Author Topic: Realistic, near-term, rotating Space Station  (Read 244273 times)

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Re: Realistic, near-term, rotating Space Station
« Reply #900 on: 07/08/2018 10:49 PM »
HTS Torque

wrong, you really don't know what you are talking about.  It is too weak.

stop demanding other people prove your claims.

It's Majkic.   ::)


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Re: Realistic, near-term, rotating Space Station
« Reply #901 on: 07/09/2018 02:43 AM »
Staging Area

you could go much smaller

Depends on what you need to accomplish, doesn't it?

In most contemporary scenarios a space station will need to support crewed missions to the Moon and Mars.

One aspect of that support role:  a staging area



In military terms, a staging area is a place, typically in-country, where transiting troops assemble in preparation for the next operation. 

What preparations would you want crews to undertake at the space station, prior to departure for, say, Mars?

One preparation:  an extensive "field trial" of the spacecraft and its deployed surface equipment.  Each spacecraft system and each piece of equipment to be deployed on Mars could be tested under realistic conditions, over weeks or months, at the station.  Within the Martian Environmental Test Facility,

- Mars drills could work on actual martian rock slabs, under martian gravity and temperatures. 

- Mars drones could take test flights through real martian dust. 

And so forth.

And while these equipment tests were underway at the station rim, pilots would put each spacecraft through its paces at the hub, e.g. within a kevlar docking tube.

Quote
We've got one more item for you when you get a chance.
We'd like you to, uh, stir up your cryo tanks.

An Apollo-13-class problem would be far more manageable at station dock.  So why not exercise every phase of the mission profile at the station, on the actual mission hardware, before heading out?

--

If the station were rigged for full crew protection, e.g. with water shielding and 1 g elevator gyms, it could support field trials lasting many months.  Crews would complete their trials without accruing significant medical problems, hopefully; i.e., no significant radiation exposure, no significant bone loss, etc.  This would be a first active phase of the Unlimited Mars Career -- the aspirational goal of LMT protective designs.

--

Completing the staging area:

We might look through the thread, and elsewhere, to explore other possible support activities. 

Q:  Which additional activities might help complete a very useful staging area, and how might each be implemented most efficiently?
« Last Edit: 07/09/2018 03:03 AM by LMT »

Offline ppnl

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Re: Realistic, near-term, rotating Space Station
« Reply #902 on: 07/09/2018 05:53 AM »


Yeah, I was only talking about the minimum to test the biological effects of gravity. You are talking on a science fiction scale. Even then 780m is really jumping the shark. That's bigger than the starship Enterprise. A habitat of 225m radius is big enough for any conceivable purpose and I think represents the extreme upper limit of what is needed for anything imaginable. That's almost 1400m around. By comparison the largest super cargo ship on the ocean is only 400m long. I cannot reasonably expect anything like this within my great great grandchildren's life time. That's not near term.

Near term keep it as simple as possible and learn enough to go bigger next time.

Offline Paul451

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Re: Realistic, near-term, rotating Space Station
« Reply #903 on: 07/09/2018 08:54 AM »
At 780m radius, less than 1.1 RPM produces a full 1g.
Working assumption was a station "designed only for martian g".  To get 1 g, you can:
1.  increase the structural mass considerably to handle 1 g across the entirety of the very large station,
(1.) is of course astronomically more expensive.

Not really. If you are building the elements on Earth, it's easier to test for 1g than try to design a too-flimsy-for-1g system by modelling forces without being able to test any elements under actual working conditions.

Also the rotation of the elevator-pod-thing is given at 30RPM.
No, the gym rotates, from passengers' perspective, only 120 degrees, once every 45 s.  Where'd you get 30 rpm?  Did you not understand the paper on the linear sled hybrid?

Quoting from the paper: "There is a half rotation (180°) to reorient the rider between acceleration and deceleration such that the  loading remains  footward, as when standing on Earth."

