Build a better Shuttle

[tater]

Aside: I realize that in the forum screwup I conflated 2 threads, assuming they were merged, and posted in the N-1 thread thinking it was this one. My bad.

15 minutes ago, NSEP said:

Isnt the ITS bassicly a sort of shuttle or not? 

It's way beyond that, frankly. I'll believe it when I see it, lol.

Really, when considering a shuttle replacement, the question is one of what is being replaced, and I'd add, would it be just replacing the Space Shuttle, or replacing the original STS concept that was killed.

In the case of the former, is @sevenperforce trying to recreate the ability to haul ~20 MT to LEO in the same size regime of the cargo bay, and X MT down, along with up to Y crew at the same time? I would then ask why those are the requirements, i.e.: why pay for a crew flight when you are dropping off a satellite, or one with an US to take it above LEO?

Seems like a replacement should be cost-effective for the desired mission. Sending a crew vehicle for any regular sat launch seems absurd, unless somehow the crew vehicle is actually cheaper than sending it on whatever LV would otherwise be used (which seems increasingly unlikely). So the only capabilities that matter would be downmass, I guess, and a vehicle with crew, airlock, and robot arm for service missions. I suppose the launch cadence of such a mission would need to be established, and then ask if it's worth the dev costs of a new shuttle type vehicle vs using available hardware plus maybe new modules.

Near future we can expect F9/FH, SLS, Vulcan, and even NG as LVs. Crew vehicles would be Orion, CST-100, and D2, along with perhaps Dreamchaser. So we have crew missions covered, and "dumb" lift capability up to 140 MT to LEO (SLS Blk 2). Seems to me you could design something in an interstage (as the Apollo LEM was lofted) that would have docking rings on each side, an airlock, as well as a robot arm. Such a pod would allow a crew vehicle to go grab a satellite and repair it. If the pod were made as a sort of tug, and lofted with a heavier LV, then maybe you keep it on orbit, and perhaps develop refueling tech for it (though sat rendezvous becomes far more complicated). The only tough tech is really downmass capability, and for that a novel vehicle might well be required, my only question is how often that would be required, and any retrieved craft would have needed to be designed for it in the first place.

[wumpus]

29 minutes ago, tater said:

Forgetting that Three Mile Island was a disaster that never happened, nuclear is still a great idea, and will always be. It's just an engineering issue.

Congress deals with what is in the public mind, not reality.  And the public thinks Three Mile Island was a big thing and never heard of the London Smog of 1952.

You'll need Bezos to cough up for the nuclear rocket, because getting Congress to pay just won't happen.

[tater]

Nuclear has been continuously funded at Marshall, and they could actually fly a test article in a not too long timeframe with some extra funding. All the NASA Mars DRAs include chemical and nuclear propulsion.

Still, I think the question is exactly what capabilities need to be replicated in a replacement, then the question to ask is "Is it cost-effective to put all the capabilities in one vehicle?"

[sevenperforce]

On 4/29/2017 at 2:25 PM, tater said:

Really, when considering a shuttle replacement, the question is one of what is being replaced, and I'd add, would it be just replacing the Space Shuttle, or replacing the original STS concept that was killed.

In the case of the former, is @sevenperforce trying to recreate the ability to haul ~20 MT to LEO in the same size regime of the cargo bay, and X MT down, along with up to Y crew at the same time? I would then ask why those are the requirements, i.e.: why pay for a crew flight when you are dropping off a satellite, or one with an US to take it above LEO?

Seems like a replacement should be cost-effective for the desired mission. Sending a crew vehicle for any regular sat launch seems absurd, unless somehow the crew vehicle is actually cheaper than sending it on whatever LV would otherwise be used (which seems increasingly unlikely). So the only capabilities that matter would be downmass, I guess, and a vehicle with crew, airlock, and robot arm for service missions. I suppose the launch cadence of such a mission would need to be established, and then ask if it's worth the dev costs of a new shuttle type vehicle vs using available hardware plus maybe new modules.

