Shuttle External Tank as Colonist Transport

el scorcho · 2006-01-20 15:27:28

Since the new HLV is based heavily on Shuttle components, I believe the most logical, cost-effective approach to sending a small colony (~100 people) to Mars is this: modify the Shuttle's external tank--basically, gut it, replacing the interior with living quarters and other necessary facilities. The bottom of the ship could house engines and power supplies, providing a few meters of radproofing for the bottom floors; its 47-meter height assures that such protection would increase toward the middle of the ship, which could serve as an emergency radiation shelter in the event of solar flares. Furthermore, the tank's 8-meter diameter assures comfortable, even spacious (when compared with past exploration vehicles) living--it sure beats my dorm room.
A crew of 25 could ride this colony ship to the Red Planet atop the proposed HLV for the Moon-Mars initiative, then unravel a tether between itself and the spent fuel tank to provide artificial gravity. Four such launches and we'd have a real "First Hundred" without the wasted billions on a multi-torused floating megalith.

Austin Stanley · 2006-01-21 00:39:08

I disagree. The primary flaw with the "Empty Stage as Spaceship/Colony/Space Station" building plan is that empty stages, such as the Shuttle external fuel tank are primarily empty fuel tanks. They are not well designed to function as habitable areas, or even to be transformed into such.

To go forward with such a plan the external tanks/empty stages would have to be redesigned to allow for such a refit. Not only is this costly, it is also going to increase there mass, which decreases the payload of your HLLV. You also have to make plans and possibly modifications (RCS and what not) to get your empty stage into a proper orbit. This wasn't an issue for the Saturn V, but it might be for the Shuttle External Tank. This makes the empty stage far more expensive, which raises the launch cost of each HLLV mission.

Then, after you have your refurbishable tank in its proper orbit, you have to shuttle up all the furnishings for it. Sensors, Electronics, Life Support, and so on and so on. These furnishings probably consist of upwards of 50-75%% of your mass anyways, so the savings in launch cost are not that great. Then you have to actualy refurbish and install all this equipment, which is going to both compiclated and time consuming. I question the safety of it all, since the furnishings cannot be tested to the same extent the could be on Earth.

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To me the ideal method for construction temporary housing in space is to make use of inflatable habitat modules, ala Trans-hab. These offer by far the largest amount volume per structure weight. Since they are constructed on Earth, they can be more reliable, and they are much easier to setup in space. The potential mass savings of an upper stage re-use program do not outweight the cost IMO.

GCNRevenger · 2006-01-21 09:01:37

Yeah, the Shuttle external tank doesn't make much of a spacecraft on its own. Its really thinner then I'm comfortable with considering the space debries environment, and a few inches of insulating foam isn't going to stop micrometeoroids nor insulate very well in space. Plus, the foam will probobly break down from the UV/Proton/Cosmis Ray radiation combined with wildly uneven heating, and might break off. The aluminum tank itself offers inferior radiation protection too.

The tank weighs about 30MT empty, which includes a tonne or two for plumbing/wiring and a tonne or two for lousy insulation, which means its "worth" about 25MT of payload. Due to the really big surface area of the tank, making it a little thicker is going to increase its mass really fast, as would adding sufficent space debries armor on the outside... if you could get it not to interfere with launch that is.

The TransHAB is really the way to go, make one with a collapsable "spine," already fitted with fabric/foam internal walls/floors, with hatches on either end, perhaps connected to a regular rigid logistics/docking node and launched on a no-EDS version of the SDV. The outter walls will be made of aluminum-sprayed polymer fabrics and foams which stand up to tiny meteors better then metal while weighing much less, and being made from lighter elements, is better inherint radiation shielding.

