Crew vehicles discussion

John_Frazer · 2005-04-04 20:54:59

GCNRevenger Feb. 05 2005
> Shuttle is going away, it doesn't matter if NASA wanted to fly it any more or not, change is going to happen reguardless.
>
> The use of a capsule on top of an expendable rocket has been a sound proven concept for travel in Cislunar space. The rocket that will carry it pretty much already exsists, and only requires modifications. The basic designs of the older capsules could even be dug up.
>
> Small reuseable spaceplanes, intended to fly often and small crews (3-4), do not have a worthwhile destination to justify their higher development costs and reduced flexibility. There is no way such a vehicle can be relied on safely return from Lunar orbit without a revolutionary heat shield material. Nor is a spaceplane with a huge drop tank really reuseable either.
>
> A large reuseable spaceplane, that we will ultimatly need some day, likewise has no destination to fly to in order to justify it. It would also incur extreme development costs.
> ...So, the only option that makes sense and that NASA can afford to fulfill VSE is to go with expendable capsules and rockets. There will be no spaceplane involved because it isn't practical return it to Earth from the Moon, it is less efficent with its wheels and wings, and will cost more to develop.

More on this later...

Where did they get the idea to make a crew vehicle for assuredly safe human flight -safe abort throughout the flight regime-, and then take it beyond LEO to the Moon and Mars? This has always sounded like a White House PR flack's idea (basically the entire "Bush Space Plan" in a nutshell), with little or no engineering or aerospace merits.

Any idea that retrofitting such a vehicle could be feasible or cost competetive compared to a safe crew ASV (Assured Safe Vehicle), and separate specialized mission specific vehicles?

I still think they should have taken a better look at the HL-20. Yes, the optimistic cost estimaes for it assumed that there wouldn't be too much graft and extra unnecessary things attached to it just to satisfy the contractors in this or that congressional district, but there was alot of good sensible work done on it.
http://astronautix.com/craft/hl20.htm]h … t/hl20.htm
http://astronautix.com/craft/hl42.htm]h … t/hl42.htm

Other things of interest
http://astronautix.com/craft/soyuztma.h … yuztma.htm
http://astronautix.com/craft/moose.htm] … /moose.htm
http://www.astronautix.com/craft/esaacr … saacrv.htm
http://www.astronautix.com/craftfam/res … rescue.htm

GCNRevenger · 2005-04-04 21:11:30

My, getting into the Bush-Bash in the first paragraph

No actually, not alot work was done on the HL-20/42 concept. Do not be decieved by the wooden (really, WOOD) mockup made by engineering grad students you see flashed around. It was no more then a box with a fake cockpit, landing gear, and black paint a "heat shield." No where near a prototype.

The problem with HL-20 is that it would weigh about double what a small capsule would, which basically means you could either carry wings & wheels or rocket fuel to get home in a single EELV throw. Pick one.

"...assumed that there wouldn't be too much graft and extra unnecessary things attached to it just to satisfy the contractors in this or that congressional district..."

Yeah yeah conspiracy to jack up prices astronomically bla bla bla... this refrain is getting old.

RobertDyck · 2005-04-05 00:29:36

Thank you John; it's nice to see an ally.

As I understand Burt Rutan's development process, SpaceShipOne was a computer engineering analysis and simulation only. It flew as a full-up vehicle. There were successive test flights, but they were all manned. There weren't any "full size scale models" intended for drop tests. This demonstrates the work on HL-20 was in fact quite extensive. The next phase would have been a full-up vehicle for flight tests.

This image of the dashboard looks a lot more than paint; that's actually a flight simulator.

HL-20 Using the extensive wind tunnel resources at Langley, researchers compiled a comprehensive aerodynamic and aerothermodynamic data base on the HL-20 concept spanning the entire speed range the PLS would fly through. Several models were built for testing in the various tunnels ranging from a 1.5 m model used for force and moment tests at low speeds to 15 cm models used in hypersonic tests. Results showed the shape possesses good flying qualities in all flight regimes. In addition to measurements of aerodynamic properties, experimental aerothermodynamic heating studies were performed. A new thermographic phosphor technique was used to study the heat transfer characteristics of a HL-20 model in high-speed wind tunnel tests. The model, coated with a phosphor, radiated at varying colour intensities as a function of temperature during test when illuminated by ultra-violet light.
Computational fluid dynamics (CFD) codes, which mathematically simulate the flow field in the vicinity of the HL-20, were also used at Langley. These advanced computational grid techniques were used in conjunction with wind tunnel tests to study patterns of flow field phenomena, shock waves, stability and control and heating on the windward and leeward surfaces of the vehicle. Such computational analyses become critical in regimes where wind tunnels cannot duplicate the entry environment. For example, heating in the flight environment on this concept was predicted to be within the limits of Space Shuttle-based high-temperature, reusable surface insulation (HRSI) everywhere except at the nose of the vehicle, where Shuttle-based carbon-carbon thermal protection was required.

