: 1769
Joined: Wed Oct 26, 2005 9:45 am

RE: Space Shuttle To Moon: Possible?

Wed Sep 03, 2008 12:46 am



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

Thank you. Nor does it fly to the moon.
 
Thorny
Posts: 1508
Joined: Thu Jul 07, 2005 8:44 am

RE: Space Shuttle To Moon: Possible?

Wed Sep 03, 2008 2:23 am



Quoting WingedMigrator (Reply 12):

Thank you. Nor does it fly to the moon.

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
Posts: 1769
Joined: Wed Oct 26, 2005 9:45 am

RE: Space Shuttle To Moon: Possible?

Wed Sep 03, 2008 4:01 am



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
Posts: 8588
Joined: Sat Jan 09, 2010 7:31 pm

RE: Space Shuttle To Moon: Possible?

Wed Sep 03, 2008 4:07 am



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
Posts: 2489
Joined: Thu Jul 14, 2005 7:51 am

RE: Space Shuttle To Moon: Possible?

Wed Sep 03, 2008 4:55 am



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.

Quoting WingedMigrator (Reply 14):
(1) hotter than LEO due to the lack of eclipse

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.
Where are all of my respected members going?
 
Curt22
Posts: 334
Joined: Sat Jul 14, 2007 11:43 am

RE: Space Shuttle To Moon: Possible?

Wed Sep 03, 2008 11:46 pm



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.

I believe the Apollo missions performed a "rotisserie" roll all the way to the moon and back as a way to manage heat (and cold), and of course they had windows too, but we didn't hear of any complaints of a strobing effected (I'm sure it's a slow roll).

Aside from the heating and consumables (time) issues...the primary problem is fuel...the orbiters cannot now, nor be modified to carry enough fuel to leave LEO.

In fact, it's all the orbiters can do to just to get "up" (366 miles) to Hubble for repair missions.
 
TheSonntag
Posts: 4303
Joined: Wed Jun 15, 2005 7:23 pm

RE: Space Shuttle To Moon: Possible?

Thu Sep 04, 2008 12:44 am



Quoting Curt22 (Reply 17):
Aside from the heating and consumables (time) issues...the primary problem is fuel...the orbiters cannot now, nor be modified to carry enough fuel to leave LEO.

Which leads to a theoretical question for Thorny: Could you put 5 or 6-segment SRBs on a Shuttle and put a bigger External tank on the Shuttle in order to increase the Shuttle payload by just burning longer? As I understand, you still need a higher Thrust than weight during takeoff in order to get the thing off the ground, but there certainly are adequate reserves in the current SRB thrust levels.

I know costs would be astronomic, but "could" it be done? Was it ever considered to put more powerful SRBs on Shuttle?
 
j.mo
Posts: 652
Joined: Fri Feb 15, 2002 12:29 am

RE: Space Shuttle To Moon: Possible?

Thu Sep 04, 2008 12:44 am



Quoting RG828 (Reply 6):
Oh, so the idea was brought up before?

It has. Have you not seen the movie Airplane II.  Wink

JM
 
rwessel
Posts: 2448
Joined: Tue Jan 16, 2007 3:47 pm

RE: Space Shuttle To Moon: Possible?

Thu Sep 04, 2008 1:18 am



Quoting TheSonntag (Reply 18):
Which leads to a theoretical question for Thorny: Could you put 5 or 6-segment SRBs on a Shuttle and put a bigger External tank on the Shuttle in order to increase the Shuttle payload by just burning longer?

In theory, sure. But there will be practical limitations. Assuming you just went with a six segment SRB design, you're going to mainly increase acceleration, not burn time. That's fine as far as it goes, but the shuttle stack is aerodynamically limited during the early stages of flight, and you can't increase the initial acceleration all that much, and there's a limit to how much you can throttle down the mains. You'd probably want to go to more complex hybrid core/end burner design, so a fairly major SRB redesign.

You'd end up with a significantly new ET design to handle the higher thrust.

And there's also a limit to how much bigger you can make the ET. The SSMEs won't be changing, so you're still left with 1.5m lbs of thrust after SRB separation, which will somewhat limit the size of the ET.

