Author Topic: Blue Origin Orbital Habitats  (Read 121992 times)

Blue Origin Orbital Habitats
« on: 05/28/2019 08:13 pm »
Blue Origin is apparently doing some work on Orbital habitats, possibly wet-workshops, which has been rumored in the past. I thought the fact that we have a render now made it "real" enough to warrant a thread.

https://twitter.com/SciGuySpace/status/1133390325249134592
Wait, ∆V? This site will accept the ∆ symbol? How many times have I written out the word "delta" for no reason?

Offline Tulse

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Re: Blue Origin Orbital Habitats
« Reply #1 on: 05/28/2019 08:22 pm »
There's been numerous suggestions over the years of using spent tanks for habs (back to Apollo), but I'm just not convinced that there's actually a benefit over a purpose-built hab, since a tank would have to be outfitted with all the hab gear anyway.  You're trading some pressurized volume that you have for a lot of on-orbit work, and presumably extensive pre-launch customization of the tank to accommodate conversion.  Without seeing actual details, the notion produces cool renders, but not much else.

Offline GWH

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Re: Blue Origin Orbital Habitats
« Reply #2 on: 05/28/2019 10:29 pm »
See starpost.space for details of how.

I think for tourists at the minimum it's a perfect fit. All that space and 7m of diameter means you can literally fly around or run laps around the perimeter. Play racket ball? Few other proposed habitats offer the kind of freedom that would provide.

Like most proposals I say they go for it and everyone else just worry a lot less about their own opinions of it being "efficient" or whatever. It will make sense for some cases, not for all, that will get sifted out as time moves on.

Offline Coastal Ron

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Re: Blue Origin Orbital Habitats
« Reply #3 on: 05/28/2019 11:04 pm »
See starpost.space for details of how.

I think for tourists at the minimum it's a perfect fit. All that space and 7m of diameter means you can literally fly around or run laps around the perimeter. Play racket ball? Few other proposed habitats offer the kind of freedom that would provide.

Some people seem to think that the future of space tourism is as zero-G playgrounds. I don't see the market for that. In fact I see a very limited market for space tourism at all in the near future.

Quote
Like most proposals I say they go for it and everyone else just worry a lot less about their own opinions of it being "efficient" or whatever. It will make sense for some cases, not for all, that will get sifted out as time moves on.

You can say that, since you aren't the one paying for it. But for those paying for it they have to have a reasonable expectation of some sort of ROI, and outside of government funding I'm not sure there is a clear business case for a commercial LEO station. If there was we'd see more from Bigelow regarding all of the Letters of Intent (LOI) that he claims to have for his LEO outpost.

And the point about wet labs is that you still need dedicated cargo flights to bring up all of the innards for the repurposed propellant tank, and you'll also need workers and inspectors brought up to outfit and validate the reconstruction process. That's why many don't see a future for that in LEO, where fully outfitted habitats are only one launch away.
If we don't continuously lower the cost to access space, how are we ever going to afford to expand humanity out into space?

Re: Blue Origin Orbital Habitats
« Reply #4 on: 05/29/2019 12:04 am »
Some people seem to think that the future of space tourism is as zero-G playgrounds. I don't see the market for that. In fact I see a very limited market for space tourism at all in the near future.

I understand where you're coming from here. Based on everything that's been announced, orbital tourism doesn't seem like it will be practical for at least the next decade.

But if Blue really is working on a 20-ish person transport to LEO, that could start to open the market up a bit. 20 people on orbit in one New Glenn launch could bring the price of a person to orbit down enough to make it a vacation option for millionaires rather than just multi-millionaires. It's a start.
Wait, ∆V? This site will accept the ∆ symbol? How many times have I written out the word "delta" for no reason?

Offline TrevorMonty

Re: Blue Origin Orbital Habitats
« Reply #5 on: 05/29/2019 12:48 am »
See starpost.space for details of how.

I think for tourists at the minimum it's a perfect fit. All that space and 7m of diameter means you can literally fly around or run laps around the perimeter. Play racket ball? Few other proposed habitats offer the kind of freedom that would provide.

Like most proposals I say they go for it and everyone else just worry a lot less about their own opinions of it being "efficient" or whatever. It will make sense for some cases, not for all, that will get sifted out as time moves on.
Going off renderings it looks like purpose built habitat as extension of US + docking module + service module. Fitting out the wet habitat can be done over time. Its actually bonus as station has vacant room to expand into as required.

