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Can the Deep Space Gateway continue without Orion?
by
redliox
on 15 Mar, 2018 15:29
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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=45002.0In 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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#1
by
hektor
on 15 Mar, 2018 15:41
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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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#2
by
speedevil
on 15 Mar, 2018 15:52
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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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#3
by
butters
on 15 Mar, 2018 15:59
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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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#4
by
redliox
on 15 Mar, 2018 16:06
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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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#5
by
redliox
on 15 Mar, 2018 16:19
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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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#6
by
ncb1397
on 15 Mar, 2018 16:22
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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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#7
by
brickmack
on 15 Mar, 2018 16:27
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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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#8
by
speedevil
on 15 Mar, 2018 16:31
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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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#9
by
ncb1397
on 15 Mar, 2018 16:32
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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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#10
by
redliox
on 15 Mar, 2018 16:42
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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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#11
by
Jim
on 15 Mar, 2018 17:02
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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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#12
by
meberbs
on 15 Mar, 2018 17:15
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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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#13
by
speedevil
on 15 Mar, 2018 17:35
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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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#14
by
Patchouli
on 15 Mar, 2018 17:51
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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
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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#15
by
Archibald
on 16 Mar, 2018 07:57
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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.
...
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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#16
by
woods170
on 16 Mar, 2018 11:13
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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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#17
by
woods170
on 16 Mar, 2018 11:18
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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
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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#18
by
okan170
on 16 Apr, 2018 23:27
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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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#19
by
Lars-J
on 16 Apr, 2018 23:46
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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.