But yes, you could get a fair increase in payload to orbit. Witness the many conventional boosters that have grown strap-ons over the years.

Which is not to say that a modestly larger SRB might not be relatively straightforward. A five segment design (with some internal changes to manage the thrust/time curve) is probably fairly straightforward, and would require only modest changes in the rest of the stack.

But why? Buy yourself a nice Delta IV Heavy, and launch the shuttle light to meet it in orbit. Unless you've got enough missions to justify this, the economics simply don't work.

Quoting TheSonntag (Reply 18):
Was it ever considered to put more powerful SRBs on Shuttle?

The FWC SRBs that were intended to use at Vandenberg for polar launches were not more powerful, but they were considerably lighter, which is basically the same thing. The advanced SRB would have increase thrust and reduced weight, and NASA did evaluate a five segment booster (or alternatively strapping on a pair of modified Delta IVs or Atlas Vs instead of the SRBs). Word was that the five segment booster would have increased payload to ISS by 15klbs+. Obviously none of those ideas went anywhere.
 
Thorny
Posts: 1508
Joined: Thu Jul 07, 2005 8:44 am

RE: Space Shuttle To Moon: Possible?

Thu Sep 04, 2008 2:12 am



Quoting TheSonntag (Reply 18):

Which leads to a theoretical question for Thorny: Could you put 5 or 6-segment SRBs on a Shuttle and put a bigger External tank on the Shuttle in order to increase the Shuttle payload by just burning longer?

The Five Segment Booster was in fact originally designed for use by the Space Shuttle around the same time (late 1990s) as the Liquid Flyback Booster was being contemplated as a Shuttle upgrade. The External Tank would have been the same size, but strengthened. Aerodynamic modeling of the new configuration would have been extensive.

Quoting Rwessel (Reply 20):
You'd end up with a significantly new ET design to handle the higher thrust.

Surprisingly, it didn't require a lot of changes. But the FSB itself was a big job, as we're finding out now with Ares I.
 
Curt22
Posts: 334
Joined: Sat Jul 14, 2007 11:43 am

RE: Space Shuttle To Moon: Possible?

Thu Sep 04, 2008 3:48 am



Quoting TheSonntag (Reply 18):
I know costs would be astronomic, but "could" it be done? Was it ever considered to put more powerful SRBs on Shuttle?

This may be the real driver...it's just not cost effective to send people to the moon (on orbit) in a shuttle type of vehicle...after all, the "mission" is not to send hardware for hardware's sake, but to send humans and there are simply less costly and less complex issues with other machines.
 
User avatar
rg828
Posts: 568
Joined: Sun Jan 25, 2004 5:12 pm

RE: Space Shuttle To Moon: Possible?

Thu Sep 04, 2008 3:59 am



Quoting BHMBAGLOCK (Reply 16):
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

It would be interesting just to see what type of numbers we´re talking about!

Quoting J.mo (Reply 19):

Quoting RG828 (Reply 6):
Oh, so the idea was brought up before?

It has. Have you not seen the movie Airplane II. Wink

Good lord, I forgot all about that movie.

Quoting DfwRevolution (Reply 15):
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.

Thanks, I did some bit of reading last night and noticed that its very similar to to Apollo, one big difference is the use of two separate launches for a single moon mission - one for the CSM and Lander, the other to launch the TLI booster . Both would hook up in LEO before heading out. Pretty much similar to this comment:

Quoting Rwessel (Reply 20):
Buy yourself a nice Delta IV Heavy, and launch the shuttle light to meet it in orbit. Unless you've got enough missions to justify this, the economics simply don't work.

Dismissing every impracticality mentioned in this thread, it would be interesting to see what a Moon-capable Space Shuttle would look like. A totally re-usable Moon spacecraft. It somehow irks me how much hardware was 'wasted´ during Apollo (and Constellation for that matter.)
I mean, a humongous Saturn V would be launched, and just the tiny CM would return (and even that was´nt used again.) Everything used in a Shuttle launch is ´recyclable.´
I dont know the key to success, but the key to failure is trying to please everyone
 
User avatar
rg828
Posts: 568
Joined: Sun Jan 25, 2004 5:12 pm

RE: Space Shuttle To Moon: Possible?