This sounds to me that they did a lot more than Burt Rutan did before his manned test flight.

Yea, any lifting body is heavier than a capsule. That's why a capsule is best for an emergency escape pod. However, a capsule can't be reused which is why a lifting body is best for a crew taxi.

srmeaney · 2005-04-05 03:28:02

Would it not make sense therefor to send the Space Shuttles into space for a Final Permanent Mission? By expanding the ISS to a population capacity of 100 passengers (such as the Bigelow hotel in Space), add a few nuclear propulsion systems and Use the shuttles as the Flight deck for each of the stations built?

SpaceNut · 2005-04-05 05:06:36

Wrong thread srmeaney for reuse of shuttle and ISS as a staging platform but it has been suggested multiple times in other threads related to the shuttle and of the ISS.

On the note of a capsule not being reusuable, Why not: other than the heat shield boiler plate. Why could it not be removeable and replaceable. Even still all internal hardware could be recycled to a new vehicle and at the very least it could be flown as a one way mission vehicle. Say to the ISS or other places.. where you know that a return vehicle awaits you.

GCNRevenger · 2005-04-05 06:01:46

Not impressed. Is that even a simulator specifically for the HL-20 rather then a general-purpose one? And so they have tested the aerodynamics, big deal. That just gives them mold lines to play with... Yep, just a short hop to a prototype, have it done next week...

And again, again with the innane, silly comparisons with Burts toy... Space Ship One is a pitiful, really quite pathetic piece of junk compared to what a real live orbital vehicle is. I feel confidant in stating that an HL-20 style vehicle would easily be an order of magnetude more difficult to do, since an order of magnetude more performance and complexity are required. And, as you know, when these things increase the price increased exponentially... This isn't like comparing an F-15 to a old F-86, its like comparing an F-15 to Cessna, the analogy is just plain deceptive or ignorant.

Another problem that also kinda kills the Space Taxi idea dead... that a capsule doesn't need any fuel to decelerate for Earth entry. This saves you a few tonnes of fuel, and provides an extra safety margin in case the burn fails.

RobertDyck · 2005-04-05 10:32:30

Another problem that also kinda kills the Space Taxi idea dead... that a capsule doesn't need any fuel to decelerate for Earth entry. This saves you a few tonnes of fuel, and provides an extra safety margin in case the burn fails.

Huh? How does this relate to anything? A capsule does need fuel to de-orbit from ISS, or any Earth orbit mission. You keep assuming all expendable vehicles. I already said this is part of a comprehensive space transportation system. Use a Lunar Transfer Vehicle that aerocaptures into Earth orbit, then parks in LEO to wait for the next lunar mission. The reusable space taxi is used to ferry astronauts to the LTV before the mission, and down to Earth from that vehicle after the mission. The space taxi never goes farther than LEO. That same LTV could be used for missions to Medium Earth Orbit (LEO to MEO and back) or to L2 where JWST would reside. Basically the LTV is your manned vehicle for cis-lunar space.

As for comparisons to SpaceShipOne, calling it a toy is not appropriate. It's the only reusable manned vehicle to fly into space twice within two weeks. That is a major accomplishment. His engineering staff did engineering design, analysis, and computer simulations. They ground tested each component of flight hardware, then flight tested the complete vehicle with a cautious incremental test plan. They never built models or mock-ups. Using that vehicle development method, the work at Langley is all that's necessary before starting construction and component testing of the complete flight vehicle.

GCNRevenger · 2005-04-05 10:55:11

Ohhh so you want to pass the EOC buck to the lander/LTV... Now the LTV has to carry a big aerobrake shield or fuel for an Earth-orbit capture burn, either way driving up the total mission mass versus a capsule.

