annala@neuro.usc.edu (A J Annala) (01/10/89)
Can the shuttle fly to the moon, land, and take off again to return to the earth. Keep in mind the moon has 1/6 the gravitational pull of the earth. Let's assume for the moment that there is adequate solid flat landing surface prepared on the moon for the landing.
sw@whuts.ATT.COM (WARMINK) (01/10/89)
In article <14549@oberon.USC.EDU>, annala@neuro.usc.edu (A J Annala) writes: > Can the shuttle fly to the moon, land, and take off again to return > to the earth. Keep in mind the moon has 1/6 the gravitational pull > of the earth. Let's assume for the moment that there is adequate > solid flat landing surface prepared on the moon for the landing. Let's assume for the moment that this is a serious question. :-) No.
roy@isieng.UUCP (Roy Wells) (01/11/89)
In article <14549@oberon.USC.EDU> weiss%neuro.usc.edu@oberon.usc.edu writes: >Can the shuttle fly to the moon, land, and take off again to return >to the earth. Keep in mind the moon has 1/6 the gravitational pull >of the earth. Let's assume for the moment that there is adequate >solid flat landing surface prepared on the moon for the landing. I don't see how it could under its present configuration. After the external tank and SRBs are gone, there isn't much fuel available for a burn to put it on a lunar trajectory, or to land and then take off, or for a burn to bring it homeward. You'd need to redesign it from the fuel point of view, and then you'd need to figure out how to get it set for a launch from the lunar surface. After all, even if it landed (unharmed) on the moon (unless you send the Army Engineers up to build a runway first) it would likely be severely damaged. Next, there's not much to cause the shuttle to have lift from the horizontal position. No atmosphere on the moon to treat the wings like those of an airplane (could it take off even given fuel+atmosphere?) and getting it to a vertical position could present some problems. For an Earth-Moon shuttle I think a totally different concept is needed. -- Roy Wells Integrated Solutions There is no distinctly native American criminal class except Congress. -- Mark Twain
mike@mfgfoc.uucp (Mike Thompson) (01/11/89)
From article <14549@oberon.USC.EDU>, by annala@neuro.usc.edu (A J Annala): > Can the shuttle fly to the moon, land, and take off again to return > to the earth. Keep in mind the moon has 1/6 the gravitational pull > of the earth. Let's assume for the moment that there is adequate > solid flat landing surface prepared on the moon for the landing. Assuming we could get the shuttle out of earth orbit, the main problem would be slowing the craft from some 20,000 mile per hour to a few hundred mph. The shuttle uses atmospheric friction to slow down from orbital speeds by converting its kenetic energy into thermal energy. This is why the heat tiles on the shuttle are so important during descent from orbit. On the moon, there is virtually no atmosphere so a shuttle like craft would have to rely solely on retro-rockets to land. Even on the moon, it would take a tremendous amount of fuel to soft land something the mass of the shuttle on it. Now Mars is a different story. Because of the design and weight of the shuttle, it will never get further than a few hundred miles from Earth, but a shuttle type device could be used to explore Mars. In fact, I have read that NASA has done studies and built small prototypes of robot planes which could be dropped into the Martian atmosphere and would be capable of flying around for several days (weeks?) taking detailed pictures of the surface of the planet. Pictures of the plane looked somewhat like a U2 spyplane with a propeller on the back. Yes, a propeller which was connected to a type of internal combustion engine which did not require oxygen to run. I think it used Hydrazaline (sp?) as its fuel. Radio control prototypes were actually made and tested out at high altitudes on Earth to simulate the thin Martian atmosphere. I think I read about this type of craft in a Popular Science article some 10 years ago. I would think that such a mission would be very exciting, to bad our congressmen don't agree. Hope this helps answer your question of why the shuttle can't land on the moon. If it could just make it to lunar orbit would be great, but it simply weighs to much to be sent higher than a few hundred miles. Mike Thompson --------------------------------------------------------------------------- Michael P. Thompson FOCUS Semiconductor Systems, Inc. net: (sun!daver!mfgfoc!mike) 570 Maude Court att: (408) 738-0600 ext 370 Sunnyvale, CA 94086 USA ---------------------------------------------------------------------------