The really neat thing about TransHAB is its ability to pack more volume into a rocket: Say the colony ship HAB module is to be launched on the HLLV inside a payload faring 18m long and 8.4m wide: the module would be in three sections, the lower third would be rigid metal that houses logistics, docking ports, airlock, solar flare shelter, furnature (before use), and of course windows. The upper two thirds would be the TransHAB inflatable module with its partially collapsable spine for living quarters, with the "spine" housing lavatory facilites, misc. storage and whatnot. The tip of the module, which would be conical and sit inside the nose cone of the SDV, would be the "bridge" or coupola module or a hatch/airlock or something.

http://science.ksc.nasa.gov/shuttle/tec … ef/et.html

Anyway, a quick comparison... Say the TransHAB module can expand to be 50% larger inflated then stowed on both dimensions compared to a Shuttle tank. Lets assume the thicker walls of TransHAB limit its internal diameter to 8m (12m dia inflated) and half the logistics section is pressurized volume, with a similar penalty for the Shuttle tank
TransHAB: 2200m3
Shuttle Tank: 1840m3 (converting gallons to m3)

The "jumbo" TransHAB is actually bigger then the Shuttle tank by a full third. It would probobly be of comparable volume to the stretch & flat top tank that the big SDV will use as a core module. Compared to "remodel" the external tank in orbit instead of just unpacking the logistics module, plus having to make it be a launch vehicle and a crew module (doubling tasks can radically increase engineering difficulty), and heavier too on doesn't make sense when you could have a purpose-built module thats so much better and just as big.

el scorcho · 2006-01-21 15:09:53

Then, after you have your refurbishable tank in its proper orbit, you have to shuttle up all the furnishings for it. Sensors, Electronics, Life Support, and so on and so on. These furnishings probably consist of upwards of 50-75%% of your mass anyways, so the savings in launch cost are not that great. Then you have to actualy refurbish and install all this equipment, which is going to both compiclated and time consuming. I question the safety of it all, since the furnishings cannot be tested to the same extent the could be on Earth.

Precisely. Perhaps I was not clear enough in my earlier post; I was not referring to transforming a spent fuel tank while in orbit, but to taking the basic design of the fuel tank and transforming it on the ground, then launching it atop the new HLV stack. Refurbishing a tank in orbit certainly would be a terrible idea, so apologies if it seemed that's what I was advocating.

Yeah, the Shuttle external tank doesn't make much of a spacecraft on its own. Its really thinner then I'm comfortable with considering the space debries environment, and a few inches of insulating foam isn't going to stop micrometeoroids nor insulate very well in space. Plus, the foam will probobly break down from the UV/Proton/Cosmis Ray radiation combined with wildly uneven heating, and might break off. The aluminum tank itself offers inferior radiation protection too.

Again, perhaps I should've been more clear; If we've only learned one thing from the last two shuttle launches, it's that foam insulation is a bad idea. The modified (i.e. totally refurbished/ready to live in even before launch) tank would forego any use of foam insulation. As for radiation/spacejunk protection, the sheer inner volume of the tank allows for ample space in which to increase protection from such hazards, while still allowing for a spacious interior living environment.

Though I must admit the transhab idea has always intrigued me.

Commodore · 2006-01-22 00:05:23

The great thing about the CaLV is the maximum payload volume of 10m by 35m. Thats huge by any standard. If a rigid structure can be built to use every bit that can be and still stay within the 125ton to LEO lift, we'll finally have modules witht he combined volume to have a nearly self sustaining craft or base.

I'm still not completely sold on inflatables. The can't be used for aerobraking, so they seriously complicate a Mars transit craft. On the surface they'd be difficult to bury, which would be required for solar flares. They might work well in LEO, but the bigger they get the harder they are to fill with usefull stuff.

As for the ET, I'm not sure at what altitude its suppose to be jettisoned. With the Shuttle it was carried all but all the way up. The Shuttle-C format would be idle for this as a mid-range lifter, but the money isn't there. If it could be jettisoned and restarted once the second stage was clear, then it could be salvaged, though not without a payload penalty. They aren't of much use in orbit for all the reasons mentioned, but they can be of great use on the surface. These can be used as partially buried rover garages and workshops, or completely buried rigid structures to house any number of much smaller inflatable structures.

The biggest issue is getting them there. And it won't be easy to get something of that size down in one place either. Your going to need equal parts fuel and strategically placed retro rockets and RCC systems all added after launch. And your not going to want to risk bringing them all down next to each other either, so a meager mode of surface transportation is needed as well.

