Hypothetical Lunar Mission Profiles - How might we return to the moon?

Michael Bloxham · 2004-02-06 02:29:45

With talk of manned moon missions by the European, Chinese, and American space programs, I thought it might be appropriate to start a new topic where Lunar (either past, present, or proposed) mission profiles can be discussed.

Here are some questions to be considered:

-Will we need an HLLV?
-Should Lunar hardware be compatible with future Mars hardware?
-Should we use in-situ techniques on the moon (i.e. manufacturing hydrogen and oxygen on the surface from ice deposits)?
-How much infrastructure might we need initially, and will long stays on the surface be an integrale part of the design?
-Will the mission require in-orbit assembly?
-Will the ISS play a role?
-How many craft might there be?
-How many launches will be required to complete the mission? One launch, a la Apollo, or multiple launches? (Seperate launches for CEV, surface hab, and a return vehicle, for example.)

This thread is intended for hypothetical discussion; all ideas, of yours and of others, may be posted here. As well as design studies of the past, and of course, lessons learned from Apollo.

Gennaro · 2004-02-06 03:50:16

Two cents, here we go.

I think the mission architecture must be designed based on what we intend to do with the moon.
I'm one of those who think a moon mission is unnecessary and just a detour as a 'stepping stone' for Mars, although Mars Direct derived equipment could be partially modified for the lunar challenge, of course.

I see two uses for the moon. One is pure astronomy as the position for the 'Lunar Observatory', particularly in regard to locating small extrasolar planets. The other is potential (allright, very speculative notion no one needs to take seriously) mineral extraction, especially in regard to hypothetical mafic-ultramafic complexes born out of impact events and the KREEP terrane. Research related to the history of the moon, Earth and solar system is almost a parallell geological activity.

On-orbit assembly and/or ISS, no! The moon is just three days away, here if anywhere should be used a direct approach.

RobS · 2004-02-06 14:33:19

Regarding ISS, its orbit is inclined to the equator too much to be used as an orbital assembly point. You can't launch to the moon from ISS at all. That was originally something the US space station Freedom was supposed to be able to provide, but it was in a 28 degree orbit, from which one can launch to the moon (just like Kennedy Space Center).

Baikonur's high latitude, by the way, is one factor that caused the Russians to lose the moon race. Launches to the moon from there require a plane change. Maybe there are one or two launch opportunities per year that don't, but I'm not even sure of that. The moon never is overhead at that latitude.

How to get to the moon: If we use chemical propulsion the whole way, we will either need something almost as big as a Saturn V or we will need a series of smaller launches (I think we'd need five or six Delta IV heavies to launch as much to low Earth orbit as a Saturn V). This does not strike me as practical, not only because of the need for orbital assembly, but the fact that an explosion on a launch pad will screw up the entire assembly schedule and make you look like a fool (unless one is using 2 or more boosters from Kennedy and Kourou, so that backup is possible; then you have administrative logistics, though).

This means one either creates a heavy lifter from the shuttle system or one uses another propulsion system once in orbit. I favor the latter approach because it uses existing launch vehicles and improves their efficiency, rather than keeping them and adding a new, larger launch vehicle to them. There are several alternative propulsion systems to consider:

1. Nuclear thermal. Twice as efficient as chemical. Disadvantages: uses liquid hydrogen, which is very bulky (big, heavy tanks). Probably fatal disadvantage: Politically difficult to implement. Will need very large, expensive facilities on the Earth surface to develop to the point where it can be launched (because you can't fire such engines in the open atmosphere any more, like you did in the 1960s). Would allow you to send about half your low earth orbit payload on a trajectory to the moon or Mars (stopping at the other end not included!).

2. Solar thermal; sunlight focused on a graphite block heats hydrogen almost as hot as nuclear thermal. No political downside, already being developed. Disadvantage: Thrust is a few pounds only, not thousands of pounds, so one must use a series of perigee kicks over a few months to lift anything out of Earth's gravity well. Can launch about 80% as much as nucler thermal and 60% or so more than chemical.

