"2001 A Space Odyssey" space station: Rotating or contra-rotating?

[sophiecentaur]

Sure, but I think that is a slightly different tactic than this thread was intended to pursue. At the risk of speaking for the OP, it didn't seem to be meant as a free-for-all exercise of the imagination for an unlimited tech level and expense; it had a starting scenario, and asked about the pros and cons of alternatives - presumably for the very near future - i.e. AD1967's take on AD2001, in the childhood of the space age.

That is the implied parameters I have been deliberately living within.Er ... none taken, I guess...? I haven't seen anyone discouraging any forward-thinking ideas. So far, only a couple have been offered. I hope I'm not (somehow) dominating the conversation. (In fact, I hope I'm keeping it alive and fertile.)

Feel free. But again, IMO, it behooves us to meet the OP's post "where it is". i.e. given a tech level, budget and function, what are alternatives, not so much what can we fancifully imagine.I mean if we want to go with imagination, I once sketched out a docking bay that allowed high throughput, while allowing shuttles to land on a runway just like an airplane, except that it was spiral-shaped, allowing the shuttle slowly spin up to rotational speed as it braked, while at the same time, easing occupants into station gravity in a more normal "down is towards my feet" orientation.

I could try to dig up the sketch if all bets are off.(BTW, we still use A.C.Clarke's geostionary orbital satellites, so I wouldn't be too quick to dismiss his ideas as archaic.)

Designing a docking bay (and I mean design) would involve some idea of traffic levels. Is it reasonable to assume high density? That would assume a lot about energy and materials supply. So advance by several more hundred years.
Why think in terms of aircraft and runways? Runways are only used because of the physics of flying these days. (Just above) Zero approach speed is easiest and safest.

I have to admit that thought designs of retro engineering systems doesn’t appeal to me. It’s a modern extension of model railway layouts in the attic; more model making than future Science.

More estimates of values and system spec would float my boat.

 

[DaveC426913]

Why think in terms of aircraft and runways? Runways are only used because of the physics of flying these days.

Because it was fanciful, and you were looking for more imaginative solutions. I didn't say it was practical.

 

[sbrothy]

Are you upset with the course of the discussion in this thread or is it the particular options under discussion that irks you?

One thing which has always been "grinding my gears" with the story is that at some point in the story Rama uses Sol as a gravity assist. Compared to it's (technomagic) engine power (which isn't much but is described in the story as "sufficient" and there's a wall to make sure the "Cylindrical Sea" in the middle of the craft doesn't overflow when it uses this "magical" propulsion.

Using Sol as a gravity assist it would have to be very precisely aligned and the power obviously couldn't exceed the inbuild propulsion or the sea would overflow. So if the gravity assist can't exceed the inbuild propulsion why use it at all? One would think that using the assist would be because it's free power which would exceed Rama's propulsion drive but all in all I have a hard time for it to make sense.

Do I make sense at all?

PS:

This post wasn't really an answer to your question as such. I just answered the last post. I' don't feel irked at all. Where did you get that impression? Or exactly perhaps I didn't answer specifically the question wasn't aimed at me. If so I apologize.

 

[Filip Larsen]

I' don't feel irked at all. Where did you get that impression? Or exactly perhaps I didn't answer specifically the question wasn't aimed at me. If so I apologize.

No worries. My question was directed to sophicentaur.

 

[Filip Larsen]

It’s the fact that the contributions seem to be from Arthur C or Hollywood.

I can of course only speak for myself, but except for the OP question which was referring to the spinning station from the movie "2001 : A Space Odyssey"(1) I am referring to real-life aerospace engineering principles to the extend that I am aware of them as an engineer that has had a life long interest in aerospace designs and simulation. Also, I feel the discussion I have been involved in here had tried to refer to relevant physical principles. Granted, the discussion has probably been on an amateur level compared to with what a professional team of aerospace engineer would have discussed if tasked with designing such a station (e.g. as a feasibility study for relevant future technologies), but that is just how this forum works.

