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#26 2015-01-28 17:22:54

SpaceNut
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Re: NASA could make 'Skylab II' first deep space 'home'

The aluminum can is to attach the equipment and other such items that require a rigid surface that can taker the G forces of launch and EDL otherwise you have an inflateable with decking that is aluminum to attach everything to but even that by itself is in a shell can of aluminum for launch and can not land or enter an atmosphere.

The risk mitigation of radiation is just that when you chose to compensate an astronaut for the chances that he will not survive a mission let alone have the latent later on miladys that one can have due to the exposure. So either we go with knowing the chances or we stay forever a victum of Earths protective megosphere.

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#27 2015-01-28 18:29:09

kbd512
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Re: NASA could make 'Skylab II' first deep space 'home'

Quaoar wrote:

Because it's lightweight, robust and cheep. You cannot have a passive shield against GCR even with polyethylene, unless you build a spaceship with two meters thick walls.
What you need is only a solar flare protected zone: a double aluminium wall filled with 20-25 cm of water ice is good. Ice it is also a very good heat sink for waste heat and a protection against meteorite puncture.
For CGR protection it will be better something like Boeing's 1500 kg superconductive mini-magnetosphere

http://arxiv.org/pdf/1406.1159.pdf

If that actually works, it's fantabulous.  This is the first such concept I've seen that didn't weigh as much or significantly more than the entire Mars DRM transfer vehicle.

Thanks for the info.

Edited to add content:

If a PE fabric composite is heavy then 25CM of water is surely far heavier.

I don't think I'd want my water supply used as ballistic protection.  It'd be pretty tough to live without if it sublimated after an impact penetrated the outer hull.

Last edited by kbd512 (2015-01-28 18:34:22)

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#28 2015-01-28 19:20:53

SpaceNut
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Re: NASA could make 'Skylab II' first deep space 'home'

I saw the term "Earth-Moon-Mars Radiation EnvironmentModule" (EMMREM) in the file and did a quick search to learn more about the topic...
Nasa page on EMMREM is to be a tool to completely characterize time-dependent radiation exposure in the Earth-Moon-Mars and Interplanetary space environments.

http://ccmc.gsfc.nasa.gov/RoR_WWW/works … C10_v1.pdf

http://emmrem.unh.edu/papers/general/EMMREM_IEEE_V5.pdf

http://emmrem.unh.edu/papers/general/Sc … k_2010.pdf

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#29 2015-01-29 05:00:47

Terraformer
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Re: NASA could make 'Skylab II' first deep space 'home'

Perhaps arranging for most radiation shielding to be around the sleeping quarters is what we should be thinking about? The crew are going to be spending a quarter to a third of their time there, after all, and they don't need much space when sleeping. Maybe give each crew member a personal study, but cluster the beds close together, and surround that with your water tanks and food.


To secure a planet it is not necessary to colonise it in its entirety, only to secure the most valuable locations. The Lunar poles and Subterran point. Mercury's poles. The equatorial region of Ceres. Hold these, prevent access to their volatiles and anchor points for beanstalks, and independent colonies cease to be viable.

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#30 2015-02-01 22:16:08

Tom Kalbfus
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Re: NASA could make 'Skylab II' first deep space 'home'

What exactly do you do with Skylab 2 at Lunar L2? Is it supposed to go somewhere? Like to Mars or Venus? Is it a staging point for a manned Ion thruster? Something at L2 is already at Escape velocity, just needs a little nudge, and it will be in its own separate orbit around the Sun.

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#31 2015-03-08 10:14:45

SpaceNut
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Re: NASA could make 'Skylab II' first deep space 'home'

With the knowledge that the ISS could possibly be de-orbited wouldn't the US (NASA) want to protect its investment as we are about to have manned capablility going to the station in the next couple of years.

form my post in the article that I link in 202* Russia to take its module and go...

"You are forcing me into this answer, and I like to give you real answers," Bolden finally said. "I don't want to try and BS anybody."

Is Skylab II possibly the answer as a one shot launch from the SLS into an orbit that could be reached from the orbital plane of the ISS by an ION thrustered tug and send up a propulsion system for the ISS as a replacement for the would be taken modules?

