Realistic, near-term, rotating Space Station

[LMT]

The Hub

Scheme assumes essential mods implemented proactively on ITS, especially:

- upgraded cargo vertical integration points for ~ 4 MN load

- upgraded / augmented cryo ullage connectors for ~ 3 MN load

Observation: 

In the ITS v1 animation a gantry crane lifts a tanker.





A similar gantry is shown in the ITS v2 animation.



Question:

Animations simplify of course, but as shown the tanker is loaded prior to crane lift.  Is it known that the gantry crane will lift ITS craft after loading?

Clarification:  Unpacking the question a bit:  Is it known that the crane will lift the ITS craft onto the booster, after loading of propellant onto the craft?

If so, the first "mod" above is already done.  Vertical integration points are already designed for >> 4 MN load, of necessity.  Otherwise, maybe not.

[Jim]

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.

Then try posting something that is interesting.  And stop with posting non viable ideas

[LMT]

stop with posting non viable ideas

ITS craft mods seem viable at first glance, even modest; though of course info highlighting a big problem is welcome. 

Mods:

- upgraded cargo vertical integration points for ~ 4 MN load

As we saw, this mod may not be a mod at all, but standard. 

- upgraded / augmented cryo ullage connectors for ~ 3 MN load

This might be accomplished by application of methods such as those of Olivieri & Francesconi 2012.  Their relatively simple, unpowered docking system requires no active locking mechanism.  Latches are engaged and disengaged only by the gentle forces imparted by the chaser craft during low-g maneuver, much in the spirit of the SpaceX propellant transfer maneuver.   



Their probe-and-drogue docking mechanism could be scaled for load and installed within the line connectors (red).  Propellants would flow around latches and perhaps through probe hollows.  Lines would be reinforced for load-bearing service (green).



Refs.

Olivieri, Lorenzo & Francesconi, Alessandro 2012. DESIGN OF DOCKING MECHANISM FOR SMALL SPACECRAFT.

[Paul451]

SpinCalc uses intentionally conservative values, based on old research.

Did he say "intentionally conservative"?

From the page:

Author	Year	RPM
Hill & Schnitzer	1962	4
Gilruth	1969	6
"optimum"	.	2
Gordon & Gervais	1969	6
Stone	1973	6
Cramer	1985	3

"Optimum" being the value that SpinCalc uses, lower than every tabled example.

The average for just those five pre-2000 papers is 5RPM. Ted's calculator uses 2RPM. This contradicts with his own comment:
"the choice is not between artificial gravity and Earth gravity, but rather, between artificial gravity and microgravity.  Upon entering microgravity, about half of all astronauts endure "space adaptation syndrome" that lasts from one to three days .  A similar period of adaptation to artificial gravity seems reasonable, considering the substantial health benefits that it offers versus prolonged weightlessness.  It may not be necessary to provide immediate perfect "comfort" in artificial gravity"

Yet "requires adaptation" is given as a red indicator. Hence if you don't actually read what he's written, read the qualifiers and explanations, but you treat the red/yellow/green indicators as Holy Writ, as you have, then you are simply using the site wrong.

Which research results give you confidence in the 6.7@20 lifestyle?

The paper that showed most people can reach >8RPM, some people can reach >15RPM with, frankly, minuscule amounts of acclimation training.

[spacenut]

Could two BFS's docked end to end be able to spin enough to give the cabin areas about 0.4g?

[Paul451]

Animations simplify of course, but as shown the tanker is loaded prior to crane lift.

I think you are misreading "propellant tanker loaded". Propellant-tanker is the name of that vehicle.

BFS is supposed to be fuelled on the launch pad, via plumbing in the BFR, which is also fuelled from its base.

[edit: tanking/tanker. BFS/BFR]

Could two BFS's docked end to end be able to spin enough to give the cabin areas about 0.4g?

Assuming 48m length for each BFS, a conservative 40m to be a metre above the "deck", then for 0.4g you need a bit under 3RPM. However, if BFS is okay being spun upside down, then a single BFS spun end-over-end can produce 0.4g at a bit over 4RPM. Which seems fine for a first round of research. (But that depends a symmetrical mass balance. I have no idea where the actual centre of mass will be.)

[LMT]

Could two BFS's docked end to end be able to spin enough to give the cabin areas about 0.4g?

Yes, comfortable Mars gravity appears feasible.

[Coastal Ron]

Could two BFS's docked end to end be able to spin enough to give the cabin areas about 0.4g?

Yes, comfortable Mars gravity appears feasible.

Is Elon Musk likely to do it? I'd say no. Musk has apparently stated he is not interested in artificial gravity at this time, so I would recommend focusing on more "realistic" near-term solutions.

[Paul451]

I completely forgot that the poster was the guy. I'm stupid like that.

Odd choice of size. If you want to do human research (as well as animal), it seems odd to focus on a 1g station right out of the gate. It's the mid-g values that you want.

Page 11 shows where I began, i.e., a zero-g free flyer with the old NASA-NASDA 2.5 meter animal centrifuges.

I saw it in 2012. It was reassuring to know that other people actually want this research. I see so much resistance to it.

It was originally designed for Falcon Heavy, since at the time it was proposed, the New Glenn hadn't been unveiled.  But once it had, and given Bezos' preference for an O'Neill-type settlement vision (not to mention Elon told me studying this problem of reduced G survival wasn't a priority for him), I defaulted to NG once it became "available."

I wasn't playing favourites between the two. Musk, like most of the "Mars Underground", thinks that spin-g research is a waste, anything that gets between them and Mars is a waste. That doesn't mean he wouldn't happily launch any payload you care to pay him for.

OTOH, if you can get actual funding from Bezos, or even just free launches, Go For It.

The 1G level is designed an an on-orbit control

It's an argument I've had with Mike LePage before. I don't think that the first test facility needs to control for low-RPM 1g. Your first and most critical point of interest is whether the micro-g health issues go away with some gravity (and if so, how much.) Your control is ISS and Earth.

Sure, later on, you can pick a high-RPM tolerant crew and do 1g research, if there's weirdness in the results that bothers people. But why risk not even getting funded by having a shock factor like >100m length, for the very first thing you make? People know what the ISS costs, when you show an image of another facility on the scale of ISS and insist that it will be vastly cheaper, you'll have already lost your audience, even if you are right.

Indeed, that's why I'd prefer to start with a free-flying short-run very-high-RPM, low-g unmanned mouse & rat study. (I've suggested a Dragon capsule (just an example) so you can get the samples back.) It's a step up from the ISS mouse-centrifuge, hopefully doable within a Discovery-level budget. Once you pin down some values for mid-g health over a larger sample-size, that gives you some concrete values for a larger - but as small as possible - man-tended animal facility. Human results would be considered very preliminary, but between long-term animal and short-term human, that gives you values for how to keep a larger human-testing facility affordable. Or values that show the whole enterprise is pointless, if humans can't adapt to low-g, mammals can't breed in low-g.

Jumping straight to the end facility before you have reasonable numbers from the earlier ones, IMO invites early rejection from funders.

I'd expect a third flight at some future time to add an axial hub extension which would either allow another arm pair to be added or to provide more docking and zero-g working volume.

Careful. Axial masses reduce stability. You are probably already pushing it with the two capsules along the spin-axis.

(That's why I prefer to hang the solar arrays/radiators at 90° to the arms, increasing the distribution of mass in the plane of spin.)

[LMT]

SpinCalc uses intentionally conservative values, based on old research.

Did he say "intentionally conservative"?

From the page:

Author	Year	RPM
Hill & Schnitzer	1962	4
Gilruth	1969	6
"optimum"	.	2
Gordon & Gervais	1969	6
Stone	1973	6
Cramer	1985	3

"Optimum" being the value that SpinCalc uses, lower than every tabled example.