At 7m diameter they could include a centrifuge for partial gravity. At very least low 1/20 gravity bathroom and kitchen.

Offline GWH

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Re: Blue Origin Orbital Habitats
« Reply #6 on: 05/29/2019 07:17 am »
Going off renderings it looks like purpose built habitat as extension of US + docking module + service module. Fitting out the wet habitat can be done over time. Its actually bonus as station has vacant room to expand into as required.

At 7m diameter they could include a centrifuge for partial gravity. At very least low 1/20 gravity bathroom and kitchen.

Exactly. People get so hung up on the concepts of wetlabs downsides by comparing them to the ISS which doesn't have more than a few square inches of bare walls. Outfitting a wet lab in the same way would lunacy, but finding ways to rethink how that space gets utilized and - gasp- leaving some space empty would totally change how a station gets utilized and the user design. I personally would go batty in the ISS with all the clutter. Nothing wrong with some bare walls and room to grow.

Ever do work in a cluttered space? Step into a larger area and see how much both efficiency and personal feelings of well being improve.
« Last Edit: 05/29/2019 07:21 am by GWH »

Offline hydra9

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Re: Blue Origin Orbital Habitats
« Reply #7 on: 05/29/2019 07:21 am »
See starpost.space for details of how.

I think for tourists at the minimum it's a perfect fit. All that space and 7m of diameter means you can literally fly around or run laps around the perimeter. Play racket ball? Few other proposed habitats offer the kind of freedom that would provide.

Like most proposals I say they go for it and everyone else just worry a lot less about their own opinions of it being "efficient" or whatever. It will make sense for some cases, not for all, that will get sifted out as time moves on.

Like the old Skylab videos using its 6.6 meter in diameter dimension for recreation.

Marcel

Offline hydra9

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Re: Blue Origin Orbital Habitats
« Reply #8 on: 05/29/2019 07:44 am »
See starpost.space for details of how.

I think for tourists at the minimum it's a perfect fit. All that space and 7m of diameter means you can literally fly around or run laps around the perimeter. Play racket ball? Few other proposed habitats offer the kind of freedom that would provide.

Some people seem to think that the future of space tourism is as zero-G playgrounds. I don't see the market for that. In fact I see a very limited market for space tourism at all in the near future.

Quote
Like most proposals I say they go for it and everyone else just worry a lot less about their own opinions of it being "efficient" or whatever. It will make sense for some cases, not for all, that will get sifted out as time moves on.

You can say that, since you aren't the one paying for it. But for those paying for it they have to have a reasonable expectation of some sort of ROI, and outside of government funding I'm not sure there is a clear business case for a commercial LEO station. If there was we'd see more from Bigelow regarding all of the Letters of Intent (LOI) that he claims to have for his LEO outpost.

And the point about wet labs is that you still need dedicated cargo flights to bring up all of the innards for the repurposed propellant tank, and you'll also need workers and inspectors brought up to outfit and validate the reconstruction process. That's why many don't see a future for that in LEO, where fully outfitted habitats are only one launch away.

The excitement of taking off from a launch pad and returning to Earth, staying in a large habitat with a large microgravity recreation area, a Cupola with a window view of the Earth, private rooms providing intimate surroundings for a wealthy couple, a FlexCraft for an EVA adventure outside of the habitat. If I were a billionaire, I'd travel to a microgravity habitat every year. And if I were worth at least a couple of hundred million, I'd travel to a microgravity habitat at least once.

But regular people around the world could also travel to private microgravity space habitats if there was a Space Lotto system where people could risk a dollar or more for a chance to travel to a space hotel and be compensated for the time off from work for astronaut training with perhaps $250,000. I bet that there's more than a billion people on Earth who would love to travel into space.

There's more than 70 government space agencies around the world with only three have crew flight capability.
 
So the only way there's no market for private space stations is only  if they're is no significant public interest in space travel.

Marcel

Offline TrevorMonty

Re: Blue Origin Orbital Habitats
« Reply #9 on: 05/30/2019 04:11 am »
There are other options for large US tanks. LH tank could be kept as vacuum and used for free flyer testing. Don't need to worry about test vehicle going AWOL as its confined. Use LOX tank as is just pressurize, could be used free flyer testing but in atmosphere, or play area for crew.

