Wetlab redux?

[Asteroza]

http://spectrum.ieee.org/tech-talk/aerospace/space-flight/nasa-funds-partnership-to-explore-making-space-habitats-out-of-used-rocket-fuel-tanks

Looks like NanoRacks wants to bring back the the old Skylab concept for a wet workshop station (module) for the Deep Space Habitat program, using a centaur upper stage, an intermediate docking node module called Ixom, and Cygnus for tug ops to ISS. Bonus points for what appears to be a SuitPort (Z2?) on the Ixom module.

If that started to become a standard pattern for Cygnus, you would effectively be ferrying a new module every flight (but outfitting will be a lot of work, but since russia was already thinking of cutting back a cosmonaut, why not dragoon/pay them to be construction workers...)

Is the ACES work for centaur helping to make a centaur wet module more practical? I would have thought the centaur's tanks would be less suitable than other upper stages for wet workshop reuse.


What would people consider the modern design space for wet modules made from upper stages? Direct conversion using what effectively is a plus-sized super payload adapter ring? Perhaps as a strongback/core for an inflatable that slipped down over the tank (if a wide/short packed inflatable shell anchored on the payload adapter could fit within the lower space of a very wide payload fairing that is much wider than the nominal upper stage)? Slide an inflatable into the inside of the tank?

[Impaler]

The wet workshop is one of thouse terrible ideas that needs to be stabbed in the heart and die. 

We don't build ocean going vessels by making a giant empty hull and then launching it into the water and then sending workmen over in smaller boats to climb inside to build all the floors and systems inside, it's laughable to even think about because their aren't opening large enough to get huge pieces of machinery through and the work would be vastly harder to do out in the water rather then in a controlled environment of a shipyard.  Like so many space cadet ideas this ignores trends that have already taken place on Earth the obsoleted the whole labor intensive methodology, and space is not a place with low labor costs.

NASA already has experience with large empty aluminum cans being attached to the ISS, the MPLM is just that and it's useful as a storage area but if that's all it's going to do then inflatables do the job better.  Habitats are 90 percent equipment mass, not pressure vessel mass, to 'outfit' the volume would require a second flight carrying tons of equipment and that equipment would have to be in a large pressure vessel, in other words it would BE a real habitat, so your just disassembling one habitat and hauling it's guts into a new space.  No launches are saved and your design is compromised in a numerous ways.

Propellant tanks like the Centaur aren't designed with the puncture resistance of the ISS western made sections which are themselves inferior to the multi-layer armor that protects all Russian modules.  Designing every piece of equipment to be disassembled and passed through an narrow tunnel is ruinous to efficiency and will impose high labor costs both to install and maintain, worst it fails to utilize any of the ISS already modular racks which could be transferred to any new module that carries the wide square meter CBM connections.  Evacuating and sealing the tanks is itself a huge problem, valves between the tank and rocket engine will be a permanent source of potential air leaks and one end of the tank will retain the obsolete engine forever meaning one one connection port is possible and modules of this type can never be strung together sausage like, they will always be dependent on node systems to form a spine which they will connect too.

I've quite certain that the results of the study will be that the idea is quite UN-feasible and I expect these guys to be dropped in later rounds as is common for these contractors that get way over their heads and try to cobble together a system out of other peoples hardware.

[A_M_Swallow]

Keep the faring instead of discarding it and the upper stage has the basis of a control room.

Make the Centaur refuellable and ULA has a space tug.

[jtrame]

Propellant tanks like the Centaur aren't designed with the puncture resistance of the ISS western made sections which are themselves inferior to the multi-layer armor that protects all Russian modules.  Designing every piece of equipment to be disassembled and passed through an narrow tunnel is ruinous to efficiency and will impose high labor costs both to install and maintain, worst it fails to utilize any of the ISS already modular racks which could be transferred to any new module that carries the wide square meter CBM connections.  Evacuating and sealing the tanks is itself a huge problem, valves between the tank and rocket engine will be a permanent source of potential air leaks and one end of the tank will retain the obsolete engine forever meaning one one connection port is possible and modules of this type can never be strung together sausage like, they will always be dependent on node systems to form a spine which they will connect too.

I've quite certain that the results of the study will be that the idea is quite UN-feasible and I expect these guys to be dropped in later rounds as is common for these contractors that get way over their heads and try to cobble together a system out of other peoples hardware.

To that I would add the small diameter of the Centaur tank as compared to just about every other alternative.  People in space need space.

[RanulfC]

The wet workshop is one of thouse terrible ideas that needs to be stabbed in the heart and die.

That's your opinion of course but...

We don't build...

Fill in the blank and then come to the realization that we don't do much of anything in space the same way we do on Earth for the very basic reason it is in fact NOT Earth.