Near future we can expect F9/FH, SLS, Vulcan, and even NG as LVs. Crew vehicles would be Orion, CST-100, and D2, along with perhaps Dreamchaser. So we have crew missions covered, and "dumb" lift capability up to 140 MT to LEO (SLS Blk 2). Seems to me you could design something in an interstage (as the Apollo LEM was lofted) that would have docking rings on each side, an airlock, as well as a robot arm. Such a pod would allow a crew vehicle to go grab a satellite and repair it. If the pod were made as a sort of tug, and lofted with a heavier LV, then maybe you keep it on orbit, and perhaps develop refueling tech for it (though sat rendezvous becomes far more complicated). The only tough tech is really downmass capability, and for that a novel vehicle might well be required, my only question is how often that would be required, and any retrieved craft would have needed to be designed for it in the first place.

My original post was more of a what-if, namely: what if the expectations in play when the Shuttle system was designed and funded (rapid launch cadence, need for frequent on-orbit servicing of payloads, and the need for downmass) had actually been accurate? Obviously they weren't, but if they had been, what systems could have performed the same tasks better than the Shuttle?

Answers could be something as simple as "use liquid boosters with crossfeed on the Shuttle" or "fly with multiple booster configurations depending on payload".

Edited May 1, 2017 by sevenperforce

[tater]

Yeah, I ask because Shuttle as-built is a specific critter, and many of the uses for it were specifically created for Shuttle. Imagine ISS if it were designed in a non-Shuttle world, all else being equal. The US would have used whatever other vehicle (say a world of Saturn derivatives) NASA had. ISS would have been lofted in far fewer flights, and if that required concurrent crew launch on another LV, so be it. Loft station part with arm and airlock. Move to existing bit with CSM, and dock. Crew can now participate in required EVA and arm-assisted berthing operations. Rinse, repeat. Perhaps the arm is added to a purpose built assembly tug that lives at station. Bottom line is that you can do what needs to be done, minus Shuttle. The principle lack of capability would be down mass---how many times was that actually used, and was it really needed, or just demonstrating the capability?

[sevenperforce]

8 minutes ago, tater said:

Yeah, I ask because Shuttle as-built is a specific critter, and many of the uses for it were specifically created for Shuttle. Imagine ISS if it were designed in a non-Shuttle world, all else being equal. The US would have used whatever other vehicle (say a world of Saturn derivatives) NASA had. ISS would have been lofted in far fewer flights, and if that required concurrent crew launch on another LV, so be it. Loft station part with arm and airlock. Move to existing bit with CSM, and dock. Crew can now participate in required EVA and arm-assisted berthing operations. Rinse, repeat. Perhaps the arm is added to a purpose built assembly tug that lives at station. Bottom line is that you can do what needs to be done, minus Shuttle. The principle lack of capability would be down mass---how many times was that actually used, and was it really needed, or just demonstrating the capability?

Yes, exactly. The ISS could have been built without the Shuttle, for sure. Unpressed downmass was never used apart from ISS missions, I don't think.

But if manned presence in space had been far, far greater than it was, then the Shuttle's capabilities would have been much more useful, and building a better version of it would have been a good idea.

[tater]

Still, the most useful bit is what exactly? Crew plus arm, plus airlock for being able to go someplace (not necessarily Station), and grapple something to work on it? Seems like that specific capability need not come at a 90-100 ton price every, single launch, particularly at a billion a launch, and the failure rate of Shuttle. Imagine F9 or other vehicles in the near future like Vulcan or NG, with a capsule on top, and 10-ish tons of unused mass to LEO capability leftover. Seems like that could include a capsule-sized airlock and remote manipulator arm module. Achieve desired orbit, grab module (like the CSM-LEM docking maneuver), and you're good to go. Obviously in this case that module would be thrown away if the mission was to some novel orbit. I suppose such a module might have ion thrusters built in, and perhaps it could move itself to another target orbit over a long time period, so that a similar mission would only require the capsule to rendezvous with it, and perhaps this module is used as a testbed for refueling operations.

