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#26 2006-05-31 09:49:46

cIclops
Member
Registered: 2005-06-16
Posts: 3,230

Re: Reusable LSAM

I think that (with or without the resuable-LSAM) an LLO module is ABSOLUTELY necessary to save the astronauts life if something goes wrong (and they must wait months for a rescue).

Yes LOR is one of the main risks of the RTTM architecture, and that is why returning direct from the moon eliminates that risk completely.

if the engines don't work the only way to save the astronauts' life is a little emergency module in LLO since they can't use the extra life support sent on the moon and the LSAM ascent module is in its last hours of life...

.

If the engine doesn't work the LSAM can't reach LLO.


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#27 2006-05-31 09:58:44

RedStreak
Member
From: Illinois
Registered: 2006-05-12
Posts: 541

Re: Reusable LSAM

Therefore it appears quite feasible to send a 12mt single stage LSAM with a LOX/CH4 engine and 32mt of fuel to the moon and return it to LEO using aerobraking. The predicted extra capacity of the CaLV is not even required! The LSAM performs the needed plane change during aerobraking to dock with the ISS in its 52° orbit.

The CEV would only be required to deliver crew to the EDS/LSAM in LEO (it should have sufficient fuel in its SM to change plane to the ISS to await use)

Advantages:
o Reduced risk through simplified architecture (no LOR, single stage single engine LSAM)
o Reduced LOC risk due to slower reentry from LEO
o CEV left in LEO (where it belongs)
o LSAM returned to LEO for inspection
o potential LSAM reuse
o Crew quarantine and checkout in LEO
o ISS utilization (it's about time)

So it is possible to create a single-stage LSAM that does the whole mission using the full CaCLV ...astounding to hear.  I hate to minimize use of theCEV (and I fear NASA will complicate this as well, wanting an 'emergency exit vehicle') but the CLV is more or less a LEO-only launcher so it could be an 'American Soyuz' if nothing else.  Still this sounds like it could work.

ISS utilization is a nice feature, but I'd hate to use it at all myself - still it would get some use as a port; although I would find it ironic if the researches would start whining about the dockings disturbing their experiments...which is yet another reason why the space station never became a vital link in space exploration it was toted to be in the Regan era.  roll

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#28 2006-05-31 10:05:20

gaetanomarano
Member
From: Italy
Registered: 2006-05-06
Posts: 701

Re: Reusable LSAM

...If the engine doesn't work the LSAM can't reach LLO...

...the engines of the LSAM (in your architecture) or the CEV (in ESAS architecture) to come back to earth...

.

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#29 2006-05-31 10:06:56

RedStreak
Member
From: Illinois
Registered: 2006-05-12
Posts: 541

Re: Reusable LSAM

if the engines don't work the only way to save the astronauts' life is a little emergency module in LLO since they can't use the extra life support sent on the moon and the LSAM ascent module is in its last hours of life....

If the LSAM is aerobraking capable (which cIclops suggests is indeed possible at minimal mass cost for a SS LSAM)  then the astronauts would do what Zubrin suggested in his Mars Direct stradegy in case of a failure to escape Cislunar space: the capsule makes a series of braking orbits that brings the astrnauts down to LEO.

This makes me wonder though...for another LSAM option could a CEV capsule be attached to serve not so much as an ascent stage but the crew habitat itself?  The advantage is this would give the crew a direct escape route to Earth; the disadvantage is how would it fit into a resuseable SS LSAM architecture?  Can a CEV capsule be secured to a LSAM while in orbit?

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#30 2006-05-31 10:13:06

gaetanomarano
Member
From: Italy
Registered: 2006-05-06
Posts: 701

Re: Reusable LSAM

...aerobraking...

can we put the astronauts' life in an aerobraking technique hands without 10+ years of unmanned tests?

and, if we start the tests now, can we wait 10+ years to start the design of the new vehicles?

I think the right way is to use the old (well known and already tested with humans...) techniques and use the aerobraking only in future

.

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#31 2006-05-31 10:26:22

RedStreak
Member
From: Illinois
Registered: 2006-05-12
Posts: 541

Re: Reusable LSAM

...aerobraking...

can we put the astronauts' life in an aerobraking technique hands without 10+ years of unmanned tests?

and, if we start the tests now, can we wait 10+ years to start the design of the new vehicles?
.