"As for comparisons to SpaceShipOne, calling it a toy is not appropriate. It's the only reusable manned vehicle to fly into space twice within two weeks."

This view is simply without any merit. "SpaceShipOne" isn't even a space ship, its a high-altitude missile with plastic wings and flimsy landing gear. You may accuse me of trying to belittle their achievement, and to that I say darn right I am. Their vehicle is puny and worthless for spaceflight. Its a toy compared to a real spaceship.

RobertDyck · 2005-04-05 12:03:08

I had looked at designing the vehicle to have either a refractory heatshield or lunar landing legs. You could travel from Earth to Lunar orbit with the shield, leave it parked in orbit and pick-up legs before proceeding to the surface. After ascent, rendezvous with the shield to pick it up and drop off the legs. That means you only need the aerocapture heat shield for transit to Earth, not landing; and only need the legs for landing, not transit to/from Earth. However, that requires stopping in Lunar orbit. You can save fuel by skipping Lunar orbit and proceeding directly to the surface. That requires the aerocapture heat shield and legs be permanently attached. Integration eliminates the mass of a latching mechanism, and eliminates the risk involved with rendezvous and docking. Admittedly that isn't a great risk, but it's something. You'ld probably need an expendable TLI stage, but the vehicle itself would be a single stage and entirely reusable. It would use a different expendable stage for TLI, transfer to L2, or transfer to MEO. In fact, if the MEO destination is low enough it could travel directly with internal fuel. You could debate whether the Lunar legs should be removable for MEO or L2 missions, but I think it would be most reliable to simply integrate them.

This wouldn't use propellant for Earth orbit insertion, it would aerocapture/aerobrake. The heat shield would be a lot lighter duty since it only skims the atmosphere. Fabric stretched over a frame is enough. AFRSI thermal blankets on the Shuttle use high purity silica fibre cloth for their outer layer (>99.9% silica); DurAFRSI thermal blankets use Nextel 440. AFRSI can only handle 1200°F while DurAFRSI can handle 2000°F, but if the application is aerocapture then you have vacuum between the fabric and aluminum skin so you don't need the batting. There are commercial forms of high temperature silica cloth that are 98% silica but can handle 2000°F. There's one that can handle 2300°F continuous and 3000°F for short duration. Nextel 440 can handle 2500°F continuous and melts at 3272°F. BF20-36 is Nextel 440 @ 0.02" thick and satin weave; it's break strength is 354 lbs. (warp) or 283 lbs. (fill), and weighs 14 oz/sqyd. 18S-36 is Silica cloth @ 0.03" thick and satin weave; it's break strength is 90 lbs. (warp) or 70 lbs. (fill), and weighs 18 oz/sqyd. Oh, well, that's pretty conclusive for Nextel 440.

Compare the mass of a Nextel 440 fabric heat shield with frame to a solid ablative heat shield, parachute, floatation bags or landing rockets, survival gear, and titanium hull instead of aluminum to handle re-entry temperatures.

GCNRevenger · 2005-04-05 12:19:23

You still would have to push the heat shield from Earth with extra TLI fuel, push the extra TEI fuel from Earth, and use this extra fuel to push the shield back to Earth from Lunar orbit.

And, since you will still be launching the space taxi with an expendable rocket, the savings aren't justifiable given the small Lunar payloads that would be adversely affected by this scheme.

I'm not at all convinced that a heat-resistant fabric alone will be enough to withstand the heat and the loadings.

RobertDyck · 2005-04-05 12:20:21

This view is simply without any merit. "SpaceShipOne" isn't even a space ship, its a high-altitude missile with plastic wings and flimsy landing gear. You may accuse me of trying to belittle their achievement, and to that I say darn right I am. Their vehicle is puny and worthless for spaceflight. Its a toy compared to a real spaceship.

That says absolutely nothing about the development methodology.

GCNRevenger · 2005-04-05 12:24:26

So what? I am concerned with the performance of the vehicle... or rather, the lack thereof.

RobertDyck · 2005-04-05 12:26:25

You still would have to push the heat shield from Earth with extra TLI fuel, push the extra TEI fuel from Earth, and use this extra fuel to push the shield back to Earth from Lunar orbit.
And, since you will still be launching the space taxi with an expendable rocket, the savings aren't justifiable given the small Lunar payloads that would be adversely affected by this scheme.

