NASASpaceFlight.com Forum
SLS / Orion / Beyond-LEO HSF - Constellation => Orion and Exploration Vehicles => Topic started by: redliox on 03/15/2018 03:29 pm
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Plans for the Deep Space Gateway - Lunar Orbiting Platform appear to be materializing, at least in paper and powerpoints. While, like many of us, I can't help questioning NASA's plans and motivations (since they've been in flux especially after the shuttles' retirement), I don't see the Gateway as a bad idea; perhaps a mild distraction from Mars at worst. However a more practical concern comes up...
Even when Orion gets up and running, there will only be 5 flights before it gets benched. This is because the OMS engines inherited from the shuttles are in limited supply. This thread elaborates on that specific issue: https://forum.nasaspaceflight.com/index.php?topic=45002.0 (https://forum.nasaspaceflight.com/index.php?topic=45002.0)
In turn, this is going to affect the Gateway's construction plans and maintenance...since both are linked with Orion flights. If everything goes right, there would be only 4 flights with modules co-manifested with Orion. This seems sufficient to create the core of Gateway, but excludes future modules agencies like JAXA and Roscosmos would be interested in providing. A bottleneck problem to say the least.
My opinion is, unless Orion gets around its upcoming service module crisis, the Gateway will inherently have to turn to other vehicles. The SLS could probably deliver more modules, so long as said-modules can fly themselves to the Gateway; adding them will be easy since there will be a robotic arm for Gateway. Orion's development is going to affect this future station, although it may not entirely impede it.
Inject your thoughts, and if there's more information about the Gateway's plans do provide it here too.
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I am sorry but your basic premise makes no sense. Do you really believe that NASA is sitting on their hands waiting for their stockpile of OMS engines to be depleted ?
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I am sorry but your basic premise makes no sense. Do you really believe that NASA is sitting on their hands waiting for their stockpile of OMS engines to be depleted ?
Given the likely delays and uncertainty driven by possible future events, a degree of hand-sitting might not be entirely inappropriate.
Committing now to purchasing engines for something required in - optimistically - 2027 may not be the frugal course of action. They have at least asked interested suppliers to contact them.
To strictly answer the question asked, there seems little insurmountable technical reason to co-manifest DSG parts with Orion.
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I don't think it makes much sense to develop Zvezda-style modules which can deliver themselves to the station. Reusable spacecraft make more sense, but neither Dragon nor Starliner have sufficient propulsion for these cislunar mission profiles. Blue Origin appears to be more focused on an exoatmospheric lander than a reentry vehicle. BFR/BFS could plausibly do cislunar missions, perhaps relying on an existing arm to transfer the module from the payload bay to the berthing mechanism.
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I am sorry but your basic premise makes no sense. Do you really believe that NASA is sitting on their hands waiting for their stockpile of OMS engines to be depleted ?
Given the likely delays and uncertainty driven by possible future events, a degree of hand-sitting might not be entirely inappropriate.
Committing now to purchasing engines for something required in - optimistically - 2027 may not be the frugal course of action. They have at least asked interested suppliers to contact them.
Exactly. I used "benched" for a reason. Orion (or more accurately its service module) may be redesigned, minimally or extensively, or outright retired depending on what's actively available in the mid and late 2020s. NASA (or the Congressmen and President directing it) may decide to go fully commercial or ESA might be unable to supply further service modules. Orion will at the least face a gap in flights just like between EM-1 and EM-2 where hardware modifications are made for the SLS blocks; at worst retired on the grounds that Gateway is complete and better options exist; Orion will likely need to evolved to survive. DSG might manage, just as ISS manages without the shuttles that built it.
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I don't think it makes much sense to develop Zvezda-style modules which can deliver themselves to the station. Reusable spacecraft make more sense, but neither Dragon nor Starliner have sufficient propulsion for these cislunar mission profiles. Blue Origin appears to be more focused on an exoatmospheric lander than a reentry vehicle. BFR/BFS could plausibly do cislunar missions, perhaps relying on an existing arm to transfer the module from the payload bay to the berthing mechanism.
There are different ways to go about it. The shuttle/STS combined the whole package of delivering a small/medium-size module with a vehicle to support it. Something like a Starliner and even Orion would have trouble tackling more than a small module, although able to contribute in small doses. The Zvezda approach may seem antiquated, but Russia and China will continue it, the Skylab was delivered in one piece this way, and the SLS could deliver at least medium-size modules to lunar orbit, so if you can knock it try it. The Gateway's core assembly will include a robotic arm, so with or without Orion it will be able to add new modules.
