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Just curious on what combining Bigalow's inflatables with Mars Direct would do to the overall mission costs; anybody have any ideas?
I came up with the idea when trying to see if we could launch Mars Direct on the Falcon rockets; i read the conversion charts from tons to kilograms as one to ~900 and came with 36000 kilogram rocket payload; out of the range for current Falcon rockets, but what if we find a way to reduce the mass . . . ?
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You would probably still have to have at least side mount on the current shuttle stack in a cargo configuration to launch at least one Bigalow's inflatables. Theoretically and depending and how big it going to inflate out to in size seen six to twelve people and on high side up to twenty people max.
But, as far as your question goes.
No!
Here why.
Bigalow's inflatable, is a habitat and not space ship and on it way to Mars, it mostly just dead weight until you get it to Mars to inflate it. You will also have to join that Bigalow's inflatable to a space ship that your sending Mars Direct in space, so you would have to some assembling in space to make that happen. You will still have to have another space ship for people to go to Mars that can support four to six people and have the supplies for those people to make that trip. You would still need Mars shuttles on the other end to either get down to the surface of Mars or leave Mars surface. You would still have to have a hydroponics Garden to supplement your Bigalow's inflatable once you did setup your Bigalow habitat on Mars, because Bigalow habitat was intended to be re-supplied from Earth from time to time and being on Mars makes that impossible on timely bases. This would be just for the minimum and does not include rovers or other necessity that should be included for our astronauts to go to Mars.
By the time you add setting up at least a four to six Cargo Shuttle launches, now your talking about a Mars Semi Direct Plan. But, to launch only two or possibly three rocket for going direct after there launch to Mars. No, that not going to happen and you will still have a weight problem to deal with.
Larry,
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The use of inflatables makes Mars Direct or Semi-Direct obsolete. You'd be crazy build anything with a higher launch weight and lower volume untill you can effectively build stronger and larger modules on the moon.
"Yes, I was going to give this astronaut selection my best shot, I was determined when the NASA proctologist looked up my ass, he would see pipes so dazzling he would ask the nurse to get his sunglasses."
---Shuttle Astronaut Mike Mullane
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Not really, because inflatable modules can't withstand the high pressures and temperatures of aerobraking needed to minimize fuel needs. If you have to bring a rigid HAB module with you from Earth to aerobrake at Mars, you might as well use it for the surface HAB too.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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I suppose we could send up two Bigalow's inflatable with one to be inflated in space and become part of the new space ship were building and leave the other one uninflected and for taking to the Mars surface. But, to build something that big would be the end of any Mars Direct Plan and maybe even a Mars Semi Direct Plan and would also eliminate any idea of using Chemical Rockets too. We would either need a fission or fusion powered rocket to power something this big and with that mass that it going have to have to take everything that it has to take Mars for a colony on Mars.
So we would still either have to harden the Bigalow's inflatable or not use aerobrake at the end, but that would have it own downs of having to use more and use more fuel too, which would make chemical fuel for it way too much to be practical.
So much for using the Bigalow’s inflatable for going to Mars on the cheap or considering it for the Mars Direct Plan.
Larry,
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As long as you can aerobrake, conventional solid core fission engines won't be a deal breaker for NASA's DRM missions, you'll just need to use the maximal SDV heavy lifter instead of the medium heavy lifter.
For propulsive capture (no aerobraking) where TransHAB spacecraft would work, the chemical situation becomes untennable and the nuclear rocket fuel bill becomes pretty big.
The NASA DRM plan considerd building a heat shield around a TransHab module, but that would have added mass and substantial construction complexity, since the shield couldn't be lifted in one piece.
I worry that even if you could apply a sufficent heat shield material to the inflatable cabin, that the pressure exerted by atmospheric entry will substantially exceed that of the internal air pressure, which could cause the whole envelope to buckle.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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Why would one leave the inflatable habitat inflated during aero-braking? Design it to be evacuated, collapsed and folded - perhaps accordion-like - back into storage. Have a small crew compartment for use for a day or two prior to and during aerobraking and landing. Any internal furnishings could be manually moved into place by the crew, and re-stowed prior to collapsing.
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As I recall, later versions of the NASA DRM proposed inflatables for the MTV (version 4.0) and to increase volume of the surface (version 3.0). the first would stay in Mars orbit and the surface ones would be inflated there. I would have thought that an inflatable would lack the structural strength needed to be landed.
Jon
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Not really, because inflatable modules can't withstand the high pressures and temperatures of aerobraking needed to minimize fuel needs. If you have to bring a rigid HAB module with you from Earth to aerobrake at Mars, you might as well use it for the surface HAB too.