Nope. The refractory heat shield is sent instead of the ablative heat shield all the other stuff of a capsule. The capsule would also need TLI fuel and TEI fuel from Earth. Also remember I'm talking about direct from Lunar surface to Earth, not ever stopping in Lunar orbit.

The space taxi won't launch with an expendable rocket, it uses a drop tank and air-launches from a 747. (http://chapters.marssociety.org/winnipe … if]picture)

GCNRevenger · 2005-04-05 15:23:04

You are still having to launch a set of wings & wheels AND push a heat shield around, which still increases mass substantially.

And frankly, the 747 trick isn't going to fly. The spaceplane is physically too small to accomodate a big main engine, a six-man crew, or nontrivial payload. The development costs would be much much higher then to put a capsule on top of a Delta-IV.

RobertDyck · 2005-04-05 15:30:11

The 747-launched space taxi is intended to carry 4 astronauts and no cargo, or replace seats with cargo. I don't know where you got the idea of a 6-man crew; the CEV spec calls for 4-person.

Given the level or work done on the HL-20, this vehicle could be completed relatively inexpensively; certainly not the $25 billion price tag you keep talking about. How many expendable capsules would you get for the $2 billion development cost of the space taxi?

And this vehicle doesn't have wings; it has a lifting body and tail fins. That's substantially lighter than wings. The lifting body and heat shield goes to LEO, not all the way to the Moon and back. Substantial propellant saving.

GCNRevenger · 2005-04-05 15:49:47

The minimum requirement is for four seats, but if it is to carry much payload and for future expansion, it ought to be big enough for six. Update EELV and it could do this... I question if your space taxi would even be big enough for four considering the engine space it needs.

"Given the level or work done on the HL-20, this vehicle could be completed relatively inexpensively"

No it couldn't, because almost no work was actually done on HL-20 beyond the aerodynamics and obsolete materials studies. $25Bn would be for a fully reuseable medium lift two-stage spaceplane the size of a 747... however, I think it not at all unreasonable to peg the price of a modern HL-20 at around $5-6Bn.

A baby HL-20 is a much heavier vehicle then a compared to a capsule, because the spaceplane has more surface area per-volume, and more wasted volume per-size, then a capsule.

You'll still be launching wings, the extra vehicle mass, the landing gear, etc for each sortie. This extra stuff weighs a large fraction what sending up a new capsule would, or the additional tonnes of propellant needed. No savings, especially considering the bigger booster adapter & escape rockets.

And say you save a billion dollars? That would be enough money for several years worth of capsules.

RobertDyck · 2005-04-05 17:36:59

And considering the baby HL-20 brings its engine back, only the tank is expended, what is the additional per-launch cost of the EELV to lift those capsules? The baby HL-20 can ferry crew to ISS as well as Lunar missions, but just look at lunar missions for a moment. Calculate the cost of lifting building just one LTV and an expendable TLI stage for each mission. The TLI stage can use cryogenic propellants, but since the LTV has a long mission use N2O4/MMH for that vehicle. The Apollo CSM used N2O4/UDMH so MMH is actually a small improvement. The Russian Progress demonstrates on-orbit fuel transfer of N2O4/UDMH regularly, and it's a very simple technology: a membrane separates the liquid propellants in the tanker from helium used to push it out. I've argued you can use the same technique for LOX & liquid methane with a Kel-F membrane, but Kel-F can't handle the cold of LH2. However, a lunar mission would use N2O4/MMH anyway. You could launch the TLI stage, tanker with LTV fuel, and life support expendables in a single launch of Shuttle-C.

Construction: lift the LTV in a single launch of Shuttle-C
Operation: 1 launch of Shuttle-C + 1 baby HL-20 per mission
What's the total system cost for 10 missions vs. expendable capsules with EELV?

Base construction is strictly one-way, so send unmanned cargo modules direct launched with Shuttle-C.

GCNRevenger · 2005-04-05 18:24:17

The price of developing the much more complex "HL-8," and its brand new engine, destroys much bennefit from its lower operational costs versus CEV+EELV, especially if NASA can get a package deal on boosters. You could perhaps fly dozens of capsule flights for the cost savings of HL-8.

And why on or above the Earth would you want to use hypergolics? They aren't very safe in large tanks, they have lousy efficency versus superior propellants like LOX/Methane or Peroxide/Kerosene, and you can't make them from Lunar soil. It would be an awful mistake to power Lunar vehicles with them.