The answer to the thread question lies in what options will be available in the mid-2020s.
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You could always just put a second copy of the the 8 backup engines in a cluster on the back. Or...just use the backup engines once those are fully qualified and tested without the OMS. Once DSG is assembled, you likely don't need the extra power(aux engines can get Orion crew home without the OMS).
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The backup engines are already thoroughly proven, but theres a reason they're backup engines. ISP is much lower, and gravity losses will be higher (though still relatively small). During most of the mission, they'd only be enough for an abort, not a complete and safe mission
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I don't think it makes much sense to develop Zvezda-style modules which can deliver themselves to the station.
I was assuming something rather simpler - FH S2, with somewhat longer than demonstrated coast directly placing the module very near the station.
I can't remotely see a role for any existing DSG hardware in a world where BFS can dump nearly a hundred tons next to the gateway in one lump, and return to earth, so I was assuming it did not exist for the purpose of this thread.
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The backup engines are already thoroughly proven, but theres a reason they're backup engines. ISP is much lower, and gravity losses will be higher (though still relatively small). During most of the mission, they'd only be enough for an abort, not a complete and safe mission
ISP on the R-4D is listed as 312 s on wikipedia. The OMS is listed at 316 s. Like I said, the extra power is only needed when towing a ~10 mT module. After construction, logistics modules would have some wiggle room in terms of logistics load. OMS engine does have about 6x the thrust, which can be counter-acted by a longer burn with some delta-v impacts. But since Orion only needs to go ~800 m/s to DSG and back, it has plenty of margin.
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I can't remotely see a role for any existing DSG hardware in a world where BFS can dump nearly a hundred tons next to the gateway in one lump, and return to earth, so I was assuming it did not exist for the purpose of this thread.
I really hope the ITS/BFS materializes, but you have to grant that from SpaceX's pov servicing the Gateway will be another job it can be paid for, regardless of utility or role.
As far as hardware, there could be more than one type of module and I'm not just talking logistics or science functions. The ISS includes both Russian modules based on the 1980s Mir and a 2010s Bigelow inflatable module; likewise Gateway could eventually develop a range of modules; imagine the core modules Orion delivers getting coupled with a Bigelow Olympus as an example.
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In turn, this is going to affect the Gateway's construction plans and maintenance...since both are linked with Orion flights. If everything goes right, there would be only 4 flights with modules co-manifested with Orion. This seems sufficient to create the core of Gateway, but excludes future modules agencies like JAXA and Roscosmos would be interested in providing. A bottleneck problem to say the least.
The premise is wrong. It is no more a bottle neck than # of remaining SSME's and SRM casings for SLS. They are limited to 4 flights. And going to other launch vehicles for DSG is a non starters. DSG exists to give Orion and SLS something to do.
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Interesting thread, I don't think SLS will fly more than 3 times if that, but I have liked the DSG idea, other than the visit frequency restrictions imposed by SLS. I never thought that SLS seemed necessary for it, and figured that it might be designed so that it could survive a cancellation of SLS. It seems like design not requiring SLS is actually happening.
SNC has specifically pitched that their PPE design could also double as a LEO-lunar cargo shuttle. If I understood it right that basically should be enough to build up the full DSG/LOP-G without SLS at all. Their PPE itself is designed to not need SLS to begin with.
The remaining question is crew, I think the PPE is primarily ion thrusters, so it might be non-ideal for crew transfer, but Blue Origin should have an orbital crew vehicle by the mid 2020s, and I'd expect they could reasonably send that to the moon. Modified dream chaser or CST-100 are also possible.
BFR is an interesting wrench, but without having added it up in too much detail, I think the multiple refuellings needed to send stuff to the moon means that there will be room for other options better optimized to send (relatively) small payloads to the moon, and at least early on I don't expect anyone will be building things that fully utilize BFR.
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BFR is an interesting wrench, but without having added it up in too much detail, I think the multiple refuellings needed to send stuff to the moon means that there will be room for other options better optimized to send (relatively) small payloads to the moon, and at least early on I don't expect anyone will be building things that fully utilize BFR.
I think it's fair to assume that refuelling 8 times is likely to be substantially cheaper than several billion dollars.
And given BFS is basically pretty much everything you could hope for in DSG, I think it's fair to neglect it totally in discussion of DSG.
