Author Topic: Are Commercial Crew Vehicles Usable/Upgradeable for Beyond-LEO Needs?  (Read 42020 times)

Offline baldusi

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In my opinion (for what it's worth) Orion should have been largely composite in structure, much like the ATK Liberty proposal which I also think might have been a 'mere' 4.5 meters in diameter and doubtlessly thousands of kilos lighter than Orion's large aluminium/lithium etc structures.

They did build a composite version of Orion, to see what the issues were.

It wasn't any lighter.

Ironically, that composite version of Orion then BECAME Liberty. :-)

Cheers, Martin
There's a paper at NSTR. First, let's remember that we are talking only about the pressure vessel. The short story is that the margins needed to cover for integration accidents, and the cost and difficulty of repairing it meant that it wasn't lighter than the metal PV, it was more expensive, and the integration was quite more difficult because attaching things is very difficult. You can't weld spot, for screws you need to make an insert and then attach. And the thermal expansion is so different.

Offline Rocket Science

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So are people thinking that Commercial Crew capsule vehicles (i.e. CST-100 and Dragon V2) could be an interim solution for short duration exploration?  For non-NASA missions, or if for some reason the Orion is not available?

Or that they could be used more expansively than that?
Golden Spike to the Moon is an example thats still out there for Dragon. Musk seems to be open to mission options if someone wants to pay for it, he'll supply the hardware.
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Online AncientU

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It believe it's passing through the radiation belts too many times that TomH may have been thinking about.

That's true also, however a habitat returning from Mars would need dozens of passes through the very upper atmosphere on a very high apogee ellipse. It would have no TPS at all and could incur very little -ΔV on each pass. I am no expert in orbital mechanics, however I believe it would take much more than the 2 weeks max you believe it would. That means more mass for food, O2, etc., and you have astronauts watching the Earth go by over and over while they cannot land, likely enduring psychological stress from being so near physically, while still so far away temporally.

This is a good argument for taking the capsule with you... separate the capsule with crew a day or two out and return the crew directly through the atmosphere.  Let the uninhabited hab spend the weeks/months aerobraking.  Becomes a trade between amount of fuel needed to decelerate the hab for rendezvous vs mass of the capsule.
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Offline Robotbeat

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IMHO, NASA should be building landers, either for Moon, Mars, or both (preferably Moon) which could double as craft to visit asteroids or Phobos/Deimos. Maybe also a deep space gateway in cislunar space or near Mars, perhaps also Mars habitats and infrastructure, maybe a SEP-based transit vehicle. Launch vehicles and now capsules are totally doable by commercial entities. It's a much better use of restores for NASA to be building landers and such, just buying the services for launch or even now crew taxis and logistics from the likes of Boeing, SpaceX, ULA, Orbital/ATK, Sierra Nevada, and Blue Origin.
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Offline Rocket Science

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IMHO, NASA should be building landers, either for Moon, Mars, or both (preferably Moon) which could double as craft to visit asteroids or Phobos/Deimos. Maybe also a deep space gateway in cislunar space or near Mars, perhaps also Mars habitats and infrastructure, maybe a SEP-based transit vehicle. Launch vehicles and now capsules are totally doable by commercial entities. It's a much better use of restores for NASA to be building landers and such, just buying the services for launch or even now crew taxis and logistics from the likes of Boeing, SpaceX, ULA, Orbital/ATK, Sierra Nevada, and Blue Origin.
I agree with all you said Chris except the "building" part... ;) Let industry do it...
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Online mmeijeri

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That does reduce deep space mission mass. It also means, however, that upon return to Earth, the hab must be decelerated to orbital V prior to rendezvous with a taxi, which means taking the prop with you to deep space and back, or you rendezvous with a tanker prior to Earth arrival. The other choice is a taxi must rendezvous with the hab as it approaches Earth, and you lose the hab.