Well, its a trade off. For more volume and less launch weight per module, you have to dust off the old Nerva plans. Frankly, sacrificing either of those to avoid development of a technology we need anyway is a sacrifice we should not make.
We should be setting very high standards for technologies and objectives for our first Mars mission. The focus must be on exploiting the landing area to the fullest extent to keep the costs of follow-up missions as low as possible.
Nothing I've seen from either Zubrin or NASA really cuts the mustrad in my opinion.
"Yes, I was going to give this astronaut selection my best shot, I was determined when the NASA proctologist looked up my ass, he would see pipes so dazzling he would ask the nurse to get his sunglasses."
---Shuttle Astronaut Mike Mullane
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From the several hundred mission proposals that have come out in the past 40 years you might like to nominate a scheme that does cut the mustard in your opinion.
Jon
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Even if you did use NERVA engines for propulsive braking, the added mass of the fuel needed exceeds the decrease in mass thanks to a TransHAB module I bet. Rigid modules make sense to me for a DRM-style mission, particularly considering that there will be no question marks about their durability or reentry worthiness.
As nice as NERVA engines are, I don't think that they are nessesarry; they would be nice, but we could probobly get by without them if we had to.
About what NASA DRM "buys you" for reuseability, I think that it does have a possible upgrade path: once Martian water is available, we will have an essentially unlimited supply of rocket fuel, which would be used to support a reuseable crew acent/decent vehicle and possibly as a fuel tanker. The ERV will be converted into a cycler, and will park in Mars orbit instead of landing. It then heads back to Earth with its chemical rocket and aerobrakes there to pick up the next crew rotation and a new Mars transit stage. This might be a good place for private launch companies to get into the game, and refill the Earth-return tanks.
This way, the only thing you need new for each crew is a Mars transit stage round trip, which I think makes DRM considerably more attractive in the long run versus MarsDirect.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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About what NASA DRM "buys you" for reuseability, I think that it does have a possible upgrade path: once Martian water is available, we will have an essentially unlimited supply of rocket fuel, which would be used to support a reuseable crew acent/decent vehicle and possibly as a fuel tanker. The ERV will be converted into a cycler, and will park in Mars orbit instead of landing. It then heads back to Earth with its chemical rocket and aerobrakes there to pick up the next crew rotation and a new Mars transit stage. This might be a good place for private launch companies to get into the game, and refill the Earth-return tanks.
This way, the only thing you need new for each crew is a Mars transit stage round trip, which I think makes DRM considerably more attractive in the long run versus MarsDirect.
By the time your architeture has evolved to this extent it's no longer recongisably a semi direct. You need a whole new cycler, new reusable Mars to cycler and back shuttles and new earth to cycler shuttles. This is something like the 1986 case for mars scenario. A whole range of other architectures could also converge on the one you suggest, including direct ones.
Jon
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I disagree, the same hardware from 100% expendable DRM-III plan is used with the exception of the reuseable lander and TEI stage; same vehicle as the ERV, same rocket to return to Earth, same medium NTR or large chemical rocket to get to Mars, same basic everything. The only big changes you need to make to the ERV is to bulk up the heat shield a little to withstand Earth aerobraking, and arrange for refueling ports for the earth-return stage. Aerobraking into Mars orbit without going through the rigors of deorbiting will be easier on the heat shield too perhaps.
With this basic system in place, launching only a new Earth-Mars rocket stage with a single HLLV and other smaller rockets (a pair of Sticks, one medium HLLV, or perhaps AltSpace launches) to refuel the TEI stage and thats it. Send up your crew on CEV with luggage and food, and off you go. This reduces the total amount of launch mass needed by ~75% and reuses the entire vehicle, which can be enabled without signifigant modification to the ERV besides making it somewhat sturdier and building a reuseable Mars/Mars-Orbit crew ferry. A hard deal to beat I think.
Bob Zubrin's dumb "Case for Mars" senario doesn't become 80-90% cheaper then a fully expendable mission with only small changes to the mission arcitecture. The bennefit of not needing to develop all new hardware in order to free up large amounts of NASA's budget for Mars development or whatnot is so benneficial, that Bob or whoever else will have to come up with a very, very convincing case to do otherwise.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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I disagree, the same hardware from 100% expendable DRM-III plan is used with the exception of the reuseable lander and TEI stage; same vehicle as the ERV, same rocket to return to Earth, same medium NTR or large chemical rocket to get to Mars, same basic everything. The only big changes you need to make to the ERV is to bulk up the heat shield a little to withstand Earth aerobraking, and arrange for refueling ports for the earth-return stage. Aerobraking into Mars orbit without going through the rigors of deorbiting will be easier on the heat shield too perhaps.