With the chances of the station not be deorbited and making the new station an international colaboration effort for science, I would say that Its a win for Bolden if he could get funding that would rush the lab into service before the date....

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#32 2015-03-08 15:35:55

kbd512
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Re: NASA could make 'Skylab II' first deep space 'home'

Relying on international partners for critical functionality is always a mistake.  I'm not sure what it would take for that to sink in.

The Russians' leadership is every bit as petulant as our leadership is.  If the Russians are intent on treating ISS like some sort of political chess piece instead of the international cooperative effort that NASA intended for it to be, then there is no "International" Space Station.  NASA needs to accept this and put forth the effort required to replace the capability the Russians modules provided or de-orbit the facility and save the taxpayers' money for real manned space exploration efforts.

NASA needs to develop its own tech for manned space exploration and Skylab II is a step in the right direction.  The capabilities that the Russian modules provide is well within our technological capability.

If NASA is at all serious about its commitment to ISS, it will divert funds to develop a SEP propulsion module and crew accommodations.  I'm guessing that it's not and the station will be brought down when the Russians leave.  Anyway, screw 'em.  Upwards and onwards.

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#33 2015-03-09 09:39:36

GW Johnson
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Re: NASA could make 'Skylab II' first deep space 'home'

As good an item as a Skylab 2 might be,  why not try another notion? 

Dock a bunch of appropriate modules together into a long baton shape,  a lot of them Bigelow inflatables with specific equipment cores.  Put the docking adapters and the solar wings in the middle at the baton cg.  Spin the thing end-over-end for artificial gravity,  varying from 1 gee at the ends to zero in the middle.  56 m radius at 4 rpm is 1 gee.  Use it to experiment with everything we do now,  plus learning about artificial gravity and partial-gee effects (for the first time).  It's also a basic technology prototype for the kinds of deep space orbit-to-orbit ships we will need.

Add a free-flyer module alongside that is your repair/assembly bay plus your zero-gee habitat.  The assembly bay is where you experiment with lighting for temperature control in a zero-gee unpressurized "shop floor" environment.  This is where you try out new maintenance procedures and new spacesuit designs,  to make possible real self-repair and self-rescue techniques for long missions.  The habitat is where you continue the zero-gee research we do now. 

Using whatever is at hand at the time,  experiment with and develop in-space refueling procedures,  up to and including cryogens,  as another free-flying-alongside item,  just at a safe distance in case of an explosion.  These would initially be things sent up,  until the techniques are developed.  Then we can incorporate them as routine operations into the spin station and the zero-gee free-flyer. 

Given today's per-unit launch prices to LEO,  this thing could be built of nominal 15 ton modules for a whole lot less money than ISS cost us.  While more expensive than another Skylab,  it does so very much more of what we need to do,  if we really want to fly men outside cis-lunar space.  It does more than ISS ever could,  at a fraction of ISS's cost.  (I don't have a good figure for that,  but the direct launch costs are now factor 10 lower for the same thrown weight.)

What we have been doing up to now (from Skylab through ISS) demonstrably doesn't address all the issues we now know we must address for deep space manned travel.  You have to do something new in order to address what has been heretofore unaddressed.  Seems like basic common sense to me. 

GW

Last edited by GW Johnson (2015-03-09 09:45:56)


GW Johnson
McGregor,  Texas

"There is nothing as expensive as a dead crew,  especially one dead from a bad management decision"

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#34 2015-03-09 18:18:05

SpaceNut
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Re: NASA could make 'Skylab II' first deep space 'home'

I went looking at what would be in the 15 ton range for module size and here is what the ISS has.

http://www.daviddarling.info/encyclopedia/I/ISS.html

Destiny Laboratory Inside the Destiny lab

Destiny.jpg

America's main workstation for carrying out experiments aboard the ISS.

The 16.7-m-long, 4.3-m-wide, 14.5-ton Destiny will support research in life sciences, microgravity, Earth resources, and space science. It consists of three cylindrical sections and two end-cones. Each end-cone contains a hatch through which crew members will enter and exit the lab.