Offline TrevorMonty

Re: Blue Origin Orbital Habitats
« Reply #10 on: 05/30/2019 05:28 am »
Its even big enough for garage if section is cut out of side. Protect vehicles or space craft from MMD.

Offline Tywin

Re: Blue Origin Orbital Habitats
« Reply #11 on: 08/06/2019 04:04 am »
See starpost.space for details of how.

I think for tourists at the minimum it's a perfect fit. All that space and 7m of diameter means you can literally fly around or run laps around the perimeter. Play racket ball? Few other proposed habitats offer the kind of freedom that would provide.

Like most proposals I say they go for it and everyone else just worry a lot less about their own opinions of it being "efficient" or whatever. It will make sense for some cases, not for all, that will get sifted out as time moves on.
Going off renderings it looks like purpose built habitat as extension of US + docking module + service module. Fitting out the wet habitat can be done over time. Its actually bonus as station has vacant room to expand into as required.

At 7m diameter they could include a centrifuge for partial gravity. At very least low 1/20 gravity bathroom and kitchen.

How many second stage you think so is necessary for a practical station with artificial gravity?

« Last Edit: 08/06/2019 04:05 am by Tywin »
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Offline Shevek23

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Re: Blue Origin Orbital Habitats
« Reply #12 on: 10/22/2019 08:42 pm »

How many second stage you think so is necessary for a practical station with artificial gravity?

For a bare minimum, as a general thing? Two!

Having three lets you have two, I envision in end to end spinning mode with some kind of structure to bind them together, and the third attaches with one end butting the central structure via some kind of despinning system so it does not rotate; you attach all your spacecraft docking ports and solar panels and so on to that. Transferring power to the spinning duo is not so tricky, but other stuff is. It might be necessary to not have continuous paths between the unspun central axial module(s) and instead have some sort of transfer capsule that alternately spins up to dock to the center of the spinning bit, and then undocks, despins and slides axially to dock with the unspun part.

Now this brings up something that I am not sure is discussed much in space station threads here or not--I think having two complete spun systems that counterrotate, so that the angular momenta of each are equal and opposite, is pretty important really. With only one spun mass (counting everything spinning together in the same sense as one of course) the whole structure, spun and despun, has the shared angular momentum, viewed abstractly as a single object. So the only way you could for instance have solar panels kept oriented at the Sun would be if the spin axis paralleled the orbital axis--then the "despun" section actually would have rotation too, just a much slower one, to track the Sun it would have a rotation period of a year.

The other problem is that in real life, there is always friction between relatively moving objects that have some effective connection, and we'd need a mechanically strong connection between the spun and despun sections which is more than a bit tricky to manage without a lot of frictional coupling, or even with that. Therefore the spun section tends to transfer its angular momentum to the supposedly unspun section, which of course degrades its own angular speed below target, while imparting undesired spin to the other part. Of course we can take off that spin again a number of ways--we could for instance have Hall thrusters on the end of long booms and thrust to counter the transferred angular momentum. But what this does, aside from requiring power and constant shipments of xeon for thruster propellant, is dump the desired angular momentum in the spun part we wish to conserve, into space via two countering streams of propellant being wasted to space. So oho, put more Hall thrusters on the tips of the two stage sections, to maintain their angular speed! Great, now we have two streams of xeon (well, four clusters altogether) being dumped into space, yay!

Can we counter friction with application of electric power without expending mass?

I don't actually think that can work, not without constantly despinning the central unit either with ongoing thruster use, or with long booms or tethers to use some combination of electromagnetic torquing or tidal stabilization. I am supposing that the powered bogie wheels actually neutralize their friction and so we might avoid transfer of angular momentum, but I imagine realistically some slips through as it were and we gradually will have the central unit tending to spin up, and despinning it will spin the ring faster and faster.

But now suppose we can add to the three units (plus interfaces and trusses and docks we festoon the unspun part with) two more spun pairs, of the same mass and at the same angular speed, but in the opposite direction? Now I think, if the couplings are sturdy enough, we have zero net angular speed, unless we want the system to have a net slow rotation to track the Sun or keep a boom pointed down to Earth or some such, and this desired collective net rotation can be about any axis we choose--

---Well, subject to the constraints on conceptual rigid bodies, which per Euler's principles have three orthogonal (that is, at right angles to each other) axes each with a characteristic moment, so that in general angular momentum is a vector that projects onto all three, and unless the three moments are precisely equalized (as with a sphere, or uniform cube) the components along each axis mean angular rotations around each at variable rates, which given conservation of momentum means that they would all be turning at different rates, resulting in a complex cycling chaotic tumbling motion of the whole. Moral, we need to trim these moments, and regulate the motion so that we can keep the whole thing stabilized, turning just the way we want and not some chaotic other way. Also, "rigid" bodies are only approximately so, especially a sprawling structure like this; all the members have some flex to them and we can excite resonant modes that can build up and wreck the structure.

