Author Topic: Are Commercial Crew Vehicles Usable/Upgradeable for Beyond-LEO Needs?  (Read 45610 times)

Online Coastal Ron

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This question came up on a different thread, so I thought I would start a specific one to collect everyones thoughts.

The subject came up when I responded to a statement from Robotbeat:

I will say one thing: since both designs chosen were capsules, they are both relevant for any future BLEO missions and should be considered for inclusion by mission planners.

None of these vehicles will be evolved for BLEO - they are too small.  Be glad to talk on another thread about it if you want...

A number of people agreed with Robotbeat, or at least with the idea that Commercial Crew vehicles could be adapted for beyond LEO needs.

My reasons for saying that Commercial Crew vehicles are too small is that I think we have learned that for humans to stay healthy in space that they need a lot of room, so future human space travelers are not going to be spending most of their time in a capsule like the Dragon or CST-100.  Plus, capsules are really only designed for transporting humans to/from a planet with an atmosphere, so at most my view is that if we take them BEO it's only for use as a lifeboat and for the "last mile" of getting humans down onto a planet.  And currently the only planet we know we can land them as currently designed is Earth, so why not leave them orbiting in LEO and just plan to meet back up with them in Earth orbit on the way back?

If you think Commercial Crew vehicles will be adaptable for BEO applications, please state what those applications are.  For instance, would you envision using a CST-100 for visiting an asteroid or only for trips to the Moon?

And if you don't think they are applicable, go ahead and state what your alternative would be.
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Offline Lars-J

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Yes. But there is limited use in taking them with you past some kind of L1/2 gateway station.

Offline TomH

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Yes. But there is limited use in taking them with you past some kind of L1/2 gateway station.

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.

All three of these involve increased risk. Aerobraking takes too much time with a crew aboard.

Offline Robotbeat

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My point was that Dragon and CST-100 and Orion and Apollo command module, etc, all would need an extra module, so all are big enough with a module and none are big enough without a module, assuming beyond short trips to and from an EML gateway or something. And they are big enough for a few days.

I mean Gemini was cartoonish lot small for 2 guys (WAY smaller than CST-100, Dragon, etc), and they spent 2 weeks in it. Dragon or CST-100 are like mansions compared to Gemini.
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Online Coastal Ron

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Aerobraking takes too much time with a crew aboard.

If a crew is coming back from a 6-month mission to an asteroid, or a 2-years mission to Mars, is spending a week or two decelerating into LEO "too much time"?

To me it simplifies the system architecture by relying on LEO-only vehicles for transport to/from Earth, and space-only vehicles for the mission.
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Offline QuantumG

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It believe it's passing through the radiation belts too many times that TomH may have been thinking about.
« Last Edit: 10/06/2014 02:08 AM by QuantumG »
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Offline Robotbeat

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Doesn't take much to thicken heatshields for faster reentry if they already use ablatives.
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Offline llanitedave

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If the habitat is launched/built separately and put in a permanent cycling orbit, then the capsule could rendevous with it during Earth approach, go along with it on the mission, then separate and return to Earth on the return leg.  That way you only have to expend the energy to accelerate the habitat once.  The capsule may still be dormant, but at least you wouldn't have to launch a new habitat along with it for each mission.
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Offline TomH

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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.

Offline TomH

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My point was that Dragon and CST-100 and Orion and Apollo command module, etc, all would need an extra module, so all are big enough with a module and none are big enough without a module, assuming beyond short trips to and from an EML gateway or something. And they are big enough for a few days.

I mean Gemini was cartoonish lot small for 2 guys (WAY smaller than CST-100, Dragon, etc), and they spent 2 weeks in it. Dragon or CST-100 are like mansions compared to Gemini.

Yea, this was the main point in the other thread, and Chris is spot on with this. For lunar missions, you only need something slightly larger/more massive than Apollo CM. For beyond lunar, you need something with much more volume than Orion. Orion is perfectly suited for.....absolutely no mission, and it is too massive for its parachutes. Something the mass of CST-100 would be fine on lunar missions. For asteroids, Mars, Phobos a hab is needed. The capsule needs to be nothing more than a taxi to either Luna or LEO and from Luna or a deeper space habitat for reentry. Either it is dormant the rest of the time or (for deeper space) it doesn't go at all.

@IIanitedave, yes an Aldrin cycler is another possibility. Much more complex mechanics are involved though. Aldrin was (is) a genius in that field. That's why he was a good #2 with Neil. Despite his ego, he was most equipped to run LOR calculations had navigational aids gone down.

Online Coastal Ron

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If the habitat is launched/built separately and put in a permanent cycling orbit, then the capsule could rendevous with it during Earth approach, go along with it on the mission, then separate and return to Earth on the return leg.