A 7 unit made out of a destiny style module makes a baton with a bit over on the overall length.

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#35 2015-03-09 19:24:05

kbd512
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Re: NASA could make 'Skylab II' first deep space 'home'

For purposes of generating artificial gravity for the deep space habitat, I was thinking something more along the lines of a swash plate with rotors and small crew accommodations at the tips, just big enough to bunk one or perhaps two crew members.  The rotors would be covered with solar cells for power and the blades would be detachable for on-orbit assembly.  The swash plate would attach to the air lock and house secondary ECLSS.  The front of the swash plate would contain another air lock with a smaller module attached to it.  The smaller module would contain additional consumables, secondary flight deck, telescope, and backup ECLSS.  The rotors would use water distribution to maintain precise counterbalance.

The habitat module would contain the primary avionics and flight deck, store the bulk of the consumables for the crew, house the active radiation shield, primary power subsystem for the active radiation shield and primary ECLSS, and attitude control systems.  The crew would enter the habitat module from the rear and then the propulsion module would attach to the docking port and seal them in for the transit to Mars.

The general idea is to not require use of a substantial separate counterweight or tether, not use propellant for start/stop, and simultaneously permit the use of SEP or NEP.  The end-over-end tumbling concept should also work, but the spin down operations are slightly more complicated.

The same habitat module with a docking adapter in place of a propulsion module could serve as a space station or L1 outpost.

My presumptions are that all propulsion and attitude control systems will be electric, Orion won't be available to serve as a counterweight due to flight costs and its inability to land anywhere but an ocean, and that the heavy lift capability provided by SLS will only be used for the deep space habitat module.

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#36 2015-03-09 19:51:17

SpaceNut
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Re: NASA could make 'Skylab II' first deep space 'home'

Had to look up the term swash plate with rotors to help understand the concept.
http://en.wikipedia.org/wiki/Swashplate_(helicopter)

Which is a single shaft with a coupling that allow for decoupling of draive which also can allow different spin rates to occur such that a fast spinning shaft can couple out to a much slower spinning end. Which gets into magnetic coupling and other such devices to control the coupling rates.

The plate sounds like the typical open wheel construction but I could be way off. Do you have an image to post?

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#37 2015-03-09 21:57:56

kbd512
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Re: NASA could make 'Skylab II' first deep space 'home'

Unfortunately, I don't have any visuals to provide.  The term swashplate was only meant to illustrate the concept.

Picture a three or four bladed rotor or propeller with flat blades and hollow cores.  Now imagine that this propeller has bulbs/bumps on the tips of the blades and hollow cavity connecting them.  The bulbs/bumps are astronaut sleeping quarters.  The transfer tunnels leading to the sleeping quarters are just big enough for the astronauts to transit through.  The hollow cores contain small cavities for water to equalize mass distribution amongst the propeller blades and provide a secondary source for potable water.  The hollow swash plate contains a pumping system for moving water amongst the blades to equalize loading.

Irrespective of whether or not a particular astronaut weighs a little more or less than the astronaut in the blade opposite from him/her, or whether or not the opposing blade is even occupied, the mass distribution system ensures that no net force is applied in a particular direction so as not to disturb the direction of travel.

The interfaces between the blades and swash plates are air locks.  The front and back of the swash plate are also air locks connected to the primary and secondary deep space habitat modules.

I wanted triple redundant ECLSS, triple redundant power supply and management, and distribution of consumables amongst the three components to reduce the weight of specific components.  If it is possible to lift all three components using F9H and larger payload fairings, that would be ideal.  I think three F9H flights and one crewed F9 flight would be sufficient for assembly.

The primary module will be launched first to provide station keeping capability during initial assembly and testing.  After assembly has been completed, SLS provides the primary propulsion module.  If SLS is not available, then two more F9H flights are required.  Irrespective of how the propulsion module arrives in LEO (fully fueled if aboard SLS or partially fueled if aboard F9H), the MTV is then mated to the propulsion module.  The propulsion module transfers the MTV to ISS for crew consumables loading and any necessary repairs/manifest additions/software upgrades.  From there, the propulsion module transfers the MTV to L1 where tests of the communications systems and active radiation shield are performed.  If everything functions as expected, the exploration crew are cleared for departure.  The crew are launched in Dragon aboard a F9H outbound to L1.  Upon arrival, the propulsion module separates from the MTV to permit Dragon to transfer the crew.  The propulsion module is then re-mated to the MTV.  The crew performs final checkout and says their goodbyes.