GCNRevenger · 2006-01-22 09:23:00

Ahh sorry el Scorcho, trying to come up with a way to reuse the spent tank somehow seems to be a reoccuring theme around here.

The basic ET design would have to be so heavily modified that it really wouldn't resemble the thing it was modeled after. Thicker walls, no more intertank, micrometeoroid armor, radiation shielding, space-type insulation, hatches/airlocks and so on.

Its not really so much an option of using the ET design, but rather a question what to build the thing out of and in what shape. Since this thing is intended to be a colony transport, I think its safe to assume that if we do have a colony in mind then conventional chemical or solid-core nuclear fission propulsion is not good enough. In such a case, that we have a high specific power propulsion system (GCNR, NSWR, VCR/VASIMR, etc) then transit times can be cut with the higher speeds available. With a high speed transit, then you will be going too fast to use aerobraking.

If we are going to be colonizing, we are probably going to need a heavy lifter thats cheaper then the great big maximal SDV. I think this will come in one of two forms, either a brand new clean-sheet booster that does away with the old millstones around NASA's neck left over from Shuttle, probably a tripple-barrel Atlas-V style rocket with larger engines. Or plan B, take the "CaLV" HLLV, replace the huge EDS with a little Hypergolic kick stage and the SSMEs with upgraded RS-68s. Either of these options should produce a vehicle in the 80MT lift range that would cost less then the big HLLV.

This is important, since a colony ship isn't going to be launched in a single shot by any practical launch vehicle, and so whichever launcher is used should have better economies of scale then the big monster HLLV.

Inflatable modules can be made rigid with self-hardening foams inflating voids in the walls and be fairly strong. Antarctic research bases are made from cheap foam and fiberglass, and they hold up okay.

John Creighton · 2006-01-22 13:15:25

Not that I’m a fan of reusing the external tank but for shielding you could surround it by inflatable modules as a micrometeorite buffer. Perhaps for life support you could cut holes in it and tie it into the life support systems of the surrounding modules. One concern I may have is leaks. Such a big tank with thin walls was might have a hole or too in it. Meaning it will leak air. But I guess all space modules do to some degree.

GCNRevenger · 2006-01-22 18:26:09

Thats alot of trouble to install such shielding, and I would't want to launch it already attached. The TransHAB walls are quite thick and mostly made of foam, so while they do bend they don't collapse down thin or anything.

Whoa whoa whoa... you lost me at "cutting holes." Nuh uh, not with any precision in zero gravity in a suit. Ain't happening... diving at the bottom of the ocean is easier then working in space even. And no, most space vehicles don't leak hardly at all, not even a little bit.

TwinBeam · 2006-01-22 20:18:35

Maybe cut off one end and insert an inflatable hab. Adds some rigidity so you can spin two of them on cables for gravity, like two buckets full of humans.

Avoids the complexities of making an inflatable become rigid enough for artificial gravity. Avoids trying to make complex changes to the Hab. It probably isn't terribly mass efficient, and I doubt it has much value against micro-meteors or radiation. Might be better off without it, as far as radiation goes, in fact - less secondary radiation.

Austin Stanley · 2006-01-22 23:19:26

I think if you engineered it correctly, you could aerocapture/aerobrake an inflatiable hab. After inflating the hab structural supports could be deployed to hold the structure rigid during re-entery. The G-Forces involved are minor in comparision to those during take-off, only 1-2G's. And the force comes mainly only from the direction of the heatshield, so it only has to be stiffened in that dimension. Francly, I would be more worried about the function a deployable/unfoldable heatshield then I would about the hab. And even if this doesn't prove practical, the hab could potentialy be de-inflated for re-entery.

GCNRevenger · 2006-01-23 07:43:02

Due to the speed involved with aerobraking, you actually want to come in fairly shallow and not straight on nose first. Doing so greatly reduces the heating on the vehicle, and makes a light-weight heat shield practical instead of something really thick and heavy. Those 1-2G loads are with a shallow decent too I bet. In this case, a TransHAB might not be practical, with the force of entry being on a corner which would complicate the structural loads and heat shield design. You couldn't just have a big flat disk shield on the front.

