Author Topic: SLS as propellant truck  (Read 38937 times)

Offline mmeijeri

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Re: SLS as propellant truck
« Reply #220 on: 01/11/2012 05:04 PM »
My out of the brain analysis indicates that your intent, in asking this question, is either to discuss Newt Gingrich's HSF politix or to exhibit an anti-shuttle bias.  Neither of these makes sense to me.

Nope, not the reason. The context is Warren's argument that it would be valuable to push for a role for SLS as a propellant launcher, with all dry payloads being launched on commercial launchers. That would require the spacecraft to be designed in a way that allows them to be launched on those commercial launchers. I think history shows that that is not particularly likely.

As for ISS specifically, I'm not sure about the relative timing between the design decisions for the ISS and the signing of the Commercial Space Launch Act, so I'm not sure it had much of an influence either way in this case. Jorge seems to be telling us that he believes there was no such influence, and as I understand it he was personally involved. Nevertheless, if the Act did apply to the ISS, then the Shuttle would have had nothing to do after the loss of Challenger if the ISS modules had been designed to be compatible with EELVs.

In the future I think you will see a continued push for designs that require high throw weights and large fairings, which will have the effect of excluding use of commercial launchers, regardless of whether that is the intent behind it. That would be a spanner in the works for Warren's plan.

Another obstacle is the propellant itself, since I think that would certainly fall under the provisions of the Act. If so, ULA, OSC or SpaceX could challenge use of SLS as a propellant launcher in court, and there would be very little the executive branch could do against it. Congress could amend the relevant legislation, but I'm not sure there would be a majority for that, since it hasn't happened so far. My guess is that a lawsuit by OSC and especially ULA would be unlikely, but not so for SpaceX. So that's a second spanner in the works.
« Last Edit: 01/11/2012 05:10 PM by mmeijeri »
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Offline mmeijeri

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Re: SLS as propellant truck
« Reply #221 on: 01/11/2012 05:07 PM »
It would not be ISS, it would be something different.  To ask "what would have happened?" in an alternate universe in order to try to once again trump up only EELVs, which are rockets and completely different than the capability that existed with Shuttle, is just more of the same from you.

The question wasn't what would have happened, the question was whether ISS modules were wilfully designed not to fit on EELVs to guarantee a future for the Shuttle after the loss of Challenger. Jorge appears quite emphatic they weren't. Nevertheless I anticipate that we will continue to see designs for spacecraft that would preclude Warren's preferred scenario, precisely in order to lock in SLS. Perhaps you anticipate different things.
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Offline Namechange User

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Re: SLS as propellant truck
« Reply #222 on: 01/11/2012 05:15 PM »
It would not be ISS, it would be something different.  To ask "what would have happened?" in an alternate universe in order to try to once again trump up only EELVs, which are rockets and completely different than the capability that existed with Shuttle, is just more of the same from you.

The question wasn't what would have happened, the question was whether ISS modules were wilfully designed not to fit on EELVs to guarantee a future for the Shuttle after the loss of Challenger. Jorge appears quite emphatic they weren't. Nevertheless I anticipate that we will continue to see designs for spacecraft that would preclude Warren's preferred scenario, precisely in order to lock in SLS. Perhaps you anticipate different things.

What is your obsession with Warren?  For the second time now you have referenced him in a response to me.  Again, I am not Warren!!

Again, Jorge's and my statments are exactly right.  You are doing what you do, trying to invalidate Shuttle, in order to gush on EELV and make comparisons where none are applicable.

For the last time, Shuttle WAS NOT EELV.  One describes a set of rockets.  These rockets launch something into LEO.  The other was an entire space platform that launched from the surface as well carrying it and an EELV-size payload into LEO as an integrated in-space platform in order to do specialized work there with a crew. 

Both have/had their place. 
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Offline mmeijeri

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Re: SLS as propellant truck
« Reply #223 on: 01/11/2012 05:20 PM »
What is your obsession with Warren?  For the second time now you have referenced him in a response to me.  Again, I am not Warren!!

It's Warren's thread, and I asked my question in order to address his arguments. You misread my intention with the question. I had no intention of showing that Shuttle was unnecessary, since Jim has amply demonstrated that in his thread on that topic and more importantly since it isn't relevant to the topic at hand. My intention was to evaluate whether it is likely that future spacecraft used for exploration would be compatible with commercial launchers and I believe history shows it isn't.

Quote
Both have/had their place. 

Perhaps, but this is not the thread to discuss it.
« Last Edit: 01/11/2012 05:21 PM by mmeijeri »
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Offline Warren Platts

Re: SLS as propellant truck
« Reply #224 on: 01/11/2012 05:27 PM »
Hey the thread belongs to everybody! :D

I'm starting to wonder if Martijn might have a point however. Forget ISS. Look at the Altair lander that was designed to fly on Ares V. A suboptimal design that neverthelss had the virtue of a 10-meters  diameter making it too big to be launched on anything but Ares V, even if it were launched completely dry.

Hopefully, the next go around, some redudancy in terms of the LV's that can be used to launch the landers and crew capsules will be built into the system.

If the law is an issue limiting the flexible use of SLS, then the law should be changed IMO.
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Re: SLS as propellant truck
« Reply #225 on: 01/11/2012 08:06 PM »
What is your obsession with Warren?  For the second time now you have referenced him in a response to me.  Again, I am not Warren!!

It's Warren's thread, and I asked my question in order to address his arguments. You misread my intention with the question. I had no intention of showing that Shuttle was unnecessary, since Jim has amply demonstrated that in his thread on that topic and more importantly since it isn't relevant to the topic at hand. My intention was to evaluate whether it is likely that future spacecraft used for exploration would be compatible with commercial launchers and I believe history shows it isn't.

Quote
Both have/had their place. 

Perhaps, but this is not the thread to discuss it.

You know nothing but pretend to know everything and it is annoying.

1.  "Jim's thread" demonstrated nothing.  What you and others continue to demonstrate is your ignorance. 

2.  "Future spacecraft" used for "exploration" can use whatever makes the most sense.  Again. you have totally bastardized and twisted the word "commercial" in order to spout ideology and mal-content for something you only think you understand. 

3.  It may not be "the thread to discuss it" but let's remember who brought it up and that person was you. 
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Re: SLS as propellant truck
« Reply #226 on: 01/12/2012 03:33 AM »
Warren (and others):  is there any indication SLS is intended to have autonomous rendezvous and docking capability?  Without that, uncrewed propellant launches aren't useful in a depot-centric architecture....
« Last Edit: 01/12/2012 03:34 AM by sdsds »
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Offline Jorge

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Re: SLS as propellant truck
« Reply #227 on: 01/12/2012 04:38 AM »
Warren (and others):  is there any indication SLS is intended to have autonomous rendezvous and docking capability?  Without that, uncrewed propellant launches aren't useful in a depot-centric architecture....

No launch vehicle has AR&D capability, and no planned LV will. AR&D is a function of the spacecraft launched atop the LV, never the LV.
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Re: SLS as propellant truck
« Reply #228 on: 01/12/2012 04:46 AM »
I believe Centaur already has 3-axis ACS. I remember seeing a presentation or two (about delivering Node 4 to ISS?) which mentioned augmenting Centaur for full 6 axis RCS to allow AR&D. That would be part of the upper stage, then. Unless you call that a spacecraft at that point.
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Offline JohnFornaro

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Re: SLS as propellant truck
« Reply #229 on: 01/12/2012 01:36 PM »
It would be valuable to push for a role for SLS as a propellant launcher, with all dry payloads being launched on commercial launchers. That would require the spacecraft to be designed in a way that allows them to be launched on those commercial launchers. I think history shows that that is not particularly likely. ...

Nevertheless, if the Act did apply to the ISS, then the Shuttle would have had nothing to do after the loss of Challenger if the ISS modules had been designed to be compatible with EELVs.

Yes, all the payloads were "willfully designed".  You don't seem to be acknowledging that there are fundamental structural and engineering differences between shuttle payloads and equivalently massed and functioned EELV launches.  Your speculation about the Act does not pertain.

Clearly, SLS has a viable role as a propellant truck.  This role would not call for the elimination of its possible role as a dry cargo launcher as well.  Should FH and the next "batch" of commercial heavy launchers come on line and have the same throw weight as SLS, then I'm sure the lawyers will get into the act about the Act.  I don't see any point in worrying about that at the moment.  Unless I'm not up to date on current law, you can't go suing the government for stuff it hasn't yet done.  So I have the Alfred E. Neuman approach on this topic.