But isn't the solution easy? You just provide relevant critique to the specific points you think are too amateurish or too much based on movies and we take it from there?

(1) I don't recall the level of detail Clark described the station with in his original story, but granted, he most likely had enough influence on how most things was depicted in the movie to call is "his" designs).

 

[DaveC426913]

Using Sol as a gravity assist it would have to be very precisely aligned and the power obviously couldn't exceed the inbuild propulsion or the sea would overflow. So if the gravity assist can't exceed the inbuild propulsion why use it at all? One would think that using the assist would be because it's free power which would exceed Rama's propulsion drive but all in all I have a hard time for it to make sense.

Do I make sense at all?

Gravity - and thus, gravity assist - works on the entire craft, wall, floor and water. The craft is in freefall, even as it is falling toward or away from the Sun. Occupants will neither see nor feel anything.

So it does not constrain acceleration - but with one caveat: if it gets too close to the Sun, it may experience tidal forces (i.e. different parts of the 50km long cylinder actually experience different degrees of gravity because it's so close).(You'll have to get up earlier than that in the morning if you want to catch A.C. Clarke out on a technical issue. :) )

 

[sbrothy]

Aaaah. That explains it. I've wondered about this since seeing Space Odyssey 2010 where they aerobreak but otherwise seem to be unaffected. In fact I've been afraid to ask this question because I thought the answer would be something along those lines and make me look like a fool :) . So no matter how hard my spacecraft is "assisted" I shouldn't worry about everything and everyone getting squished up against one wall?

How incredibly unintuitive but we've been over that.

Thank you.

 

[Ibix]

So no matter how hard my spacecraft is "assisted" I shouldn't worry about everything and everyone getting squished up against one wall?

You're in free fall the whole time, just like being in orbit (because you are in orbit, just a hyperbolic one). Tidal forces will still affect you and tend to elongate you along the radial direction, but unless you're orbiting close over a neutron star or black hole you'd need specialist equipment to spot it inside a reasonable sized spacecraft.

 

[DaveC426913]

... a reasonable sized spacecraft.

Rama is 50km long.

(Only 20 across, if they wanted to orient it to minimize tidal forces.)

Actually, it shouldn't matter. The Cylindrical Sea rings the waist of the ship - at its CoM - and far from the poles, where the most tidal forces would be felt.

Any water tidal action would only be across the width of the Sea from wall to wall, which is less than 20km. And it would be equal. In other words, it would not slosh toward one wall more than the other; it would simply get a smallish sea swell on each wall, as the water bowed slightly toward the poles.

You'd have to be in a pretty good tidal gradient - acting across less than 20km - to get the Sea to overflow its banks.

 

[Ibix]

Rama is 50km long.

The Earth is 12,800 km across and the lunar tides vary water height by a few meters. You'd have to do the calculations for a relatively close pass of the Sun (the mass is a lot more than the Moon, but you can't get so close as we are to the Moon).

 

[DaveC426913]

The Earth is 12,800 km across and the lunar tides vary water height by a few meters. You'd have to do the calculations for a relatively close pass of the Sun (the mass is a lot more than the Moon, but you can't get so close as we are to the Moon).

The Cylindrical Sea is only 20km across - much smaller than the largest lakes, which do not experience tides to-speak-of. Someone needs to do some calcs (not 'it'!).

 

[Nik_2213]

A reminder that AC Clarke's memorably elegant 2001 docking sequence was a blatant 'Middle Finger' to his critics who'd said docking with a rotating space-station was 'impossible'.
Non-trivial, certainly, and needing those computer-assists to be sure, to be sure...

Also, perhaps, he did rather 'over-egg the pudding'.
A telescopic 'air-bridge' or tele-handler that allowed connection at a safe-to-breakaway distance, then hauled the 'secured' arrival indoors would have been wiser.
My 'Convention' tales call such 'Mantis Grapples'...

( I've never heard of mantids hunting in threes or fours, but... )