I would imagine the best reason to build a moonbase is that eventually, the goal is to build a base on Mars, for extensive exploration and research on the Martian surface. If we send men to Mars ( which is the plan), they’re going to stay a while (you don’t travel for 6 months to stay for a weekend). The moon program will help prepare NASA to live on Mars…try the moonbase thing to see if we can do it, before we think about sending it to Mars. That’s one of the biggest reasons to build a moonbase.
I’m not sure about the mass and volume limits of the Shuttle, but it seems like you might be able to get the Shuttle to a very high orbit with a lunar lander in the cargo bay, and then send spare fuel/oxidizer tanks up on separate rockets (like maybe the Energia). Continue attaching them to the outside of the shuttle until you’ve got enough fuel to do a lunar burn and a return burn.
I know the SSMEs are very efficient, although the nozzle bells are shaped for high atmospheric efficiency… maybe you also send up some carbon-fiber exit cone extension kits? Anyway, using the SSMEs makes a lot more sense to me than bringing another less-efficient engine up and having to bring all of its plumbing along with you.
So you get to lunar orbit, shove the lander out the pod-bay doors, do your landing mission quickly, and then fire the built-in hydrazine rocket to get off the surface and back to orbit. Dock with the shuttle, ditch the empty fuel tanks over the Pacific, and then reenter with standard Shuttle hardware.
It would be an ugly and horribly inefficient mission but it trims a bunch of requirements off of your lander design, and makes maximum use of existing hardware. You might need to get several space-faring nations to each use their best booster to put a fuel tank up (e.g. China use a CZ-3B, Russia use an Energia, France use an Ariane) so you could do parallel launch ops and reduce the number of days the crew would have to spend on earth orbit using up their food and water.
And I haven’t done the math on how much fuel it would take to give the Shuttle the required delta-V to reach lunar orbit. It might be an impractically large amount.
Sure, there is:
From merriam-webster.com:
Main Entry: 1dark
Pronunciation: \ˈdärk\
Function: adjective
Etymology: Middle English derk, from Old English deorc; akin to Old High German tarchannen to hide
Date: before 12th century
1 a: devoid or partially devoid of light : not receiving, reflecting, transmitting, or radiating light <a dark room> b: transmitting only a portion of light <dark glasses>
2 a: wholly or partially black <dark clothing> bof a color : of low or very low lightness c: being less light in color than other substances of the same kind <dark rum>
3 a: arising from or showing evil traits or desires : evil <the dark powers that lead to war> b: dismal, gloomy <had a dark view of the future> c: lacking knowledge or culture : unenlightened <a dark period in history> d: relating to grim or depressing circumstances <dark humor>
4 a: not clear to the understanding b: not known or explored because of remoteness <the darkest reaches of the continent>
5: not fair in complexion : swarthy
6: secret <kept his plans dark>
7: possessing depth and richness <a dark voice>
8: closed to the public <the theater is dark in the summer>
Not anymore, at least since 1969 .
:smack:
NASA has performed several studies on this from back in the STS late proposal/early conceptual design days through the ‘Nineties. Feasibility of Cislunar Flights Using the Shuttle Orbiter (warning: PDF) is the latest study I know of. As outlined here and in other places there are a number of problems with the proposal:[ul]
[li]The Orbiter propulsion system is not designed for this mission: Although the Space Shuttle Main Engines (SSME) are restartable on a test stand, they were never designed to be cold-restartable in vacuum, and the Orbiter’s fuel system isn’t configured for in-space refueling. (I don’t have Jenkins’ pace Shuttle: The History of the National Space Transportation System The First 100 Missions–an excellent resource on all things pertaining to STS design and operation–at hand at the moment, but I believe that the SSMEs are fed through pyrovalves that are then actuated after SSME cutoff and External Tank jettison, permanently closing off the fuel system until the Orbiter is refurbished for the next mission.) There is also the difficulty of achieving an in-flight refueling, which would require attaching external tankage to the Orbiter in-situ; this would be a challenge even with a purpose designed system and probably impossible using the existing mounting hardpoints and hardware. So this would require extensive redesign of extant systems.[/li][li]Flight duration capability of the Shuttle is marginal: The original Orbiters were designed with a nominal 7 day on-orbit mission capability with a maximum of 10 days. The Extended Duration Orbiter configuration, applied at various times to Endeavor, Atlantis, and Columbia, gives a nominal mission maximum of 16 days on-orbit with an extreme of 18-19 days mission capability. A cislunar mission for the Shuttle would involve ascent to orbit, Earth Orbit Rendezvous with fuel tankage and check out (assume 2 days) and cislunar transit (4-5 days one way to a parking orbit). That gives 10-12 days in mission time just coming and going, giving a nominal 4 days on station, and 6-7 on the outside. (This doesn’t include any on-orbit maneuvering that would need to be done to do a Lunar polar mission.) So even with the EDO config the Orbiter would be marginal for a mission of significant duration.[/li][li]Payload capacity: The Orbiter Main Cargo Bay was optimally designed to carry surveillance satellites. (Seriously; this was a main driver and a prerequisite for guaranteed funding to support the Air Force Blue Shuttle program, capable of being launched from Vandenberg AFB in a once-around polar orbit profile.) It cannot fit an Apollo LM (which would stick up several feet through the bay doors) and although I’ve only seen conceptual sketches and artist’s rendering of the Constellation LEM it definitely couldn’t carry that, either. You would have to design a purpose built LEM to fit within the relatively narrow confines of the SMCB, which could probably be done (it might look something like the Eagles from Space: 1999) but would likely not be optimal. Remember that the Orbiter would have to bring along a lot of parasitic mass in the form of wings, structure, et cetera, which a purpose-built cislunar transport would not, and all of that dead mass eats away at your payload budget. So far from reducing requirements on the lander design, it actually creates a lot of design constraints and drivers that may limit what you can do with the envelope.[/li][li]Thermal protection and re-entry systems: The Orbiter is designed to perform re-entry from LEO velocities, entering the Earth’s atmosphere in a shallow glide with a speed of around 27,000 kph. A direct cislunar return would put the shuttle by about half again as much speed, and at much to steep of an angle to avoid skipping right off the atmosphere; you’d either have to enter an extended elliptical orbit and slowly kill speed at multiple apogee passes so as to enter in at an acceptable speed and angle of attack. The only other option is to bring along enough fuel to bring the re-entry speed down on a direct return, which again eats away at your payload (in fact, given all the dead mass you are having to decelerate, it probably eliminates your payload entirely). The Orbiter thermal protection systems (the carbon-carbon leading edges, insulating tiles, and thermal blankets) do not have high margins, nor does the substructure have large thermal structural margins, so getting more performance out of it by modification is probably not an option. In comparison, the blunt-arsed Apollo capsule with its simple spherical heat shield had very high margin and demonstrated great robustness even in an out-of-design scenario such as happened with the Apollo XIII re-entry. (I think Gemini VIII had an aggressive re-entry profile as well owing to their emergency on-orbit abort, which it survived handily.)[/ul][/li]
So trying to adapt the Shuttle Orbiter for cislunar missions is probably far more costly and less desirable than building a purpose-designed system, IMHO, the problems with the current effort.
Stranger