Question about Centrifugal Gravity

So a lot of movies, TV shows, illustrations, etc., show spacecraft
generating "gravity" via rotating hull sections. In many cases, this
rotating section spins around a stationary central hull.

The question I have for those more knowledgeable in this area than I
is: What is the connection between these two sections? Obviously
there shouldn't be a physical connection between the two hull sections
(right?). But would this mean space enough between the spinnning hull
and the stationary hull for the interior atmosphere to escape? Or is
it sealed somehow?

Sorry if this is a beginner's or nitpicker's question; it's just
something that I've been wondering about for a while.

Thanks in advance to everyone who'll help me expand my knowledge
here.

--James

On 15/02/2011 10:35 PM, James W wrote:
So a lot of movies, TV shows, illustrations, etc., show spacecraft
generating "gravity" via rotating hull sections. In many cases, this
rotating section spins around a stationary central hull.

The question I have for those more knowledgeable in this area than I
is: What is the connection between these two sections? Obviously
there shouldn't be a physical connection between the two hull sections
(right?). But would this mean space enough between the spinnning hull
and the stationary hull for the interior atmosphere to escape? Or is
it sealed somehow?

Sorry if this is a beginner's or nitpicker's question; it's just
something that I've been wondering about for a while.

Thanks in advance to everyone who'll help me expand my knowledge
here.

--James


In 2001 A Space Odyssey, it was clear that the entire rotating assembly
was inside the non-rotating pressure hull, so that the issue of air
leakage didn't arise.

In Mission to Mars, that was not the case, and it would have required
some kind of sliding hermetic seal which is probably not feasible.

In practice, the most obvious solution seems to be to rotate the entire
spacecraft, but doing that removes many of the cinematically interesting
scenes.

Sylvia.

In article 93da4e6e-38dd-40de-93b9-1b11ddbfe026

@s11g2000yqc.googlegroups.com, says...



So a lot of movies, TV shows, illustrations, etc., show spacecraft

generating "gravity" via rotating hull sections. In many cases, this

rotating section spins around a stationary central hull.



The question I have for those more knowledgeable in this area than I

is: What is the connection between these two sections? Obviously

there shouldn't be a physical connection between the two hull sections

(right?). But would this mean space enough between the spinnning hull

and the stationary hull for the interior atmosphere to escape? Or is

it sealed somehow?



Sorry if this is a beginner's or nitpicker's question; it's just

something that I've been wondering about for a while.



Thanks in advance to everyone who'll help me expand my knowledge

here.



--James



Example he



Nautilus-X - NASA's Multi-mission Space Exploration Vehicle Concept

http://www.onorbit.com/node/2970



In the above article is a link to the "full document" (Powerpoint).



Jeff

--

" Solids are a branch of fireworks, not rocketry. :-) :-) ", Henry

Spencer 1/28/2011

James W wrote:
So a lot of movies, TV shows, illustrations, etc., show spacecraft
generating "gravity" via rotating hull sections. In many cases, this
rotating section spins around a stationary central hull.

The question I have for those more knowledgeable in this area than I
is: What is the connection between these two sections? Obviously
there shouldn't be a physical connection between the two hull sections
(right?). But would this mean space enough between the spinnning hull
and the stationary hull for the interior atmosphere to escape? Or is
it sealed somehow?

If you have separate rotating and non-rotating sections (as in, for
example, the movie "2010"), then yes, you need a rotating air-seal
between them. This takes a bit of effort for the engineers, but is
certainly possible.

--
-- "Jonathan Thornburg [remove -animal to reply]"
Dept of Astronomy, Indiana University, Bloomington, Indiana, USA
"Washing one's hands of the conflict between the powerful and the
powerless means to side with the powerful, not to be neutral."
-- quote by Freire / poster by Oxfam

On 18/02/2011 1:30 AM, Jonathan Thornburg [remove -animal to reply] wrote:
James wrote:
So a lot of movies, TV shows, illustrations, etc., show spacecraft
generating "gravity" via rotating hull sections. In many cases, this
rotating section spins around a stationary central hull.

The question I have for those more knowledgeable in this area than I
is: What is the connection between these two sections? Obviously
there shouldn't be a physical connection between the two hull sections
(right?). But would this mean space enough between the spinnning hull
and the stationary hull for the interior atmosphere to escape? Or is
it sealed somehow?

If you have separate rotating and non-rotating sections (as in, for
example, the movie "2010"), then yes, you need a rotating air-seal
between them. This takes a bit of effort for the engineers, but is
certainly possible.


Do you have any references describing how it could be achieved? I've
looked, and I cannot find anything.

Sylvia.

On Feb 18, 9:03 pm, Sylvia Else wrote:

Do you have any references describing how it could be achieved? I've
looked, and I cannot find anything.

Fluidic seals of various sorts are one possibility. See, for example,
http://en.wikipedia.org/wiki/Ferrofluidic_seal

In article , lid

says...



On 18/02/2011 1:30 AM, Jonathan Thornburg [remove -animal to reply] wrote:

James wrote:

So a lot of movies, TV shows, illustrations, etc., show spacecraft

generating "gravity" via rotating hull sections. In many cases, this

rotating section spins around a stationary central hull.