So what you are proposing is not a true cycler, orbiting between earth and Mars with minimal use of propulsion. You are proposing a reusable ERV (probably better termed a Mars Tansfer Vehicle). However, with the ability to be refueled and resupplied at both earth and Mars, the ability to aerocapture to both Mars and earth orbit, and a usable TPS, this is reading like a completely new spacecraft.
Certainly such an evolution is possible and perhaps desirable but I suggest it is a bigger step than first appears, especially when you look at the resupply requirements,
Bob Zubrin's dumb "Case for Mars" senario doesn't become 80-90% cheaper then a fully expendable mission with only small changes to the mission arcitecture. The bennefit of not needing to develop all new hardware in order to free up large amounts of NASA's budget for Mars development or whatnot is so benneficial, that Bob or whoever else will have to come up with a very, very convincing case to do otherwise.
A mars direct architecture is probably more likely to evolve into a true cycler mode, given the fact it bypases Mars orbit altogether. Zubrin's Mars Direct proposal (not the same thing), although flawed in some respects can hardly hardly dumb, as it evolved into the semi-direct architecture that was the basis of the DRM. The DRM is not without its flaws and intrinsic draw backs as well, else it would not have gone through five iterations.
Jon
Jon
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Sounds like GCNRevenger is talking about the "Mars Orbit Rendezvous" plan that I talked about on this board and actually presented at this year's Mars Society conference. Send what I call an Interplanetary Transit Vehicle (ITV) from Low Earth Orbit to High Mars Orbit, and back. Take an inflatable surface hab that isn't inflated until you're on the surface. The surface hab doesn't need a micrometeoroid shield, just a dust/scuff layer against sand blasting from wind storms and astronauts accidentally brushing against it. The surface hab would come with a tiny pressurized capsule with as much room per astronaut as a Gemini or Mercury capsule; just a seat. The surface hab can have life support and toilet that uses gravity. No need for zero-G equipment for a dedicated surface hab.
The ITV will have all the zero-G equipment and micrometeoroid shield. The thermal layer for the surface hab must be something like Thinsulate or fibreglass batt insulation, but the ITV can use layers of aluminized Mylar like a spacesuit. All dedicated and purpose-built. The ITV can be inflatable. Actually, if you look at the layers of TransHAB, most of it is the micrometeoroid shield. It uses Nextel to break-up micrometeors, a foam spacer to let them separate, then ballistic Kevlar like a bullet-proof vest to stop them. This sandwich is repeated 3 times for safety. The Kevlar restraint layer, redundant pressure bladders, and internal scuff layer will be the same on Mars. Even the outermost layer will be different. TransHAB uses either fiberglass or Ortho-fabric, but the surface hab will use Gore-tex complete with the moisture barrier sized to keep fines instead of water while out while letting water vapour and carbon dioxide gas pass. You don't want ice (water ice or dry ice) accumulating in your hab insulation, and you certainly don't want it weighed down with fines.
An inflatable ITV can aerobrake. The acceleration of aerobraking must be controlled so it doesn't kill astronauts. Once you keep G forces survivable, the acceleration load one the inflatable becomes quite manageable. The heat will be more than TransHAB can handle, but the heat is also more than an aluminum shell can handle. You need a heat shield. Nextel 440 can handle the heat, so use this fabric stretched over a frame like an umbrella. Separate the heat shield from the hab's normal thermal insulation; the vacuum of space will prevent conductive or convective heat transfer, and the reflective layers of normal space insulation will stop radiant heat from the back of the heat shield.
Remember how I want to return to Earth? Use the Mars Ascent Vehicle (MAV) as the TEI stage for the initial science mission. Just use chemical propulsion. Once an advanced propulsion system is available and a base is established on Mars, bring fuel up to refill the propellant tanks. Or harvest fuel from one of Mars' moons. The initial TMI and MAV/TEI stages will be expendable. The advanced propulsion stage can just bolt-on when it's available. Let engine designers compete; leave it open for nuclear thermal or nuclear electric. Electric could be VASIMR, MPD, ion, TAL hall effect, or even microwaved water. Each has different specific impulse and thrust.
Maybe we can actually agree on something.