The average for just those five pre-2000 papers is 5RPM. Ted's calculator uses 2RPM. This contradicts with his own comment:
"the choice is not between artificial gravity and Earth gravity, but rather, between artificial gravity and microgravity.  Upon entering microgravity, about half of all astronauts endure "space adaptation syndrome" that lasts from one to three days .  A similar period of adaptation to artificial gravity seems reasonable, considering the substantial health benefits that it offers versus prolonged weightlessness.  It may not be necessary to provide immediate perfect "comfort" in artificial gravity"

Yet "requires adaptation" is given as a red indicator. Hence if you don't actually read what he's written, read the qualifiers and explanations, but you treat the red/yellow/green indicators as Holy Writ, as you have, then you are simply using the site wrong.

Which research results give you confidence in the 6.7@20 lifestyle?

The paper that showed most people can reach >8RPM, some people can reach >15RPM with, frankly, minuscule amounts of acclimation training.

I don't follow.  Which paper(s) are you referencing, to recommend 6.7+ RPM?   Globus & Hall 2015 seems clear enough:

While the data are not definitive, a survey of the literature strongly suggests that free-space
settlements can provide comfortable 1g artificial gravity by rotating at up to 4 or even 6 rpm...

With smaller radius, lower tangential velocity, and higher angular velocity, Coriolis acceleration
becomes increasingly significant. The smaller settlements proposed here will be most likely to
succeed if designers remain vigilant of the effects and take appropriate measures in planning
activities and motion paths.

So what is the smallest a space settlement can be? We don’t know yet, but it is probably at least
25 m radius (50 m diameter), the size of a 6 rpm settlement. Other factors, perhaps
psychological, social or environmental stability, may well dictate somewhat larger systems.

[spacenut]

I was thinking that NASA may want to pay for two BFS's to dock end to end and spin to test long term effects of Mars gravity.  This would determine if long term colonization would be OK for the human body. 

IF NOT, then O'Neil colonies may be the only solution for long term human space colonization until we can go interstellar.  Say an O'Neil colony in Mars orbit, one at LL1 or LL2 and mine or use Mars and moon raw materials for processing at the O'Neil colonies. 

[Paul451]

I don't follow.  Which paper(s) are you referencing, to recommend 6.7+ RPM?

http://www.spacearchitect.org/pubs/AIAA-2017-5139.pdf

After just ten 25-minute incremental sessions, 7 out of 10 subjects tolerated 15RPM. four subjects exceeded 20RPM.

[QuantumG]

We find that rotation rates of up to 4 rpm, corresponding to a 56 m radius, should be acceptable, although visitors may require some training and perhaps a day or so of adaptation for those particularly susceptible to motion sickness. A rotation rate of up to 6 rpm (25 m radius) should be acceptable for residents but visitors will almost certainly need training and/or a few days to adapt. While higher rotation rates (up to 10 rpm) may be acceptable with training, such small structures are not suitable for permanent residence (9 m radius at 10 rpm).

From the abstract of his rotation paper.

[Coastal Ron]

I was thinking that NASA may want to pay for two BFS's to dock end to end and spin to test long term effects of Mars gravity.  This would determine if long term colonization would be OK for the human body.

At this time the United States Government is not spending money on sending humans to Mars. And so far they are not YET spending money to send humans to the surface of our Moon.

So it's unlikely that the U.S. Government would be interested in doing such specific research for Mars when their first goal would likely be our Moon - and no need to do space station studies for Moon gravity when you can use the same money to just land on the Moon. No rotation issues to worry about either... 

IF NOT, then O'Neil colonies may be the only solution for long term human space colonization until we can go interstellar.  Say an O'Neil colony in Mars orbit, one at LL1 or LL2 and mine or use Mars and moon raw materials for processing at the O'Neil colonies.