3. Solar ion: Already widely used on communications satellites and on two deep space probes, but needs to be scaled up in size about fifty to one hundred times. Eight to ten times more efficient than chemical propulsion, but requires a large engine. Allows one to push about two thirds of a low earth orbital payload to the moon or Mars, but over a six-month period.

4. Nuclear ion: Project Prometheus is developing this, but the nuclear reactor seems to be too small to send payload from Earth orbit (though it would be plenty to push a one-tonne vehicle around in Jupiter space over many months of time.) The ion engine being developed, however, could be scaled up for #3.

In my opinion, nuclear thermal is politically dead and solar ion is most developed, and therefore is the likely route to take. It will also be useful for pushing commercial payloads to geosynchronous orbit, so it has a commercial application. As I've said in various other postings, one Delta-IV heavy could launch a solar-ion tug and enough xenon propellant to push about two payloads (25.7 tonnes each) to the lagrange point between the Earth and the moon, a good spot to assemble vehicles for flights to the lunar surface or Mars. Subsequent launches would reuse the tug, which could push about 3/4 of each payload to the lagrange point.

Why go to the moon: The big arguments for Mars involve water at the lunar poles and experience for the Martian surface. If one is using a heavy lifter to send everything to Mars, a lunar detour does not strike me as essential, though it is helpful. If we're using chemical propulsion for 3.2 km/sec to escape the Earth and get to Lagrange, why not use it for the remaining 1.3 km/sec to go to Mars? Of course, that extra delta-v decreases payload quite a bit. Lagrange as a refueling stop makes the most sense if we are using small vehicles to get stuff to orbit and ion tugs to get the payloads to Lagrange, because ion makes the remaining trip to Mars rather slow and a chemical kick from Lagrange is a good tradeoff of mass for time, especially if the mass comes from the moon.

As for testing things on the lunar surface, I won't touch that issue here! There are a lot of space experts who say it makes sense. There are some who downplay it or say it is not necessary at all. And on this list there is a variety of opinions. I am not sure if any of us on this list is sufficiently informed to make good arguments.

The main reason to go to the moon first, in my opinion, is that it ends the war between the moon lobby and the Mars lobby and unites them behind one plan. Politicially, that's important.

-- RobS

Bill White · 2004-02-06 15:11:27

This means one either creates a heavy lifter from the shuttle system or one uses another propulsion system once in orbit. I favor the latter approach because it uses existing launch vehicles and improves their efficiency, rather than keeping them and adding a new, larger launch vehicle to them.

What about doing both simultaneously? Then you could send large structures to the moon.

RobertDyck · 2004-02-06 16:45:08

Regarding ISS, its orbit is inclined to the equator too much to be used as an orbital assembly point. You can't launch to the moon from ISS at all. That was originally something the US space station Freedom was supposed to be able to provide, but it was in a 28 degree orbit, from which one can launch to the moon (just like Kennedy Space Center).
Baikonur's high latitude, by the way, is one factor that caused the Russians to lose the moon race. Launches to the moon from there require a plane change. Maybe there are one or two launch opportunities per year that don't, but I'm not even sure of that. The moon never is overhead at that latitude.

You can launch to the Moon from any inclination. The higher the inclination the shorter the launch window, so a lower inclination is more convenient. With a high inclination you have to wait until the plane of the orbit intersects your trajectory to the Moon. With an orbital inclination that matches the Moon's orbit, a trans-lunar trajectory is always in that plane. With a polar orbit, the plane sweeps across the Moon rather quickly. The closer the match, the more time the Moon is within the plane of your starting orbit.

ISS has an inclination that matches Svobodniy, not Baikonur. Svobodniy (also known as Mirniy) has latitude 51.6? (the fraction depends which launch pad you measure), while Baikonur is 46.1? north.