And all that mess with Shuttle-C for just one crew rotation? You could pull of a rather modest Lunar mission with some cargo if you launched the CEV seperatly, or even without if you upgraded SDV to Ares class and put an escape tower on top.

If you want a reuseable system, then build a reuseable TLI/TEI stage powerd by LOX/H2 or LOX/Me so that you can fuel it with Lunar oxygen, so having it perform a Earth orbit capture later on is easy since you didn't drag TEI fuel up. Same with the lander, which should be easy to make reuseable, so you don't have to haul lander fuel later on... Or at least the LOX.

Base construction is definatly not just one way, not if you want to develop anyway. A reuseable cargo network would eventually be a must, and so making the current vehicles with an evolutionary path to full reuseability is a smart idea.

By the time we are ready to need that though, Shuttle-II should be the reuseable launch vehicle, not a dinky crew taxi.

RobertDyck · 2005-04-05 19:20:46

LOX/LCH4? Ok. That's what I was going to propose, and did mention it in a paper to NASA, but was afraid cryogenics wouldn't last for an entire lunar mission. OME has an Isp of 316 seconds in vacuum, RD-160 Isp is 381 seconds. That's a fair bit better, but RD-183 also uses LOX/LCH4 and its Isp is only 360 seconds. Then there's fuel density which translates to tank size; but LOX does have the potential to harvest from lunar regolith.

By the way, the RS-82 engine uses H2O2/Kerosene and its Isp is only 320 seconds; hardly better than OME's 316. AR2-3 for X-37 also uses H2O2/Kerosene but its Isp is merely 245 seconds. It's storable but low performance.

If I had my way, along with a dinky crew taxi I would have the X-43 guys build a series of 5 more vehicles, culminating in a SSTO RLV technology demonstrator. It wouldn't carry any cargo or crew; just demonstrate SCRAM/Hypersonic technology. After it works NASA can debate whether to separate cargo and crew or re-combine them into a new full-size shuttle.

Reusable LOX/LCH4 TLI stage? I also mentioned that in the paper I sent to NASA, but since have been wondering just how big it has to be. Ok, don't flinch, stick to the design concept.

SpaceNut · 2005-04-05 19:42:02

As far as I can see the creation of Lox from insitu lunar or martian regolith is going to be a show stopper unless the power sources required can be created.
How much down mass could the lifting body give say as a far off Mars lander?

GCNRevenger · 2005-04-05 19:45:03

I think that LOX/LMe is a pretty attractive choice if boiloff can be minimized except perhaps for TLI, when Isp is paramount. It could probobly hit 390sec or so if you used a modified RL-10 engine to burn it (which has been test fired and proposed for use on NASA-DRM and NASA "QQ" TEI stages). If Lunar water is discoverd, then Hydrogen for all engines except TEI and Lunar acent would be preferred, with the option to switch to Hydrogen with minimum development headaches later hopefully.

Anyway, my strategy differs from yours as follows... That development costs and time for the first Lunar expeditions are paramount, even if that means absorbing a higher operating cost. This points to using a capsule-centric system for the early exploration and base setup missions up to the point where Lunar fuels (or at least LOX) are available and mining technologies are ready to go...

...Then the TLI stages and landers are switched to "reuseable" mode, and some time not long after that we go directly to building Shuttle-II to carry both crew and cargo (though not nessesarrily at the same time) and skip building the little HL-8 contraption entirely.

Commodore · 2005-04-05 20:03:35

Weren't there orginally plans to launch the X-38 on a EELV?

The trouble with that is it was only designed to be used once, in the event of a dire emergency were odds are the ISS wouldn't be there to return to.

RobertDyck · 2005-04-05 20:32:33

Uh, yea. There are problems with X-38 for an OSP, although it was studied. X-38 has based on the X-24A which was lighter than HL-20 for the same number of crew, but X-24A has major handling problems at low speed such as landing. X-38 solved that with a parafoil, but that mass defeats the savings vs. HL-20. X-38 had a separate expendable solid de-orbit stage, HL-20 had internal liquid engines/tanks. HL-20 had wheels for landing vs. X-38 skids. HL-20 had solid rocket abort motors and floatation air bags. Basically X-38 was designed to be a single use life boat while HL-20 was purpose built to be a reusable Orbital Space Plane.