So in principle, we could have something like this:

A central repurposed stage that does not spin;

Two sets of repurposed stages mounted firmly at one end each to a ring truss that surrounds the central unit's diameter, with let us say rails on either the ring or on the hull of the inner despun unit, and load bearing passive wheels akin to railroad wheels with some powered traction wheels driven by electric motors, and some kind of tensioning/pressuring system to keep them in contact; the wheels have flanges to make sure they don't slip off the tracks. I suggest the ring truss has the passive rails and the wheels on bogies are mounted to the central unit since it is the "unmoving" to a first approximation center that is by far most convenient to power, with solar panels mounted on booms. There will be friction so power is always needed to maintain the spin rates. To get people, objects and fluids into and out of the spun section we have an auxiliary track enclosing a transfer vehicle that can either dock with the central unit or pressurized passages in the ring, and connect fluid transfer ports for water, waste materials, air and other utility gases (perhaps in cryogenic liquid form) and what not. The "vehicle" could in principle be an entire ring itself and to prevent wobbling we might well want to do it that way--note the "ring" is conceptual and could be angularly chopped up into various tanks, bins, and human transfer compartments, as long as the masses balance, so some tanks are just for ballast. People who want to go from one spun unit to the other need to climb up ladders (good for exercise) or ride elevators, if just your basic window-washing type platform on set of winches, as we will want for heavy or bulky items anyway, and note shifting weights up and down involves changing the moments of each unit, so we need some kind of trim ballast system there too, probably involving pumping fluids from a central tank near the central mount and distal tank at the bottom. At the central truss, spin gravity is very low but not zero, and people walk around, there are tracks or paths for items secured to a dolly or overhead rail system perhaps to be shifted around to the other side, and there be variously winched down, flow down through pipes and conduits, or climb down ladders. If instead they want to go into the central despun unit, they need to request the transfer vehicle/ring to undock from that unit, spin up, and phase and dock with the ring, transfer in, then undock, be despun, and dock to the central unit, now in free fall or very close to it. Power can be transferred a variety of ways from central unit to the hanging spun units, by brush or hard wheel contacts (which we have anyway) or by induction.

So to complete the picture, say this first pair of units is spinning clockwise, relative to some standard direction in the central unit axis. Now we double down and have a second ring, transfer unit, and stage pair set of the same masses and trimmed moments, turning counterclockwise on the same reference, some distance down the length of the central unit. We obviously want the counterrotating units to be separated from each other! In space there is no air drag (well, very little in a low orbit) but conceivably in some contingency the hanging units could wobble, and we don't want their tips to collide! So presumably one ring is at or near one tip of the central unit, the other is at the other end. This makes it risky and awkward to mount anything sticking out of the central unit between them, and for some distance beyond the tips, but it is possible to have booms running along the axis of the central unit to get that distance and them have them branch out like a tree, to support solar panels, heat rejection radiators, spacecraft docking ports, and so forth.

We won't generally want operational airlocks on the hanging spun cylinders, but it would be easy to incorporate them on the transfer rings without cutting more hatches into the central hull--note that any hatches and fluid transfer ports and so on we do have there under the transfer ring would be protected from space junk.

We still will want the spin axis of the two counterrotating sets, and therefore the axis of the central unit and thus the booms at one or both ends getting separation from the respective spun sets at each end of the central cylinder, all oriented parallel to the axis of whatever orbit is most relevant. Earth's strong tidal effect will be most relevant gravitationally to anything in LEO, whereas moving out of LEO we need to talk about radiation protection, for people and for equipment. But for simplest Solar panel mounting, which also provides shade for radiators mounted behind them, we will want the "despun" parts to actually turn over a year, not a LEO orbital cycle, which is just in the ballpark of 90 minutes to two hours. Tidal forces will tend to violently disagree with this agenda! We could mount the panels so their normals are parallel to the axis, and set up a big but hopefully light mirror at 45 degrees or so to reflect the light "down" to the fixed panels while the station turns over the orbital period, or we could have the panels mounted on trusses that are spun differently than the rest of the station--power can be transferred efficiently enough, but it might be tricky to transfer thermal control fluid (ammonia on ISS, probably here too, if not water) to the radiators to get cooled, but if we have a high friction liquid coupling that rotates, the rate is slow anyway.