There is talk of reusing upper stages (ULA?) on orbit as tugs already, so this is not that far-fetched.

[sevenperforce]

6 minutes ago, tater said:

Still, the most useful bit is what exactly? Crew plus arm, plus airlock for being able to go someplace (not necessarily Station), and grapple something to work on it? Seems like that specific capability need not come at a 90-100 ton price every, single launch, particularly at a billion a launch, and the failure rate of Shuttle. Imagine F9 or other vehicles in the near future like Vulcan or NG, with a capsule on top, and 10-ish tons of unused mass to LEO capability leftover. Seems like that could include a capsule-sized airlock and remote manipulator arm module. Achieve desired orbit, grab module (like the CSM-LEM docking maneuver), and you're good to go.

Yeah, exactly. This sort of system could have enabled the Hubble servicing missions readily enough. 

[Bill Phil]

44 minutes ago, sevenperforce said:

Yes, exactly. The ISS could have been built without the Shuttle, for sure. Unpressed downmass was never used apart from ISS missions, I don't think.

But if manned presence in space had been far, far greater than it was, then the Shuttle's capabilities would have been much more useful, and building a better version of it would have been a good idea.

One must consider the system, not the vehicle. The system has capabilities, but if these capabilities can be offered in other  ways, perhaps for much less cost, then the system isn't particularly good... and the shuttle's only advantage was down mass. But that's a very large cost for down mass.

[tater]

Canadarms on Shuttle cost ~150 M$ each. 

The Quest airlock module for ISS cost 164 M$.

So an airlock designed to last for decades, plus an arm is about 300 M$. 

Seems like an airlock unit could be designed that would fit inline below existing or soon to exist crew vehicles. The other plus is that capsules have LES, and reentry failures are more limited to trajectory issues than the sort of flight damage that Columbia sustained.

[Capt. Hunt]

One of the problems with the shuttle was that NASA was forced to use it for too many mission profiles.  Congress forced NASA and the Air Force to give up their mid-range expendable rockets in favor of the shuttle.  While being able to service a satellite on the same mission as its release or return a payload from orbit came in handy a couple of times, the vast majority of satellite deployments could have been done cheaper and easier with the legacy Atlas, Delta and Titan rockets that the shuttle replaced.

Edited May 1, 2017 by Capt. Hunt

[tater]

Yeah, hence wondering about the real utility of some capabilities. If you actually need to haul a ISS module sized thing back to Earth---you need Shuttle. Of course ISS modules are only Shuttle sized because of Shuttle in the first place. If SLS and NG are flying for a while, then the standard diameter for some stuff might become closer to 8m than 4m, for example.

[sevenperforce]

1 hour ago, tater said:

Canadarms on Shuttle cost ~150 M$ each. 

The Quest airlock module for ISS cost 164 M$.

So an airlock designed to last for decades, plus an arm is about 300 M$. 

Seems like an airlock unit could be designed that would fit inline below existing or soon to exist crew vehicles. The other plus is that capsules have LES, and reentry failures are more limited to trajectory issues than the sort of flight damage that Columbia sustained.

This sort of thing could easily be a drop-in replacement for something like an upgraded/reworked Dragon 2 or the New Glenn equivalent.

Having LES is a huge deal. Really huge. There were SO many failure modes for the Shuttle which resulted in LOCV.

[HebaruSan]

Sympathy for the Shuttle (<-- signifies Devil's advocacy)...

Why an all-in-one vehicle? Because as long as you keep that one supply chain going, you have all of your capabilities available. No need to worry about a critical subcontractor going out of business because their particular specialized vehicle went unused for too long. And any improvements you make to the single launch stack benefit all missions, such as running the engines at 109%.

Why send crew on satellite launches? Because if you want to maintain an astronaut corps, they need flights. Not even to be able to re-fly experienced crew (though I am finding a fair number of examples of that), but as a reason to join NASA and go through all the training and simulators in the first place. Maybe there would have been the same quantity and quality of applicants and long-term corps members if manned flights were drastically reduced, but that's far from a sure thing.