DSG only happens (in its 'final' form) if BFS and other efforts fail utterly.
This is of course a possibility.
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Plans for the Deep Space Gateway - Lunar Orbiting Platform appear to be materializing, at least in paper and powerpoints. While, like many of us, I can't help questioning NASA's plans and motivations (since they've been in flux especially after the shuttles' retirement), I don't see the Gateway as a bad idea; perhaps a mild distraction from Mars at worst. However a more practical concern comes up...
Even when Orion gets up and running, there will only be 5 flights before it gets benched. This is because the OMS engines inherited from the shuttles are in limited supply. This thread elaborates on that specific issue: https://forum.nasaspaceflight.com/index.php?topic=45002.0 (https://forum.nasaspaceflight.com/index.php?topic=45002.0)
In turn, this is going to affect the Gateway's construction plans and maintenance...since both are linked with Orion flights. If everything goes right, there would be only 4 flights with modules co-manifested with Orion. This seems sufficient to create the core of Gateway, but excludes future modules agencies like JAXA and Roscosmos would be interested in providing. A bottleneck problem to say the least.
My opinion is, unless Orion gets around its upcoming service module crisis, the Gateway will inherently have to turn to other vehicles. The SLS could probably deliver more modules, so long as said-modules can fly themselves to the Gateway; adding them will be easy since there will be a robotic arm for Gateway. Orion's development is going to affect this future station, although it may not entirely impede it.
Inject your thoughts, and if there's more information about the Gateway's plans do provide it here too.
A modified Dragon.CST-100,or Dream chaser probably could do most of the things Orion does as far as operations at DSG go but they probably would simply restart production on the original OME which is pretty much just an uprated Shuttle OMS engine.
it's a simple pressure fed engine and has been in production recently so restarting the line would not be any where as difficult as the RS-25.
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DSG exists to give Orion and SLS something to do.
Which is pretty disgusting, because the very concept of a DSG has been around since 1999 and backed by brilliant people, all the way from the late Robert Farquhar to Harley Thronson and the FISO group.
A cislunar Gateway (preferably sitting at EML-2) makes some sense as a) building from ISS experience on space stations b)aggregate international cooperation, c) strategic emplacement on the Moon / Mars crossroads and d) limited budgets that do not allows to build a lunar base
(note about a) and b): makes no mistakes, early history of the ISS, from 1984 -1993 to 2010, was pretty horrible and flawed. Since then however the ISS has regained some prestige and limited usefulness).
I mean, politics led to SLS, SLS tainted Orion, and now these two are tainting the DSG / Gateway concept. This is sickening.
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Then again, Musk is coming fast with BFR / BFS, the later refueled in LEO can throw large payloads to the lunar surface and build a Moon base at lower cost thanks to complete reusability.
So maybe all the above is moot, and we might get a lunar base within the next 15 years... with NASA buying BFS flights CCDEV, COTS, or Soyuz style. Just like an airline buying 747s. Or a passenger buying a ride aboard a 747. Who knows ?
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Then again, Musk is coming fast with BFR / BFS, the later refueled in LEO can throw large payloads to the lunar surface and build a Moon base at lower cost thanks to complete reusability.
So maybe all the above is moot, and we might get a lunar base within the next 15 years... with NASA buying BFS flights CCDEV, COTS, or Soyuz style. Just like an airline buying 747s. Or a passenger buying a ride aboard a 747. Who knows ?
Emphasis mine.
If and when NASA goes BFS it will be the latter option.
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Even when Orion gets up and running, there will only be 5 flights before it gets benched. This is because the OMS engines inherited from the shuttles are in limited supply. This thread elaborates on that specific issue: https://forum.nasaspaceflight.com/index.php?topic=45002.0 (https://forum.nasaspaceflight.com/index.php?topic=45002.0)
They may be in short supply, but why do think NASA has issued an RFP for a (near) identical replacement engine?
Considering the projected SLS flight-rate: by the time the fifth Orion has flown a replacement engine will be available.
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Then again, Musk is coming fast with BFR / BFS, the later refueled in LEO can throw large payloads to the lunar surface and build a Moon base at lower cost thanks to complete reusability.
So maybe all the above is moot, and we might get a lunar base within the next 15 years... with NASA buying BFS flights CCDEV, COTS, or Soyuz style. Just like an airline buying 747s. Or a passenger buying a ride aboard a 747. Who knows ?