Rather than complicating the architecture with a surface stay, the first mission will be an orbital mission designed to prove that the MTV and propulsion module are up to task.  The mission might include exploration of Phobos or Deimos just to say we landed on something or it might not.

Even now, interplanetary travel is a monumental human achievement, so I'm going to divide the task into achievable mission objectives.  With tech that will be available within the next five to ten years, this is doable.  I imagine that the tech required for surface stays is another ten to fifteen years away after that.  Slowly but surely, we'll get there.

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#38 2015-03-09 23:24:32

kbd512
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Re: NASA could make 'Skylab II' first deep space 'home'

For a crew of six, my design requires a four bladed artificial gravity device.  One crew member bunks in each blade tip.  Two crew members are on watch at all times in the primary or secondary flight deck, so only four bunks are required.  During normal operations, all airlocks are sealed to prevent a penetration in one compartment from endangering the entire crew.  Apart from meals and recreation the crew will remain in separate MTV modules for the same reason.  All three modules will contain a shower, toilet, and galley.  The primary module will be more lavish than the secondary module or swash plate, but a systems casualty won't instantly make the astronauts hate life.

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#39 2015-03-10 17:03:29

Terraformer
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Re: NASA could make 'Skylab II' first deep space 'home'

Gravity doesn't help you if you're sleeping... if you're only going to have a centrifuge in part of it, make it at least the exercise area, and ideally put the restrooms and dining area there as well. The crew can sleep in freefall.


To secure a planet it is not necessary to colonise it in its entirety, only to secure the most valuable locations. The Lunar poles and Subterran point. Mercury's poles. The equatorial region of Ceres. Hold these, prevent access to their volatiles and anchor points for beanstalks, and independent colonies cease to be viable.

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#40 2015-03-10 18:10:39

kbd512
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Re: NASA could make 'Skylab II' first deep space 'home'

Terraformer wrote:

Gravity doesn't help you if you're sleeping... if you're only going to have a centrifuge in part of it, make it at least the exercise area, and ideally put the restrooms and dining area there as well. The crew can sleep in freefall.

The problem with having gravity in the exercise room would be disturbing the orientation of the MTV.  The propulsion system is low thrust electric.  There's no real issues with tumbling a MTV if impulsive burns are used.  Sleeping on an incline will have to suffice.

An inflatable wheel would also work and provide enough space for the crew to work from, but it'd be heavier.  I wanted to keep the solution as light as possible to make the loads manageable using three F9H flights.

I'll believe SLS will be available when the funding to use it materializes.  There's no funding for an upper stage, so SLS is 70t to LEO, 85t with advanced boosters, and maybe 90t with composite tankage.  There's no advantage to using a booster that's more than ten times as expensive to fly as F9H, unless you just want to burn money.

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#41 2015-03-10 19:50:21

SpaceNut
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Re: NASA could make 'Skylab II' first deep space 'home'

Falcon 9 heavy Fairing

SpaceX's payload fairing, used on both Falcon Heavy and Falcon 9, is a composite structure fabricated in-house by SpaceX that protects satellites during delivery to low-Earth orbit (LEO), geosynchronous transfer orbit (GTO), and beyond. The fairing is 13.1 meters (43 feet) high and 5.2 meters (17 feet) wide. It consists of an aluminum honeycomb core with carbon-fiber face sheets fabricated in two half-shells.