Braking shouldn't be too much of a problem, if it means inserting into a high earth orbit rather than LEO. The most obvious option would be L1/L2, especially if you have a gateway station there.
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Offline baldusi

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Look at the threads about commercial ISS replacements. There I state some of the things NASA should be working on if they actually wanted to go to BEO. And they could spur a commercial LEO industry. My guess is that if CCtCap is successful and CRS-2 gets at least as good prices as CRS-1, then commercial approach will be validated for HMD. Then we might see some plan for procuring commercially an ISS follow on. But that would be a 2018/19 initiative. That's why the extension to 2028 is so critical. To enable a smooth transition to commercial.
But that can only happen if they don't spend 3B/yr on cargo and crew to the ISS. Else, they simply will not have enough budget. They should get the full commercial services for that amount of nominal money.

Online mmeijeri

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2.  LEO to the region of the Moon and back - this would be a reusable vehicle, likely refueling and refurbishing in LEO.  Getting to the Moon is pretty straight forward, but returning to LEO requires perfecting new techniques.  But if we can't figure this part out then we're not going to be able to afford to send many people BEO.

Things become a lot easier if you give up on symmetry. There is no pressing need to return to LEO, returning from Moon/Mars to L1/L2 and then returning from L1/L2 to Earth without stopping in LEO is much easier.
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Offline ngilmore

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If you think Commercial Crew vehicles will be adaptable for BEO applications, please state what those applications are.

I would say that to be fair, we should assume that the Commercial Crew adapted solution can be as heavy as Orion. Whatever could launch Orion could launch the adapted solution.

Wikipedia says the dry Orion capsule mass is 8,913 kg and the service Module mass 12,337 kg, and propellant 7,907 kg. Habitable volume 8.95 cubic meters.

It says Dragon v2 dry is about 4,200 kg.
Just by way of example of a structure that could be the base of a mission module, the Leonardo MPM is/was 4,082 kilograms and habitable volume 31 cubic meters.

Is 11,962 kg enough mass margin for adding radiation shielding and ECLSS to a mission module and coming in at or below the total Orion mass? And the MPLM is an oversized example, you could cut it in half and still have more room than Orion.

Adding a requirement that the mission module be re-usable is a separate constraint. If the difference in designing a re-usable mission module meant you have to launch on SLS instead of Falcon Heavy, then the total system cost would be lower to not have a re-usable mission module, correct?


Online AncientU

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Need to add LAS mass
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Offline enkarha

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It says Dragon v2 dry is about 4,200 kg.

I'm pretty sure that's just an unsourced copy-paste from the Dragon v1 mass - it should be significantly higher than that with Superdracos/extra tanks, ECLSS, windows &c. Probably more like 6+ tons dry.
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Offline baldusi

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It says Dragon v2 dry is about 4,200 kg.

I'm pretty sure that's just an unsourced copy-paste from the Dragon v1 mass - it should be significantly higher than that with Superdracos/extra tanks, ECLSS, windows &c. Probably more like 6+ tons dry.
Let's not forget the habitat's power generation, heat rejection, cooling, thermal/radiation insulation and comms. And then the fuel for all that. rocket equation applies just as much (assume 35% of stack should be fuel for Orion's equivalent delta-v).

Offline ngilmore

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Need to add LAS mass

Yes, thank you, even more margin. NASA says the gross liftoff weight of the LAS is 7,314 kg.
http://www.nasa.gov/pdf/617408main_fs_2011-12-058-jsc_orion_quickfacts.pdf

The same NASA fact sheet says the total Orion system gross liftoff weight is 31,380 kg.

So that should be top line comparison when asking if commercial crew vehicles could be adapted for BEO.

Online AncientU

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Need to add LAS mass

Yes, thank you, even more margin. NASA says the gross liftoff weight of the LAS is 7,314 kg.
http://www.nasa.gov/pdf/617408main_fs_2011-12-058-jsc_orion_quickfacts.pdf

The same NASA fact sheet says the total Orion system gross liftoff weight is 31,380 kg.