In fact, the Russians in charge of Angara are talking about looping communication satellites around the Moon to use the Moon's gravity to change orbital inclination. That would enable them to launch from Plesetsk at 62.9? without the extreme fuel cost of inclination change to equitorial for a geostationary orbit. It's only lower fuel cost because insertion directly into trans-lunar trajectory without entering Earth orbit at all is less than insertion into geosynchronous transfer orbit, and capture into GEO is not much more than circularization from GTO to GEO. Of course launching from the equator and using ion engines to circularize the orbit is much cheaper, but it demostrates that you can get to the Moon from anywhere.

Bill White · 2004-02-06 17:25:36

Regarding ISS, its orbit is inclined to the equator too much to be used as an orbital assembly point. You can't launch to the moon from ISS at all. That was originally something the US space station Freedom was supposed to be able to provide, but it was in a 28 degree orbit, from which one can launch to the moon (just like Kennedy Space Center).
Baikonur's high latitude, by the way, is one factor that caused the Russians to lose the moon race. Launches to the moon from there require a plane change. Maybe there are one or two launch opportunities per year that don't, but I'm not even sure of that. The moon never is overhead at that latitude.
You can launch to the Moon from any inclination. The higher the inclination the shorter the launch window, so a lower inclination is more convenient. With a high inclination you have to wait until the plane of the orbit intersects your trajectory to the Moon. With an orbital inclination that matches the Moon's orbit, a trans-lunar trajectory is always in that plane. With a polar orbit, the plane sweeps across the Moon rather quickly. The closer the match, the more time the Moon is within the plane of your starting orbit.
ISS has an inclination that matches Svobodniy, not Baikonur. Svobodniy (also known as Mirniy) has latitude 51.6? (the fraction depends which launch pad you measure), while Baikonur is 46.1? north.
In fact, the Russians in charge of Angara are talking about looping communication satellites around the Moon to use the Moon's gravity to change orbital inclination. That would enable them to launch from Plesetsk at 62.9? without the extreme fuel cost of inclination change to equitorial for a geostationary orbit. It's only lower fuel cost because insertion directly into trans-lunar trajectory without entering Earth orbit at all is less than insertion into geosynchronous transfer orbit, and capture into GEO is not much more than circularization from GTO to GEO. Of course launching from the equator and using ion engines to circularize the orbit is much cheaper, but it demostrates that you can get to the Moon from anywhere.

RobertDyck, RobS, or any other of the technically gifted, can you recommend some resources to self-teach these basics of orbital mechanics?

RobS · 2004-02-06 20:24:31

Thank you for the correction, Robert. Let me see whether I understand the point. If a vehicle is in a polar orbit and the moon were orbiting exactly "over" the equator, one could fire the engine of the vehicle when it is flying over the pole, when its trajectory is parallel to the plane of the moon's orbit, and head for the moon.

I have not studied orbital mechanics in school and am self-taught from various sources. I don't know very much. But the other day I came across this university paper and it seems to explain a lot, plus give equations that people with more mathematical facility than I could use quite usefully:

[http://www.stanford.edu/~klynn/mars_paper.htm]http://www.stanford.edu/~klynn/mars_paper.htm

-- RobS

Ad Astra · 2004-02-06 22:14:41

I think everyone on this forum wants to see an HLLV, and practically that is the best way to get a spacecraft to the moon (after all, that's how we did it the first time.)

Now the question is one of Lunar Orbit Rendezvous, Earth Orbit Rendezvous, or "Moon Direct." Personally, I prefer a reusable nuclear-thermal "shuttle" that would dock with the CEV-lander in earth orbit, take it to the moon, and separate. When it's time to return, the two craft will dock again for the trip to earth.

Nuclear thermal might be politically doomed, but it remains the fastest way of getting humans to the moon. A solar-powered ion tug would spend too much time in the Van Allen belts and cook the crew. An NTR, on the other hand, could sprint to the moon, possibly within 24 hours after launch. See [http://www.marsinstitute.info/rd/facult … t23-3.html]this Stanley Borowski study from 1997 and decide for yourself.