campbelr@hpsel1.HP.COM (Bob Campbell) (01/11/89)
> Can the shuttle fly to the moon, land, and take off again to return > to the earth. Keep in mind the moon has 1/6 the gravitational pull > of the earth. Let's assume for the moment that there is adequate > solid flat landing surface prepared on the moon for the landing. ---------- In a word, no. The modifications required to do that would leave you with something that is no longer a shuttle. The shuttle is designed to only go up to low earth orbit, and once there it has no fuel for the main engines. Assuming an Amoco station with LH2/LOX and tankage is on the moon, the problem still exists that the shuttle is designed for vertical takeoff. A "runway" takeoff is difficult as wings do not do much without air. If a launch complex also exists, the shuttle has limited life support . . . The "best" design is still to use multiple vehicles designed for specific tasks. Bob Campbell Some times I wish that I could stop you from campbelr@hpda.hp.com talking, when I hear the silly things you say. Hewlett Packard - Elvis Costello
rcj@killer.DALLAS.TX.US (Robert Johnson) (01/11/89)
Well, in a word, no. There is a posibility that the shuttle could
get into lunar orbit if it was supplied with fuel from an external
tank (just launch a tank up there on the end of a Titan and have an EVA
to mate the two craft). But, once the shuttle got into lunar orbit,
it couldn't land too well! The only way for a shuttle to land is like
an airplane, and there is no atmosphere on the moon, thus there is no
lift for the wings.
Robert C. Johnsonannala@neuro.usc.edu (A J Annala) (01/11/89)
In article <14549@oberon.USC.EDU> weiss%neuro.usc.edu@oberon.usc.edu writes: >Can the shuttle fly to the moon, land, and take off again to return >to the earth. Keep in mind the moon has 1/6 the gravitational pull >of the earth. Let's assume for the moment that there is adequate >solid flat landing surface prepared on the moon for the landing. > Let's also suppose that the shuttle either carries fuel for its extra atmospheric burns in the cargo bay ... or that it meets up with a fuel dump placed in orbit by a heavy lift vehicle. Let's further assume that the shuttle uses its main engine in an attitude normal to the surface of the moon to slow it's descent to the lunar surface (this is because the shuttle's wings would be ineffective in the moon's limited "atmosphere". Finally, let's suppose that a shock absorbing tripod of some kind can be extended from the shuttle's body to stabilize it's attitude once in contact with the lunar surface.
willisa@cs.glasgow.ac.uk (Mark Willis) (01/11/89)
In article <14549@oberon.USC.EDU> weiss%neuro.usc.edu@oberon.usc.edu writes: >Can the shuttle fly to the moon, land, and take off again to return >to the earth. Keep in mind the moon has 1/6 the gravitational pull >of the earth. Let's assume for the moment that there is adequate >solid flat landing surface prepared on the moon for the landing. No definitely not. Even assuming you cound get a shuttle to land on the moon, (you couldnt, it doesn't carry enough fuel) how would you get it to lift off again? Put it on your shoulder and set it down vertically on a rock exactly the right shape to act as a launch pad and not damage the engines or tail fin? Unlikely! Mark ---- -- ARPA: willisa@cs.glasgow.ac.uk | JANet: willisa@uk.ac.gla.cs USENET: mcvax!cs.glasgow.ac.uk!willisa | Voice: +44 41 not telling! ------------------------------------------+------------------------------- British_Space_Program: No such file or directory
logajan@ns.UUCP (John Logajan x3118) (01/12/89)
A J Annala asks:
> Can the shuttle fly to the moon?
No. Consider that the ultimate result of burning all that fuel (both liquid and
solid) is the final speed -- orbital speed of approximately 17000 mph, and
getting to the moon requires closer to 25000 mph. Thus the shuttle would have
to carry at least 1/4 again as much fuel as it does. Quite a significant
increase!