Thu Sep 04, 2008 4:19 am



Quoting Thorny (Reply 7):
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.

I´m guessing this is because a Lunar return entry profile is much steeper than a LEO entry, correct? Is it also faster because of the TEI-burn, and/or the Earth´s gravity working on it?

I guess thats why the Apollo re-entries were somehow ... ´discreet,´ compared to Shuttle re-entries - which make for quite a show, lasting over a long period of time and crisscrossing huge lengths of the atmosphere.

Thanks all of you, I love space talk!
I dont know the key to success, but the key to failure is trying to please everyone
 
rwessel
Posts: 2448
Joined: Tue Jan 16, 2007 3:47 pm

RE: Space Shuttle To Moon: Possible?

Thu Sep 04, 2008 5:23 am



Quoting RG828 (Reply 23):
Dismissing every impracticality mentioned in this thread, it would be interesting to see what a Moon-capable Space Shuttle would look like. A totally re-usable Moon spacecraft. It somehow irks me how much hardware was 'wasted´ during Apollo (and Constellation for that matter.)
I mean, a humongous Saturn V would be launched, and just the tiny CM would return (and even that was´nt used again.) Everything used in a Shuttle launch is ´recyclable.´

Except for the external tank and fuel, of course.

Yet the shuttle is in many ways worse than a Saturn V. All that recycling is terribly expensive. Mind you that the S-V could put something like 100t into LEO. So can the shuttle, except that three quarters of that is the orbiter. You're right, all that came back from the moon was the CM (although the SM did end up back on earth - just in little bitty pieces). If you wanted to actually send the shuttle, you'd have a vastly larger mass to return, and the fuel requirements start going up hugely.

And given that even something like fuel becomes hugely expensive once you've had to boost it into orbit, wasting fuel can easily be more expensive than throwing away hardware.

If you want to recycle stuff, and you are flying enough missions to justify it, build a dedicated vehicle to transfer between LEO and lunar orbit, and then a dedicated lunar lander to cycle between the moons surface on lunar orbit.

Quoting RG828 (Reply 24):
I´m guessing this is because a Lunar return entry profile is much steeper than a LEO entry, correct? Is it also faster because of the TEI-burn, and/or the Earth´s gravity working on it?

No, that's just the speed an object falling to earth with reach when started from a couple of hundred thousand miles away. The actual steepness of the reentry is a different matter. The shuttle naturally takes a fairly shallow dive, but so did Apollo - it didn't just center punch the earth on the way back, it hit rather off center, so that it flew a considerable distance sideways (relative to the earth's surface) during reentry.
 
Thorny
Posts: 1508
Joined: Thu Jul 07, 2005 8:44 am

RE: Space Shuttle To Moon: Possible?

Thu Sep 04, 2008 4:57 pm



Quoting RG828 (Reply 23):
Thanks, I did some bit of reading last night and noticed that its very similar to to Apollo, one big difference is the use of two separate launches for a single moon mission - one for the CSM and Lander, the other to launch the TLI booster . Both would hook up in LEO before heading out.

Not quite. The Lander will go up with the TLI booster. The CSM rides alone on the Ares I.

Quoting RG828 (Reply 24):


I´m guessing this is because a Lunar return entry profile is much steeper than a LEO entry, correct? Is it also faster because of the TEI-burn, and/or the Earth´s gravity working on it?

All of the above.
 
User avatar
rg828
Posts: 568
Joined: Sun Jan 25, 2004 5:12 pm

RE: Space Shuttle To Moon: Possible?

Thu Sep 04, 2008 8:09 pm



Quoting Rwessel (Reply 25):
If you want to recycle stuff, and you are flying enough missions to justify it, build a dedicated vehicle to transfer between LEO and lunar orbit, and then a dedicated lunar lander to cycle between the moons surface on lunar orbit.

That makes sense, dedicated machines for dedicated tasks - helps avoid the complexities of designing a spacecraft that does everything (ooopss, sounds like project Constellation/Ares?)