The space shuttle itself was pretty much an aerobraking vehicle.  It also was a working testbed - the temperatures its design put on its tiles is easily as great if not greater than any experienced by an incoming aerobrake craft.

Its more a matter of geometry than actual materials required gaet, and in the vicinity of Earth with TDRES and all kinds of tracking satellites you won't get a better, safer place in the solar system (which can't be said for Mars if you want something to really complain about) for aerobraking.

Oh...and btw the first use of aerobraking was done by Magellean at Venus in the mid 90s...so there's your 10 years.

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#32 2006-05-31 10:44:29

cIclops
Member
Registered: 2005-06-16
Posts: 3,230

Re: Reusable LSAM

...If the engine doesn't work the LSAM can't reach LLO...

...the engines of the LSAM (in your architecture) or the CEV (in ESAS architecture) to come back to earth...

.

In the ESAS architecture all three engines have to work: the LSAM descent engine, the LSAM ascent engine and the CEV SM engine. In the single stage LSAM scenario the engine has to work to even land on the moon, so the risk of it not working for ascent is greatly reduced.


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#33 2006-05-31 10:53:01

cIclops
Member
Registered: 2005-06-16
Posts: 3,230

Re: Reusable LSAM

This makes me wonder though...for another LSAM option could a CEV capsule be attached to serve not so much as an ascent stage but the crew habitat itself?  The advantage is this would give the crew a direct escape route to Earth; the disadvantage is how would it fit into a resuseable SS LSAM architecture?  Can a CEV capsule be secured to a LSAM while in orbit?

The LSAM provides a crew environment for transfer between LLO and the lunar surface as well as a habitat while the crew is on the surface.  Not duplicating (in fact triplicating) that environment by having three crew environments (CEV, LSAM descent, LSAM ascent) saves mass and complexity and thus risk. The CEV primary function is to transfer crew between Earth and LEO. Just as it made little sense to carry wings and wheels to orbit, what sense does it make to carry a heavy reentry heatshield, airbags etc etc all the way to LLO and back?


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#34 2006-05-31 11:26:35

gaetanomarano
Member
From: Italy
Registered: 2006-05-06
Posts: 701

Re: Reusable LSAM

...what sense does it make to carry a heavy reentry heatshield, airbags etc etc all the way to LLO and back...

you're right

months ago on a space forum I've suggested to build a lunar-ferry that goes to the moon orbit and back to earth earth orbit with current (engines and fuel) bracking technologies

but now I think it's less efficient if compared with a fleet of reusable-LSAMs that wait in lunar orbit

if the "single vehicle that come to earth" is little, it don't needs so much fuel/big-tanks like a "single LSAM vehicle" because the CEV is only a capsule without the lunar-hardware, the landings' strut, pads, etc.

again... why send back to earth the full (single-vehicle or multi-vehicle) LSAM if it can simply wait in lunar orbit?

another advantage of the reusable architecture with a little ISS' like lunar-orbit module is that up to eight astronauts can (simply) live six months in lunar orbit and accomplish dozens moon missions

it don't need to the CEV and/or the LSAM to go to moon orbit and come back to earth orbit

from earth they will receive only the moon surface/orbital re-supply and new fuel/tanks for the LSAMs

when the missions ends, they come back with the CEV

.

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#35 2006-05-31 11:43:11

GCNRevenger
Member
From: Earth
Registered: 2003-10-14
Posts: 6,056

Re: Reusable LSAM

Now that I have time to read the thread...

Not according to Kraisee over on nasaspaceflight.com

Ha, please tell me you are kidding. You are quoting a random anonymous poster that goes by an odd spelling of "crazy" over offical published breifings from NASA? And how can the CaLV possibly get this sudden 50% increase in performance by using an engine with inferior performance? (RS-68 410sec Isp versus SSME 453sec) CaLV can't possibly carry more then ~120-130MT. The increase in propellant mass DOES NOT yeild a linear increase in payload mass.

As to the aerobraking shield, this would consist of the LSAM engine, landing structure and the solar panels fitted underneath to protect the tanks.