Time of rotation is given as 1.12 to 1.67s. Therefore rotation rate is 27 & 18RPM respectively. They're using high-RPM repeated pulsing and a horribly complex mechanism to avoid low-RPM continuous.

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Re: Realistic, near-term, rotating Space Station
« Reply #904 on: 07/09/2018 12:40 PM »
Yeah, I was only talking about the minimum to test the biological effects of gravity. You are talking on a science fiction scale. Even then 780m is really jumping the shark. That's bigger than the starship Enterprise. A habitat of 225m radius is big enough for any conceivable purpose and I think represents the extreme upper limit of what is needed for anything imaginable. That's almost 1400m around. By comparison the largest super cargo ship on the ocean is only 400m long. I cannot reasonably expect anything like this within my great great grandchildren's life time. That's not near term.

Near term keep it as simple as possible and learn enough to go bigger next time.

The station's suggested protective 1 km3 marshalling yard has 782 m radius.  Its panel-fold scheme speeds deployment.  I think a telerobotic team might deploy it with a month of round-the-clock work. 

Why defer that particular work to our "great great grandchildren's life time"?  I don't see any problems so terrible as that.

Actually it would be nice to get some engineering feedback on the marshalling yard concept, especially the telerobotics.  Telerobotics have advanced rapidly of late; it would be good to fill in some blanks there, with best examples of relevant current tech.





« Last Edit: 07/09/2018 11:35 PM by LMT »

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Re: Realistic, near-term, rotating Space Station
« Reply #905 on: 07/09/2018 01:08 PM »
At 780m radius, less than 1.1 RPM produces a full 1g.
Working assumption was a station "designed only for martian g".  To get 1 g, you can:
1.  increase the structural mass considerably to handle 1 g across the entirety of the very large station,
(1.) is of course astronomically more expensive.

Not really. If you are building the elements on Earth, it's easier to test for 1g than try to design a too-flimsy-for-1g system by modelling forces without being able to test any elements under actual working conditions.

Also the rotation of the elevator-pod-thing is given at 30RPM.
No, the gym rotates, from passengers' perspective, only 120 degrees, once every 45 s.  Where'd you get 30 rpm?  Did you not understand the paper on the linear sled hybrid?

Quoting from the paper: "There is a half rotation (180°) to reorient the rider between acceleration and deceleration such that the  loading remains  footward, as when standing on Earth."

Time of rotation is given as 1.12 to 1.67s. Therefore rotation rate is 27 & 18RPM respectively. They're using high-RPM repeated pulsing and a horribly complex mechanism to avoid low-RPM continuous.

No, the big expense delta is launch of all that extra mass, relative to the cost of merely rotating elevators.  Nothing to do with "modeling forces".

And I don't know what you're complaining about re: Terrestation elevator gym.  The researchers have already verified that their very quick flip is tolerable.  And of course the Terrestation elevator gym wouldn't need and wouldn't do that quick flip; just a leisurely, smaller flip every 45 s.

Also calling their hybrid sled a "horribly complex mechanism" sounds like special pleading.  cf many other, less mature designs in forum, which draw no such dismissive comment.
« Last Edit: 07/09/2018 02:41 PM by LMT »

Offline mikelepage

Re: Realistic, near-term, rotating Space Station
« Reply #906 on: 07/11/2018 06:45 AM »
Actually it would be nice to get some engineering feedback on the marshalling yard concept, especially the telerobotics.  Telerobotics have advanced rapidly of late; it would be good to fill in some blanks there, with best examples of relevant current tech.

Dude.  I'd ask you to read the thread title again (And please do so before you get a perfectly good thread locked).

I was criticising Roy_H's proposal for requiring in-space assembly that is too far beyond what has been demonstrated yet, but at least it was within the ballpark of current achievements (e.g. ISS).  Your 780m monolith is not.

Btw, I'm not criticising you for thinking big, I'm criticising you for seemingly not understanding how big projects get done.  The Egyptians didn't build the great pyramid first... they were already experienced pyramid builders before they even conceived of building something so big.