Quoting Thorny (Reply 26):
Not quite. The Lander will go up with the TLI booster. The CSM rides alone on the Ares I.

Thanks for the correction. I guess that by dividing the lunar payload in 2 launches, you can maximize the payload.

I´m curious (again.) Whats more costly: an SRB or the fuel for the shuttle´s main engines? In other words, solid or liquid?

Thx
I dont know the key to success, but the key to failure is trying to please everyone
 
Thorny
Posts: 1508
Joined: Thu Jul 07, 2005 8:44 am

RE: Space Shuttle To Moon: Possible?

Thu Sep 04, 2008 10:01 pm



Quoting RG828 (Reply 27):
That makes sense, dedicated machines for dedicated tasks - helps avoid the complexities of designing a spacecraft that does everything (ooopss, sounds like project Constellation/Ares?)

No, Ares is a one-trick pony. We'd actually be better off with a DIRECT-like infrastructure that would be able to support more than just Constellation. Orion is a moon ship, it can do Space Station missions too, but that's about the extent of it. Shuttle was actually the vehicle ruined by trying to be all things to all customers.

Quoting RG828 (Reply 27):
I´m curious (again.) Whats more costly: an SRB or the fuel for the shuttle´s main engines? In other words, solid or liquid?

Most likely, the solid propellant is more expensive than LOX (pennies per pound) and LH2 (more expensive, but not budget-busting.) Of course, the LOX and LH2 need an engine to burn them, and that is more expensive. But an SRB versus a LOX/LH2 first stage, the SRB is cheaper. I think, but can't say for sure, that the hypergols (hydrazine derivatives) are the most expensive fuels and their strict handling precautions drive up their costs even more.
 
User avatar
rg828
Posts: 568
Joined: Sun Jan 25, 2004 5:12 pm

RE: Space Shuttle To Moon: Possible?

Fri Sep 05, 2008 1:05 am



Quoting Thorny (Reply 28):
Most likely, the solid propellant is more expensive than LOX (pennies per pound) and LH2 (more expensive, but not budget-busting.) Of course, the LOX and LH2 need an engine to burn them, and that is more expensive. But an SRB versus a LOX/LH2 first stage, the SRB is cheaper. I think, but can't say for sure, that the hypergols (hydrazine derivatives) are the most expensive fuels and their strict handling precautions drive up their costs even more.

What systems uses Hypergolic fuels nowadays, for orbital thrusters? Do Shuttles use them?

Thanks for all the info Thorny.
I dont know the key to success, but the key to failure is trying to please everyone
 
WingedMigrator
Posts: 1769
Joined: Wed Oct 26, 2005 9:45 am

RE: Space Shuttle To Moon: Possible?

Fri Sep 05, 2008 2:00 am



Quoting RG828 (Reply 27):
Whats more costly: an SRB or the fuel for the shuttle´s main engines?

That stuff is in the noise. What's costly is the labor to design, build and fly these things.
 
Thorny
Posts: 1508
Joined: Thu Jul 07, 2005 8:44 am

RE: Space Shuttle To Moon: Possible?

Fri Sep 05, 2008 2:11 am



Quoting RG828 (Reply 29):
What systems uses Hypergolic fuels nowadays, for orbital thrusters? Do Shuttles use them?

Yes, the Shuttle's maneuvering and attitude-control thrusters use Monomethyl Hydrazine and Nitrogen Tetroxide.

Delta II's second stage uses hypergolic propellants, the AJ-10-118K which traces its heritage all the way back to Vanguard. A derivative of this engine will power Orion. Early plans to use non-toxic propellants (LOX/Methane) in Orion were abandoned due to cost and complexity.

Many satellites and deep space spacecraft use them.
 
rwessel
Posts: 2448
Joined: Tue Jan 16, 2007 3:47 pm

RE: Space Shuttle To Moon: Possible?

Fri Sep 05, 2008 10:11 pm



Quoting RG828 (Reply 29):
What systems uses Hypergolic fuels nowadays, for orbital thrusters? Do Shuttles use them?