Nonsense, we're talking a vehicle that aerobrakes at Earth quickly, not a space probe that aerobrakes slowly at Mars. The only reason that Mars probes can get away with it is is becaues the Martian atmosphere is >100 times thinner, and there is no rush - probes take ~6mo to aerobrake. It simply won't work for manned vehicles returning to Earth.

Optional transfer to the ISS would be done by the CEV SM. I think the ISS will be there until at least 2017, probably much longer once a cheaper COTS is available.

The primary objective is not to save the LSAM but to reduce risk by simplifying the architecture by eliminating LOR and returning the vehicle intact for inspection. Reuse would be a bonus.

If COTS is ever available... and if the station can be bubble-gum/duct-tape for years to come, which I don't think it can.

Why is LOR so bad compared to EOR? Skipping the LOR event means having a second EOR when you return, plus requires highly accurate and window-sensitive Earth orbital insertion to mate with the CEV or ISS, or else the crew will die, they'll just die in LEO instead of on/around the Moon.

RobertDyck took up this idea, fronted by the T/Space fools, but I'll repeat one additional point about abort anyway: if something goes wrong in transit to or from, and you can't enter orbit around the Earth in such a fasion that you can dock, you are dead anyway. If your vehicle is disabled and you can't dock, then what good is it? Thats an awful risk, which the ESAS plan doesn't have.

Such a vehicle would need an escape pod with a pressurized cabin for the full crew for several days, a heavy duty heat shield, and attitude control. Hey, I know, how about the CEV capsule? Oh wait, NASA is doing that already!


"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw

The glass is at 50% of capacity

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#36 2006-05-31 11:55:14

GCNRevenger
Member
From: Earth
Registered: 2003-10-14
Posts: 6,056

Re: Reusable LSAM

...aerobraking...

can we put the astronauts' life in an aerobraking technique hands without 10+ years of unmanned tests?

and, if we start the tests now, can we wait 10+ years to start the design of the new vehicles?

I think the right way is to use the old (well known and already tested with humans...) techniques and use the aerobraking only in future

You are a dumb little man gaetano, you keep on mindlessly parroting the "oh but we don't KNOW" business, which is patently stupid.


"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw

The glass is at 50% of capacity

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#37 2006-05-31 12:00:04

GCNRevenger
Member
From: Earth
Registered: 2003-10-14
Posts: 6,056

Re: Reusable LSAM

Just as it made little sense to carry wings and wheels to orbit, what sense does it make to carry a heavy reentry heatshield, airbags etc etc all the way to LLO and back?

It makes perfect sense, because if something goes wrong, all you have to do is seperate the CEV from the LSAM and return to Earth directly.


"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw

The glass is at 50% of capacity

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#38 2006-05-31 12:11:53

GCNRevenger
Member
From: Earth
Registered: 2003-10-14
Posts: 6,056

Re: Reusable LSAM

To repeat my take on a reuseable LSAM and point out a few more problems:

-LSAM is not worth saving; it will cost more to return it to LEO/LLO, refurbish, and reload then saved by simply building a new one. Economies of scale will really help here.

-LSAM cannot be saved easily, the fuel required to launch off the surface after 6mo (loiter at a Lunar base) amounts to several extra tonnes over the acent module only, which cuts too deeply into the payload.

-LSAM cannot be fueled with Hydrogen, since it could not loiter 6mo without fuel boiloff. Since LSAM will also be used to enter Lunar orbit, using Methane will deeply cut into the payload here as well.

-LSAM will not be able to go anywhere on the Moon easily if it is stored in orbit, because plane change in Lunar orbit would expend too much fuel, return from the surface would be impossible.

-LSAM cannot reenter Earth's atmosphere, so it cannot ferry back and forth from LEO without the difficulty of precision orbital insertion at Earth and subsequent docking operation, which would not likly be possible if there were a serious failure. The crew would all die.


"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw

The glass is at 50% of capacity

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#39 2006-05-31 12:51:58

cIclops
Member
Registered: 2005-06-16
Posts: 3,230

Re: Reusable LSAM

And how can the CaLV possibly get this sudden 50% increase in performance by using an engine with inferior performance? (RS-68 410sec Isp versus SSME 453sec) CaLV can't possibly carry more then ~120-130MT. The increase in propellant mass DOES NOT yeild a linear increase in payload mass.

