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#80
by
Nilof
on 02 Dec, 2014 19:42
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Imho, a lot of the issues are due to the fact that the Orion is way too big for a reentry vehicle.
If Orion is too big for a reentry vehicle, then what was Shuttle?
[ Huge embedded image ]
Winged, and too heavy to bring with you beyond LEO. The issue of Orion is that it's geometry is a scale-up of the Apollo shape. But because it is bigger, its ballistic coefficient will naturally be higher and it's L/W ratio will be lower, meaning it has to brake down lower in the atmosphere and be subjected to more g's. To alleviate the issue you have to push it to the edge of material science, which explodes development cost. It also leaves the vehicle oversized and unnecessarily heavy for missions that do not require the extra volume.
The ideal design for the reentry module of a beyond-LEO craft imho, is lightweight and just barely big enough to cram your crew into for the reentry/earth return. If you want living space, there are much more lightweight designs available as a result of the ISS program.
Wrong, it is not "too"big, nor is it for long duration flights. There is no need to "split"it, and long duration flights will have another module.
The thing is, if it isn't for long-duration flights, and it isn't a competitive LEO vehicle, what is it for? If a vehicle is outperformed by existing vehicles in all but an extremely narrow set of missions and is costly enough to cut NASA's unmanned mission manifest by half, it is a monstrosity that should be canceled immediately. For the very few missions where it may outperform the competition (such as ARM), you're better off accepting the disadvantages of alternative vehicles than wasting your entire manned budget on a vehicle that will never see use.
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#81
by
Oli
on 02 Dec, 2014 21:49
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Orion's diameter is only 44cm or ~10% larger than that of CST-100. I'm not sure that qualifies as being too big. If you would make it smaller, you'd need an additional habitat module for every transfer to cis-lunar space. I guess its a trade-off.
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#82
by
Endeavour_01
on 03 Dec, 2014 01:01
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The JPL missions certainly do return a lot of science per dollar. Sadly, there's going to be a lot fewer of them in this decade. Orion/SLS is swallowing up a very big slice of the Nasa budget.
That is incorrect. SLS/Orion account for about 1/6th of the NASA budget. SMD gets a bit less than a third. SLS/Orion aren't eating up SMD funds. The fact is that the current administration is not a fan of most of what NASA does (that includes manned (except for Com. Space) and unmanned space exploration). The administration has been cutting back on Planetary Science of their own accord.
Imho, the best way forward would be to get rid of the Orion entirely, and consider a Dragon expanded with a Cygnus or an MPLM-derived habitat for mission durations that are actually interesting, instead of trying to fight physics to make the Orion reentry work out.
Dragon V2 is optimized for manned LEO trips. I don't think you could just slap a hab module on it and it would be good to go. If it can then fine I say lets use it. What I am not in favor of is canceling something we have poured a lot of time and resources into just because we
might have something that can do the job coming down the pike.
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#83
by
MattMason
on 03 Dec, 2014 01:18
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My two cents as an ordinary space enthusiast:
SLS isn't a saleable item without a mission. And "asteroid retrieval" certainly isn't going to keep any Congress funding it for long.
But asteroid impact prevention (as in, "Holy crap, it's coming right for us!")? That's saleable. Make a joint session of Congress and make a mix-up film reel of "When Worlds Collide," "Armagaddeon" and "Deep Impact." Tell them that, if a big rock comes right now, we have nothing like that now, as seen in the movies, to stop it.
At the very least, Congress could be convinced to make SLS a vehicle that could do the job. In fact, NASA's already selling us that as "asteroid mining" or something silly. Logical so tin-foil folks won't assume an asteroid is really coming with that message.
And then, NASA can say, "going to the moon and creating a base there will be our starting point." SLS can haul what's needed. This can be the launch point for a new station for exploration, commercial, scientific and world defense. NASA can test out the things that are needed to survive BEO, especially radiation shielding, food production, power systems and fuel production.
All we need is someone to clearly form a plan and a reason. And, get a Commercial Crew/Exploration initiative for any businesses that want to locate there. And bonus points for a hotel initiative.
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#84
by
JH
on 03 Dec, 2014 01:30
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If Orion is too big for a reentry vehicle, then what was Shuttle?
A really nifty camel?