We need to build something, anything, first, and have it show that it can be useful.
The concept of minimum viable product is really important here.

Offline Paul451

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Re: Realistic, near-term, rotating Space Station
« Reply #907 on: 07/11/2018 09:30 AM »
If you are building the elements on Earth, it's easier to test for 1g than try to design a too-flimsy-for-1g system by modelling forces without being able to test any elements under actual working conditions.
No, the big expense delta is launch of all that extra mass, relative to the cost of merely rotating elevators.  Nothing to do with "modeling forces".

You're proposing a 1.5km wide station and you're worried about launch costs?

Where'd you get 30 rpm? Did you not understand the paper on the linear sled hybrid?
Quoting from the paper: "There is a half rotation (180°) to reorient the rider between acceleration and deceleration such that the  loading remains  footward, as when standing on Earth."
Time of rotation is given as 1.12 to 1.67s. Therefore rotation rate is 27 & 18RPM respectively. They're using high-RPM repeated pulsing and a horribly complex mechanism to avoid low-RPM continuous.
And I don't know what you're complaining about re: Terrestation elevator gym. The researchers have already verified that their very quick flip is tolerable.

As I said before, if they are saying a 28RPM spasm every few seconds is tolerable, then constant 4RPM is eminently tolerable, making the elevator-thing pointless.

[edit: fixed quotes]
« Last Edit: 07/11/2018 09:30 AM by Paul451 »

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Re: Realistic, near-term, rotating Space Station
« Reply #908 on: 07/11/2018 12:37 PM »
Actually it would be nice to get some engineering feedback on the marshalling yard concept, especially the telerobotics.  Telerobotics have advanced rapidly of late; it would be good to fill in some blanks there, with best examples of relevant current tech.

Dude.  I'd ask you to read the thread title again (And please do so before you get a perfectly good thread locked).

I was criticising Roy_H's proposal for requiring in-space assembly that is too far beyond what has been demonstrated yet, but at least it was within the ballpark of current achievements (e.g. ISS).  Your 780m monolith is not.

Btw, I'm not criticising you for thinking big, I'm criticising you for seemingly not understanding how big projects get done.  The Egyptians didn't build the great pyramid first... they were already experienced pyramid builders before they even conceived of building something so big.

We need to build something, anything, first, and have it show that it can be useful.
The concept of minimum viable product is really important here.

Sure, you can always scale down to some minimum-tolerable, prototype design.  Value depends on the customer's need, and no one's sent out a Request For Proposal, that I know of.   :)

Roy_H wanted 56 BA330s for his design, right?  How many ITS flights (cargo and crew) might that require?  And ISS was constructed from 40-odd units over, what, 41 flights?   I'd estimated the full-scale marshalling yard would require 20-25 ITS cargo flights with some uncertain number of crewed flights.  Telerobotics should limit the crewed flights, if implemented effectively, which is why you'd want to take some time to explore the present possibilities there. 

The initial crewed station kit might add one hub airlock, one elevator, one Mars-g inflatable and airlock, and other gear comparable to ISS circa 2000.  That might ballpark 10-20 flights, cargo and crew.  So altogether the initial structure seems to be in line with ISS history and thread notions, just re number of flights required.

And that would all be at full scale.  The station would just have "room to grow".

Perhaps the "pyramid" could be staged very roughly as below, just for discussion.  And again, relevant current telerobotics are of interest.

--

Notional Terrestation Staging

(conceptual image only, not scaled.  Or maybe it is scaled, if you want to consider the prototype minimum.)