::Edit:: I should add, a space inflatable can be done but what is the durability of an inflatable over serveral missions vs. a metal hull? I don't know, that's why I ask.
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The Bigelow Inflatable is more likely to be a space passenger craft with a Moon land and Launch concept because there is no atmosphere. The prospect of the Inflatable habitats being used to construct an "ocean liner" that sails from the moon on a short tour around the earth, the moon, and even out for an observation from great distance towards Mars is most likely.
If the Space Commonwealth provided a free passenger service just to get you to the moon, it would still cost travelers about twenty million each to take the Bigelow tour to Mars.
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Bigelow's Inflatable space hotel to blast off
two Russian Dnepr rockets, which are converted SS-18 intercontinental ballistic missiles. Each rocket will launch a scaled-down prototype of the company's inflatable space habitat into low-Earth orbit later this year. The launch dates cannot be divulged because the use of an ICBM means the information falls under US arms trade restrictions.
Hopefully news will come soon of the launch...
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Hopefully the SS-18 launches are sufficiently funded this time.
Too many failures have we seen lately, using these things, due to insufficient monitoring etc...
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...which is why Bigelow bought two
And this is the SS-18 land-based ICBM, not the SS-N-20 submarine based SLBMs that have been failing recently.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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I stand corrected. :oops:
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While Bigelow's hotel seems to be nearing a go others still have been working towards simular goals.
Space Hotels; A Zero-G Getaway yup you guessed it Space Island Group, it won't be long before vacationers are packing their bags for space.
Space Island Group is developing a stand-alone, orbital space structure that could serve a number of purposes, including a hotel. Meyers anticipates the hotel, 400 miles above Earth, will hold 400 guests and 100 crewmembers. He also anticipates the eventual workforce to reach 20,000 employees by 2020. All they'll need, says Meyers, is a one-week training course.
Meyers says that 2009 will see the first of his hotel launches...
Space Island Group plans to generate $10 billion for the startup through sales of solar power technology to India or China. The Space Island Group has been negotiating with both governments and is planning to strike a deal by the end of the year.
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...others still have been working towards simular goals.
Space Hotels; A Zero-G Getaway yup you guessed it Space Island Group, it won't be long before vacationers are packing their bags for space.
Space Island Group is developing a stand-alone, orbital space structure that could serve a number of purposes, including a hotel. Meyers anticipates the hotel, 400 miles above Earth, will hold 400 guests and 100 crewmembers. He also anticipates the eventual workforce to reach 20,000 employees by 2020. All they'll need, says Meyers, is a one-week training course.
Meyers says that 2009 will see the first of his hotel launches...Space Island Group plans to generate $10 billion for the startup through sales of solar power technology to India or China. The Space Island Group has been negotiating with both governments and is planning to strike a deal by the end of the year.
*Just laaaughs*
five HUNDRED people...
ten BILLION dollars...
*wipes his eyes...*
Bigelow's plans are so much less crazy that its night and day... I really have to wonder if these Space Island shmucks are really just pulling a big marketing prank on the world.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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Reading the link... some real whoppers:
"We're sticking with technology that has been developed and used"
...which has proven to be ruinously expensive for NATIONAL space programs, much less private ones.
"a one-week trip will cost $200,000 for a couple, which will include the flight up to the hotel"
...these people are out of their freaking minds!
"visitors will also share only-in-space experiences—like floating outside the station to the help the crew make repairs"
The lack of accidents and cool demeanor of astro/cosmonaut space-walkers has definatly screwed up the preceptions of this guy. A space suit isn't like a scuba diving suit, it is a delicate and difficult thing to wear. You wouldn't let vacationers at a resort go deep-sea diving in freezing water, neither would you let them spacewalk.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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At least he didn't attack Griffin or NASA like Forrest Gump. I think that trying to find a use for CaLV outside of NASA is a noble goal. It is easier for a space start up to build a payload for a craft than it is to build an LV after all.
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[URL=http://www.msnbc.msn.com/id/13171475/from/RS.2/]Russians delay test launch for space hotel; Launch of Bigelow Aerospace’s inflatable module now set for July[/URL]
The test flight is expected to subject the flexible exterior wall material to space conditions for an extended period of time, while interior instrumentation will monitor pressure and temperature. In theory, a flexible wall should be even more resistant than a metal wall to penetration by micrometeorites and space debris
A 1/3 rd sized module will be launched.
They will be launching on a commercialized version of the SS-18 called the Dnepr or what is the SS-18 Satan intercontinental ballistic missile from an active Russian military missile base capable of carry up to 3 tons of cargo into orbit.
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