De-inflating the HAB isn't going to work very well I think. You could gain alot of structural strength by filling the walls with perminantly hardening foam. Also, I doubt you could get it to fold up so nicely as when it was packed on Earth too. It might be possible to use a fabric heat shield to make TransHAB aerobraking practical, but that would take some work.

In any event, why? We aren't going to colonize Mars with chemical or simple nuclear engines, they really aren't practical. And, if we have some advanced propulsion system, we can easily afford short transit times, which will mean speeds higher then are possible for aerobraking.

PurduesUSAFguy · 2006-01-23 08:22:12

Due to the speed involved with aerobraking, you actually want to come in fairly shallow and not straight on nose first. Doing so greatly reduces the heating on the vehicle, and makes a light-weight heat shield practical instead of something really thick and heavy. Those 1-2G loads are with a shallow decent too I bet. In this case, a TransHAB might not be practical, with the force of entry being on a corner which would complicate the structural loads and heat shield design. You couldn't just have a big flat disk shield on the front.
De-inflating the HAB isn't going to work very well I think. You could gain alot of structural strength by filling the walls with perminantly hardening foam. Also, I doubt you could get it to fold up so nicely as when it was packed on Earth too. It might be possible to use a fabric heat shield to make TransHAB aerobraking practical, but that would take some work.
In any event, why? We aren't going to colonize Mars with chemical or simple nuclear engines, they really aren't practical. And, if we have some advanced propulsion system, we can easily afford short transit times, which will mean speeds higher then are possible for aerobraking.

Would a biconic type aerobrake surrounding a TransHab derived modual simplify aerobraking with an inflatable vs a disk type aerobrake? I seem to remember some NASA renders from one of the DRMs a few years back featuring such a set up.

I was wondering if maybe there is a best of both worlds approach to the inflatables, prehaps some sort of collapsable hard shell that would be in overlapping pannels while the hab was collapsed for launch which would then lock into place with each other once the hab was inflated. This would prehaps add the rigidity needed for aerobraking as well as lending strength if you wanted to burry the hab for radiation protection.

Actually that got me thinking, if you had equipment on the surface to produce concrete, which I think would be pretty straight forward to develop once you had a reactor and suitable water source on the surface, you could take dozens of light plastic membranes, inflate them on the surface and then spray concrete onto them to create a series of monolithic domes. That would be a really easy way to produce a large permanent base out of materials that would be easy to extract and light weight to import from Earth.

I guess the next step might be an automated smelter to produce magnesium alloy rebar, lol, although that strikes me as being a much heavier system to launch and more complicated to develop. But then again with the recent development of microwave smelting of steel, it could be made significantly lighter weight.

GCNRevenger · 2006-01-23 14:16:39

A folding rigid heat shield would be very hard, considering the absolutely-can't-leak seals. I think it makes it hard enough that it defeats the purpose of a TransHAB, you may as well stick with metal walls if one of them has to support a rigid heat shield. A fabric or ablator shield is the only option for a TransHAB. Again, I think this is moot anyway, since we aren't going to use aerobraking for colony ships.

It seems to me that concrete would be a waste of water, which is going to be precious stuff reguardless where it comes from. If the inflatable plastic dome can handle the weight of drying concrete, it can handle internal air pressure on its own, skip the concrete completly.

Austin Stanley · 2006-01-24 05:35:10

Due to the speed involved with aerobraking, you actually want to come in fairly shallow and not straight on nose first. Doing so greatly reduces the heating on the vehicle, and makes a light-weight heat shield practical instead of something really thick and heavy. Those 1-2G loads are with a shallow decent too I bet. In this case, a TransHAB might not be practical, with the force of entry being on a corner which would complicate the structural loads and heat shield design. You couldn't just have a big flat disk shield on the front.