No launch vehicle has AR&D capability, and no planned LV will. AR&D is a function of the spacecraft launched atop the LV, never the LV.

Is there any indication that the spacecraft intended for SLS would have autonomous rendezvous and docking capability?

I would say, today, that AR&D needs to happen for SLS before manrating.  All else being equal, an unmanned launch will be less expensive than a manned one.  Pricing is one of SpaceX's strong points with Dragon.  The future, if it should be sustainable, will require a lot of orbital assembly of fairly large, connectively simple pieces in various orbits.  Obviously, people need to get up there ASAP, since the typical sense is that the machines work for the people, not the other way around.

As development stands at the moment, it may be that Orion will actually be developed before SLS can support spacecraft with AR&D; but that remains to be seen.  In any case, Orion should be LV agnostic.  If development is already at the point where Dragon and Orion have differing LIDS and adaptor rings, then I'd say let there be these two standards only.  Should SpaceX claim that Dragon's interface is proprietary and therefore it will not share, fine.  Let Orion have the publicly available interface. 

The pathway to opening up the cis-lunar market in America will be in reducing the cost of entry.  This can be partially achieved by standardization, reducing the capital costs of each company re-inventing the wheel, so to speak.  The analogy here is the standard American railroad gage.
« Last Edit: 01/12/2012 01:39 PM by JohnFornaro »
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Offline Warren Platts

Re: SLS as propellant truck
« Reply #230 on: 01/12/2012 02:19 PM »
Warren (and others):  is there any indication SLS is intended to have autonomous rendezvous and docking capability?  Without that, uncrewed propellant launches aren't useful in a depot-centric architecture....

No launch vehicle has AR&D capability, and no planned LV will. AR&D is a function of the spacecraft launched atop the LV, never the LV.

Maybe AR&D won't be necessary? E.g., using the "sticky boom" technology that Goff and associates are working on, it might be possible to transfer propellant without actually docking; it would be more like refueling an airplane than docking with ISS.
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Offline mmeijeri

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Re: SLS as propellant truck
« Reply #231 on: 01/12/2012 04:17 PM »
Yes, all the payloads were "willfully designed".  You don't seem to be acknowledging that there are fundamental structural and engineering differences between shuttle payloads and equivalently massed and functioned EELV launches.

Of course I am, otherwise there wouldn't be an issue: all payloads could be launched on any launcher. If Warren's plan is to work, then the spacecraft will have to be capable of being launched on commercial launchers. That may be difficult if they require the throw weight or wide fairings of an SLS. Nevertheless I expect that is precisely what we'll continue to see. As a result there would not be a choice between SLS for propellant and dry payloads on commercial launchers on the one hand or everything on SLS on the other. The latter choice would be the only available option.

Quote
Clearly, SLS has a viable role as a propellant truck.

Technically yes, but not necessarily legally, assuming dry spacecraft are launched separately.

Quote
This role would not call for the elimination of its possible role as a dry cargo launcher as well.

Correct.

Quote
Should FH and the next "batch" of commercial heavy launchers come on line and have the same throw weight as SLS, then I'm sure the lawyers will get into the act about the Act.  I don't see any point in worrying about that at the moment.

That's the point, if you separate dry cargo and propellant as Warren advocates, then commercial launchers are suddenly technically capable of delivering the propellant. Regardless of whether you think that is desirable, there would then be a legal requirement to procure the launches competitively. Or at least that's how I understand it. Some may argue that the law needs to be changed, and perhaps it should.

If you launch the spacecraft with a full load of propellant on the other hand, then you will need the throw weight of an HLV.
« Last Edit: 01/12/2012 04:28 PM by mmeijeri »
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Offline Warren Platts

Re: SLS as propellant truck
« Reply #232 on: 01/12/2012 06:27 PM »
Yes, all the payloads were "willfully designed".  You don't seem to be acknowledging that there are fundamental structural and engineering differences between shuttle payloads and equivalently massed and functioned EELV launches.