I would imagine this would require a powerful upper stage to do this, and let's say it's possible.

But is this the type of transportation system what we want to use for enabling us to send more humans beyond LEO?  It doesn't seem very scaleable to me.

I would think that what we should be shooting for is a transportation system that is broken up into the following segments:

1.  Earth to LEO and back - this would be covered by Commercial Crew vehicles, and any others that come along.  Essentially this will already be paid for by NASA because of their ISS support needs.

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.

3.  Transportation to/from Earth's orbit - this too should be a reusable vehicle, although refueling and refurbishing may need to take place near the region of the Moon.  Lots of options for this, including the cycler-type vehicle, or one that slows down by spending time dipping down into Earth's gravity well.

Now maybe this is an ideal transportation system, and certainly we're only just getting close to getting the transportation segment to LEO and back put in place.

But if we're going to spend money on ways to leave LEO, I would hope we take the long view.  That doesn't always happen with government programs, and NASA certainly isn't funded for doing that today.  And that's a topic of it's own...

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?
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Online Coastal Ron

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...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.

Isn't that what the crew on LEO space stations experience all the time, watching the Earth go by?

Look, if being able to see the Earth close-by after being gone for potentially years doesn't bring comfort to the crew, then I think we would have chosen the wrong people...
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Offline sdsds

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Orion is perfectly suited for.....absolutely no mission

To the contrary I think Orion is the right size to taxi a crew of four between Earth and a space station in the lunar vicinity, e.g EML1, EML2, or DRO.

The current design is too heavy for this (due to the parachute issue), and no one who knows why seems willing to say. I've expressed my guess that it's the result of structural mass left over from CxP mission requirements that is not required in this taxi role. That mass could be taken out by redesigning the structure. Alternately, EFT-1 may show a way to reduce mass, if it indicates the heat shield is over-built.
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Offline enkarha

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I though Orion was pretty good for journeys to/from L-point gateways for all the reasons Baldusi mentioned in the other thread.
But having BEO rated avionics, heat transfer through heat plates, high distance comm system, long term ECLSS, BEO astrogation capabilities, limited radiation protection for crew, etc. those thing are the hard part.
Orion is just about capable of a 8 day journey out and 4 days back(~350 m/s outbound and ~1200 return) or the reverse. For those long journeys to/from those points a nice roomy spacecraft is doubtlessly better. What I'm unsure of is that adding these various capabilities to the CC vehicles can be done without adding back mass and cost.

However, if Dragon V2 is something like the vehicle the DragonFly EIS describes, it might be capable of doing 8 day trips both ways to L2 if they launch on falcon heavy and use the upper stage for the moon swingby burn, or even without that if they slim it down a few hundred kilos.
« Last Edit: 10/06/2014 06:33 AM by enkarha »
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Offline R7

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To the OP: Whose BLEO needs?

The Chief Designer: obviously Dragon is on it's path to fulfill his.

NASA: BLEO CCVs would give Orion severe existential crisis. Might have to consider building a lander instead  :o

Inspiration Mars: too late for their window?

Mars One: *giggle*
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Offline MATTBLAK

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Orion is perfectly suited for.....absolutely no mission

To the contrary I think Orion is the right size to taxi a crew of four between Earth and a space station in the lunar vicinity, e.g EML1, EML2, or DRO.

The current design is too heavy for this (due to the parachute issue), and no one who knows why seems willing to say. I've expressed my guess that it's the result of structural mass left over from CxP mission requirements that is not required in this taxi role. That mass could be taken out by redesigning the structure. Alternately, EFT-1 may show a way to reduce mass, if it indicates the heat shield is over-built.

Because it's 5 meter diameter has always made it a bit too large to have credibly light mass - with the original 5.5 meter spec was even sillier. 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 possibly lighter than Orion's large aluminium/lithium etc structures. And I'm thinking if CST-100 (wish they'd give it a name) was given Orion's Service Module and other upgrades (life support, rad-shielding, flight software, heatshield  ::) ) then could it be a substitute for Orion if it were ever cancelled?!
« Last Edit: 10/07/2014 06:11 AM by MATTBLAK »
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Offline MP99



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. :-)

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Offline newpylong

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Of course they could, but after modifications they are no longer the commercial crew vehicles we know of today, they are bigger, and bulkier like Orion.

Offline Rocket Science

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Add Cygnus as a Hab to CST-100 (with heat shield upgrade to BEO) and the Orion SM and you're good to go...
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Online Coastal Ron

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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?
If we don't continuously lower the cost to access space, how are we ever going to afford to expand humanity out into space?

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