--
- John M. Logajan @ Network Systems; 7600 Boone Ave; Brooklyn Park, MN 55428 -
- ...rutgers!umn-cs!ns!logajan / logajan@ns.network.com / john@logajan.mn.org -jay@ncspm.ncsu.edu (Jay C. Smith) (01/12/89)
In article <6745@killer.DALLAS.TX.US> rcj@killer.Dallas.TX.US (Robert Johnson) writes: >Well, in a word, no. There is a posibility that the shuttle could >get into lunar orbit if it was supplied with fuel from an external >tank (just launch a tank up there on the end of a Titan and have an EVA >to mate the two craft). But, once the shuttle got into lunar orbit, >it couldn't land too well! The only way for a shuttle to land is like >an airplane, and there is no atmosphere on the moon, thus there is no >lift for the wings. I initially laughed at the question, but if this response truly indicates a feasible method of getting the shuttle into lunar orbit, then the question of the lunar landing is now easy: put the small lunar lander in the cargo bay and leave the shuttle in lunar orbit. I'm now fascinated by this.... -- "I don't care too much for money. Money can't buy me love." --------------------------------------------------------------------- Jay C. Smith uucp: ...!mcnc!ncsuvx!ncspm!jay Domain: jay@ncspm.ncsu.edu internet: jay%ncspm@ncsuvx.ncsu.edu
jmturn@pluto.UUCP (James Turner) (01/12/89)
In article <14549@oberon.USC.EDU> weiss%neuro.usc.edu@oberon.usc.edu writes:
:Can the shuttle fly to the moon, land, and take off again to return
:to the earth. Keep in mind the moon has 1/6 the gravitational pull
:of the earth. Let's assume for the moment that there is adequate
:solid flat landing surface prepared on the moon for the landing.
The landing ain't the hard part, it's the getting there. I'm pretty sure
the Shuttle doesn't have sufficient fuel to get much above the 500km
operational ceiling (I know it's around 500, might be off by as much as
30% one way or the other). In any event, the only way we've ever gotten
anything to the moon was by throwing away most of it along the way.
Now, assuming you could get the shuttle to a lunar orbit, you get other
interesting problems. The shuttle does an atmospheric approach on Earth,
and depends on the air to preform the S-turns it uses to slow down. A
lunar landing would take drastically different stratgeries. You'd
probably want to do a straight in dive parallel to the runway.
--
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* James M. Turner * The world would be in one hell of *
* Automation Research Partners * a lot more trouble if I could ever *
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******************************************************************************donegan@stanton.TCC.COM (Steven P. Donegan) (01/12/89)
In article <14549@oberon.USC.EDU>, annala@neuro.usc.edu (A J Annala) writes: > Can the shuttle fly to the moon, land, and take off again to return > to the earth. Keep in mind the moon has 1/6 the gravitational pull > of the earth. Let's assume for the moment that there is adequate > solid flat landing surface prepared on the moon for the landing. 1) It MAY be possible for the shuttle to carry enough fuel/strap on's to get to the moon in theory (I say MAY), but... 2) There is no air on the moon (or reasonable equivalent) so a horizontal, 'normal' shuttle landing CANNOT occur... 3) The shuttle is not equipped for a vertical/tail down landing... 4) Why the hell would you want to do this? I can see using the 'enhanced' (ie strap on booster/fully fueled) shuttle to attain lunar orbit and leave goodies in orbit for later lunar space station construction and thus way station duty for lunar colony construction. But why try a direct approach? Too costly in terms of fuel/payload delivered (intact :-) ) to the moon surface for me... Other 'simple' problems: Is the shuttle's environmental support sufficient for a moon insertion and return orbit? Could strap-on's and full fuel tanks support a payload worth moving to moon orbit? Any NASA folk out there who have looked at this somewhat bizarre scenario? Big smiley's intended... -- Steven P. Donegan These opinions are given on MY time, not Area Telecommunications Engineer Western Digital's Western Digital Corp. stanton!donegan || donegan@stanton.TCC.COM || donegan%stanton@tcc.com
petej@phred.UUCP (Pete Jarvis) (01/12/89)
In article <14549@oberon.USC.EDU> weiss%neuro.usc.edu@oberon.usc.edu writes: >Can the shuttle fly to the moon, land, and take off again to return >to the earth. Keep in mind the moon has 1/6 the gravitational pull >of the earth. Let's assume for the moment that there is adequate >solid flat landing surface prepared on the moon for the landing. The Shuttle could not go to the Moon even if they wanted to. There is not the fuel capacity on board to do such a flight. There are other limitations such as fuel cell capacity, etc. The landing gear only comes down once on tires that are inflated to land on Earth's surface. The Shuttle only has the ability to go about 400 miles out into an Earth orbit. Peter Jarvis..........Physio-Control........Redmond, WA.