So we would need a lot of structure beyond the basic units, and their combined mass and long moment arms point to needing pretty strong trusses, which in turn will be applying some strong moments on the central 5-repurposed stage structure, which could go far beyond design stresses on these objects, which might also be gradually weakened after years of high intensity solar heating and other radiation exposure, thermal stresses and fatigue under flexing mechanical forces. So we might need to add a cage of external trusses to reinforce the central unit and take stress off of its own integral structure, and with more difficulty reinforce the hanging units.

But what we gain by having two counterrotating sets is neutral angular momentum or nearly so overall, depending on how we want the larger station structures to rotate. Also, if we have either a place to store the kinetic energy of the two units or the ability to bleed it off, we can gradually brake both of them down to a stop in free fall, and do stuff like add reinforcing units, and perhaps add more pairs of units, and perhaps light or strong cross connecting tunnels between them so people don't actually have to climb up to the center to go to another unit--this again requires attention to ballasting of course.

And as noted, the counterrotating units are in fact a major power storage, a pair of flywheels in fact, and in an emergency by gradually braking both down in unison, considerable power draws can be supplied, at the cost of lowering the "gravity" of course. Thus fluctuations in power supply, as by going from being exposed to the Sun to being eclipsed behind Earth at night, can be stored in spinning them up a little bit more, and drawn out again in braking them down. This adds flexing and has to be watched carefully lest resonant modes be excited of course, but it is an option.

Why do we want spinning habitats? Well, for one thing, we want it for health of people in space.

But actually at this point we mainly need and want it for the sheer science of it; we actually have no certain idea what happens to Terran organisms in medium gravity, between Earth's full 9.81 m/sec^2 and free fall. At what sustained acceleration do human bodies stay close to Terran general fitness standards, with or without extraordinary exercise regimes? What about chickens, rabbits, guinea pigs or edible bugs? Does the fact that aquatic and marine organisms on all scales all float buoyed in water have any bearing on their adaption to various gravity regimes?

Unfortunately this is not a problem for first generation space habitat/labs; the masses involved in shipping water up in sufficient tonnage to give large organisms a decent habitat are tremendous, as are structures that can contain these tonne per cubic meter masses under decent acceleration, though obviously small aquaria for small organisms should be feasible, and medium and large aquaria even investigating actual free fall have the bonus of being excellent radiation shielding, but if we want to know how aquarium organisms such as vat farmed shrimp or krill or oysters or lobsters or tuna or catfish are going to do even on the Moon, let alone Mars, we are rather SOL--to be sure setting up such experiments actually on the Moon, perhaps using polar water and other volatiles for ammonia, nitrogen, and stuff like that might be a lot more cost effective than a LEO lab, and the tonnage of water comes in handy as cosmic ray shielding too--as it does in LEO, but alas this seems to require O'Neill habitat/Stanford torus levels of commitment and we'd probably want generations to prepare for that, though I say sooner the better.

Anyway what about plants? What about vertebrate and mammalian reproduction?

If a woman becomes pregnant on the Moon, do we even have time to rush her down to Earth again? (as a feminist, I also dislike the ethical conundrums that can arise from differential treatment of the sexes in the space program too--again, knowledge is needed before we make hasty rules). In fact will the "problem" assuming a pregnancy is not wanted just go away naturally because it takes so long after fertilization for a woman to know she is pregnant, and will fatal abnormalities doom any embryos even if they can in fact implant? (In discussions on this subject elsewhere, many people firmly hold "of course full G is necessary for normal development, it is pervasive and universal here on Earth, naturally all organisms are adapted to it and reproductive abnormalities must follow in different G fields!" But consider the female gibbon! She lives her life swinging madly through the trees, in endless gymnastics. When a gibbon becomes pregnant, does she instinctively immobilize herself and become dependent on other gibbons to come bring her food and so forth? Of course not, she just goes on gyrating around the tree tops! Obviously then mammalian embryos and feti cannot be too dependent on one fixed steady gravity field, and there is no way for crucial cell division and structure formation processes to "know" when their mother might suddenly need to put on a mad burst of speed and go zigzagging through the underbrush fleeing a predator for her life--if the cells "know" that you'd think evolution would gift the adult animal's brain with access to such precognition! Perhaps such crucial processes can indeed be triggered by cues the mother has entered some sleep state where she is indeed immobilized--all placental mammals dream; but not marsupials or other vertebrates let alone insects and so on. Perhaps there is a connection here, and in the relatively rare cases a female pregnant mammal thinks she is secure enough to enter such sleep states but is rudely surprised, and must run or fight for her life unexpectedly, the pregnancy miscarries?