If by "O'Neil colonies" you mean "O'Neill cylinders" those would not be "near-term". They border on the realm of even being possible, so not germane to this thread.

[QuantumG]

If by "O'Neil colonies" you mean "O'Neill cylinders" those would not be "near-term". They border on the realm of even being possible, so not germane to this thread.

Why? If ya bother to read Globus you'll discover that space colonies are easier than ever, and with fully reusable super-heavy lift on the horizon, the only thing missing is the will to do it.

[spacenut]

My thinking is within 10 years, we should have BFR/BFS.  SpaceX might even have made the first landing on Mars.  At this point SLS has been made obsolete.  NASA may then want to hook up with SpaceX for Mars missions, and maybe a test 0.4g long term space station made from two BFS's.  This could be done in LEO for one year or longer to study long term effects of 0.4g vs 0g on the human body.  This would be a cheaper and safer way for NASA to determine if Mars colonization is possible.  I know we will have outposts, mining and such on Mars, but what would the long term effects be.  Maybe going to Mars and staying for 18 months as SpaceX is proposing to do between synods of short travel between earth and Mars would be adequate without spinning two BFS's together. 

We know the long term effects of 0g but not the long term effects of 0.4g.  The moon is so close, I don't foresee anyone staying longer than 6 months at a stint on the moon if and when we build a moon base. 

[QuantumG]

I disagree. If you're on Mars, or the Moon, it makes no sense to "test" partial gravity anywhere else. It especially doesn't make any sense to do it in LEO with a short-rotational axis.

Rotating space stations make sense for one reason: growing humans in 1.0 g.

i.e., colonising orbit.

[LMT]

I don't follow.  Which paper(s) are you referencing, to recommend 6.7+ RPM?

http://www.spacearchitect.org/pubs/AIAA-2017-5139.pdf

After just ten 25-minute incremental sessions, 7 out of 10 subjects tolerated 15RPM. four subjects exceeded 20RPM.

Oh, I see.  It was just a head tilt, with the rest of the body motionless.  One of those restricted-motion AG experiments, hopefully useful for things like SANS and muscle tone. 

That's a far cry from Hall's "normal activity within the habitat", especially motion across a multistory habitat like a spun ITS, where Coriolis illusion, Coriolis forces and gravity-gradients would likely mix unpleasantly, and a lot, beyond 6 rpm. 

So you shouldn't read so much into that sort of experiment; i.e., no "Holy Writ" posts, with feels.    1 g at 3 rpm is just a much safer bet.

[Coastal Ron]

If by "O'Neil colonies" you mean "O'Neill cylinders" those would not be "near-term". They border on the realm of even being possible, so not germane to this thread.

Why? If ya bother to read Globus you'll discover that space colonies are easier than ever, and with fully reusable super-heavy lift on the horizon, the only thing missing is the will to do it.

And the money and time (and technology) to build giga-ton sized habitats that won't kill their inhabitants when hit by space debris. Yeah, sure, near-term... 

[LMT]

NASA may then want to hook up with SpaceX for Mars missions, and maybe a test 0.4g long term space station made from two BFS's.  This could be done in LEO for one year or longer to study long term effects of 0.4g vs 0g on the human body.  This would be a cheaper and safer way for NASA to determine if Mars colonization is possible.

And to that end, with ITS you could probably afford to run 3 long-duration tests concurrently:

1.  low g in a single non-rotating ITS
2.  Mars g in a tail-docked ITS pair
3.  Earth g in the 4-ITS-plus-hub config I've been noodling on in thread

Maybe put them all in a lunar L1 halo orbit, with everyone undertaking lunar telerobotic base-building together.   

It would be good to collect all that mission data concurrently, to get the best controlled experiments - the best apples-to-apples gravity comparisons - that may be possible.  The results would likely weigh heavily [pun] upon both Mars flight design and Mars base design.