bturner@hpcvlx.HP.COM (Bill Turner) (01/13/89)
> I initially laughed at the question, but if this response truly indicates a > feasible method of getting the shuttle into lunar orbit, then the question of > the lunar landing is now easy: put the small lunar lander in the cargo bay and > leave the shuttle in lunar orbit. > > I'm now fascinated by this.... Seems like a waste of fuel to send the whole shuttle on the trip, when all you really need is the cargo bay. Better perhaps to use the shuttle to shuttle materials to LEO and send that to the moon. --Bill Turner
dsmith@hplabsb.HP.COM (David Smith) (01/13/89)
In article <1064@ns.UUCP> logajan@ns.UUCP (John Logajan x3118) writes: >> Can the shuttle fly to the moon? >No. Consider that the ultimate result of burning all that fuel (both liquid and >solid) is the final speed -- orbital speed of approximately 17000 mph, and >getting to the moon requires closer to 25000 mph. Thus the shuttle would have >to carry at least 1/4 again as much fuel as it does. Quite a significant >increase! It's worse than that. To start with, the 1/4 figure is too low. (25000-17000)/17000 = 1.47 > 1.25. (The ratio of excape to circular orbit velocity is actually sqrt(2).) Then you are nailed by the fact that the final speed gain of a rocket is the exhaust velocity times the *log* of the mass ratio. Let's take our favorite shuttle on a swing around the moon. That will take a delta-v of ~7200 mph. Isp of the SSMEs is 455 sec => exhaust velocity is 10,000 mph. So the mass ratio must be exp(7200/10000), or just over 2. That means propellant required is just a bit more than the weight of the orbiter plus its fuel tank -- around (probably over) 250,000 pounds. That is 4 times the used-to-be max quoted payload of the shuttle, so it would take four flights (4 times the fuel) to send one shuttle around the moon. Quite a significant increase! Actually, I expect that more than 64,000 pounds of fuel could be brought up at a time. Just send up shuttles with empty cargo bays. The fuel not burned on the non-cargo is greater than the would-be weight of the non-cargo, and the thrust-to-weight ratio is greater. And once safely in orbit, the performance margin fuel could be transferred. Or if we used high-end shuttle-C (i.e., the variant with 3 SSME's), it would take just one tanker flight. If we wish send a shuttle on a lunar orbit mission, we must tack on another 3000 mph each for lunar orbit insertion and trans-Earth injection burns. Then the mass ratio goes up to 3.7, and we need 675,000 lb. of fuel: ten tanker shuttles, or three shuttle-C's. Now we have to work out how to manage reentry, since the shuttle will come in with twice the kinetic energy of an orbital flight. -- David R. Smith, HP Labs dsmith@hplabs.hp.com (415) 857-7898
chiaravi@silver.bacs.indiana.edu (Lucius Chiaraviglio) (01/13/89)
In article <5108@hplabsb.HP.COM> dsmith@hplabsb.UUCP (David Smith) writes: |In article <1064@ns.UUCP> logajan@ns.UUCP (John Logajan x3118) writes: |>> Can the shuttle fly to the moon? |>No. Consider that the ultimate result of burning all that fuel (both liquid |>and |>solid) is the final speed -- orbital speed of approximately 17000 mph, and |>getting to the moon requires closer to 25000 mph. Thus the shuttle would have |>to carry at least 1/4 again as much fuel as it does. Quite a significant |>increase! | |It's worse than that. To start with, the 1/4 figure is too low. |(25000-17000)/17000 = 1.47 > 1.25. [. . .] This can't be what you meant. (25000 - 17000) / 17000 = 0.47. Perhaps part of your formula is missing? -- | Lucius Chiaraviglio | ARPA: chiaravi@silver.bacs.indiana.edu BITNET: chiaravi@IUBACS.BITNET (IUBACS hoses From: fields; INCLUDE RET ADDR) ARPA-gatewayed BITNET: chiaravi%IUBACS.BITNET@vm.cc.purdue.edu Alt ARPA-gatewayed BITNET: chiaravi%IUBACS.BITNET@cunyvm.cuny.edu