...ocean going vessels by making a giant empty hull and then launching it into the water and then sending workmen over in smaller boats to climb inside to build all the floors and systems inside, it's laughable to even think about because their aren't opening large enough to get huge pieces of machinery through and the work would be vastly harder to do out in the water rather then in a controlled environment of a shipyard.  Like so many space cadet ideas this ignores trends that have already taken place on Earth the obsoleted the whole labor intensive methodology, and space is not a place with low labor costs.

Actually you're wrong about ship building as until recently, (and in many cases still) while the decks and bulkheads were installed prior to launching most of the interior work and fitting of equipment was done by moving stuff in to the hull from nearby and installing it. Hence almost everything either broke down to a point to go through a hatch or you cut holes in the hull and resealed them for larger equipment. In any vehicle design (and space specifically) if you have it inside initially you have to ensure it fits through a 'door" for it to be useful later so your argument isn't even applicable to what we do on Earth.

Further, well it's space not Earth and frankly we're bringing up empty tanks anyway so the "space" is there and not using it means it simply goes to waste. It's work both on the ground and in space to make changes but none of them are impossible, just more difficult than we are used to thinking about. Point of fact Von Braun and several senior engineers and a half dozen astronauts all climbed into suits and tested the idea in the neutral buoyancy tank and found the labor difficult be not really challenging. The main issue was, (and remains) that no space suits have been designed or built with manual labor in mind.

NASA already has experience with large empty aluminum cans being attached to the ISS, the MPLM is just that and it's useful as a storage area but if that's all it's going to do then inflatables do the job better.

Eh that's not even close to what the "experience" was, and your argument is pretty shaky since at least one WAS used as a permanent module. (https://en.wikipedia.org/wiki/Leonardo_(ISS_module)) Note that while there was some modification it wasn't all that much and there were numerous proposals to leave MORE MPLMs attached but not acted on.
So while inflatable are in fact better for the purpose when all is said and done the argument that we "don't/didn't" do it before is simply saying we didn't bother with it before so why do so now?

Habitats are 90 percent equipment mass, not pressure vessel mass,

Actually not. Work spaces may be up to 90 percent equipment but that's not indicative of what is required for something like a simple 'living,' storage or utility space so your percentage goes way down.

...to 'outfit' the volume would require a second flight carrying tons of equipment and that equipment would have to be in a large pressure vessel, in other words it would BE a real habitat, so your just disassembling one habitat and hauling it's guts into a new space.  No launches are saved and your design is compromised in a numerous ways.

That old argument again? Really the whole "everything you ever need has to be launched at once" is one of those basic terrible ideas that needs to be stabbed in the heart to die.

Seriously, you argue the MPLM is just a "big-empty-module" that happened to be packed with cargo but would be useless as a "habitat" (pressurized space is actually the description you're looking for) because it is already a "habitat"! And you also don't have to bring up vast amounts of equipment in a single flight. If someone is going to be coming and going a lot, (which is actually a requirement if you ever plan on doing more than visiting space on an occasional, short term basis which is what we do now) every flight brings some equipment to install. The initial flight may bring up enough materials and equipment for initial conversion and operation. The design is of course not going to be perfect as one that is purpose built but it has the utility of being already in-place and available.

Propellant tanks like the Centaur aren't designed with the puncture resistance of the ISS western made sections which are themselves inferior to the multi-layer armor that protects all Russian modules.

And most propellant tanks incorporate a diaphragm for the pressurization system which could be replaced with a bellows to create a more robust interior. Oh and the best "armor" is that based on the TransHab/Bigelow inflated modules which are vastly superior to both the aluminum US and Russian hulls. NASA determined that prior to handing the testing results over to Boeing who then re-did the tests and came to the conclusion, (what a surprise) that the Boeing module hulls were in fact superior to the Russian modules and "just as good" as the inflatable ones.

The left in the part where it was proposed to retro-fit all the ISS modules with inflatable armor panels though. And the idea of replacing some of the current insulation with combined insulation/inflatable armor has been vetted but not significantly studied.

Designing every piece of equipment to be disassembled and passed through an narrow tunnel is ruinous to efficiency and will impose high labor costs both to install and maintain,

Actually this is already done for replacement and expansion of the installed equipment where possible. Part of the known problem with MIR that the ISS shares is older and/or malfunctioning equipment is difficult to repair and/or replace because much of it was built in monolithic units that do not break down or can be replaced easily.

...worst it fails to utilize any of the ISS already modular racks which could be transferred to any new module that carries the wide square meter CBM connections.