Because at sea level the SSME Isp is 363 with a thrust of 190t (109%), whereas the RS-68 produces 295t of thrust with an Isp of 365


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#40 2006-05-31 13:37:06

gaetanomarano
Member
From: Italy
Registered: 2006-05-06
Posts: 701

Re: Reusable LSAM

To repeat my take on a reuseable LSAM... to go anywhere...

the LSAM wil NEVER come back to earth orbit, but will be REUSABLE

I'm sure that NASA will change the LSAM because this is the only way to accomplish many moon missions with the VSE budget

the weight of the CEV/SM is around 23 mT, the weight of the expendable-LSAM is around 43 mT, then, 2/3 of the payload (and EDS fuel) at TLI come from the LSAM

with a reusable-LSAM both the CLV and the CaLV will be completely unnecessary

a rocket with 80 mT payload (with a different missions' architecture) will be sufficient

NASA can't "go everywere on the moon" with its funds

the CEV LOI will needs only a larger SM with more fuel (like the Apollo SM)

.

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#41 2006-05-31 14:44:57

GCNRevenger
Member
From: Earth
Registered: 2003-10-14
Posts: 6,056

Re: Reusable LSAM

And how can the CaLV possibly get this sudden 50% increase in performance by using an engine with inferior performance? (RS-68 410sec Isp versus SSME 453sec) CaLV can't possibly carry more then ~120-130MT. The increase in propellant mass DOES NOT yeild a linear increase in payload mass.

Because at sea level the SSME Isp is 363 with a thrust of 190t (109%), whereas the RS-68 produces 295t of thrust with an Isp of 365

The reason for the difference is that all Hydrogen engines suffer at high ambient air pressure, but this is not a big factor: the air pressure drops over very fast, and is close to zero after the first minute of the ~9min acent, after which SSME really pulls ahead with its higher chamber pressure and outpreforms RS-68 hands-down. Which is why RS-68 needs far more propellant to deliver the same payload.

Thrust is a terrible, terrible indicator of performance and should never ever be used to compare rockets. For a rocket to enter orbit, there are three things that it uses its engines to do:

  • -Accelerate the rocket to orbital velocity
    -Counteract gravity during acceleration
    -Push the rocket through the atmosphere

Of these, the first one accounts for >90% of the fuel required for the rocket, with the second one being several percent, and the last a distant third. The first item is completly unaffected by thrust, but is strongly influenced by the engines' fuel efficiency. The third is largely controlled by drag and not thrust, which leaves only the second.

And for the second item, its a matter of thrust-to-mass and not only absolute thrust, so the higher mass of the extra propellant will counteract the RS-68's higher thrust. Modern rockets already do item two pretty well, excepting Delta-IV Heavy, and there isn't alot of room for improvement. Even a rocket with infinite thrust won't have but 5-10% more performance I would estimate.


"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw

The glass is at 50% of capacity

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#42 2006-06-01 13:21:01

RedStreak
Member
From: Illinois
Registered: 2006-05-12
Posts: 541

Re: Reusable LSAM

Technical details aside, I think in the long rong NASA's choice of the RS-68 over the SSME solved more problems than it created.

A simple engine capable of burning for the 10 or so minutes of flight will be far better to use than the SSME designed for repetative use on an already complicated and overrated vehicle.  If its a desposable booster like the shuttle ET (new modification aside) then the engines should also be desposable, and focused on lasting long enough to get the job done - ensure maybe a small margin but nothing excessive.

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#43 2006-06-03 21:44:21

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 15,866

Re: Reusable LSAM

It sort of bugs me that we have so many threads of simular topics that do not show up under the normal search function. Here again we have had a few threads about reusuable lunar landers (LSAM for short) and yet we start new ones that do not even stick to topic. shakes head:

This particular thread Re-useable lunar lander gets to the ppoint of using private comapnies through the X Prize Cup to help NASA develop a Lunar RLV and early on the A Reusable Lunar Lander was just a possible means of lowering costs.