1.   @400 km build 4 electrical booms.  3 booms will frame the station interior (2 diameter booms, 1 axial-radius boom), and a multi-km boom will ascend as exterior axial mast.
2.   Install PV panels along the 2 diameter booms. 
3.   Mount LH2 tank and ZBO H2 recovery unit on mast base.
4.   Connect booms as station frame, in standard ISEP orthogonal configuration.
5.   Field-test LH2 HTS ISEP for drag-compensation and attitude control @400, on this low-drag frame.
6.   Maneuver frame to 250 and dock several ITS craft at lower axis pole.
7.   Deploy ITS boom-mount assembly lines of dexterous telerobotics.  ITS cargo-bay base stabilizes and powers each bot.
8.   Construct the marshalling yard shell.  Telerobotically unfold PV polygon strips and connect the edge struts at vertices. 
9.   Build out from the axial pole.  Reposition ITS lat/lon docking points inside the growth edge of the shell periphery.  Connect final polygons to the 2 diameter booms.
10.   Throughout construction the interconnected polygon struts feed PV power to axial boom and mast boom.  Thereby ISEP power and drag-compensation thrust increase in sync with the shell’s increasing drag, to hold the Terrestation @250 electrodynamically throughout construction.
11.   When shell construction is complete, repurpose the telerobotics.  Detach from ITS craft and reattach to the station’s axial-radius boom, for use at the station’s upper dock, and at future warehouse and other conceivable low-g facilities.
12.   Begin construction of minimum pressurized facilities:  hub airlock, elevator, Mars-g inflatable, etc., as suggested above.
« Last Edit: 07/12/2018 01:24 AM by LMT »

Offline Lampyridae

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Re: Realistic, near-term, rotating Space Station
« Reply #909 on: 07/11/2018 12:44 PM »
As I said before, if they are saying a 28RPM spasm every few seconds is tolerable, then constant 4RPM is eminently tolerable, making the elevator-thing pointless.

[edit: fixed quotes]

Agreed.

For comparison, a kid's merry-go-round with the bobbing horses is 3-4RPM. Taking a typical highway circular ramp (50m radius) at 60kph is 3RPM and is pretty much the scale you'd expect a rotating space station to start at, generating 0.57g in microgravity. Taking the same ramp at 80kph generates an equivalent of 1g.

There's ample research starting with DiZio's work that indicates that higher spin rates are tolerable long-term.
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Re: Realistic, near-term, rotating Space Station
« Reply #910 on: 07/11/2018 01:46 PM »

I'd ask you to read the thread title again (And please do so before you get a perfectly good thread locked).


And numerous report to mods alerts show annoyance with his posts, so LMT, no more. Other people want to talk about viable on topic ideas. This isn't your personal Q&A thread. Thanks.
« Last Edit: 07/11/2018 01:47 PM by Chris Bergin »

Offline mikelepage

Re: Realistic, near-term, rotating Space Station
« Reply #911 on: 07/13/2018 03:41 AM »
For comparison, a kid's merry-go-round with the bobbing horses is 3-4RPM. Taking a typical highway circular ramp (50m radius) at 60kph is 3RPM and is pretty much the scale you'd expect a rotating space station to start at, generating 0.57g in microgravity. Taking the same ramp at 80kph generates an equivalent of 1g.

There's ample research starting with DiZio's work that indicates that higher spin rates are tolerable long-term.

One advantage I had assumed with any such space station is that crew will be able to move between 0g and spin gravity on a daily, if not hourly or more frequent basis.  I'd argue that the spin rate threshold we're interested in is not what is just tolerable long-term, but rather what people can adapt to switching between 0 and x rpm quickly.  I'm not sure whether that was tested in DiZio's work but I suspect not? 

Offline Paul451

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Re: Realistic, near-term, rotating Space Station
« Reply #912 on: 07/13/2018 04:09 AM »
One advantage I had assumed with any such space station is that crew will be able to move between 0g and spin gravity on a daily, if not hourly or more frequent basis.  I'd argue that the spin rate threshold we're interested in is not what is just tolerable long-term, but rather what people can adapt to switching between 0 and x rpm quickly.

If you mean a single solid station, where people move between the hub and the rim, then 0g isn't 0RPM.

If you mean a semi-separate non-rotating section, then there may be an adjustment period. But there is with zero-g anyway.