After the Hermes was cancelled, ESA looked at X-38 on top of Ariane 5, but that was cancelled for political reasons. (It wasn't European.) It did require some modifications but never would have been as good as HL-20.

John_Frazer · 2005-04-05 23:24:57

> My, getting into the Bush-Bash in the first paragraph

No, I was bashing, if you want to call my criticizing that, the halfway thought-out "space plan" that showed very little sign of having engineering or aeronautical input. (It also immediately showed no progress or support from Bush's administration, and doesn't to this day.)
I note that you didn't say anything about my comment, other than atributing political motivations to it. Anything to say I'm wrong in my assessment of it?

> No actually, not alot work was done on the HL-20/42
concept... No where near a prototype.

I never said it did. Only that they later seem to have ignored what was done, and proceded with the older SLI spaceplane and the CEV without referencing it. Standard procedure, I guess.
And there was more done than aerothermodynamic programs and wind-tunnel models and the plywood model.
And only a fool would think that the "rollout" of the "human factors mock up" of the HL-20 was a flight prototype, and only a bigger fool criticizes it as if it were assumed to be so.

> The problem with HL-20 is that it would weigh about
double what a small capsule would, which basically means you
could either carry wings & wheels or rocket fuel to get home
in a single EELV throw. Pick one.

Yes, for a given throw-weight to orbit, a booster could toss up a slightly bigger ballistic capsule. No news there.
The question we could get into, is if a winged/lifting body vehicle has merits over a capsule. Granted also, it's easier to see a non-reusable capsule, and assume greater cost for a plane, since it is reusable. Again, it's worth debating either way.

I note that the HL-20 was designed to be thrown by a later model Titan booster, and the all-up weight was just over ten tonnes. Variations of present unmanned boosters could handle it without a problem. Do we need more than this thing's payload in a PLS Crew safety vehicle?
The HL-42 launch mass was about 30 tonnes, so it's more problematic.
What sort of capsule were you thinking of? I note that the Soyuz TMA is about 7.2 tonnes.

>> ...assumed that there wouldn't be too much graft and
extra unnecessary things attached to it just to satisfy the
contractors in this or that congressional district..."
>
> Yeah yeah conspiracy to jack up prices astronomically bla
bla bla... this refrain is getting old.

It is getting old to see our progress in space hampered again and again by political pandering in the government procurement process.
But I guess Uncle Sam is really a lilly-white pure virgin, and no such thing goes on in our government.

Let's ignore that and concentrate of learning about the vehicle options.

I for one don't like the HTO piggyback, MAKS type variation. Too much complexity it seems, especially since it hasn't been done (more than the SS1/White Knight or Pegasus), and it assumes adding main propulsion to the spaceplane which as designed cuts costs and complexity by concentrating on carrying crew safely with as little innovation as possible. IMO, I always thought the Spiral/System 49/Bizan/MAKS planes might have amounted to something if they'd stuck with vertical stacking rocket launch, as they have plenty of experience with.
Then again, maybe an expendable engine package attached to the back of the tank or to the plane as the HL-20 was intended to have the booster adaptor and escape rockets attached... Sort of the Bizan without the recoverable main engines.
The System 49 also seems simpler with the orbiter stacked atop the in-line rocket stages, more like the Spiral.

I also don't like the concept of taking the crew launch vehicle -something specifically built to assure crew safety throughout launch, orbit, and landing- out of LEO. That's one of my doubts about the "CEV" multi-use crew vehicle. Stick with LEO and launch safety, and don't try ramming it into the atmosphere at interplanetary transfer velocities.
That was another of my first points I wanted to discuss here: is there any sense in designing one vehicle to be adaptable to do all that, when what we need is a safe crew space launch vehicle?

(edited comment)
To GCNR: please please if you can, avoid the snide comments and witticisms at the expense of other posters. Some of us here don't have our egos involved and don't feel the need to appear superior at all costs and in all ways, about any and all topics.
I note that text-based writing has the tendency of being able to appear more harsh and unforgiving, and I'm trying to take it into account. Please try to be more polite, is all.
(No, you didn't hurt anybody's feelings. Get over yourself.)

srmeaney · 2005-04-06 04:17:48

I realy thought ESA's Hermes would have been a good prospect for the replacement crew vehicle.

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