jay@ncspm.ncsu.edu (Jay C. Smith) (01/14/89)
In article <101420003@hpcvlx.HP.COM> bturner@hpcvlx.HP.COM (Bill Turner) writes: >Seems like a waste of fuel to send the whole shuttle on the trip, when >all you really need is the cargo bay. Better perhaps to use the shuttle to >shuttle materials to LEO and send that to the moon. Hey, come on, we're not trying to get practical or something, are we? :-) -- "I don't care too much for money. Money can't buy me love." --------------------------------------------------------------------- Jay C. Smith uucp: ...!mcnc!ncsuvx!ncspm!jay Domain: jay@ncspm.ncsu.edu internet: jay%ncspm@ncsuvx.ncsu.edu
vail@tegra.UUCP (Johnathan Vail) (01/14/89)
>tires that are inflated to land on Earth's surface. The Shuttle only has the >ability to go about 400 miles out into an Earth orbit. I thought it barely made it to about 100 miles. Can it really get an apogee of 400 miles? "Gravity pulls the trousers down Morality pulls the trousers up" -- Bedful of Metaphysicians _____ | | Johnathan Vail | tegra!N1DXG@ulowell.edu |Tegra| (508) 663-7435 | N1DXG @ 145.110-, 444.2+, 448.625- -----
karn@jupiter..bellcore.com (Phil R. Karn) (01/14/89)
>I thought it barely made it to about 100 miles. Can it really get an >apogee of 400 miles? Yes, it can, but you sacrifice quite a bit of payload capacity. The altitude the shuttle can reach depends strongly on the payload mass, orbital inclination, the eccentricity of the orbit (high altitudes are easier if you make them the apogee of an eccentric orbit), and whether any extra fuel tanks are carried for the OMS. It also depends on the specific orbiter being used. The Atlantis flight that launched Lacrosse was operating at about the very limit of its capability for the payload mass and the orbit that was reached. Phil
henry@utzoo.uucp (Henry Spencer) (01/15/89)
In article <14549@oberon.USC.EDU> weiss%neuro.usc.edu@oberon.usc.edu writes: >Can the shuttle fly to the moon, land, and take off again to return >to the earth. Keep in mind the moon has 1/6 the gravitational pull >of the earth. Let's assume for the moment that there is adequate >solid flat landing surface prepared on the moon for the landing. No. It can't carry the fuel to get into a lunar trajectory, its main engines are not restartable in space, its auxiliary engines almost certainly won't suffice, it can't make a rocket landing (no air on the Moon, remember), it can't take off horizontally (or indeed at all, without elaborate facilities), its landing gear cannot be retracted in flight, its thermal protection isn't built for the extra heat of reentry from deep space, and various subsystems (navigation, life support, etc etc) would need substantial modifications. It's a dedicated Earth-to-low-orbit system. -- "God willing, we will return." | Henry Spencer at U of Toronto Zoology -Eugene Cernan, the Moon, 1972 | uunet!attcan!utzoo!henry henry@zoo.toronto.edu
tneff@well.UUCP (Tom Neff) (01/16/89)
I want to congratulate A J Annala for the most thought-provoking Stupid Question in quite a few months! :-) No cutdown intended, sometimes you have to ask an outrageous question in order to get people's minds REALLY working. "No OF COURSE that wouldn't work silly, there's X and Y and Z and, hummmmmm..., however what WOULDN'T be so silly, come to think of it, would be _______________..." Keep it up, don't let your respectable career stamp it out. Note to whoever started musing about sending up landers and tanks of fuel in the cargo bay: Remember Challenger and the Flying Bomb Phobia. If they refuse even to take a Centaur up, they're sure not going to take a lander or a load of hydrazine up. Save that for ELVs... let the shuttle bring up the construction crew instead.