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#85
by
Nilof
on 03 Dec, 2014 10:31
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Orion's diameter is only 44cm or ~10% larger than that of CST-100. I'm not sure that qualifies as being too big. If you would make it smaller, you'd need an additional habitat module for every transfer to cis-lunar space. I guess its a trade-off.
Well yes... you'd need an extra habitat for... two transfers to cis-lunar space. One of which is being postponed for god knows how many years. If congress wants a lunar landing, the orbital module can be replaced with a lunar lander. There are very few missions for which you'd want to send a capsule and nothing else BEO.
A 10% linear scaleup corresponds to a ~33% mass increase. It is the difference between a vehicle that can be launched on a Falcon 9/Atlas V 421, and requiring a much more expensive Delta IV heavy or custom-built Ares I to lift it. The extra weight really kills off any hope of using the Orion for any LEO activities.
Compare the current LockMart Orion to Boeing's proposal from 2005, which handled the BEO requirement with an optional orbital module. The capsule itself evolved into the CST-100, which is a financially viable vehicle for sending people to the ISS. It could have served both the BEO and the ISS needs without the current duplication of effort. Now NASA is effectively paying for both proposals.
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#86
by
Oli
on 03 Dec, 2014 11:52
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There are very few missions for which you'd want to send a capsule and nothing else BEO.
Sure but with Orion you can put any type of cargo in the lower position.
It is the difference between a vehicle that can be launched on a Falcon 9/Atlas V 421.
Boeing's CEV you mention was 26t with mission module and 20t without. Orion is 21.25t.
http://www.astronautix.com/craft/cevoeing.htm
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#87
by
Nilof
on 03 Dec, 2014 13:15
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Boeing's CEV you mention was 26t with mission module and 20t without. Orion is 21.25t.
http://www.astronautix.com/craft/cevoeing.htm
That is using a high delta-v service module with 9.5 tonnes of Methalox propellant for a lunar mission, which is sized to push the entire stack mass regardless of the mass of the reentry module. The Boeing reentry module would have weighed in at 6.5 tonnes vs 9t for the Orion capsule. And it got reworked into a capsule that actually delivered a competitive offer for ISS crew transport, which was not the case for Orion.
Either way, the Dragon is even lighter and cheaper. Docked to an extended Cygnus, you could get ~36 cubic meters of pressurized space vs 20 cubic meters in an Orion, for a similar mass and a smaller development budget. Both vehicles are already competitive ISS resupply vehicles so they do not have to defend their existence. You also get more redundancy in case of an Apollo 13 incident, which cannot be provided by a single-vehicle design like Orion. And as an added bonus, you don't have to depressurize the entire vehicle for an EVA.
I could go on and on about why I feel that the Orion is a lackluster spacecraft. But my primary argument is that it provides no unique capability that is both useful and was not available before. The budget would be better spent on a specialized spacecraft that is actually capable of extended missions, leaving the reentry role to Dragon.
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#88
by
Endeavour_01
on 03 Dec, 2014 14:39
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Either way, the Dragon is even lighter and cheaper. Docked to an extended Cygnus, you could get ~36 cubic meters of pressurized space vs 20 cubic meters in an Orion, for a similar mass and a smaller development budget.
I love Dragon and I like using an extended Cygnus as a hab but I don't think Dragon can fulfill the BEO role that Orion can. Dragon V2 is optimized for LEO while Orion is optimized for BEO. Dragon V2 doesn't need to have as many redundancies as Orion since it is only going to LEO and back with people.
I could go on and on about why I feel that the Orion is a lackluster spacecraft. But my primary argument is that it provides no unique capability that is both useful and was not available before. The budget would be better spent on a specialized spacecraft that is actually capable of extended missions, leaving the reentry role to Dragon.
Orion isn't perfect but it also isn't a "lackluster" spacecraft. Why can't we all be happy that we have 2 LEO ships and 1 BEO ship coming down the pike instead of badmouthing Orion and treating Dragon as "the one and only true spacecraft?"
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#89
by
Oli
on 03 Dec, 2014 15:19
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Either way, the Dragon is even lighter and cheaper. Docked to an extended Cygnus, you could get ~36 cubic meters of pressurized space vs 20 cubic meters in an Orion, for a similar mass and a smaller development budget.
Oh please, you know its not that easy.
Both vehicles are already competitive ISS resupply vehicles so they do not have to defend their existence.