I indicated earlier that ISS module Destiny was 16.7-m-long, 4.3-m-wide, 14.5-ton and while its wthin the mass its outside of the length so we would need to redesign all modules of the ISS to fit and a clean slate design is not much better when we look at how to leverage what we have in designs currently, this would raise the cost of building any station.

http://en.wikipedia.org/wiki/Atlas_V

The standard payload fairing sizes are 4 or 5 meters in diameter and of various lengths, and are made by RUAG Space. Fairings sizes as large as 7.2 m in diameter and up to 32.3 m in length have been considered

ISS modules would fit nicely unaltered it would seem.

http://en.wikipedia.org/wiki/Delta_IV

To encapsulate the satellite payload, a variety of different payload fairings are available. A stretched Delta III 4-meter composite payload fairing is used on 4-meter variants, while an enlarged, 5-meter composite fairing is used on 5-meter variants.

Not enough details to tell if they would fit.

payload to LEO is 53,000 kg (117,000 lb) http://en.wikipedia.org/wiki/Falcon_Heavy

As of March 2013, Falcon Heavy launch prices are below $1,000 per pound ($2,200/kg) to low-Earth orbit when the launch vehicle is transporting its maximum delivered cargo weight. The published prices for Falcon Heavy launches have moved some from year to year, with announced prices for the various versions of Falcon Heavy priced at US$80-125 million in 2011, US$83-128 million in 2012, US$77.1-135 million in 2013, and US$85 million for up to 6,400 kg to GTO (with no published price for heavier GTO or any LEO payload) in 2014. Launch contracts typically reflect launch prices at the time the contract is signed.

Hard to figure a price when its a range in value. 77.1 + 135 = [$212.1] /2 = $106.05 million average
53,000 kg at $2,200 a kg = $116,600 see what I mean

If a launch price is less than 200 million we do beat Boeing's Delta IV Heavy price performance and the same is for the Atlas V , but with the Atlas V Heavy still a paper design we have an unknown.

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#42 2015-03-11 09:26:19

GW Johnson
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Re: NASA could make 'Skylab II' first deep space 'home'

Don't forget that you might not need a payload fairing at all.  A cylindrical module whose skin is not too fragile can be its own "payload fairing",  riding naked on top of the launcher.  It just needs a small "pointy hat" to reduce air drag some.  That would a small conical fairing on its end, covering the docking gear there from supersonic bow waves,  going up. 

Ascent heating is just not that big a deal,  since you leave the "dense" air (enough to have significant heating) at about Mach 2-ish at around 100+ kilofeet-ish.  Higher and faster the temperatures are high,  yes,  but the density is actually so low there is little heat actually transferred,  plus it's a brief transient.  It really is NOT re-entry-in-reverse,  we don't ascend with trajectories like that at all! 

GW


GW Johnson
McGregor,  Texas

"There is nothing as expensive as a dead crew,  especially one dead from a bad management decision"

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#43 2015-03-11 23:09:00

kbd512
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Re: NASA could make 'Skylab II' first deep space 'home'

GW Johnson wrote:

Don't forget that you might not need a payload fairing at all.  A cylindrical module whose skin is not too fragile can be its own "payload fairing",  riding naked on top of the launcher.  It just needs a small "pointy hat" to reduce air drag some.  That would a small conical fairing on its end, covering the docking gear there from supersonic bow waves,  going up.

I intended for all three major components to be covered with solar cells and radiators, so that probably means some protection is required during ascent.  The swash plate and blades will be somewhat more delicate than the primary or secondary modules, as there are five separate components included that are assembled on-orbit.

GW Johnson wrote:

Ascent heating is just not that big a deal,  since you leave the "dense" air (enough to have significant heating) at about Mach 2-ish at around 100+ kilofeet-ish.  Higher and faster the temperatures are high,  yes,  but the density is actually so low there is little heat actually transferred,  plus it's a brief transient.  It really is NOT re-entry-in-reverse,  we don't ascend with trajectories like that at all! 

GW

I don't think it's possible to design an inexpensive deep space habitat, but I'm trying to use available technology.  The secondary module is a small ISS module and the primary module is a SLS gas can.  The design goals are triple redundancy for subsystems that can put a damper on your exploration activities (like power, consumables, and ECLSS), distribution of consumables, distribution of the crew amongst the modules, and some measure of artificial gravity.  The closed loop ECLSS, active radiation shielding, and the swash plate and blades all require further development.