Why put construction crew in the same vehicle with payload rather than separate launches? Because coordinating two simultaneous launches is more complex than one; double the infrastructure and ground staff to monitor everything, plus dealing with all the dependencies between the launches (if we need to use that wonderful pod LES, what happens to the other rocket? vice versa?).

Bonus answer: Because Shuttle launches were awesome.

I don't think the STS's non-conformance to the strict market requirements of the time is a valid strike against it. NASA's mission includes promoting US spaceflight capabilities (I think; I've looked for references on this and not found them, someone please chime in if you can). Sometimes that means funneling cash to aerospace contractors, and sometimes it means going beyond current necessities with projects that aren't absolutely necessary right now but provide opportunities to learn and improve. That approach opens the possibility of colonizing the solar system over the long term; I don't think the more conservative approach does.

[mikegarrison]

This talk of sending an arm up with some other spaceship seems to ignore the sheer physical dimensions of the arm. The arm was 15 meters long. That's not a convenient load to fit ... unless you have a 18 meter long payload bay.

[_Augustus_]

3 hours ago, tater said:

Seems like an airlock unit could be designed that would fit inline below existing or soon to exist crew vehicles. T

Maybe a small airlock that fits inside Dragon's trunk for launch?

2 hours ago, tater said:

Of course ISS modules are only Shuttle sized because of Shuttle in the first place. If SLS and NG are flying for a while, then the standard diameter for some stuff might become closer to 8m than 4m, for example.

The Deep Space Gateway is going to use 4m diameter modules - Node 4 and Raffaello at least, anyway...

2 minutes ago, mikegarrison said:

This talk of sending an arm up with some other spaceship seems to ignore the sheer physical dimensions of the arm. The arm was 15 meters long. That's not a convenient load to fit ... unless you have a 18 meter long payload bay.

Couldn't you just make the arm fold up at its joints?

[tater]

@HebaruSan, excellent points, really, though I'd rather the "make work" for crews was something more interesting.

4 minutes ago, mikegarrison said:

This talk of sending an arm up with some other spaceship seems to ignore the sheer physical dimensions of the arm. The arm was 15 meters long. That's not a convenient load to fit ... unless you have a 18 meter long payload bay.

This is quite true, but how much of the length requirement in fact had to do with clearing the shuttle itself?  A smaller craft could simply get closer. That said, such an arm might well have to bend a few times to fit. Attached to something within an SLS or NG fairing, it could be larger. 

How many missions was the shuttle arm required that doesn't include removing some payload FROM the shuttle?

[mikegarrison]

5 minutes ago, _Augustus_ said:

Couldn't you just make the arm fold up at its joints?

The original arm had two long pieces, so at most you could get it down to something like 8 meters long, and of course it would be twice as wide. No matter how you do it, it's an awkward fit with something like a standard capsule design.

Edited May 1, 2017 by mikegarrison

[tater]

Regarding Dragon trunk... maybe, the trunk is about as big as the capsule.

I can only assume that since there are firms tooled up for 4m habs, they are going with what they can do off the shelf.

The F9 fairing is 4.6x11.4m or something like that (inside), and just shy of 14m long (outside). The D2 capsule with the trunk is maybe 2m shorter than the fairing. Seems like you could make an interstage such that the trunk and the extra couple meters hold the airlock unit.the arm could be folded along the side, and that module could be approaching 10m long. There's certainly a straight shot at 8m in there. I have no idea what a minimum volume is for an airlock, particularly one that is not to be used over and over.

[mikegarrison]

I don't understand this talk of an airlock for Dragon. Dragon is a commuting car. It's intended to get crew up to the space station and then return. The shuttle was an RV -- designed to be lived out of for days at a time. Does Dragon even have a toilet? How much food and water does it carry? How comfortable would it be to work and live out of for several days?