Bill White · 2004-02-06 23:08:21

Nuclear thermal might be politically doomed, but it remains the fastest way of getting humans to the moon. A solar-powered ion tug would spend too much time in the Van Allen belts and cook the crew. An NTR, on the other hand, could sprint to the moon, possibly within 24 hours after launch. See [http://www.marsinstitute.info/rd/facult … t23-3.html]this Stanley Borowski study from 1997 and decide for yourself.

This [http://www.marsinstitute.info/rd/facult … /at26.html]link to an NTR mission to Mars is also marvelous. Isn't NTR really pretty simple to deploy once you have a space rated reactor?

Concerning political feasibility, my instincts are to attempt to lobby key Democrat candidates (including folks like Senator Nelson of Florida and the candidate for the open Senate seat in Louisiana). Explain how NTR is safe and how NTR plus shuttle derived allows NASA to start doing big things NOW not in 10 or 15 years and how shuttle derived keeps voters employed in Florida and Louisiana.

And stress how a more aggressive space policy than that announced in January can "steal" the issue from Bush. Just as the space shuttle needs to make a planned roll a few seconds after lift off, after the Democratic convention, the nominee will need to make a planned roll to the "Right" just as Bush has already thrown bones to the "Left" with immigration and drug benefits.

$16-17 billion per year is chump change in the federal budget. Persuade a Democrat he can get massive "moving right" PR for a pro-space policy and it makes good political strategy for a Democrat to advocate an ambitious NASA-ESA-Russian program to put folks on the moon before the 2015 date announced by President Bush.

This could be difficult to do, but if we don't, we end up with the "same-old same-old" tired debate where Republicans are pro-space and Democrats are anti-space. If President Bush ends up with the only pro-space platform heading into November space advocates will lose no matter who wins.

Since the country politically split 50-50 (more or less) and will be split 50-50 for the foreseeable future, if space vision is seen as a "Bush thing" or a "Republican thing" we will be in big trouble in years to come.

= = =

If the Senate race in Louisiana (an open seat) appears close, a plan that keeps Michoud open would be attractive to both political parties.

= = =

If the Mars Society has any K Street connections (lobbyists) and/or money to pay them, to focus on the Democrats maybe more useful since the final Bush plan will likely be decided behind closed door by bigger players than we can touch.

(Who else has read Keith Cowing's scornful dismissal of Zubrin's influence?)

If the Democrats adopt a more aggressive space policy, its a win-win election for space advocates.

RobS · 2004-02-07 09:40:26

One problem with nuclear thermal that may have a solution: no experts I've heard of have felt you could aerobrake the engine. That means you have to use it both up and back to Earth, which decreases its effectiveness somewhat.

The other problem is that no one will test an NTR in the open atmosphere and the only facility in the US currently existing could only test a 10,000 pound thrust engine. Otherwise you have to spend a few billion to build a larger facility. I think this is mentioned by Zubrin in Mars Direct.

Solar-ion can only be used for cargo, obviously, but that's most of your mass. The humans in their capsule will go up using chemical propulsion. Cargo can be made to handle the van Allen belts.

Ad Astra · 2004-02-07 11:42:06

The small size of the proposed NTR test facility shouldn't be a show-stopper. You'd want to use several small NTR engines in a cluster rather than building one giant one. You can also increase the thrust through a LOX-afterburner.

I don't think that aerobraking the NTR is impossible, but do you really want to subject a nuclear reactor to extreme heating and aerodynamic stresses? The solution is to use propulsive capture when returning to earth, then refuel the NTR with hydrogen and LOX from a reusable shuttlecraft.