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#44 2015-10-13 20:08:06

SpaceNut
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Re: NASA could make 'Skylab II' first deep space 'home'

I located a document that talks about the methods used by Apollo to make the SLS do the same in creating a SkylabII

http://spirit.as.utexas.edu/~fiso/telec … -27-13.pdf

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#45 2016-02-03 17:44:01

SpaceNut
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Re: NASA could make 'Skylab II' first deep space 'home'

Here is the topic for others for the way to build a station at the ISS by using the fuel tanks to make it possible....

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#46 2016-02-03 19:18:43

RobertDyck
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Re: NASA could make 'Skylab II' first deep space 'home'

The problem with proposals for "Skylab II" is that it launches wet. The purpose for using a propellant tank is to launch wet. If you launch dry, then it can't be a propellant tank, it'll be a custom module.

Skylab was designed and built to launch wet. The only reason it was launched dry was Nixon cancelled Apollo, so NASA had Saturn V launch vehicles laying around. They were supposed to launch Apollo 18, 19, and 20. Saturn 1B cost less than a single Shuttle launch. The first designs by Wernher von Braun were an S-II stage, the second stage of Saturn V. That design would launch wet, but all equipment would be housed in an "equipment module". So no equipment in LH2. The third stage would be a hollow shell, a continuous volume enclosed by the interstage between 2nd & 3rd stages, and the adapter that housed the LM and support the CSM. The equipment module contained within that space. Once the S-II stage was in orbit and the LH2 tank empty (and dry), then the equipment module would drop in. A portion of the equipment module would remain outside the LH2 tank: docking ports, air lock, and whatever outside equipment the station needed. Launching the smaller S-IVB based Skylab on the big Saturn V was just waste.
800px-Dr._von_Braun%27s_Sketch_of_the_Space_Station_8883912_original.jpg

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#47 2016-02-03 21:03:05

kbd512
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Re: NASA could make 'Skylab II' first deep space 'home'

RobertDyck wrote:

The problem with proposals for "Skylab II" is that it launches wet. The purpose for using a propellant tank is to launch wet. If you launch dry, then it can't be a propellant tank, it'll be a custom module.

If you launch it wet, you contend with the following issues:

Cryogenic propellants require slosh baffles that would make it heavier than required for habitation

Cryogenic propellants require insulation that would make it heavier than required for habitation

Rocket stages require separate fuel and oxidizer tanks that would make it heavier than required for habitation

Rocket stages require thrust structures and engines that would make it heavier than required for habitation

Habitats require MMOD protection

Habitats require electrical wiring for lighting

Habitats require creature features like plumbing for toilets, showers, and laundry

Habitats require food and water storage

Habitats require internal structure for ECLSS and scientific equipment stowage

It's possible to outfit the module on-oribt, but that's the orbital assembly everyone is trying so hard to avoid.  The avionics, solar arrays, radiators, and airlock can be mounted outside of the cryogen can / habitat, so no real issues there.  If you can outfit the habitat and load the consumables at ISS, the wet habitat is feasible.  That's quite a bit of on-orbit work just for a larger habitat.

RobertDyck wrote:

Skylab was designed and built to launch wet. The only reason it was launched dry was Nixon cancelled Apollo, so NASA had Saturn V launch vehicles laying around. They were supposed to launch Apollo 18, 19, and 20. Saturn 1B cost less than a single Shuttle launch. The first designs by Wernher von Braun were an S-II stage, the second stage of Saturn V. That design would launch wet, but all equipment would be housed in an "equipment module". So no equipment in LH2. The third stage would be a hollow shell, a continuous volume enclosed by the interstage between 2nd & 3rd stages, and the adapter that housed the LM and support the CSM. The equipment module contained within that space. Once the S-II stage was in orbit and the LH2 tank empty (and dry), then the equipment module would drop in. A portion of the equipment module would remain outside the LH2 tank: docking ports, air lock, and whatever outside equipment the station needed. Launching the smaller S-IVB based Skylab on the big Saturn V was just waste.