So that should be top line comparison when asking if commercial crew vehicles could be adapted for BEO.
A BA-330 is supposed to 20mT, plus some if shielding for BEO missions is added. That's a lot of room for a crew of six. First BA-330 flight is scheduled for a couple years from now (2016 or 2017, I believe).
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Online TrevorMonty

Both Dragon and CST100 would be ideal for transport to a EML1 way station. The capsules should be able support 3-4 crew for 3.5 days. Both company's have LVs capable of delivering the capsules.


Offline raketa

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Dragon 2 will be probably able to land on Mars, but will be not able to launch back LMO.
1/Dragon 2 landing on Mars - confirm ability to land on Marrs
2/Dragon 2 + Second stage Falcon 9
- will land on Mars I>IIIIIIIIII something like that. Dragon heat shield will slow down and 2 stage will land on Mars with Dargon on top
-refueling methan and launch back to orbit to interplanetary vehicle
-Dargon heat shield will slow down inflatbale at Mars and at Earth, interplanetary vehicle will stay on Mars orbit or  earth orbit. Dragon will slow it just to keep it on the orbit.

Offline pathfinder_01

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2.  LEO to the region of the Moon and back - this would be a reusable vehicle, likely refueling and refurbishing in LEO.  Getting to the Moon is pretty straight forward, but returning to LEO requires perfecting new techniques.  But if we can't figure this part out then we're not going to be able to afford to send many people BEO.


Anyways, that's part of the reason why I don't think today's Commercial Crew capsules are part of the evolutionary line of vehicles that we'll need in the future - I just don't see how they help us scale up the number of people leaving LEO.  And isn't that really the goal?

In terms of going to and from the region of the moon direct reentry to earth would probably be the best bet. It costs less in delta V and you get your vehicle back on the ground where it can be inspected and reused(in theory). I think Dragon at least is perfect for this role. It has enough space that with an smaller crew it could make it to L1/L2 with some upgrades and because it also has an role in LEO should be capable of both missions.

Online Coastal Ron

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In terms of going to and from the region of the moon direct reentry to earth would probably be the best bet. It costs less in delta V and you get your vehicle back on the ground where it can be inspected and reused(in theory).

To me that's like saying all Boeing aircraft would have to land in Everett WA to be inspected and refueled after every flight.  It's hard to scale a transportation system like that.

If we want to expand humanity out into space, then fuel has to become a commodity in space, just like it is here on Earth.  And with that fuel you don't have to worry as much about delta V, because that just becomes part of your fuel budget.  Breaking transportation routes into segments also allows you to build vehicles that are optimized for each route segment, as well as reusable.

We have to get past the Apollo paradigm if we want to do more in space.
If we don't continuously lower the cost to access space, how are we ever going to afford to expand humanity out into space?

Online guckyfan

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To me that's like saying all Boeing aircraft would have to land in Everett WA to be inspected and refueled after every flight.  It's hard to scale a transportation system like that.

I disagree. Landing back on earth is the operationally simplest and cheapest method once you have reduced launch cost through reusability. What you are suggesting is another airport somewhere out in the desert to go to instead of flying between two destinations. With that airport in the desert being out of the way and needing a lot of additional facilities that are only needed because you chose to build that extra airport.

Online mmeijeri

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We have to get past the Apollo paradigm if we want to do more in space.

Sure, but that doesn't mean choosing direct return to Earth is an example of the Apollo paradigm.

I see the most promising path as commercial transport to a commercially operated LEO way station, followed by commercial transport to a waiting NASA MTV based at L1/L2 (using as many commercially available components as possible, such as Bigelow habs) which is supplied by commercially operated tankers at L1/L2, Sun Mars L1/L2 and Phobos / Deimos / LMO. Eventually, there could also be commercially operated way stations at L1/L2, Sun Mars L1/L2 and Phobos / Deimos / LMO.

Aerobraking back to LEO is very difficult, propulsive return to LEO is expensive, while propulsive return to L1/L2 and direct return from L1/L2 to Earth are both cheap and straightforward. I don't see much benefit from changing to a separate LEO capsule for return, especially since the return capsule from L1/L2 can be a properly modified Dragon or CST-100.
« Last Edit: 10/07/2014 05:58 PM by mmeijeri »
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