(That's probably one of the things we need to research: how quickly can people who've adapted to zero-g, then moved to spin-g, adapt back to zero-g. Not just vice-versa.)



Aside: Advocates of higher RPM, like myself, often use DiZio&co to justify being skeptical of the older work. However, to get to 10RPM they used step-wise increases in RPM, with time to move and adapt between each step. If you have a continuously rotating station, which doesn't spin-down for docking, there won't be an opportunity for such gradual spin-up.

Offline mikelepage

Re: Realistic, near-term, rotating Space Station
« Reply #913 on: 07/13/2018 04:32 AM »
One advantage I had assumed with any such space station is that crew will be able to move between 0g and spin gravity on a daily, if not hourly or more frequent basis.  I'd argue that the spin rate threshold we're interested in is not what is just tolerable long-term, but rather what people can adapt to switching between 0 and x rpm quickly.

If you mean a single solid station, where people move between the hub and the rim, then 0g isn't 0RPM.

If you mean a semi-separate non-rotating section, then there may be an adjustment period. But there is with zero-g anyway.

(That's probably one of the things we need to research: how quickly can people who've adapted to zero-g, then moved to spin-g, adapt back to zero-g. Not just vice-versa.)



Aside: Advocates of higher RPM, like myself, often use DiZio&co to justify being skeptical of the older work. However, to get to 10RPM they used step-wise increases in RPM, with time to move and adapt between each step. If you have a continuously rotating station, which doesn't spin-down for docking, there won't be an opportunity for such gradual spin-up.

One notion born out of having a habitat (+flywheel) which can spin up and down, is that all docking could occur at the rim when stopped, with capsules that are minor in mass compared to the structure and balanced.  That way, in an emergency, your capsule is something you climb *down* into, and when it undocks, it falls away from the space station.

A consequence of this is that if you were doing high RPM, you would be able to spin up gradually for adaptation purposes.

A secondary consequence of this is that your hub module (or double ended cupola as I like to think of it) could be solid with the rest of the craft.  I like to imagine there would be some kind of cage/frame that was rotating inside this module at 0rpm, so you really could have a 0g/0rpm experience where you could look out into space, floating, without a space suit.

Offline Paul451

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Re: Realistic, near-term, rotating Space Station
« Reply #914 on: 07/13/2018 05:23 AM »
One notion born out of having a habitat (+flywheel) which can spin up and down, is that all docking could occur at the rim when stopped, with capsules that are minor in mass compared to the structure and balanced.  That way, in an emergency, your capsule is something you climb *down* into, and when it undocks, it falls away from the space station.

I don't think it would work with a wheel type station, (at least near-term, when still using mere capsules) because of the complication of trying to balance the mass. The more mass you have to balance, the more dead-weight you need. It's one thing to transfer your potable water between two tanks, but it's another when you need many tonnes extra to balance a capsule.

But it's a natural for a tumbling-pigeon/baton type. Works well even if the capsule is a good percentage of the station-mass. The capsule adds mass to one end, moving the centre-of-mass towards it, therefore "lengthening" the opposite arm, therefore allowing it to simulate a higher g-level.

Offline Lampyridae

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Re: Realistic, near-term, rotating Space Station
« Reply #915 on: 07/13/2018 09:46 AM »
For comparison, a kid's merry-go-round with the bobbing horses is 3-4RPM. Taking a typical highway circular ramp (50m radius) at 60kph is 3RPM and is pretty much the scale you'd expect a rotating space station to start at, generating 0.57g in microgravity. Taking the same ramp at 80kph generates an equivalent of 1g.

There's ample research starting with DiZio's work that indicates that higher spin rates are tolerable long-term.

One advantage I had assumed with any such space station is that crew will be able to move between 0g and spin gravity on a daily, if not hourly or more frequent basis.  I'd argue that the spin rate threshold we're interested in is not what is just tolerable long-term, but rather what people can adapt to switching between 0 and x rpm quickly.  I'm not sure whether that was tested in DiZio's work but I suspect not? 