See, we just don't know all this stuff. It seems highly improbable to me that human beings cannot develop pretty normally from fertilization to death at a ripe old age under the 0.9 G field of the planet Venus, whereas I have grave concerns about such fields as Luna's or Titan's, and Mars seems at least a bit dubious. This is exactly the kind of stuff we need to learn! And frankly should have been learning in the decades between the first launch of Columbia in 1981 and the present date; we should have had centrifugal habitat labs, if not for big mammals like cows then at least for little ones like rabbits and mice, and also learned more hard facts to draw serious and stronger inferences from regarding space radiation too.

One little thing I do know (if I can assume this report I read years ago isn't some sort of fraud or spoof) is that the Russians in the past couple decades did an experiment with cockroaches. Female roaches store sperm after mating and don't immediately let themselves be fertilized, so it was possible to launch some inseminated but not yet fertilized roaches up on a minilab in LEO that flew free in free fall for a sufficient time to assure most of the roaches would in fact fertilize some eggs, and then bring them down again before the eggs would be ready to hatch. So these space roaches in fact were fertilized in zero G, and also underwent early stages of basic body plan formation, and then experienced high G on reentry while still in the egg and after that, regular Earth gravity.

According to the news reports I read, the things developed something vaguely akin to Marvel Comics "Mutate" superpowers! They matured stronger, bigger, with faster reactions, than their mothers or other normal roaches of their species. In Marvel Comics, this would be attributed to the radiation, not the free fall conditions, of course. None of them were actually made of rock, or could burst into flames unharmed, or turn invisible as far as I know.

Perhaps they were more akin to Vampire Slayers and space is an abode of demons?

Moral--when launching more or less habitable units, for human use, or for various space biology/medicine investigations of ecosystems, by the love or fear of whatever you hold holy, make damn sure the shipment has no cockroaches::)

OKay then, for a first generation rotating habitation, I think our major focus should be space biology, and since it is not easy to provide adequate shelter from cosmic rays in spaces under acceleration, it is of course mainly about the gravity, though we cannot separate out the radiation medicine stuff completely. Being in LEO means half the cosmic ray exposure of deep space and shelter via the magnetic field from the swarms of relatively low energy but numerous solar charged particles, so we can focus on free fall versus medium fields from 1/7 to say 0.9 G (the latter being quite ambitious of course) with particular attention to Martian and Lunar surface gravity. Of course in practically sized spinning habs, we have serious Coriolis force and rapidly varying fields with height, but that should not be too severe if we are looking at small animals in confined spaces, and besides humans would be affected by that too. My personal hope is that it will turn out we can adapt pretty well to fairly high angular speeds, say 4 to perhaps 10 RPM, which would allow decently high acceleration on reasonably compact spacecraft of various types, and that the minimum field in which human gestation and childhood development is acceptably close to Terran normal is not greater than Mars's, though personally I am more interested in Venus--although I like the idea of exploring and even colonizing Titan too, and that world's field is definitely low. We might fortuitiously discover that with moderate exercise and medication, women can conceive and bear children even in the Moon's and possibly Titan's, low fields, though the poor kids will definitely need to be put through a heavy exercise regimen, might require serious "heavy time" in fairly high fields, and it might be they definitely cannot adapt to Earth conditions and may or may not have seriously curtailed lifespans even in their birth fields. I have the Russian cockroach experiment to give me a bit of hope, but humans (despite our occasional causes to doubt in some cases) are not in fact roaches, and vertebrates in general, mammals in particular, and large bodied organisms evolved to live on land generally are quite different across the board.

This then is the mission of a spun for gravity habitat then, to learn more about the critical factors involved here.