Mad Grad Student · 2004-02-07 15:05:46

Obviously, the ideal way to get to the Moon would be through a space elevator. The kinds of space elevators that everyone talks about are the ones that merely reach GEO for quick, cheap acces to Earth orbit, but an overlooked detail is that if you make the elevator a little bit longer it's tip velocity exceeds Earth's escape velocity. This would be an extremely cheap, not to mention propellantless, way to launch payloads both to the moon and to Mars, but has the problem that it revolves around technology not-yet-developed. It could be quite a while before we can do this.

I don't think that an HLLV is the answer to a new Moon vehicle. All that would do is get more payload to the Moon, but at a huge propellent usage cost. Rather, we should look into more efficent ways to get off the ground than conventional chemical rockets. My proposal somewhere else here was to build a chemical rocket with an exhaust speed of orbital velocity, which would reduce fuel needs by a fifth or more, and could concievably be done soon enough.

Assuming we have a launch vehicle like this, it would be relatively simple to launch 100,000 lb. payloads into Earth orbit for a cheap price. Once there unmanned cargo trips should use solar-ion engines, because they're really in no rush to get there. However, a better solution would be to just build infrastructure on the moon and not need cargo runs. Manned vehicles would carry a second stage, enabling them to carry 50,000 lb. payloads to the Moon in three days.

My idea for a vehicle for getting there would be something like a "Moon shuttle" If you take the lunar module and reshape it to be a 40-foot long cylinder with a tail and canards, this would be its configuration. It would be capible of carrying small payloads to its landing zones, thereupon starting a Moon base. Once the inital base is in place, infrastructure for water drilling, a chemical plant, and metallurgy would be implaced as well. Pretty soon you have the beginings of a Moon city, with Moon shuttles ferrying in up to 15 people at a time. Upon re-entering the atmosphere they would deploy a parachute like those used in para-gliding (Scaled up, of course) and land like airplanes.

Any thoughts?

Ad Astra · 2004-02-24 11:44:09

There are a lot of people (most notably the aerospace blogger Rand Simberg) who think multiple EELV launches are the answer. The line of reasoning is that even something like Shuttle-C will cost too much to develop, and it won't fly often enough to justify its operating costs. However, multiple launches of existing EELV's will bring down their costs. My feeling is that this vehicle could fly just as routinely as the EELVs if we committed to a sustained lunar base. It might also occur where the flight rate of the EELV can't keep pace with that's necessary for our exploration schedule (as was the case with ther shuttle and ISS.) If we're aiming for flags and footprints, an EELV is fine. But resupplying bases on the moon and Mars demands that we have much bigger rockets.

infocat13 · 2004-02-24 19:28:57

If the nasa admin folks intend on using exsisting atlas or delta V then on orbit assembly will be required but wait? the Zubrin idea of keeping cargo seperate from crew transport could be used for luner missions.I.E preposition cargo landers, space station conponents in L-1 or whatever the final plan ends up being.

the CEV would use atlas or delta V to get crew to the moon/L-1 .

the landers,L-1 space station/moon orbiting station would be launched by shuttle-C or yet more atlas and delta V.
mars will require more then this,nuclear and shuttle-Z ect.

on orbit assembly from ISS is a long term bad idea we could use ISS at first but if you must have human back up to on orbit assembly of the atlas or delta V then an human tended equtorial station would be a better idea.like the eelv the station parts have all ready had there developement costs paid for.ISS station parts could used as lunar orbiters/L-1/lunar ground station housing. with the exception of the cev all of these things could be transported with shuttle-c and a ion tug.ION tug could also manuver the HST to an orbit above the ISS.

quasar777 · 2004-03-09 14:17:49

i think the next time a space vehicle is in need of deleting, like the russian MIR station. instead of letting it burnup in earth`s atmosphere, send it to the Moon. & especially we should if such an artifact has a camera. this would be a cheap hard-landed lunarprobe.

Lars_J · 2004-03-09 15:49:13

The kinds of space elevators that everyone talks about are the ones that merely reach GEO for quick, cheap acces to Earth orbit, but an overlooked detail is that if you make the elevator a little bit longer it's tip velocity exceeds Earth's escape velocity.