To add to what Thorny said, hypergolics have two huge advantages: First they’re easy to store, despite being fairly unpleasant. You can use low pressure tanks and you don't have to worry about boil-off like you do with LOX or (shudder) LH2. You might need a tank heater to keep it from freezing, but other than that, it's easy to store for long periods of time.

Second, the engine itself, especially small ones, are dead simple and ultra reliable. There's not even an ignition system, and so long as you can pump both components into the combustion chamber, it'll run. You don't even have to do a terribly accurate job of metering the two components, and the engine will still produce thrust (although less efficiently, of course).

In fact, attitude control thrusters (and some not-so-small station keeping thrusters on satellites) are often nothing more than a pair of valves feeding into an otherwise inert combustion chamber/expansion bell. You keep a bit of pressure in the two tanks, and when you want thrust, you just blip the two valves.

All that, and a respectable (if not great) ISP, makes hypergolics very attractive.
 
User avatar
rg828
Posts: 568
Joined: Sun Jan 25, 2004 5:12 pm

RE: Space Shuttle To Moon: Possible?

Fri Sep 05, 2008 11:21 pm



Quoting Rwessel (Reply 32):
To add to what Thorny said, hypergolics have two huge advantages: First they’re easy to store, despite being fairly unpleasant

To me, the Me 163 always comes to mind when it comes to Hypergolics, its a surprise that they are still in use despite its volatility. Especially in the shuttle!

Thanks you all, this is all great reading for me.
I dont know the key to success, but the key to failure is trying to please everyone
 
Thorny
Posts: 1508
Joined: Thu Jul 07, 2005 8:44 am

RE: Space Shuttle To Moon: Possible?

Sat Sep 06, 2008 12:40 am



Quoting RG828 (Reply 33):
To me, the Me 163 always comes to mind when it comes to Hypergolics, its a surprise that they are still in use despite its volatility. Especially in the shuttle!

Hypergolics had been used on Gemini and Apollo, so they were a known, low-risk (developmentally speaking) approach for Shuttle. NASA started a development effort to replace them on Shuttle in the late 1990s (with LOX/Alcohol, I think) but the funding never materialized to bring it to fruition. Then Columbia happened and all of the Shuttle upgrades (Reusable First Stage, Electric APU, etc.) were abandoned.
 
ebj1248650
Posts: 1517
Joined: Mon Jun 06, 2005 6:17 am

RE: Space Shuttle To Moon: Possible?

Sun Sep 07, 2008 12:52 am

Seems to me the most significant question centers on why you'd want to send something that big to go exploring around the moon? What experiments would you perform? What reconnaissance equipment or surveying equipment would you carry on the shuttle that you couldn't carry on a much smaller vehicle? As I understand it, NASA is developing smaller vehicles for deep space exploration. Wouldn't those be adequate for future exploration of the moon?
Dare to dream; dream big!
 
prebennorholm
Posts: 6430
Joined: Tue Mar 21, 2000 6:25 am

RE: Space Shuttle To Moon: Possible?

Tue Oct 07, 2008 7:55 pm

The Shuttle around the Moon is a big no-no for a hundred reasons. The two major reasons:

1. The Shuttle system will never be able to lift off the ground with the fuel load needed to reach escape velocity 25,000 mph.

2. The thermal protection system will no way survive re-entry at escape velocity.

But there are so many design properties which are tailored exactly to low Earth orbit and totally wrong for anything else.

For instance the re-entry procedure is unique and totally different compared to any other spacecraft. It was designed to re-enter at slightly slower speed than LEO speed. Then the wing lifts at an angle of attack of roughly 15 degrees. It keeps the Shuttle high up in the extremely thin air where speed can bleed off at a low rate which doesn't heat the thermal protection system to destruction, as it does on all other spacecrafts.

Trying the same stunt going 25,000 mph instead of 17,500 mph (much faster than LEO speed instead of slightly slower), then it would make a "touch and go" on the upper atmosphere and continue a couple of hundred thousand miles out into space on the other side of the Earth.

Those wings are not just for landing. The keep the Shuttle flying high up, even at FL3000, so the speed can bleed off much more slowly, keeping the heat buildup within non-destructible limits.