Emphasis mine.
If and when it NASA goes BFS it will be the latter option.
Ok- the worship and faith in this statement is just extraordinary. And it would be a terrible loss to the legacy of spaceflight research for public space to go that route.
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Then again, Musk is coming fast with BFR / BFS, the later refueled in LEO can throw large payloads to the lunar surface and build a Moon base at lower cost thanks to complete reusability.
So maybe all the above is moot, and we might get a lunar base within the next 15 years... with NASA buying BFS flights CCDEV, COTS, or Soyuz style. Just like an airline buying 747s. Or a passenger buying a ride aboard a 747. Who knows ?
Emphasis mine.
If and when it NASA goes BFS it will be the latter option.
Ok- the worship and faith in this statement is just extraordinary. And it would be a terrible loss to the legacy of spaceflight research for public space to go that route.
You speak of NASA as if it was a crucial aspect decreed by the founding fathers. It is not. NASA was formed because a historical need. Eventually that need will go away, and NASA will disappear or morph into something else. NASA is not the end-all or be-all of spaceflight in this country. It is "worship and faith" in NASA that needs to be shaken.
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Then again, Musk is coming fast with BFR / BFS, the later refueled in LEO can throw large payloads to the lunar surface and build a Moon base at lower cost thanks to complete reusability.
So maybe all the above is moot, and we might get a lunar base within the next 15 years... with NASA buying BFS flights CCDEV, COTS, or Soyuz style. Just like an airline buying 747s. Or a passenger buying a ride aboard a 747. Who knows ?
Emphasis mine.
If and when it NASA goes BFS it will be the latter option.
Ok- the worship and faith in this statement is just extraordinary. And it would be a terrible loss to the legacy of spaceflight research for public space to go that route.
You are going to have to clarify what you are referring to. What you quoted is statements about a possible future using proper conditionals so I don't see how "worship and faith" applies.
I also fail to see how making use of affordable launches to greatly expand the work done in space would be a "terrible loss" to anything. The difference between the 2 routes that were referred to at the end is just who is technically the owner/operator, which wouldn't make much practical difference due to all the other things needed to actually do a launch, though I agree with woods170, the passenger paying for a ride model (similar to CRS/commercial crew) is what would likely happen early on for simplicity.
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You speak of NASA as if it was a crucial aspect decreed by the founding fathers. It is not. NASA was formed because a historical need. Eventually that need will go away, and NASA will disappear or morph into something else.
You could say the same thing about SpaceX, Boeing, or any other entity involved in spaceflight today. Sure, organizations change and won't last forever. What is your point?
NASA is not the end-all or be-all of spaceflight in this country.
No one said it was. I believe Nathan is saying that space exploration should not be a totally private endeavor. There is still a vast public interest in space, from scientific knowledge to inspiration to innovation, that requires a public space exploration organization like NASA. How that organization goes about its business is up for debate but I firmly believe it is necessary.
It is "worship and faith" in NASA that needs to be shaken.
While I am sure there are people that put NASA on too high a pedestal I think the opposite opinion (i.e. NASA can't do anything right, end the organization, etc.) is just as wrong. What we should do is respect NASA's great accomplishments and offer respectful criticism when they fall short.
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You speak of NASA as if it was a crucial aspect decreed by the founding fathers. It is not. NASA was formed because a historical need. Eventually that need will go away, and NASA will disappear or morph into something else.
You could say the same thing about SpaceX, Boeing, or any other entity involved in spaceflight today. Sure, organizations change and won't last forever. What is your point?
My point was to respond to Okan's outrage about NASA possible not being in the lead (or building the hardware) for a future spaceflight endeavor. (paraphrasing here of course) NASA is a temporary construct. What does SpaceX or Boeing have do to with this?
If you quoted with context it should have been clear.
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My point was to respond to Okan's outrage about NASA possible not being in the lead (or building the hardware) for a future spaceflight endeavor. (paraphrasing here of course) NASA is a temporary construct. What does SpaceX or Boeing have do to with this?
I was curious what your point was regarding NASA ceasing to exist at some point. Every organization, government or non-government, changes or ceases to exist. It seemed you were stating a truism.
If you quoted with context it should have been clear.
I try not to overload my posts with excessive quoting when the relevant posts are close by. Too much quoting makes reading more difficult, at least for me. I didn't realize that my post would be on the next page so I figured the context would be obvious. I was not trying to place your remarks out of context.