While NASA retraces its steps to the moon; Agency updates exploration technologies for the 21st century

This sort of bugs me:

The lunar lander is probably the least well-developed of any of those pieces of infrastructure that the government plans to provide

really should say we have no formal plans for what it will look like nor how we will construct it or the type of engines or fuels.

Really how hard is it to look at what we have already used to do the job... make a few tweaks to its design and go.... Make more improvements with the years to come but at least get us started.

This has been thought of before in that where will we go:

Six Apollo lunar landers touched down on the moon between 1969 and 1972. These two-person vessels enabled moonwalkers — often called the “dusty dozen” — to carry out work on the lunar landscape, from Apollo 11’s modest 2.5 hours to Apollo 17’s campaign of forays that added up to more than 22 hours.

Most likely it will be at least 1 or 2 of these places at least.

So why is Nasa putting so much effort it just another piece of hardware to land on the moon:

For their part, NASA internal teams are scrutinizing a variety of items, from the design of the lunar lander itself, crew cabin layout, to piloting sightline/visibility, as well as airlock design and landing gear — even how to package lunar lander hardware for launch from Earth.

Also, there’s interest in exploring options for deployment of a lunar outpost in pieces that can be packaged within the touchdown mass allowance for a lunar lander.

The LRO and others to come use to be under the Robotic Lunar Exploration Program and now they will be the Lunar Precursor and Robotic Program. These will set the stage for future manned missions to the moon. Other than the size there are many simularities that they will all need.

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#44 2006-06-05 13:02:01

gaetanomarano
Member
From: Italy
Registered: 2006-05-06
Posts: 701

Re: Reusable LSAM

.

I think that a reusable-LSAM may give great advantages (for astronauts' safety and moon exploration) if joined with some Crew Habitats on the Moon and a Lunar Space Station www.gaetanomarano.it/articles/009_LSS.html

.

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#45 2006-06-05 14:24:55

cIclops
Member
Registered: 2005-06-16
Posts: 3,230

Re: Reusable LSAM

.

I think that a reusable-LSAM may give great advantages (for astronauts' safety and moon exploration) if joined with some Crew Habitats on the Moon and a Lunar Space Station www.gaetanomarano.it/articles/009_LSS.html

.

Yes one the key advantages of a reusable LSAM that went from LEO to the lunar surface and back would be safety, it would eliminate the risks of LOR operations and multiple engines. RTTM includes the idea of an outpost base to enable extended stays of six months. A very useful Mars analog station to help understand low gravity adaptation as well as providing extensive exploration facilities.

What would be the purpose of a Lunar space station? this would be incredibly expensive.


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#46 2006-06-05 15:03:27

gaetanomarano
Member
From: Italy
Registered: 2006-05-06
Posts: 701

Re: Reusable LSAM

...What would be the purpose of a Lunar space station? this would be incredibly expensive...

the main reason for a Lunar Space Station (and some Crew Habitats on the moon) is to "SAVE the Astronauts' LIFE" (like I write in my article from the title)

all missions' architecture without a LSS and some CH need that ALL work well, since they have not a "B" plan (no matter how much efficient they are)

the cost of a LSS with two modules is not too high, since it can be built with the same ISS' technologies and factories

however, it may save the astronauts' life if something goes wrong (and the human life is priceless)

.

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#47 2006-06-05 18:58:28

GCNRevenger
Member
From: Earth
Registered: 2003-10-14
Posts: 6,056

Re: Reusable LSAM

A lunar space station is a terrible idea, and offers no safety bennefits

If you are on the Moon and something goes wrong, you would have to launch off the surface and to the waiting stations in Lunar orbit: this involves the proper function of the main engine, the proper function of the guidence system, the proper function of the docking system, and the proper function of life support during this operation to reach a hypothetical Lunar space station. And if you can do all that, then chances are there isn't a problem, at least not one you need a space station, life support is very likly the last thing that will go wrong, especially since it doesn't have to do anything really riggerous like a rocket engine.

If the ~$1.0-1.5Bn price tag of each of the American modules on the ISS is any indicator, it would cost in the region of $3.0-4.0Bn if you add power, cooling, and stationkeeping ability. Then you would need the rockets to send the thing, which would run you in the region of $1.5-2.0Bn (about 3-4 CaLVs I bet), in part for the heavy-duty radiation shielding and LOC fuel. Add another $1.5Bn for 25% margin and you are talking around $8.0Bn for the space station.