There are definetly alot of methods for aerobraking, but I don't see the advantage in going at it nose-on as opposed to anyother posture, regardless of angle of approach. Certianly going at it shield first would have the advantage of being inhernitly stable. As for the re-entery G loads I quoted, those are from the Shuttle, which does have a fairly gentle re-entery profile in general, and is certianly moving much slower than a Mars Mission would be. 1G is the typical load with 2G's being the structural max. Soyuz does re-entery at about 4G's. But as I said at the start, aerobraking can very greatly depending upon your profile, and if you are only shooting for aero-capture then the load shouldn't be as bad.

De-inflating the HAB isn't going to work very well I think. You could gain alot of structural strength by filling the walls with perminantly hardening foam. Also, I doubt you could get it to fold up so nicely as when it was packed on Earth too. It might be possible to use a fabric heat shield to make TransHAB aerobraking practical, but that would take some work.

I agree that folding the thing back up would be impractical, but it's not technicaly impossible, by any means. If you plan on folding the thing up during re-entery and don't unfold it untill you fire-off you TMI burn, then there realy isn't any reason to make the walls super stiff. Strong enough to resist puncture and what not for sure, but they shouldn't face any signfigant loads in zero-g.

In any event, why? We aren't going to colonize Mars with chemical or simple nuclear engines, they really aren't practical. And, if we have some advanced propulsion system, we can easily afford short transit times, which will mean speeds higher then are possible for aerobraking.

I was think more in terms of ITV being used in more near term missions. In fact, one of the ideas I've been toying around with is how to get the logistics of a re-usable ITV working. Such a vehicle would benifit greatly from the Trans-hab concept, as it wouldn't be hampered by the need to land on a planet.

A folding rigid heat shield would be very hard, considering the absolutely-can't-leak seals. I think it makes it hard enough that it defeats the purpose of a TransHAB, you may as well stick with metal walls if one of them has to support a rigid heat shield. A fabric or ablator shield is the only option for a TransHAB. Again, I think this is moot anyway, since we aren't going to use aerobraking for colony ships.

I mostly agree on the rigid fabric heat shield concept. However, if we could keep the load down to where a metal heat shield could be used, I could see how a folding-metal shield could be used. The metal shield is unfolded by whatever means works best (inflation, mechanical, whatever). The metal plates are fitted into a semi-tight lock during this process. During re-entery the metal plates would expand, very effecticly sealing the joints bettwen them. Proper joint design (sawteeth or what not) could lead to a very effective hold.

GCNRevenger · 2006-01-24 07:49:26

There are different types of aerobraking, but only one of them lets you get away with a modest structure and light-weight heat shield, which is the shallow decent called for in NASA's DRM plan. Going in nose-first is going to require a very heavy shield and put alot of stress on the vehicle. Are the other options? Sure, but none worth the trouble.

Folding up the hab is impractical, so why do you care that its technically possible or not? Is it practical, or isn't it? Stiffend walls will make for lighter walls or at least better over all meteor armor. TransHAB's current design calls for a thick layer of foam to decelerate meteor fragments, and this isn't going to be easy to bend after its deployed. The difference in temperature of the outer skin will also complicate things if the polymers are thick or temperature sensitive enough that their ability to flex will be different. I'm sure there are other reasons that I haven't thought of too.

Any near-term cycler vehicle is going to be powerd by chemical or simple nuclear engines, which makes aerobraking very desireable to hold down fuel mass. Combine this with the small crews (like, 6-8 each) involved and smaller vehicle required, the total structure mass of regular Aluminum vehicle isn't going to be a whole lot greater then a TransHAB. To top it off, chances are we are going to Mars with a direct landing vehicle first before we think about a cycler, so we will have a proven design already suited to aerobraking.

Put all these things together, and I think it makes more sense to use a derivitive of the direct landing vehicle as an early cycler to minimize development headache instead of switching to TransHAB to try and eeke out a tonne or two of mass at huge expense. If we have rockets powerful enough to send a direct landing vehicle to Mars, then they are powerful enough to send a rigid cycler too, and you won't save money if a TransHAB vehicle still requires the same class of launch vehicle.