You could also argue that commercial crew makes no sense when the ISS is retired early (2020/2024).
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#90
by
dks13827
on 03 Dec, 2014 19:28
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Way too many HSF events these days seems to be in "5 or 10 years, or more". I would call this a very disturbing trend. Very disturbing.
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#91
by
sdsds
on 03 Dec, 2014 21:02
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Way too many HSF events these days seems to be in "5 or 10 years, or more". I would call this a very disturbing trend.
It is important to keep track of which "events" really matter. Humans once again launching from the United States matters. Humans once again heading to (and safely returning from) beyond LEO matters. Humans crawling around on a captured piece of asteroid? Not so much.
If the visit to an asteroid is put off far enough, some other crewed mission can be inserted into the manifest before it. That mission, if accomplished successfully, will be a sign of an encouraging rather than disturbing trend!
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#92
by
pathfinder_01
on 03 Dec, 2014 22:15
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I love Dragon and I like using an extended Cygnus as a hab but I don't think Dragon can fulfill the BEO role that Orion can. Dragon V2 is optimized for LEO while Orion is optimized for BEO. Dragon V2 doesn't need to have as many redundancies as Orion since it is only going to LEO and back with people.
Orion isn't perfect but it also isn't a "lackluster" spacecraft. Why can't we all be happy that we have 2 LEO ships and 1 BEO ship coming down the pike instead of badmouthing Orion and treating Dragon as "the one and only true spacecraft?"
In terms of redundancies ah, coming down from the ISS isn't the same as pulling over to the side of the road with an car. It is more like flying where you need back up systems. Orion simply has more endurance and a deep space capable communications an navigation ability. Basically more supplies and better electronics. Something a different service module could fix and it is useless for much in BEO. No lander means can only orbit the moon, no hab means very short missions only and the need to depressurize the cabin is really going to limit spacewalks.
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#93
by
jtrame
on 03 Dec, 2014 22:43
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I love Dragon and I like using an extended Cygnus as a hab but I don't think Dragon can fulfill the BEO role that Orion can. Dragon V2 is optimized for LEO while Orion is optimized for BEO. Dragon V2 doesn't need to have as many redundancies as Orion since it is only going to LEO and back with people.
Orion isn't perfect but it also isn't a "lackluster" spacecraft. Why can't we all be happy that we have 2 LEO ships and 1 BEO ship coming down the pike instead of badmouthing Orion and treating Dragon as "the one and only true spacecraft?"
In terms of redundancies ah, coming down from the ISS isn't the same as pulling over to the side of the road with an car. It is more like flying where you need back up systems. Orion simply has more endurance and a deep space capable communications an navigation ability. Basically more supplies and better electronics. Something a different service module could fix and it is useless for much in BEO. No lander means can only orbit the moon, no hab means very short missions only and the need to depressurize the cabin is really going to limit spacewalks.
Neither Dragon or CST 100 have. airlocks either, and they do not have the comms, the navs, supplies, etc.
At least NASA is talking about Habs. The opportunity exists to leverage the SLS tooling and build a hab large enough to address shielding and the need for humans to have enough interior space to keep sanity on a long voyage (Skylab 2, if you want to google the concept). Yes, just a powerpoint, yes no roadmap, yes no funding.
In the 3 years I've been hanging out here this same discussion comes up periodically, the thread keeps changing but the only constant is SLS is being built, infrastructure at the cape is being changed to accommodate it, the first Orion FTA launches tomorrow, and the naysayers have changed from "it will never fly" to "well it will only fly once, or twice, or definitely not more than three times, or twelve times."
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#94
by
Coastal Ron
on 03 Dec, 2014 23:08
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Neither Dragon or CST 100 have. airlocks either, and they do not have the comms, the navs, supplies, etc.
Capsules of any type, including the Orion, are not the future of space travel. They are too small to support humans for any length of time in space, and are really only needed when close to a planet with a thick enough atmosphere.
At least NASA is talking about Habs.
NASA "talks" about a lot of things, but actually is allowed to do very little per their budget.
The opportunity exists to leverage the SLS tooling and build a hab large enough to address shielding and the need for humans to have enough interior space to keep sanity on a long voyage (Skylab 2, if you want to google the concept).
There is no known reason that I'm aware of to build habitable modules larger than what we already know how to build for the ISS (essentially ~5m in diameter). The designs and tooling already exists and the hardware has already been proven out in space.