Most of the racks can in fact not be moved without significant and intensive effort and this is one of the main factors that are driving the ISS "life-time" calculations. Smaller, more modular and easier to move racks are a "need" listed for future space stations as well as more modular and easier to move, repair, and/or replace equipment and systems in general. People who live and work on the ISS are requesting the opposite of what you claim are advantages that preclude tankage based pressurized space.

Evacuating and sealing the tanks is itself a huge problem, valves between the tank and rocket engine will be a permanent source of potential air leaks and one end of the tank will retain the obsolete engine forever meaning one one connection port is possible and modules of this type can never be strung together sausage like, they will always be dependent on node systems to form a spine which they will connect too.

Firstly the evacuation and sealing has been addressed multiple times, multiple ways and "sealing" the vents and propulsion connections is actually the easiest part of the operation. Removing the engine and propulsion section would require EVA work and most importantly a commitment to actually learning to work effectively in space rather than staying "in-doors" all the time unless force to go outside. Station a couple of FLEXcraft on the ISS and design a more labor friendly space suit would be a great start to such a commitment. (Heck ROVs and automated work units would be effective as well))

That's probably the main issue with expanded manned space effort since admitting you actually have to work IN space as well as inside a can "in space" has to be taken seriously if you are doing anything more than dabbling and which no one seems to want to actually do. By doing so it would be committing to planning and carrying out real orbital and beyond orbital missions and effort but that is simply not what anyone really wants to come about.

I've quite certain that the results of the study will be that the idea is quite UN-feasible and I expect these guys to be dropped in later rounds as is common for these contractors that get way over their heads and try to cobble together a system out of other peoples hardware.

While I'd question using the Centaur and Cygnus as a basis the basic idea is feasible and has been shown as such in multiple studies and experiments. I see challenges that need to be overcome to make this happen but the basic concept is quite sound. The reason these get dropped is not because the contractors are in over their heads or because they end up having to build to complex or expensive of a system but that the basic premise behind current manned space flight is based on putting people into space only for limited outcomes with as little ability to expand or do work outside of a highly restricted framework as possible.

We continue to take "short-cuts" to dead ends, quite logically (based on flawed bias' and assumptions) ignoring and avoiding building a fundamental framework and infrastructure to support and expand manned spaceflight and cling to the idea we would be wasting time/effort/money unless we continue to do what we have done for the past 50 years as it is obviously the only way to do manned spaceflight.

Every transportation system has undergone more than one fundamental change along the way to becoming more efficient and productive. Every form of industry from construction to computers has done the same. For some reason while we often claim that space travel should be more like or used as some analog on Earth at the same time we also claim that doing it the same way we've been doing it for the last half-century will in fact bring about one or more fundamental changes. The simple truth is that space is NOT capable of being directly analogues to Earth based capability but in general human thinking and planning can and should draw lessons from those capabilities. But at the very end THE main change has to be a change of mindset that takes us from visiting space occasionally with a few people at great expense to regular access with maximum use of materials and energy available to us.

Randy

[KelvinZero]

There are all these technical reasons against tanks for habitation that people bring up. To me the biggest issue is that this means you are not reusing your rocket tanks as rocket tanks, so the possible usefulness is sandwiched between today and the supposed day of MCT.

Can anyone make a case for this as a long term technology? For a moonbase there is the motivation that you might keep collecting tanks whether you want them or not, so there is much more motivation to find a use for them then.

It also helps if your use requires a lot of volume, many tanks, which is different from ISS etc. I have seen people compare the price of ISS to it's volume but volume really wasn't the goal or limiting factor as far as I have heard.

[Asteroza]

For this particular iteration, unless you make a concerted effort, you will retain your upper stage RL-10 engine(s). Ordinarily this is dead mass for a station that is undesirable. The major exception is where you would want mass and hab space, and strictly generic mass, not mass with a specific purpose, like radiation shielding.

The easiest example of needing mass is with a momentum exchange tether, particularly a gravity gradient stabilized one which would feature a center and/or upper endpoint station/mass collection. One could imagine humans working within the mass collection due to low g in an upper station. The situation becomes less ideal in a rotovator end mass scenario, as the rotovator end mass experiences higher g. Upper stages are great in compression, but their tension capabilities are less than ideal. Though this could be overcome if you can separate engine from tank, so the tank can be used for a rotovator center station, with engines in a net bag or remounted on  a mass hanging bar for end mass.

[TrevorMonty]

If it can fitted out in space then it should be easier to repair/upgrade or replace modules.

[GWH]

On Main Engine Cut Off podcast there was a recent interview with Mike Johnson, chief designer at NanoRacks with a really good overview of the NextSTEP wetlab proposal:
https://mainenginecutoff.com/podcast

Interview is title T+20 and was on September 7 2016.