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I'll just leave this here:
'Public space, space belongs to everyone': only dozens of people fly to space in 40 years, selected exclusively among the best, with extensive training; their plan to go to Mars involves landing 4 people every 5 years, starting 20 years from now... maybe; does not care about lowering the costs of spaceflight, SLS has to fly after all, whatever it takes! On the other hand the 'public rockets' have to be made by the same 3-4 main contractors, and have for 50 years.
'Elite space, evil private spaceflight': wants to maximize competition and diversity in the industry, aims to develop the 747 of human spaceflight, allowing millions of people to reach orbit and potentially the moon and Mars; is deeply focused on reducing the cost of reaching orbit, widening availability and trying to bring normal people to space. Opens new markets and launch endeavors that 'wouldn't have been possible if it wasn't for lower launch costs' (referring to Iridium, as an example).
okan and others, you always complain about how wrong people are when they get excited for SpaceX, Blue Origin, RocketLab, and other new space companies.
Don't you ever even wonder that maybe you are wrong? That maybe there's a reason if a lot of people are excited for this, and it's not that people are stupid?
Don't you think it's natural, reasonable and I dare say good, that people cheer for the ones who offer the better perspectives and vision for the future?
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My point was to respond to Okan's outrage about NASA possible not being in the lead (or building the hardware) for a future spaceflight endeavor. (paraphrasing here of course) NASA is a temporary construct. What does SpaceX or Boeing have do to with this?
I was curious what your point was regarding NASA ceasing to exist at some point. Every organization, government or non-government, changes or ceases to exist. It seemed you were stating a truism.
Yes, it is a truism for sure. But one that needs to be stated if a person thinks that NASA should always lead spaceflight.
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Each of the Lunar Orbital Platform - Gateway modules are expected to mass about 10 tonnes. The Power and Propulsion Element (PPE) used for station keeping is also a 50kW SEP space tug massing 5 to 8 tonnes wet mass, (2.5 tonnes of Xeon) that could push single modules from Earth Orbit to lunar orbit. LEO to EML-1 delta-v of 7.0km/s. Extra propellant can be launched separately. ISP of the 13kW Hall thruster is 3000 seconds, which is the likely ISP of the PPE.
8 tonne + 10 tonne = 18 tonne
There are several launch vehicles that can launch ~20 tonnes to LEO.
A manned vehicle may be needed to dock the modules together.
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let's not get into a public vs private slugfest in this thread ok? thanks!
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Could the DSP or LOP-G continue without the NASA Orion spacecraft? Of course. The Orion is a general purpose crew vehicle, and it's reasonable to expect that another transportation system could replace it.
The bigger question though is WOULD the DSP or LOP-G continue if the Orion was not available. Because that is a political question, not a hardware question.
I think the DSP/LOP-G doesn't have strong foundations at this point (i.e. business case is shaky), so if the Orion and SLS were not needed to be used, that may reduce the political support for the effort too.
But as others have mentioned, the OMS engine need is still far enough out into the future that I don't see it as a problem right now. So this is not yet a problem...
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Then again, Musk is coming fast with BFR / BFS, the later refueled in LEO can throw large payloads to the lunar surface and build a Moon base at lower cost thanks to complete reusability.
So maybe all the above is moot, and we might get a lunar base within the next 15 years... with NASA buying BFS flights CCDEV, COTS, or Soyuz style. Just like an airline buying 747s. Or a passenger buying a ride aboard a 747. Who knows ?
Emphasis mine.
If and when it NASA goes BFS it will be the latter option.
Ok- the worship and faith in this statement is just extraordinary. And it would be a terrible loss to the legacy of spaceflight research for public space to go that route.
I believe that NASA's role/the public role does not have to be in designing rockets -- it is clear with the Constellation and SLS/Orion exercises that NASA's rocketry legacy has retired. The Nation needs a R&D leader in spaceflight -- NASA's primary role by charter. The private sector is taking a share of this role away as NASA burns its budget on old tech... SLS propulsion systems, ocean splashing capsules, tin can space habs, etc. In other words, but default, not decision.
As departing AA Lightfoot said today, NASA has become about process over product. This needs to be reversed.
Lightfoot: when we make mistakes, we usually fix it by adding something to the process. Can end up being vicious cycle. Worry it becomes more about the process than the product.
https://twitter.com/jeff_foust/status/986269088669319169