Also, if the cycler is a copy of the direct landing vehicle, then we know its heat shield is going to be sturdy, since it has to withstand Mars deorbiting as well as aerocapture. I think this is important, since heat shield reliability will be a major factor in how many times it can be reused, but more importantly if it can handle Earth aerocapture too.

My plan is for NASA to go ahead with a DRM-III style mission with vehicles sized to fit on the VSE CaLV without an EDS stage, and then mate them to either a 80MT nuclear stage or a 120MT chemical stage for TMI. A cargo ship design in the 80 or 120MT class would be built for one-launch cargo missions too. After a base is established and a source of water is secured, NASA would then send a DC-X style reuseable lander to Mars and be powerd only by local fuels. With this vehicle, subsequent HAB vehicles would stay in Mars orbit rather then landing, crews would be exchanged, and then the HAB would return to Earth with chemical engines.

We will already have a cycler big enough to seat eight, why bother with TransHAB?

I really don't like the idea of a folding heat shield still. It can't be that easy if NASA is so parinoid about the little seals around Shuttle wheel wells. What if the seals fail before the shield heats up and expands? Or how do you cope with uneven heating? And most importantly, how will the thing fit? Its just easier to stay with a proven design with a rugged shield and spend the development money on propulsion instead.

PurduesUSAFguy · 2006-01-24 08:48:34

There are different types of aerobraking, but only one of them lets you get away with a modest structure and light-weight heat shield, which is the shallow decent called for in NASA's DRM plan. Going in nose-first is going to require a very heavy shield and put alot of stress on the vehicle. Are the other options? Sure, but none worth the trouble.
Folding up the hab is impractical, so why do you care that its technically possible or not? Is it practical, or isn't it? Stiffend walls will make for lighter walls or at least better over all meteor armor. TransHAB's current design calls for a thick layer of foam to decelerate meteor fragments, and this isn't going to be easy to bend after its deployed. The difference in temperature of the outer skin will also complicate things if the polymers are thick or temperature sensitive enough that their ability to flex will be different. I'm sure there are other reasons that I haven't thought of too.
Any near-term cycler vehicle is going to be powerd by chemical or simple nuclear engines, which makes aerobraking very desireable to hold down fuel mass. Combine this with the small crews (like, 6-8 each) involved and smaller vehicle required, the total structure mass of regular Aluminum vehicle isn't going to be a whole lot greater then a TransHAB. To top it off, chances are we are going to Mars with a direct landing vehicle first before we think about a cycler, so we will have a proven design already suited to aerobraking.
Put all these things together, and I think it makes more sense to use a derivitive of the direct landing vehicle as an early cycler to minimize development headache instead of switching to TransHAB to try and eeke out a tonne or two of mass at huge expense. If we have rockets powerful enough to send a direct landing vehicle to Mars, then they are powerful enough to send a rigid cycler too, and you won't save money if a TransHAB vehicle still requires the same class of launch vehicle.
Also, if the cycler is a copy of the direct landing vehicle, then we know its heat shield is going to be sturdy, since it has to withstand Mars deorbiting as well as aerocapture. I think this is important, since heat shield reliability will be a major factor in how many times it can be reused, but more importantly if it can handle Earth aerocapture too.
My plan is for NASA to go ahead with a DRM-III style mission with vehicles sized to fit on the VSE CaLV without an EDS stage, and then mate them to either a 80MT nuclear stage or a 120MT chemical stage for TMI. A cargo ship design in the 80 or 120MT class would be built for one-launch cargo missions too. After a base is established and a source of water is secured, NASA would then send a DC-X style reuseable lander to Mars and be powerd only by local fuels. With this vehicle, subsequent HAB vehicles would stay in Mars orbit rather then landing, crews would be exchanged, and then the HAB would return to Earth with chemical engines.
We will already have a cycler big enough to seat eight, why bother with TransHAB?
I really don't like the idea of a folding heat shield still. It can't be that easy if NASA is so parinoid about the little seals around Shuttle wheel wells. What if the seals fail before the shield heats up and expands? Or how do you cope with uneven heating? And most importantly, how will the thing fit? Its just easier to stay with a proven design with a rugged shield and spend the development money on propulsion instead.