Of course I am, otherwise there wouldn't be an issue: all payloads could be launched on any launcher. If Warren's plan is to work, then the spacecraft will have to be capable of being launched on commercial launchers. That may be difficult if they require the throw weight or wide fairings of an SLS. Nevertheless I expect that is precisely what we'll continue to see. As a result there would not be a choice between SLS for propellant and dry payloads on commercial launchers on the one hand or everything on SLS on the other. The latter choice would be the only available option.

For better or worse, I am afraid you will turn out to be right about that one, Martijn. We shall see....
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Offline mmeijeri

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Re: SLS as propellant truck
« Reply #233 on: 01/12/2012 06:32 PM »
For better or worse, I am afraid you will turn out to be right about that one, Martijn. We shall see....

Indeed we will, one way or another. What we can do however is to argue for spacecraft that can be launched on commercial launchers.
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Re: SLS as propellant truck
« Reply #234 on: 01/12/2012 07:48 PM »
{snip}
Is there any indication that the spacecraft intended for SLS would have autonomous rendezvous and docking capability?

I would say, today, that AR&D needs to happen for SLS before manrating.  All else being equal, an unmanned launch will be less expensive than a manned one.  Pricing is one of SpaceX's strong points with Dragon.  The future, if it should be sustainable, will require a lot of orbital assembly of fairly large, connectively simple pieces in various orbits.  Obviously, people need to get up there ASAP, since the typical sense is that the machines work for the people, not the other way around.

As development stands at the moment, it may be that Orion will actually be developed before SLS can support spacecraft with AR&D; but that remains to be seen.  In any case, Orion should be LV agnostic.  If development is already at the point where Dragon and Orion have differing LIDS and adaptor rings, then I'd say let there be these two standards only.  Should SpaceX claim that Dragon's interface is proprietary and therefore it will not share, fine.  Let Orion have the publicly available interface. 

The pathway to opening up the cis-lunar market in America will be in reducing the cost of entry.  This can be partially achieved by standardization, reducing the capital costs of each company re-inventing the wheel, so to speak.  The analogy here is the standard American railroad gage.

This assumes that the SLS upper stage is the tanker.  An alternative is for the tanker stage to replace (or fit) the faring.  Possible sources for the AR&D avionics are the Cygnus and the DreamChaser.

Offline JohnFornaro

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Re: SLS as propellant truck
« Reply #235 on: 01/12/2012 07:59 PM »
This assumes that the SLS upper stage is the tanker.  An alternative is for the tanker stage to replace (or fit) the faring.  Possible sources for the AR&D avionics are the Cygnus and the DreamChaser.

Yes, but there's no a priori law of physics which would insist that the only SLS upper stage be a tanker.  I'd think that there would be several tanker sizes; obviously an F9 tanker would be smaller.  As to Cygnus and DreamChaser, I don't know.
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Re: SLS as propellant truck
« Reply #236 on: 01/13/2012 07:28 AM »
Warren (and others):  is there any indication SLS is intended to have autonomous rendezvous and docking capability?  Without that, uncrewed propellant launches aren't useful in a depot-centric architecture....

No launch vehicle has AR&D capability, and no planned LV will. AR&D is a function of the spacecraft launched atop the LV, never the LV.

Good point.  Thanks for correcting that.  Three followup questions, though:

 - are you effectively saying SLS will never be a propellant truck; it can only launch propellant trucks?

 - how does the notion that the spacecraft is never some part of the launch vehicle jive with e.g. Agena, which was (IIUC) both a stage that participated in the ascent to orbit and also a spacecraft that participated in (albeit as the passive target of an human-guided chaser) rendezvous?

- is there any reason in principle why a stage like the CxP EDS couldn't both provide propulsion during ascent and then rendezvous with a depot to offload its excess propellant?
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Offline 93143

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Re: SLS as propellant truck
« Reply #237 on: 01/13/2012 08:29 AM »
- is there any reason in principle why a stage like the CxP EDS couldn't both provide propulsion during ascent and then rendezvous with a depot to offload its excess propellant?

Of course not.  You're blurring the line between LV and spacecraft, but then that's been done before - Shuttle, for instance.  ACES would have to do something like that, as the tanker is just a stretched upper stage.

Skylon is an extreme example; as an unpiloted single-stage orbital shuttle designed with station and depot servicing in mind, the entire launch vehicle has to be capable of AR&D...
« Last Edit: 01/13/2012 08:31 AM by 93143 »

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