[_Augustus_]

49 minutes ago, mikegarrison said:

I don't understand this talk of an airlock for Dragon. Dragon is a commuting car. It's intended to get crew up to the space station and then return. The shuttle was an RV -- designed to be lived out of for days at a time. Does Dragon even have a toilet? How much food and water does it carry? How comfortable would it be to work and live out of for several days?

Dragon is every bit as suitable for deep space as Apollo was. Apollo didn't have any of the things you mention.

Logically, if we're adding an airlock, we could probably expand that into a "mission module" with extra supplies and a toilet.

[mikegarrison]

19 minutes ago, _Augustus_ said:

Dragon is every bit as suitable for deep space as Apollo was. Apollo didn't have any of the things you mention.

Logically, if we're adding an airlock, we could probably expand that into a "mission module" with extra supplies and a toilet.

Apollo certainly did have food and water.

And yes, some people live out of cars, but that doesn't mean they are really intended as even temporary housing. I have no doubt that one could manage to find a way to keep a small crew in Dragon or CST for a week or so, just like the old days (Apollo, Gemini, etc.). But why do it?

And weren't you going to stick an arm on that airlock too? That seems less like an airlock and more like a handwave. Anything that is a problem for Dragon to deal with is reduced to "we'll build it into the airlock".

Furthermore, the entire airlock module is disposable, right? Dragon can't bring back the "trunk", so I'm pretty sure if wouldn't be able to bring back this airlock either. Or the arm. Or the expensive toilet. Or the EVA suits. Or whatever else you want to put in or on the airlock.

Edited May 1, 2017 by mikegarrison

[tater]

Dragon2 was just an example, but the "taxi" nature of D2 and CST-100 (also in the pipes, and can replace D2 in any comments above) is well taken, but how long do you need to be in space to fix a satellite, assuming there are some that actually need fixing? Sierra Nevada has proposed exactly such a mission module for HST service, for example, stuck onto Dream Chaser.

Let's assume that using commercial crew vehicles (we'll include Dream Chaser for kicks) would work for this purpose with some sort of mission module. The expense of such a mission might double... LV cost, crew vehicle cost (all 3 designed to be reused though, so you only use a fraction of the total uses), plus module cost (which might be able to come down to a couple hundred million, say, perhaps cheaper). We're still likely cheaper than a single shuttle launch by a wide margin.

I think the argument about astronaut launch cadence is a good one, but assuming we have someplace to go to, cheaper access can only make that better, right? (obviously you need someplace to go to).

Sticking on an arm (assuming one is needed) is not really all that difficult, it's not like they would be inventing it from scratch, it's fairly mature at this point, and telepresence is improving constantly. The big shame would really be deorbiting something that useful. Remember the bar for this discussion in some ways is "can you do the same thing for under 1.2 billion $ for that particular mission?"

GO back to the original STS concept. What if we actually built a crew vehicle for space? A tug, and that has the RMA on it, and an airlock, etc? At some point, we need orbital refueling (the Chinese just tested that on their station, BTW), so the tug gets refueled when the crew is delivered to it (capsule docks with tug, tug and capsule do work, capsule returns to Earth).

[_Augustus_]

15 minutes ago, mikegarrison said:

I have no doubt that one could manage to find a way to keep a small crew in Dragon or CST for a week or so, just like the old days (Apollo, Gemini, etc.). But why do it?

SpaceX is doing it next year with that lunar flyby mission.

[mikegarrison]

2 minutes ago, tater said:

GO back to the original STS concept. What if we actually built a crew vehicle for space? A tug, and that has the RMA on it, and an airlock, etc? At some point, we need orbital refueling (the Chinese just tested that on their station, BTW), so the tug gets refueled when the crew is delivered to it (capsule docks with tug, tug and capsule do work, capsule returns to Earth).

This makes more sense, but of course it leads to a pretty significant problem. Your workshop/tug is in one orbit, and the thing you want to work on is in another orbit. Changing orbital planes is either expensive or time consuming (if you do it using precession).

1 minute ago, _Augustus_ said:

SpaceX is doing it next year with that lunar flyby mission.

Will that happen before Half-Life 3 is released?