I agree with you on most points, and I understand the concern over the folding heat shields, it would arguably be one of the most mission critical items on that you would launch, the problem I see is that if you are going with a disk type aerobrake, how would you go about launching it? It would certainly be a bigger diameter then the 8.4m-10m CaLV shroud diameter. Or are they base lining biconic type heat sheilds in the DRM? I seem to remember graphics as such but I've had a hard time tracking down the actual DRM document? Know where I can find its .pdf?

As far as cargo goes though, if and when we implement cycling or reusable crew transfer spacecraft, what will be the most economical means to send cargo. Any expanding base is going to have a healthy need for replacement parts, exploration vehicles, and eventually construction equipment and automated factories. Will the best way to go still be two CaLV launches for the cargo and upper stage (be in chemical, NTR, or NEP) on a low energy transfer orbit?

Actually speaking of cyclers there is a really interesting NASA presentation over on nasaspaceflight.com over the work they’ve done on permanent transfer spacecraft with artificial gravity, I was impressed by the fire baton concept, assembled in only three 120 tonne class CaLV launches and one assembly crew. I mean, it would be a bad idea to base your initial program around anything with on orbit assembly, but this seems doable, especially after several years of manned Mars missions.

GCNRevenger · 2006-01-24 13:24:14

No, no disk-shaped shield, the DRM vehicle calls for an biconic ("bullet") shape that doubles as a shroud and as aerobrake/entry shield.

The most economic way to send cargo would be a reuseable vehicle powerd by a GCNR or NSWR engine, fueled and reloaded by a fully 100% "no really!" RLV spaceplane (probobly two--stage) on the Earth end, and unloaded (perhaps refueled too) at the Mars end by a DC-X style RLV.

The next best way would be to use an HLLV, preferably just big enough to send ~20MT direct to Mars. This could either be a CaLV without a full size EDS stage, or maybe an EELV derived vehicle in the 80MT range.

If it turns out that small payloads are a must, a vehicle able to fit on a single Stick or Delta-IV HLV would be preferred, but it won't be able to carry much, especially when its not the biannual launch window.

Or, for really big payloads, a full size CaLV HLLV with EDS stage or even the full size DRM type vehicle (two launches) with cargo.

publiusr · 2006-01-27 17:10:43

Not that I’m a fan of reusing the external tank but for shielding you could surround it by inflatable modules as a micrometeorite buffer. Perhaps for life support you could cut holes in it and tie it into the life support systems of the surrounding modules. One concern I may have is leaks. Such a big tank with thin walls was might have a hole or too in it. Meaning it will leak air. But I guess all space modules do to some degree.

This at least gives you something of a double hull and allows a rigid structure underneath to attach euipment to. I don't like inflatables for anything other than stations, cyclers or bases. For something with maneuver capability, I want a rigid form. ET tank stations were proposed by Marshall some time ago, but we've been over that.

GCNRevenger · 2006-01-27 17:39:06

"For something with maneuver capability, I want a rigid form"

Why? A TransHAB is not soft like a balloon or beach ball, its quite sturdy. And what are you going to have in the thing that has to be bolted down for a colonist transport?

publiusr · 2006-02-03 13:37:51

It is still something best suited for stationary use. I just like ET or dedicated dry stage structures. Not that an HLLV launched inflate wouldn't also be welcome. The original Skylab was to be a wet stage craft.

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Re: Shuttle External Tank as Colonist Transport

#15 2006-01-24 07:49:26

Re: Shuttle External Tank as Colonist Transport

#16 2006-01-24 08:48:34

Re: Shuttle External Tank as Colonist Transport

#17 2006-01-24 13:24:14

Re: Shuttle External Tank as Colonist Transport

#18 2006-01-27 17:10:43

Re: Shuttle External Tank as Colonist Transport

#19 2006-01-27 17:39:06

Re: Shuttle External Tank as Colonist Transport

#20 2006-02-03 13:37:51

Re: Shuttle External Tank as Colonist Transport

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