Launching Skylab wet was an idea NASA toyed with and ultimately decided against for all the reasons listed above.  No free lunches.  The first version of SLS can easily orbit Skylab II.  However, you need another SLS launch to send it to wherever it's going.  The dV requirement for impulsive transfer from LEO is substantial.  IIRC the LUS, which is the largest upper stage concept currently under consideration, can throw 41t (Edit: LUS can throw 31t to TMI, not 41t) or thereabouts to TMI from LEO.

It is very interesting to note that the Skylab II concepts have the same or very similar mass requirement as NASA's ISS-derived 500 day DSH, but have as much as 500% more habitable volume.  Kinda makes you wonder whether or not the ISS-derived solutions are worth the effort when you can have a much, much larger habitat for comparable cost.  We're getting SLS whether we want it or not.  May as well make a few extra barrels for Skylab II DSH's.  That way that FSW equipment at Michoud is not sitting around collecting dust.

Last edited by kbd512 (2016-02-03 22:03:08)

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#48 2016-02-03 22:15:55

RobertDyck
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Re: NASA could make 'Skylab II' first deep space 'home'

Skylab was not "toyed with", it was built. It was launched. It flew in space. The reason it had open mesh hexagonal grid floor is to permit LH2 to flow through during launch. Walls were not open mesh, they were sheet, because they acted as anti-slosh and anti-vortex baffles.
skylab4_inside.gif 12169644-standard.jpg
Notice the design feature: structures do more than one function. If you know what you're doing.

Actually, the S-IVB LH2 tank didn't have much for baffles, because it used a common bulkhead with the LOX tank. The LOX tank had substantial baffles. The LH2 siphon was at the outside edge, at the bottom of the LOX dome. The LH2 tank had "3D" textures to foam insulation on the inside of the tank, but that was it. They didn't need baffles because of the LOX dome. But that's another example of intelligent design. A common bulkhead mean the LH2 tank didn't need a bottom, but also meant the LH2 tank didn't need baffles.

This comes back to the Skylab design for floor and walls. They were designed as baffles anyway. That same design can be used. That means no separate slosh baffles.

Space station modules do have thermal insulation. It's usually multi-layer insulation, to try to reduce mass. That's aluminized Mylar to reflect radiant heat (IR), with fishnet spacers. The vacuum of space between reflectors. That acts as a Dewar, or Thermos bottle. However, you can design insulation to integrate cryogenic insulation. Skylab did. The micrometeoroid shield sprung out once in space to create separation. The micrometeoroid shield would break up larger micrometeoroids, causing small chunks to hit the hull. Micrometeoroid shield of TransHAB uses the same principle, just different materials. But putting vacuum between the micrometeoroid shield and hull instead of foam like TransHAB meant no conductive heat transfer. So the micrometeoroid shield doubled as sunshade. Today blankets for ISS modules use the same materials as EMU spacesuits: Orthofabric exterior layer, then multilayer thermal insulation. Micrometeoroid shield of TransHAB (or Bigelow hab) is more substantial. The point is why use multilayer insulation if you have foam insulation for the cryogenic tank? Just use a single later of aluminized Mylar outside the foam, then Orthofabric.

I could go on, but you fail to truly see the point. You can't compare a self-launching module to just a rocket stage, or just an ISS module. You have to compare a self-launching module to the total mass of rocket stage + ISS module. The self-launching module has a single pressure hull, not two. And several shared features. The result is lower total mass.

And look at what I said in the other discussion thread. I said discard the LOX tank, inter-tank structure, engines, and thrust structure.

And no, you don't have to fit equipment on-orbit. Skylab was designed to launch with electrical wiring, plumbing, food, water, life support, and scientific equipment inside during launch. Yes, they would be immersed in LH2. Yes, they have to endure being frozen. I think this time we would want food and electronics kept outside the cryogenic tank, and membrane filters for the life support. Keep additional stuff down to what can fit in a single Dragon or Cygnus cargo ship. Even water storage can freeze; just use a plastic bag that isn't completely full so has enough flexibility to expand. Plumbing must be completely dry before you freeze it.