It's not an overlooked detail - its a basic feature of a space elevator. It must have equal mass above and below GEO, otherwise it will "fall down". (And everyone around the equator will have a really bad day)

Ad Astra · 2004-03-15 14:39:19

[http://www.thespacereview.com/article/115/1]Return to the moon for under $30 billion

The plan has a lot of similarities with "Mars Direct" and "Moon Direct." The biggest drawback is the requirement for a new booster. IF the shuttle stack can be modified to throw 57 tonnes to the moon, it might save a substantial amount of money. Still, $30 billion for a moon mission and $50 billion for "Mars Semi Direct" is a small cost to pay for opening a new frontier.

Yang Liwei Rocket · 2004-03-15 17:39:58

I've seen some news before about the Chinese and European asking for the ISS to help build and construct a bio-dome in outerspace, but the Chinese aren't doing anything now but I think Europes Italy space agency is doing something. The idea was in this project the large bio-sphere would be construct in space and planeted with green and organism and water moved up from Earth. ESA people were thinking of using their newer Ion Engines, like the one in ESA Smart Launcher to transport this bio dome to the moon, lunar transport of materials is a good future and lets hope in the future they can put a base there on the moon for good.

bolbuyk · 2004-04-07 05:00:07

I think the return to the moon should be done as a general repetition of a journey to Mars, that means, a Mars-excursion-like module should be used with the same length of stay on the lunar surface. When this is done on the back of the Moon, psychological effects of isolation can be simulated. So, also a HLLV should be used, which is, to my opinion, necessary for an mission to Mars.

New Mars Forums

Announcement

#1 2004-02-06 02:29:45

Re: Hypothetical Lunar Mission Profiles - How might we return to the moon?

#2 2004-02-06 03:50:16

Re: Hypothetical Lunar Mission Profiles - How might we return to the moon?

#3 2004-02-06 14:33:19

Re: Hypothetical Lunar Mission Profiles - How might we return to the moon?

#4 2004-02-06 15:11:27

Re: Hypothetical Lunar Mission Profiles - How might we return to the moon?

#5 2004-02-06 16:45:08

Re: Hypothetical Lunar Mission Profiles - How might we return to the moon?

#6 2004-02-06 17:25:36

Re: Hypothetical Lunar Mission Profiles - How might we return to the moon?

#7 2004-02-06 20:24:31

Re: Hypothetical Lunar Mission Profiles - How might we return to the moon?

#8 2004-02-06 22:14:41

Re: Hypothetical Lunar Mission Profiles - How might we return to the moon?

#9 2004-02-06 23:08:21

Re: Hypothetical Lunar Mission Profiles - How might we return to the moon?

#10 2004-02-07 09:40:26

Re: Hypothetical Lunar Mission Profiles - How might we return to the moon?

#11 2004-02-07 11:42:06

Re: Hypothetical Lunar Mission Profiles - How might we return to the moon?

#12 2004-02-07 15:05:46

Re: Hypothetical Lunar Mission Profiles - How might we return to the moon?

#13 2004-02-24 11:44:09

Re: Hypothetical Lunar Mission Profiles - How might we return to the moon?

#14 2004-02-24 19:28:57

Re: Hypothetical Lunar Mission Profiles - How might we return to the moon?

#15 2004-03-09 14:17:49

Re: Hypothetical Lunar Mission Profiles - How might we return to the moon?

#16 2004-03-09 15:49:13

Re: Hypothetical Lunar Mission Profiles - How might we return to the moon?

#17 2004-03-15 14:39:19

Re: Hypothetical Lunar Mission Profiles - How might we return to the moon?

#18 2004-03-15 17:39:58

Re: Hypothetical Lunar Mission Profiles - How might we return to the moon?

#19 2004-04-07 05:00:07

Re: Hypothetical Lunar Mission Profiles - How might we return to the moon?

Board footer