Theoretically the re-entry could be initiated inverted so the lift of the wing could bend its trajectory to more or less equal to the curvature of the Earth. But if it had to bleed off speed from 25,000 to 17,500 mph so fast that it wouldn't touch and go, then it would have to enter at a rather steep angle and therefore be treated to heat and forces so great that it would burn to ashes. And if that wasn't the case, then it would suffer a structural breakup.

But first of all, fueled to reach the Moon, it will never lift an inch off the ground.
Always keep your number of landings equal to your number of take-offs
 
WingedMigrator
Posts: 1769
Joined: Wed Oct 26, 2005 9:45 am

RE: Space Shuttle To Moon: Possible?

Tue Oct 07, 2008 11:12 pm



Quoting Prebennorholm (Reply 36):
Then the wing lifts at an angle of attack of roughly 15 degrees

Max L/D is achieved closer to 50 degrees, not 15.

Quoting Prebennorholm (Reply 36):
It keeps the Shuttle high up in the extremely thin air where speed can bleed off at a low rate

This would lower the peak heating rate but increase the total heat load absorbed into the vehicle structure (versus rejected into the flow)... it is not desirable, which is why the Shuttle performs steep banking maneuvers to get down more quickly.
 
User avatar
rg828
Posts: 568
Joined: Sun Jan 25, 2004 5:12 pm

RE: Space Shuttle To Moon: Possible?

Sat Oct 11, 2008 6:36 am

I found these great lectures about the origins of the Space Shuttle on Youtube, sponsored by MIT Aero Astro no less, and by the original project people.

http://www.youtube.com/watch?v=iiYhQtGpRhc

Guide for the lectures: http://ocw.mit.edu/OcwWeb/Aeronautic...5JFall-2005/LectureNotes/index.htm

Chris Kraft´s was most entertaining, dont miss it.

I havent seen all of them, but most on the list above are on Youtube. They are pretty long, b/w 1:45 to 2 hours long, but very, very interesting. Thorny, have you seen them? I think they might be right up your alley.

If you have´nt seen them, I recommend you watch them, its a learning experience.

RG

Oh, I nearly forgot - They mention somewhere that they did consider Moon missions for the Shuttle, I think its on lecture 1 or 2.
I dont know the key to success, but the key to failure is trying to please everyone
 
Thorny
Posts: 1508
Joined: Thu Jul 07, 2005 8:44 am

RE: Space Shuttle To Moon: Possible?

Mon Oct 13, 2008 4:58 pm



Quoting RG828 (Reply 38):
Oh, I nearly forgot - They mention somewhere that they did consider Moon missions for the Shuttle, I think its on lecture 1 or 2.

I haven't watched these videos, but I'd be interested in the timeframe of these "considerations". Remember, the "Space Shuttle" was originally a much smaller spacecraft, intended only to replace Apollo, not the Saturn rockets. That original 1960s Shuttle would have been much easier to send to the moon (although still a heavyweight compared to Apollo.)

Also, in the 1990s, there were proposals for lunar missions involving Shuttle launches in concert with launches of upgraded Titan IV/Centaurs. But the Shuttle itself would not have gone to the moon.

Any suggestion of sending the contemporary Shuttle to moon is simply ridiculous, the stuff of cheesy science fiction movies and novels.
 
Flighty
Posts: 7715
Joined: Thu Apr 05, 2007 3:07 am

RE: Space Shuttle To Moon: Possible?

Mon Oct 13, 2008 6:30 pm

I was thinking also the Shuttle's wings are not strong enough to bear the heavy Lunar loads. And there are also serious ETOPS considerations.
 Big grin
 
Oroka
Posts: 1077
Joined: Sat Dec 09, 2006 4:37 am

RE: Space Shuttle To Moon: Possible?

Tue Oct 14, 2008 12:53 am

Sure you can, you can send the USS Enterprise (CVN 65) to the moon if you strap enough rocket power to it. Cost considerations and practicality is a whole different matter.

Who is online

Users browsing this forum: No registered users and 7 guests