The question I have for those more knowledgeable in this area than I

is: What is the connection between these two sections? Obviously

there shouldn't be a physical connection between the two hull sections

(right?). But would this mean space enough between the spinnning hull

and the stationary hull for the interior atmosphere to escape? Or is

it sealed somehow?



If you have separate rotating and non-rotating sections (as in, for

example, the movie "2010"), then yes, you need a rotating air-seal

between them. This takes a bit of effort for the engineers, but is

certainly possible.





Do you have any references describing how it could be achieved? I've

looked, and I cannot find anything.



Nautilus-X (see the link to the Powerpoint in the article below)

http://www.spaceref.com/news/viewsr.html?pid=36068



Jeff

--

" Solids are a branch of fireworks, not rocketry. :-) :-) ", Henry

Spencer 1/28/2011

Sylvia Else wrote:
On 18/02/2011 1:30 AM, Jonathan Thornburg [remove -animal to reply] wrote:
James wrote:
So a lot of movies, TV shows, illustrations, etc., show spacecraft
generating "gravity" via rotating hull sections. In many cases, this
rotating section spins around a stationary central hull.

The question I have for those more knowledgeable in this area than I
is: What is the connection between these two sections? Obviously
there shouldn't be a physical connection between the two hull sections
(right?). But would this mean space enough between the spinnning hull
and the stationary hull for the interior atmosphere to escape? Or is
it sealed somehow?

If you have separate rotating and non-rotating sections (as in, for
example, the movie "2010"), then yes, you need a rotating air-seal
between them. This takes a bit of effort for the engineers, but is
certainly possible.


Do you have any references describing how it could be achieved? I've
looked, and I cannot find anything.

It can be done at simplest with the kind of rubber seal used in car
engines to keep the oil in, or with various other rotating seals of
greater complexity - but it doesn't usually need to be done.

For instance in a long flight, eg to Mars, you spin up the living
capsule say at one end of a tether and the landing module or whatever at
the other end, and it just stays spinning until a day or two before you
arrive.

For a space station with two sections the airlock between them (you do
want an airlock there!) either mates with the spinning section or with
the stationary section.

When moving from the rotating section the airlock opens to the RS,
people transfer into the airlock, it closes, it unmates with the RS, it
despins, then it mates with the stationary section etc.



In some scenarios the sections should not be in contact, if possible -
the main reason for having two sections is that you want microgravity in
one section and earthlike gravity in the other.

In order to have good microgravity with eg a rotating seal the center of
gravity of the rotating section must be at the center of the seal - but
this causes problems as eg people move around the rotating section. This
also puts pressure on the seal. It may be best to have no actual contact
between the sections, just a transfer airlock.



-- Peter Fairbrother

Originally Posted by Peter Fairbrother

Sylvia Else wrote:
On 18/02/2011 1:30 AM, Jonathan Thornburg [remove -animal to reply] wrote:
James wrote:
So a lot of movies, TV shows, illustrations, etc., show spacecraft
generating "gravity" via rotating hull sections. In many cases, this
rotating section spins around a stationary central hull.

The question I have for those more knowledgeable in this area than I
is: What is the connection between these two sections? Obviously
there shouldn't be a physical connection between the two hull sections
(right?). But would this mean space enough between the spinning hull
and the stationary hull for the interior atmosphere to escape? Or is
it sealed somehow?

If you have separate rotating and non-rotating sections (as in, for
example, the movie "2010"), then yes, you need a rotating air-seal
between them. This takes a bit of effort for the engineers, but is
certainly possible.


Do you have any references describing how it could be achieved? I've
looked, and I cannot find anything.

It can be done at simplest with the kind of rubber seal used in car
engines to keep the oil in, or with various other rotating seals of
greater complexity - but it doesn't usually need to be done.

For instance in a long flight, eg to Mars, you spin up the living
capsule say at one end of a tether and the landing module or whatever at
the other end, and it just stays spinning until a day or two before you
arrive.

For a space station with two sections the airlock between them (you do
want an airlock there!) either mates with the spinning section or with
the stationary section.

When moving from the rotating section the airlock opens to the RS,
people transfer into the airlock, it closes, it unmates with the RS, it
despins, then it mates with the stationary section etc.



In some scenarios the sections should not be in contact, if possible -
the main reason for having two sections is that you want microgravity in
one section and earthlike gravity in the other.

In order to have good microgravity with eg a rotating seal the center of
gravity of the rotating section must be at the center of the seal - but
this causes problems as eg people move around the rotating section. This
also puts pressure on the seal. It may be best to have no actual contact
between the sections, just a transfer airlock.

-- Peter Fairbrother

I have not seen a good solution other than separate habitats that are tethered together or a very large spoked wheel. A moving seal means considerable air loss into space and/or considerable energy loss to friction. With a fission or fusion power plant, perhaps the energy loss is aceptable. If we find 0.38 g (Mars) is acceptable, the hazard to people is perhaps no worse than moving sidewalks and rotating platforms used in theme park rides, which only stop in an emergency. Neil

Yes,Person precisely standing at the axis of rotation i.e. either of poles , observes no torque hence no external force exerted due gravitational field .