alastair@geovision.uucp (Alastair Mayer) (01/17/89)
In article <17360001@hpsel1.HP.COM> campbelr@hpsel1.HP.COM (Bob Campbell) writes: [...] >The "best" design [for Earth-Moon transport] >is still to use multiple vehicles designed for specific >tasks. Not necessarily true. If a sufficiently flexible vehicle can be built that can do the whole trip, and can be built and operated inexpensively enough (read: mass produced and low operations cost) then that might be the "best" design. Case in point, Pacific-American Launch Co's "Phoenix" design. This is a ballistic, single-stage-to-orbit, vertical-take-off/vertical-landing vehicle. (Utilizing LH2/LO2 fuel and aerospike engine. It's been mentioned around here before, I think). This requires refueling in LEO, but one version of the Phoenix is configured as a 'tanker' to do the job. Once refueled, the vehicle has sufficient delta-Vee to leave LEO for the Moon, soft land on the Moon, and return to Earth. Since it's a ballistic VTOVL, landing on the moon presents no special difficulties, and it can land with sufficient fuel to take off again. The catch is the orbital refueling, which could take as many as 10 tanker launches. However, the Phoenix is designed to be *highly* reusable with low operations costs and rapid turnaround. -- "The problem is not that spaceflight is expensive, | Alastair J.W. Mayer therefore only the government can do it, but that | alastair@geovision.UUCP only the government is doing spaceflight, therefore | al@BIX it is expensive." |
bturner@hpcvlx.HP.COM (Bill Turner) (01/17/89)
>In article <101420003@hpcvlx.HP.COM> bturner@hpcvlx.HP.COM (Bill Turner) writes: >> [text deleted] >Hey, come on, we're not trying to get practical or something, are we? I know, stupid me... :-)
henry@utzoo.uucp (Henry Spencer) (01/19/89)
In article <10366@well.UUCP> tneff@well.UUCP (Tom Neff) writes: >Note to whoever started musing about sending up landers and tanks of >fuel in the cargo bay: Remember Challenger and the Flying Bomb Phobia. >If they refuse even to take a Centaur up, they're sure not going to >take a lander or a load of hydrazine up... NASA has no major objection to hydrazine and the like in the cargo bay; the Lacrosse/KH-12/whatever on Atlantis undoubtedly had quite a bit of it aboard for maneuvering and orbit maintenance. The problem with Centaur was a combination of cryogenic fuels and a very heavy load (which meant, for example, that an abort would have required dumping the Centaur fuels before landing). However, it probably is a better use of limited shuttle tonnage to take a lander up dry, and fuel it in orbit using fuel taken up by expendable tankers. Sigh... there was a proposal, which quietly got forgotten, to take the Centaur up dry and fuel it in orbit from leftovers in the External Tank. No cryogenics in the payload bay, no weight problems on an abort, and a high-performance upper stage. -- Allegedly heard aboard Mir: "A | Henry Spencer at U of Toronto Zoology toast to comrade Van Allen!!" | uunet!attcan!utzoo!henry henry@zoo.toronto.edu
campbelr@hpsel1.HP.COM (Bob Campbell) (01/20/89)
>>The "best" design [for Earth-Moon transport] >>is still to use multiple vehicles designed for specific >>tasks. >Not necessarily true. If a sufficiently flexible vehicle can be built that >can do the whole trip, and can be built and operated inexpensively enough >(read: mass produced and low operations cost) then that might be the "best" >design. Sure, if a Millenium Falcon with anti-grav drive could be built, it would be swell. I stand by my opinion that the most efficient design must exist in three different environments and what you need for one is dead weight in the others. > Case in point, Pacific-American Launch Co's "Phoenix" design. This is >a ballistic, single-stage-to-orbit, vertical-take-off/vertical-landing >vehicle. (Utilizing LH2/LO2 fuel and aerospike engine. It's been mentioned >around here before, I think). > This requires refueling in LEO, but one