I have some experience, prepared my house to let it freeze. Years ago a friend asked me to help him close his cottage for the season. He drained all plumbing, and poured antifreeze into the "U" joints of sinks, bathtub, and toilet. So I did the same with my house. Discovered stores sell "plumbing antifreeze" for just this purpose. Certified for burst protection to -50°C. The week I froze my house it got down to -27°C. Flushed the toilet and splashed water out of the tank, to ensure no water in the tank. Drained the hot water tank. Left all taps open to ensure all water drips out, and no pressure remains as it froze. Disconnected hoses for the washing machine from the taps, left the hoses lying on the floor so they would drain too. It worked. Had difficulty getting the furnace pilot light to stay lit. There's a thermocouple in the pilot light flame, if it detects no heat from the pilot light it shuts off the natural gas. Safety feature. Held the "reset" knob to keep the pilot light on long enough to heat the thermocouple. It wouldn't stay on. Eventually called a service technician, who did exactly the same thing I did, but when he did it, it worked. I can only guess that heat finally got to all the parts of the furnace that needed it. My PVR is acting up: sometimes when I press a button on the remote it doesn't respond for several seconds. But everything else works: my tube TV, phone, "tower" personal computer, tube monitor, LCD monitor, and iMac with built-in LCD display, laser printer. The remote had to fully warm before it worked again. Batteries don't work well when they're cold.

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#49 2016-02-03 22:41:34

kbd512
Administrator
Registered: 2015-01-02
Posts: 4,892

Re: NASA could make 'Skylab II' first deep space 'home'

Rob,

I'm aware of the fact that they actually launched Skylab and some of the features built in were intended to provide a function if the habitat was launched wet.  The point is, they didn't launch it wet.  They didn't think it was worth the hassle.  Moreover, it's just not necessary and serves no real purpose when you want to use it as habitat.  You can't live inside when it's wet.  You want to send this thing to orbit wet, but the Skylab C-3 variant only weighs 41t (6 crew for 1000 days) and you still need more propellant to send the Skylab/TMI/MOI/TEI/EOI/Orion stack to TMI than a single SLS would ever be capable of lifting.

On-orbit assembly is nothing more involved than mating the propulsion stages to Skylab II.  I posted a NTRS document that contains info about how NASA figures this could be done.  You need more than one SLS rocket.  Why is that a big deal?  You could send more mass to orbit if Skylab was wet, but to what end?  It's not required to sustain the crew and you still need more than one rocket to launch the other hardware required to do the mission.


SLS 1 - MAV and TMI/MOI stages

SLS 2 - Skylab II and MSH (also MDV)

Falcon Heavy 1: TEI and EOI stage

Falcon Heavy 2: TMI 2 and MOI stage

SLS 3 - TMI 1 stage

That's a totally reasonable number of launches that takes care of virtually all requirements to do the mission and it doesn't require SEP or aerobraking or ISPP.

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#50 2016-02-03 23:28:13

RobertDyck
Moderator
From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 6,890
Website

Re: NASA could make 'Skylab II' first deep space 'home'

And my concern was that using a EUS LH2 tank as the ITV would be too big. A single deck hab would be smaller, consequently lower mass. But that would be too small for the LH2 tank for launch. Hmm. Two LH2 tanks? Nah, too complicated. If you can't use the upper stage tank as your habitat, then may as well launch dry.

A soft habitat could fit within a Falcon 9 fairing, but that would create problems with artificial gravity. You want a firm floor to stand on, for so furniture doesn't move around when you walk, and simply for structural support. So that brings me back to a large diameter habitat. We could shrink it a bit. Mars Direct was designed on purpose to maximize use of the large diameter core stage. Robert Zubrin said so in his book. Skylab did pretty well with a 6.6 metre diameter, but sleeping quarters were vertical. You can do that in zero-G, but not with artificial gravity.

Again, with a single deck, the walls will be weight bearing to hold the ceiling and floor together. Against pressure. So you can have a flat floor, and a low dome to the ceiling, similar to the end of an ISS module. Or the roof of MDRS or FMARS. Not a hemispherical dome. That is part of the design of a dedicated habitat, not a propellant tank.

So again I come to the same conclusion. Either self-launching, or not use a propellant tank.

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