...With the CEV in orbit offers you exactly the same safety option, expect if your orbital allignment or docking guidence system isn't perfect the CEV would be maneuverable enough to match orbits and pick you up. And if you have sick/wounded astronauts, you could light up the TEI burn and return to Earth directly and immediatly.

Even better, the CEV will be "fresh" from Earth less then six months ago, while the Lunar space station will be years old and becomming decrepit like Mir, especially thanks to the lack of manned maintenance.

Also, Lunar orbit is not 100% stable like Earth orbit, and so the station would require occasional orbital reboosting or adjustment. The station will however, unlike the CEV, have to do this when there are astronauts on the Moon or not, which will prove expensive. Also it will weigh far more than CEV and importing fuel is difficult.

Edit: My precience tells me that you will soon jump up and down with bold red letters and exclamation marks about the possibility of solar flares.

This is easy to address:

  • -For short term exploration missions, the chances of a solar flare are small for the two-week trip
    -For long term base missions, the Lunar base will have a radiation shelter in which case they won't need to flee to a space station.
    -The CEV's electronics won't be any more vunerable to solar flares then the space station will, unless the latter has an absurd amount of shielding
    -Acending to the station before a solar flare would hit would be unlikely anyway, better to hide behind a boulder/crater/LSAM and wait it out


"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw

The glass is at 50% of capacity

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#48 2006-06-05 19:30:14

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 15,866

Re: Reusable LSAM

I really dislike when we get so far off topic.
Before we go to far off topic of a reusuable lunar lander lets make a new topic thread for further discusion as this does warrant some as both cIclops and GCNRevenger have indicated by there posts. I will copy these last few posts to start the thread, I hope no one will mind.

I will call it gaetanomarano Lunar Space Station
Safe haven or for rescue of lunar crew.

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#49 2006-06-06 04:23:47

RedStreak
Member
From: Illinois
Registered: 2006-05-12
Posts: 541

Re: Reusable LSAM

A lunar space station is a terrible idea, and offers no safety bennefits

Edit: My precience tells me that you will soon jump up and down with bold red letters and exclamation marks about the possibility of solar flares.

This is easy to address:

  • -For short term exploration missions, the chances of a solar flare are small for the two-week trip
    -For long term base missions, the Lunar base will have a radiation shelter in which case they won't need to flee to a space station.
    -The CEV's electronics won't be any more vunerable to solar flares then the space station will, unless the latter has an absurd amount of shielding
    -Acending to the station before a solar flare would hit would be unlikely anyway, better to hide behind a boulder/crater/LSAM and wait it out

Reading through all this I have to agree.  Given in particular that note on Lunar Orbit being unstable as well putting a space station there is ineed a bad thought, especially if its half the cost of the ISS or more.  If its put anywhere it would have to be one of the LaGrange points, most likely L1 since its en route or possibly L4 or L5 due to their better stability.

I can see only two legitamate, but not essential, merits to a lunar station and it needent even be manned in both cases:

  • -A place to safely stow/refurnish a reuseable LSAM
    -An LOX orbital storage facility.

Potentially helpful, but its not needed in the short-term since LOX production would take some time to establish anyway as well as the development of a R-LSAM.

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#50 2006-06-06 06:38:16

GCNRevenger
Member
From: Earth
Registered: 2003-10-14
Posts: 6,056

Re: Reusable LSAM

Oh and it gets better, that if you are on the Moon at a much different longitude then the stations' orbit, you can't launch to it just any time you want, you would have to wait for some days for the Moon to rotate so the orbit overflies you. The LSAM just can't carry enough fuel to make huge plane changes.

Why would you want to do maintenance on the LSAM in orbit? Wouldn't it be much easier to do that on the ground at the Lunar base? If its not reliable enough to make at least two trips without anything beyond an electronic diagnostic and refueling, then its not reliable enough.

And why can't a tanker dock directly with the orbiting LSAM, skipping this station business altogether?


"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw

The glass is at 50% of capacity

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