Now this is part of why I focused on "dumbbell" configurations instead of say having two stages parallel to each other and either spinning with the axis in the plane they lie in, or parallel to the stage axes. These alternatives involve little or no variation in the effective acceleration on the contents of the modules, as they would be at constant or nearly so radius from the spin axis. Radial spoke orientation on the other hand provides relatively little area or cubic at a given acceleration, but does provide a spectrum from the maximum we apply at the tips to zero at the center, so it is well suited to setting up parallel experiments on different levels and comparing the outcomes directly.

I also did so for structural reasons; the other two configurations involve the modules being quite distant from each other and we'd need a lot of long truss or tether between them, and tethers as opposed to heavier rigid trusses would leave them open to modes of oscillation and general wobbliness--to be sure the radial orientation involves major shifts of the moment of inertia when things move up or down. But we can anchor the central tips to each other firmly with short structures, even in principle butt them together directly, and their entire diameter serves to stabilize them in the angular and out of plane wobbling axes.

Especially since we are not doing this so much for tourism or space worker habitation, but for SCIENCE, space biology particularly, this simple and direct procedure seems best. It is also not bad for space medicine for humans committed to being in space having treatment options available, being brought down gradually from free fall to maximum forces at the tip.

If it makes sense to keep building on this approach, rather than start over with a clean sheet, I would envision that each radial counterrotating set is eventually brought up to 6 spokes. At that point you might think we would want to connect the tips with another bunch of stages, another 6 each to be exact, forming spoked hexagons, but actually I think by the time we have 13 stages employed structurally like this, we would want instead to start using structures either shipped up in cargo as elements to be installed by the by now numerous people up there, or even in some cases manufactured in LEO or beyond from Lunar or more distant space resources. In any case (assuming realistically first generation structures are made from Terran made materials) I envision as mentioned not using spent stages which go straight from one tip to another tip (with large gaps, remember the core is not two stages butted together but each one hangs from a ring of greater radius than the diameter of the stages) but instead something like inflatable Bigelow type structures, initially little more than the pressurized equivalent of rope bridges to allow people to walk or jog perhaps over to the next module without having to climb up to and down from the central ring, perhaps though laid out with extra strength anticipating gradual stiffening and elaboration into full Space Station V type rings. As noted, we might do better to start over from scratch; it depends on how well stage based core structures age and wear I guess.

Can we then start out even simpler than my basic three, which I immediately kicked up to five for the sake of counterrotation? Can we revert to my first line, and start with just two?

I suppose maybe perhaps, even if we do plan to eventually insert the central stage to make it three. We might start with just the ring structure, and temporarily reinforce with load bearing short tethers right across the central gap. But this would be a poor approach I fear. We'd do better to start with the central structure first, with a solar/radiator mast going out one way and the other end being developed into a docking port, and colonize the former propellant tanks with accumulating free fall structure, and cut the hatches out we plan to use to access each ring, then assemble the ring structures at each end and transfer structure. Then when we are ready for two, or better yet all four of the first 4 of 12 radial modules, we bring them in, and dock them and secure them in their sockets and set up the passages and plumbing and wiring and so on, and once that is well begun, spin them up in counterrotation a bit. We probably do better to stock them with basic stocks of water, air, soil and so forth before doing that, but there is something to be said for instead spinning them up largely empty and adding the contents gradually later. Either way we spin them up in counterrotation ideally, in stages approaching whatever angular speed we want for our final goal.

So while two is the bare minimum for a brief and difficult to access experiment, realistically I think the right answer to your question is "three" and that "five" is a better answer. From there we eventually add eight more for 13 all up, and after that turn to lighter bridging circumferential structures, which by the way we might add level after level to to eventually fill a solid disk, and perhaps then add axial layers to to approach a central wall be build up between the zones, and thus fill a cylinder with two counterrotating drums. Honestly I suppose long before we get that far, the station will have aged to Mir EOL conditions and we will want to simply decommission and scrap it, either scavenging it to recycle the materials or deorbiting it to burn up over the Pacific or something like that.

Offline high road

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Re: Blue Origin Orbital Habitats
« Reply #13 on: 10/24/2019 08:41 am »

The problems pointed out above have been discussed in the relevant threads in the advanced concepts section (realistic, near term, rotating space station and the like).

Let's first focus on getting enough demand going to keep five modules profitable without relying on government support (other than rent of said modules), before we start adding massive cost and complexity (without benefiting most of the paying customers) by providing gravity.