Building HLV-sized modules limits where the hardware can be built (i.e. transportation limitations), which means factories for existing space hardware can't be used. That increases the costs for HLV-size missions, which is already an issue for using the Orion and SLS.
Yes, just a powerpoint, yes no roadmap, yes no funding.
Just like all plans that require the Orion and the SLS...
In the 3 years I've been hanging out here this same discussion comes up periodically, the thread keeps changing but the only constant is SLS is being built, infrastructure at the cape is being changed to accommodate it, the first Orion FTA launches tomorrow, and the naysayers have changed from "it will never fly" to "well it will only fly once, or twice, or definitely not more than three times, or twelve times."
The other constant that you forget to mention is the lack of any funding to USE the Orion or the SLS. That continues to be the true indicator of what's in store for the Orion and SLS, not any of our opinions.
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#95
by
ncb1397
on 03 Dec, 2014 23:28
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The other constant that you forget to mention is the lack of any funding to USE the Orion or the SLS. That continues to be the true indicator of what's in store for the Orion and SLS, not any of our opinions.
I thought they were essentially going to at minimum fly an Apollo 8-esque mission(an achievement in its own right), which although sort of depressing is less depressing than the retreat of U.S. HSF capabilities from Lunar, to LEO and eventually to outsourcing to the Russians with the eventual future trajectory suggesting this will end with a trampoline to test the techniques and capabilities of HSF operations on another planetary surface.
Anyways, spending the real money for payloads to fly SLS frequently is a bit presumptuous. You have to show that it works first. Cancelling yet another HSF program before a more capable alternative is available won't solve anything and will simply perpetuate the trend described above.
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#96
by
pathfinder_01
on 04 Dec, 2014 03:42
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Anyways, spending the real money for payloads to fly SLS frequently is a bit presumptuous. You have to show that it works first. Cancelling yet another HSF program before a more capable alternative is available won't solve anything and will simply perpetuate the trend described above.
The trouble is that it can take 8-10 years to develop payloads to go on top of a rocket, any rocket so SLS idles with nothing worthwile to do for an long time and Orion simply can't do much by itself. It can't attempt to replace the ELV the way the shuttle tried but failed to do back before 1986. When it launched communications satellites and so on. It can't land a man on the moon asap as no lander is in development(unlike Apollo where all elements needed were developed in parrell and like Apollo risks being shutdown for lack of use).
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#97
by
sdsds
on 04 Dec, 2014 04:27
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The trouble is that it can take 8-10 years to develop payloads to go on top of a rocket
Sure it
can. But it doesn't
have to take that long. Particularly if the payload is an easy derivative of a prior payload. In particular, a second Orion modified to be a mission module could come off the existing assembly line in much less time than that. Just leave off the heat shield; how hard can that be to develop?
Now some may think such a payload and the mission it would enable aren't "worthwhile." Frankly, those pessimists would do well to reconsider what's worth what!
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#98
by
symbios
on 04 Dec, 2014 11:58
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Way too many HSF events these days seems to be in "5 or 10 years, or more". I would call this a very disturbing trend.
It is important to keep track of which "events" really matter. Humans once again launching from the United States matters. Humans once again heading to (and safely returning from) beyond LEO matters. Humans crawling around on a captured piece of asteroid? Not so much.
If the visit to an asteroid is put off far enough, some other crewed mission can be inserted into the manifest before it. That mission, if accomplished successfully, will be a sign of an encouraging rather than disturbing trend!
I can not understand this. If we are to expand into space we need resources. It is to expensive to get everything out of any gravity well (Earth/Moon/Mars). We need inexpensive rides to space and we need resources in space.
Any ship that is going to be good enough to travel in our star system has to be built in space. To do this we need a community in space. To do this there has to be resources in space.
Asteroids is the only way I see this ever happening. Anything that will get us there is a good thing. That is why I am positive to this mission and companies working for this goal.
We need to get into space not get stuck in another gravity well.
Edit: (Well it would also be nice to be able to redirect rocks aimed at Earth.)
That is my 2 cents.
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#99
by
gospacex
on 04 Dec, 2014 11:59
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"Orion’s crewed asteroid mission unlikely to occur prior to 2024" because "Orion’s crewed asteroid mission unlikely to occur at all".