version of the Phoenix is configured >as a 'tanker' to do the job. Once refueled, the vehicle has sufficient >delta-Vee to leave LEO for the Moon, soft land on the Moon, and return to >Earth. Since it's a ballistic VTOVL, landing on the moon presents no >special difficulties, and it can land with sufficient fuel to take off again. Of course this "tanker" has shown that the Phoenix is not designed for the task. That is, it is not a single solution. Those "tankers" would be modified enough in my mind to classify as another class of vehicle. > The catch is the orbital refueling, which could take as many as 10 tanker >launches. However, the Phoenix is designed to be *highly* reusable with >low operations costs and rapid turnaround. 10 Launches!!! Surely you admit that is not efficient! Bob Campbell Some times I wish that I could stop you from campbelr@hpda.hp.com talking, when I hear the silly things you say. Hewlett Packard - Elvis Costello
zeke@fornax.UUCP (Zeke Hoskin) (01/21/89)
(everything about Phoenix and shuttles deleted, but Alastair's signature retained for esthetic reasons) > -- > "The problem is not that spaceflight is expensive, | Alastair J.W. Mayer > therefore only the government can do it, but that | alastair@geovision.UUCP > only the government is doing spaceflight, therefore | al@BIX > it is expensive." | A Lunar round trip has to :take off from Earth, achieve Lunar injection, slow down enough to land on the moon, take off from the moon, achieve Terran insertion, slow down enough to land here, and land. It makes good sense to use some kind of LEO system to tank up/assemble before step 2, and likewise a low-lunar-orbit system between lunar takeoff and T.I. However, an object approaching Earth from Lunar orbit is coming fast. The options are: burn up the same amount of delta-vee needed for Lunar insertion from LEO in order to re-enter LEO, match with Earth lander, and land; or use Earth's atmosphere to aerobrake and land. (All right, you could also aerobrake in a shallow graze of atmosphere, trying to slow down enough to enter LEO with a minor correction, but this requires you to carry pretty much everything you'd need for direct landing, so why bother?) It would be easier to tank up a Shuttle in LEO and fly it to LLO and back to an aerobraked landing, than to send something else to the Moon and have it rendezvous with the Shuttle on the way home. Not _possible_, I'm not claiming that, just _easier_. We start out with a project to build/modify an orbiter to do LEO refueling and, say, make it out as far as Clarke orbit... (NB: refueling the hypergolic OMS motors would be safer and easier than trying to restart the LH2/LOX main ones.) -- What makes one step a giant leap|Zeke Hoskin/SFU VLSI group,Burnaby,BC,Canada Is all the steps before | ...!ubc-cs!sfu_fornax!zeke
childers@avsd.UUCP (Richard Childers) (01/26/89)
In article <14549@oberon.USC.EDU> weiss%neuro.usc.edu@oberon.usc.edu writes: >Can the shuttle fly to the moon, land, and take off again to return >to the earth. Keep in mind the moon has 1/6 the gravitational pull >of the earth. Let's assume for the moment that there is adequate >solid flat landing surface prepared on the moon for the landing. No, I don't think it has room for all the fuel it would need to manuever, accelerate, deccelerate, land, take off, maneuver, accelerate, deccelerate, and touchdown. But I don't see why, given that all of the control surfaces are superfluous in vaccuum, one couldn't weld on massive, perhaps detachable, fuel tanks, as well as lifters for controlling descent and ascent, and make the trip in a shuttle, using it for its spacetight properties alone ... >For an Earth-Moon shuttle I think a totally different concept is needed. Eventually, yes, but in an emergency physics reigns supreme ... -- richard -- * Bismillah hir-Rahman nir-Rahim * * * * ..{amdahl|decwrl|octopus|pyramid|ucbvax}!avsd.UUCP!childers@tycho * * AMPEX Corporation - Audio-Visual Systems Division, R & D *