NanoRacks' anouncement about their mission to test cutting up an upper stage simulant in space had me thinking practical applications wouldn't be ready in time to prevent prefabricated space station alternatives from cornering most of the market. (although I liked the idea and who knows what practical applications might come of it). But if it's coming from Blue, I think by the time they're ready to launch, we'll no longer consider using an upper stage for anything else than launching another payload.

Offline yg1968

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Re: Blue Origin Orbital Habitats
« Reply #14 on: 03/27/2021 03:20 pm »
See below:

Blue Origin is interested in habitats:

https://twitter.com/ac_charania/status/1308172569770700803

Quote from: Blue Origin
To develop Blue Origin’s vision of millions of people living and working in space, humanity will require places for them to live and work: space destination systems in which value-creating economic activity can occur. LEO (low Earth orbit) habitable stations, learning from but going beyond the ISS (International Space Station), are a first step. Such stations, supporting a robust LEO economy, will be fundamentally different from “exploration” habitats designed for small, professionally trained crews in deep space.

https://blueorigin.wd5.myworkdayjobs.com/en-US/BlueOrigin/job/Kent-WA/Orbital-Habitat-Formulation-Lead_R4688
« Last Edit: 03/27/2021 03:23 pm by yg1968 »

Offline yg1968

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Re: Blue Origin Orbital Habitats
« Reply #15 on: 03/27/2021 03:23 pm »
Blue is among the companies interested in the upcoming commercial LEO free flying habitats procurement:

https://twitter.com/thesheetztweetz/status/1375799375742525440
« Last Edit: 03/27/2021 03:28 pm by yg1968 »

Re: Blue Origin Orbital Habitats
« Reply #16 on: 03/27/2021 03:37 pm »
I think that Blue Origin would be very well served by spending their near future focused on LEO habitats and space stations. This could be a really good opportunity for them.
Wait, ∆V? This site will accept the ∆ symbol? How many times have I written out the word "delta" for no reason?

Offline high road

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Re: Blue Origin Orbital Habitats
« Reply #17 on: 03/29/2021 07:03 am »
Ah, already preparing for the next project to further divide their efforts, I see. Wouldn't actually want to finish or cancel something first.

Offline spacenut

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Re: Blue Origin Orbital Habitats
« Reply #18 on: 03/29/2021 01:33 pm »
I've never understood why NASA never developed these "wet workshops" from spent upper stages.  The ribbing inside the tanks could have been designed with holes or attach points and an opening to allow a hatch to be installed for entry.  Components could have been brought up with cargo and supplies.  Going inside a tank after purging and filling with breathable air, in shirt sleeves to assemble rooms, racks, shelving lockers, or any other equipment would not be that hard.  The astronauts handle 100 lb bags or water, exercise equipment, computers, etc, already when unloading cargo from incoming spacecraft. 

You had the huge Shuttle tanks that could have been used.  Skylab used and empty Saturn V 3rd stage. 

This may be what Blue Origin plans or hopes to do.  Their New Glenn rocket upper stage is 7m in diameter which is fairly large for a huge module.  Even the outside could have attach points added to add solar panels or more equipment later. 

Offline tbellman

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Re: Blue Origin Orbital Habitats
« Reply #19 on: 03/29/2021 03:46 pm »
I've never understood why NASA never developed these "wet workshops" from spent upper stages.

Because it is a lot of work to install everything needed to turn an empty metal shell into a habitable space.  You need to install electrical wirings; lights; ventilation ducts, fans, heating, cooling, CO2 scrubbers, and everything else that goes into environmental control and life support; isolation on the walls; and so on, und so weiter, med mera.  And some of that needs to be done while wearing space suits; you can't doff the suits until you have the ECLSS up and running, and that in turn needs electricity.

And before you install everything on the inside, you need to cut a hole in the tank and install a docking port and/or air lock.  Unless those were installed before launch, but having them installed beforehand might compromise the original function as tank (e.g. things might protrude into airstreams or into spaces where other things want to be).

And you probably need to install external solar panels, and route the electrical connections for them through the tank walls somehow.

All of this needs to be done by astronauts, in microgravity, and parts of it while wearing EVA suits.  Which means that it will take much longer than if people down on Earth did it.  And astronaut time is expensive.

So far it has always turned out to be cheaper to outfit a habitat down on Earth and send that up with a separate launch, than to take a spent upper stage (or the Shuttle External Tank) and outfit it in orbit.  Much cheaper.

This might change in the future, when (if) astronaut time gets cheaper, but it hasn't done so yet.

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