Adaptation seems to be long term; ie once you have been habituated to it, for at least 30 days there is a high level of retention. Also, you can train on the ground with a spin-up rate suited to you, then take that adatation to orbit. Most literature I've found suggests that people are less susceptible to rotation motion sickness in 0ganyway, probably because there's no cross-coupling with a gravity field.

As far as current state of the art is concerned, ~3m radius is perfectly fine as a starting point. (Note that the lead author is James Engle, chief space architect at Boeing, though Boeing != NASA). All experimental stages of course, since you'd have a couple of (un)lucky astronauts stepping into a space spin drier for scienceTM. Mice seem ok with their short-radius, high g-gradient, high-RPM environments - but then those are mice, not humans. Still, with a short radius you could probably generate g for sleeping and other activities like exercise for part of the day, and work in 0g for the rest, getting the advantages of both worlds as you say.

What you might want for casual space tourists is another matter entirely, but 5RPM seems to be the minimum to which most people can adapt.

http://www.spacearchitect.org/pubs/AIAA-2017-5139.pdf
« Last Edit: 07/13/2018 10:12 AM by Lampyridae »
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Re: Realistic, near-term, rotating Space Station
« Reply #916 on: 07/13/2018 11:35 AM »

I'd ask you to read the thread title again (And please do so before you get a perfectly good thread locked).


And numerous report to mods alerts show annoyance with his posts, so LMT, no more. Other people want to talk about viable on topic ideas. This isn't your personal Q&A thread. Thanks.

Understood, but it's nicer to just ignore uninteresting things.

Technical discussions are more interesting when we explore new methods that offer new advantages.  In free-wheeling forum [pun], we should be careful not to dismiss methods that are potentially useful and physically sound, if unfamiliar.  That's all.

Offline blasphemer

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Re: Realistic, near-term, rotating Space Station
« Reply #917 on: 07/13/2018 03:20 PM »
Quote
Realistic, near-term, rotating Space Station

Hi all!

I put together a 3D model of a near-term rotating station based on two B330 Bigelow expandables, connected by triangular truss structure and a central rigid module for docking. Diameter 230 meters, which should be long enough to simulate Martian gravity at very comfortable 2 RPM and Earth gravity at less than 3 RPM. Truss structure has no transversal trusses yet and also needs some kind of a central elevator for things to go up and down. The center module is just a Destiny model, so it lacks side docking ports, but good enough for a quick mock-up.

Thoughts?






Offline Paul451

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Re: Realistic, near-term, rotating Space Station
« Reply #918 on: 07/13/2018 03:24 PM »
Adaptation seems to be long term; ie once you have been habituated to it, for at least 30 days there is a high level of retention.

Thanks for that. I hadn't realised the adaptation was retained that long.


{laughs} Yeah, good luck getting that past the ISS gatekeepers.

Offline Paul451

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Re: Realistic, near-term, rotating Space Station
« Reply #919 on: 07/13/2018 03:53 PM »

Diameter 230 meters, which should be long enough to simulate Martian gravity at very comfortable 2 RPM

One of us screwed up our maths, because for 0.38g at 2RPM, I get 170m.

However, given the discussion about our ability to easily adapt to at least 5RPM, and perhaps more than 10, why not use 5RPM and a length of just under 30m. You might be able to eliminate the truss altogether.

Ie,
Module-Dock-Module.

two B330 Bigelow expandables, connected by triangular truss structure

The other structure that has been discussed is to have a pressurised tunnel made from Bigelow-skin, with tensile cables running down the walls putting the tube under compression. Each component is strong enough to support the loads individually, but when you combine the tensile and compression elements, you get a much more rigid system.

As a bonus, you have a pressurised tube to transfer between modules (and repair the cables). Avoiding the "elevator", which would need to be a mini-spaceship, with two docking events for every trip.

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