A major problem in designing space habs orbiting the Earth/Moon system is
the amount of shielding material that has to be launched into space. Why not
start with rotating space habs buried under the Moon's surface? The 'ground'
will have to be tilted by about 10 degrees to counter the Moon's gravity.
Illumination will be through electric lighting.
Selvaraj
One problem: Even in 1/6 G, a habitat sized for any decent population at all would require truly massive and strong bearings. Even an orbital habitat the mass of Island 3 would have very small and flimsy bearings in comparison (and that's with the assumption of a despun section; we might could get along without one), since under normal circumstances they would come under little to no load.
Second problem: If something ever went wrong with the systems which made up for frictional losses in the bearings, in the orbital case the gravity would become less and less in a asymptotic fashion. In the lunar case, same, only past a point, things would start sliding down to a "wall" that eventually becomes the new "floor", with catastrophic consequences for interior furnishings.
Read O'Neill's list of advantages of orbital habitats over habitats built on celestial bodies:
http://space.mike-combs.com/spacsetl.htm#advantages
The only way lunar habitats would be better than O'Neill habitats (even assuming the same "gravity") was if the cost savings in not having to lift materials out of the lunar gravity well were so great that they overcame the economic disadvantages of being on the surface. Given the lunar mass-driver assumption, I don't expect that to be the case.
I can see a revolving lunar gymnasium, useful for people fixing to head back to Earth. But nothing on the scale of even the more modest habitats O'Neill envisioned for orbit.
Regards,
Mike Combs
From: spacesettlers@yahoogroups.com [mailto:spacesettlers@yahoogroups.com] On Behalf Of sraj
Sent: Wednesday, June 23, 2010 1:06 PM
To: spacesettlers@yahoogroups.com
Subject: [spacesettlers] : Space habs buried under the moon's surface
A major problem in designing space habs orbiting the Earth/Moon system is
the amount of shielding material that has to be launched into space. Why not
start with rotating space habs buried under the Moon's surface? The 'ground'
will have to be tilted by about 10 degrees to counter the Moon's gravity.
Illumination will be through electric lighting.
And then there are the energy costs to keep the thing spinning.
Back to square one. The idea of habitats of a permanent nature on the moon or mars is ludicrous compared to asteroids.
Having the moon and mars for recreational purposes, a sort of landing site and socialization center around which we park the asteroid colonies is a fine plan.
But trying to deal with making artificial Gs on a lunar or martian surface turns out to be a giant engineering problem with even more enormous energy costs.
--- In spacesettlers@yahoogroups.com, "Combs, Mike" wrote:
I think a 250 m dia spherical hab rotating at 3 rpm is a doable proposition.
Yes you will need quite a bit of power to rotate the hab; in the region of
5000 to 1000 Kw. But you will need power any way for lighting purpose.
Catastrophic failure? A second row of backup bearings can be thought of.
Since this hab is not too big the danger from things falling can be
contained. Let's remember that the g level will be only 1/6 that on earth
and people in the hab will be like supermen if the g level were to drop. The
soil will get compacted over a period of time and get interlaced with plant
roots (perhaps it will be better to avoid very big trees).
Not as good as habs in space, but a good way to get started. The total land
area will be about 98000 m^2. If 60 m^2 is enough to feed one person, then
this hab can hold 1600 people! The hab will be impressively spacious.
Evidently, it will be more difficult to build such habs on Mars; its gravity
is higher!!
Regards
Selvaraj
P.S. if air bearings can be made the power required for rotation can be
reduced.
On 24 June 2010 00:01, Combs, Mike wrote:
magnetic/ air bearings will certainly cut down on friction and thus energy costs, but on the other hand they aren't as reliable as actual bearings and have their own steep energy costs.
I'm not sure what you intend to do about the one sixth of a G pull creating a sort of hill effect inside of the cylinder, for instance,
everything would still fall "down."
So it would seem from an experiential perspective that your flat interior rotational surface was always up a very steep hill.
I suppose the best answer for that and why i would bring it up is that
this then creates a situation where the smart thing to do is distort your torus so that it bulges out as it goes up, so that people can get
traction from real gravity and aren't trying to climb a vertical slope
from the perspective of real gravity.
Of course thats complicated also, because the actual pseudo G force will change depending on distance from the center, but we already assumed that the habitat would have pseudo G forces between 1.1 Gs and
. 6 Gs depending on where in the habitat you are.
Other than that, good luck with such a project, I still think its ...
a messy proposition...
peace and light to ya.
:)
--- In spacesettlers@yahoogroups.com, sraj wrote:
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This shape will be better. Effectively bank the 'land' by 10 degrees. You
will not then, get the feeling that you are climbing a hill.
Selvaraj
On 27 June 2010 07:28, pan p wrote:
--- In spacesettlers@yahoogroups.com, "Combs, Mike"
wrote:
> population at all would require truly massive and strong bearings.
Either that or thousands of smaller bearings. These would also have
the advantage of providing massive redundancy in case any of them
fail.
This however could add the problem of noise, produced by all these
bearings. How they would deal with this I'm not sure. All those
bearings are also going to have to be constantly checked and
maintained.
In spacesettlers@yahoogroups.com, "pan p"
>
> Even with magnetic bearings, the energy costs are thru the roof.
According to who? Actual numbers? The spinning surface settlement
is going to be consuming lots of energy to start out with, for
lighting, heating/cooling, etc.
I don't think the idea of spinning hubs for providing 1 G on the
moon/mars has been studied in any kind of thorough engineering-
oriented way. Or if it has, I'd like to know where the studies can
be found.
Bearing technology is very advanced. This is one technology we can really
depend on.
Selvaraj
On 27 June 2010 23:29, William wrote:
er... i don't get it.
like a paint drawing would be nice.
i agree, about 10 degrees, maybe less..
--- In spacesettlers@yahoogroups.com, sraj wrote:
lets assume magnetic bearings or IE a magnetic system like a bullet train.
As I understood it, NASA did a few studies. No clue where to find them.
I will put up a drawing in a blog. Will take some time.
Selvaraj
On 28 June 2010 12:26, pan p wrote: