space station design ideas
harry
although we usually 'like' to be weightless in space (for scientific study),
humans are accustomed to gravity and our bodies have evolved with it.
when considering long term space travel, do develop drugs and techniques to
deal with 0 g or do we take gravity with us? (question 1)
if we take gravity with us, i was considering the following idea:
a rotating space station consisting of two or more 'nodes' tethered together
by a cable. the nodes rotate around the center of gravity to create an an
acceleration to provide 'gravity'.
the nodes could could move farther or closer together to adjust the
rotational period.
if this station orbited the earth, which would be the appropriate plane of
rotation ? (of the three that i can imagine) (question 2)
how would the orbit effect the rotational mass over time.? (question 3)
could this configuraton generate power as has been done in the other
tethered experiments? (4)
harry
nj
David Blenkinsop
harry wrote in message ...
>how about this:
>
>although we usually 'like' to be weightless in space (for scientific study),
>humans are accustomed to gravity and our bodies have evolved with it.
>
>when considering long term space travel, do develop drugs and techniques to
>deal with 0 g or do we take gravity with us? (question 1)
Amazing, isn't it, just how little the currently planned International Space
Station seems to do to help deal with the business of "taking gravity with us?"
Maybe it's just assumed that any near term human voyages will be to a low-g
destination, like an asteroid, so it the astronauts get thoroughly acclimatized
to zero-g, it doesn't matter? Also, in practical engineering terms it would
presumably be difficult to effectively and safely add rotating modules *directly*
to a station that's been designed primarily for zero-g experiments.
>
>if we take gravity with us, i was considering the following idea:
>
>a rotating space station consisting of two or more 'nodes' tethered together
>by a cable. the nodes rotate around the center of gravity to create an an
>acceleration to provide 'gravity'.
Just as a bit of a technicality here, it's not hard to calculate that, if you put
two nodes at the ends of a 200 meter cable, a spin rate of two rotations per
minute will then give you a "gravity" level of 4.4 meters per second squared,
which is a bit higher than Mars gravity, or a bit less than half Earth gravity.
As I understand things, it could be important to keep the rotation rate to two
rpm or less, to minimize any chance of resulting motion sickness. This has
implications for the radius of rotation, hence the need for putting these station
modules on the ends of a cable. For instance, you wouldn't want to cut the
rotation radius to much less than my choice of 100 meters, in the "Mars gravity"
example that I'm using here, because if you do, the appropriate formula tells you
that you must then spin the whole thing at a faster rpm to maintain the roughly 4
meters per second squared that I want to stick to! What I want to see for this,
without spinning things so fast as to cause motion sickness, is a Mars-type spin
"gravity" level, for reasons that maybe should be obvious?
>
>if this station orbited the earth, which would be the appropriate plane of
>rotation ? (of the three that i can imagine) (question 2)
A rotating station could be a good idea, it's been talked about for years. I
presume the orbit of such a station could be similar to that of ISS, perhaps a
bit higher? If space agencies need any special motivation for experimenting with
something like this, maybe they should be reminded that spin gravity is a likely
requirement for an eventual manned Mars mission? After all, you don't want your
astronauts to be all flabby when it's time to land on another planet, so maybe it
would make sense to get some sort of practice with using something like this,
even way in advance of an actual mission! What I suspect is that it really
shouldn't be too difficult to build some extra ISS modules to make an entirely
separate, small, rotating-type station, just purely for the sake of sending
astronauts to live in that sort of environment from time to time.
I confess I have an ulterior motive in suggesting this, as I understand that spin
gravity could have real benefits for long term human use of space, even if
*Earth* is the only planet to be landed on, in the end! How about it, would it
complicate things way too much to launch a small rotating station, so that ISS
astronauts could spend their "weekends" beefing up a little? Even if we don't get
to Mars very soon, the benefits for space station astronauts could be quite real,
and -- and, darn it, it's an interesting thing to find out about, right? Just how
good *is* that sort of gravity level for maintaining human health in space?
>
>how would the orbit effect the rotational mass over time.? (question 3)
>
I'm not sure what you mean by "rotational mass". Do you mean rotational moment of
mass, or spin angular momentum, or something like that?
- David Blenkinsop
Frank Crary
harry <pcs_...@mailexcite.com> wrote:
>if this station orbited the earth, which would be the appropriate plane of
>rotation ? (of the three that i can imagine) (question 2)
I think you would want the spin axis of the station to point through
the center of the Earth. That would minimize tidal forces. Tidal
forces would slow down the station's rotation rate, which is probably
undesirable.
>could this configuraton generate power as has been done in the other
>tethered experiments? (4)
Sure, but not for free. Such a configuration could generate power,
but only at the price of slowing its orbital velocity and spin rate.
Overall, I wouldn't try it: Mechanical tethers seem (from very limited
experience) to be more reliable than electrodynamic tethers.
Frank Crary
CU Boulder
Nicholas Landau
>>when considering long term space travel, do develop drugs and techniques to
>>deal with 0 g or do we take gravity with us? (question 1)
>Amazing, isn't it, just how little the currently planned International Space
>Station seems to do to help deal with the business of "taking gravity with us?"
>Maybe it's just assumed that any near term human voyages will be to a low-g
>destination, like an asteroid, so it the astronauts get thoroughly acclimatized
>to zero-g, it doesn't matter? Also, in practical engineering terms it would
>presumably be difficult to effectively and safely add rotating modules *directly*
>to a station that's been designed primarily for zero-g experiments.
Interesting. I thought that I had read that rotating modules were
planned for the ISS. I thought that the media had pubished sketches
of cylindrical modules rotating axially, attached to the main structure
of ISS at the axis (and so one could come and go from the station without
having to move "uphill" nor "downhill"). With the Soviet and Russian
data on physical degeneration in free-fall, it would be nuts not
to include such a module. It could mean the differences between the
return to 1G being a trivial affair and months upon months of virtual
paralysis.
BTW, you need not have two halves of the station tethered. You could
tether the station to a small, dense counterweight if you wanted.
I mention this because the two-station system might cause shadows
to be cast across parts of the stations, making temperature and
power generation a little more complicated.
Jorge R. Frank
>
> "David Blenkinsop" <bl...@spaminacan.sk.sympatico.ca> writes:
>
> >>when considering long term space travel, do develop drugs and techniques to
> >>deal with 0 g or do we take gravity with us? (question 1)
>
> >Amazing, isn't it, just how little the currently planned International Space
> >Station seems to do to help deal with the business of "taking gravity with us?"
> >Maybe it's just assumed that any near term human voyages will be to a low-g
> >destination, like an asteroid, so it the astronauts get thoroughly acclimatized
> >to zero-g, it doesn't matter? Also, in practical engineering terms it would
> >presumably be difficult to effectively and safely add rotating modules *directly*
> >to a station that's been designed primarily for zero-g experiments.
>
> Interesting. I thought that I had read that rotating modules were
> planned for the ISS.
Nope. There's a module containing a centrifuge, but the module itself
will not rotate.
--
JRF
Reply-to address spam-proofed - to reply by E-mail,
check "Organization" and think one step ahead of IBM.
Henry Spencer
David Blenkinsop <bl...@spaminacan.sk.sympatico.ca> wrote:
>Amazing, isn't it, just how little the currently planned International Space
>Station seems to do to help deal with the business of "taking gravity with us?"
That's because it's primarily a microgravity lab. It is relevant, but
only somewhat indirectly, in the sense that some of what it does may help
settle how necessary it is to take gravity with us.
Bear in mind that political support for manned exploration is weak, and a
space station dedicated to such purposes probably would have been
cancelled. (There was a time, during the Bush administration, when
Congress was actively seeking out and killing anything that even *sounded*
like it might be related to SEI.)
--
The good old days | Henry Spencer he...@spsystems.net
weren't. | (aka he...@zoo.toronto.edu)
David Blenkinsop
On Feb 2, 1999, Jorge R. Frank wrote:
>Nicholas Landau wrote:
>>
>> David Blenkinsop writes:
>>
>>
>> >Amazing, isn't it, just how little the currently planned International Space
>> >Station seems to do to help deal with the business of "taking gravity with
us?"
>> >Maybe it's just assumed that any near term human voyages will be to a low-g
>> >destination, like an asteroid, so it the astronauts get thoroughly
acclimatized
>> >to zero-g, it doesn't matter? Also, in practical engineering terms it would
>> >presumably be difficult to effectively and safely add rotating modules
*directly*
>> >to a station that's been designed primarily for zero-g experiments.
>>
>> Interesting. I thought that I had read that rotating modules were
>> planned for the ISS.
>
>Nope. There's a module containing a centrifuge, but the module itself
>will not rotate.
>
Ah, a centrifuge! I just found a link on this, it can be accessed from
http://lifesci.arc.nasa.gov/sitemap.html , just go from there to the "Space
Station Biological Research Project" link, to find out all about the centrifuge
and plans for raising rats, mice, bugs, fish, and plants in a spinning 1g
environment. Note that this 2.5 meter diameter centrifuge has to spin at 28 rpm
to generate 1g of "gravity effect", this would undoubtedly be quite crowded and a
very uncomfortably fast spin if one were to try to house humans in this thing :-)
Among other things, the Web pages describe the careful balancing system needed to
prevent the centrifuge from generating vibrations which would interfere with the
zero-g experiments in the rest of the station. Presumably, the engineering
problems would be that much more difficult for any hypothetical human-scale
centrifuge that one might think of attaching directly to the current station.
Henry Spencer wrote:
[in regard to International Space Station]
>
>That's because it's primarily a microgravity lab. It is relevant, but
>only somewhat indirectly, in the sense that some of what it does may help
>settle how necessary it is to take gravity with us.
>
>Bear in mind that political support for manned exploration is weak, and a
>space station dedicated to such purposes probably would have been
>cancelled. (There was a time, during the Bush administration, when
>Congress was actively seeking out and killing anything that even *sounded*
>like it might be related to SEI.)
Trouble is, I keep hearing about how manned space flight is going to cost $100
billion over the next ten years -- does this $100 billion figure include all
shuttle flights during that time frame, or just the ISS-related flights? With
that kind of money going into finding out about the human uses of space, one
might hope they'd be able to plan a spin gravity experiment that's suited to us
humans, as a worthy "follow up" project, if nothing else. Even if we *don't* have
firm plans for the Space Exploration Initiative of going to Mars, finding out
what spin gravity does for humans "still" sounds like something worth knowing.
For instance, maybe we'll ultimately need something like this to maintain the
health of lunar tourists? As long as real money is being spent to maintain humans
in space anyway, why not take an extra step to find out about "spin gravity" as
well? Oh well, at least it's encouraging that biological centrifuge experiments
are planned, "where no rat has ever gone before", and all that!
- David Blenkinsop
For email replies, remove the canned spam from the address header.
Samuel P. Uselton
I don't know where the $100 billion for manned space flight over the
next 10 years came from. Can you give a reference?
My impression is that the NASA budget has been quite flat recently
(even though other research oriented agencies finally got some
increases). I believe it is on the order of $13 billion per year.
$10 billion per year probably covers *everything* that is even vaguely
space related (eg EOS) not just manned space flight. There might be
$3 billion going to the aeronautics programs (the first A in NASA
after all).
Of course there *could* be a proposal for increases, but I wouldn't count
that until Congress votes on it.
Sam Uselton
use...@nas.nasa.gov
David Blenkinsop
Bruce Sterling Woodcock
> Trouble is, I keep hearing about how manned space flight is going to cost
> $100 billion over the next ten years -- does this $100 billion figure
> include all shuttle flights during that time frame, or just the
> ISS-related flights?
This doesn't answer your question, but virtually *all* of the shuttle
flights for the next 5 years will be ISS-assembly flights. There are
a few exceptions, like HST servicing and Earth topography, and 1999 is
something of a slow shuttle year, but I would guess the ISS-assembly
flights account for 80% or more of the total costs.
Now, you did say ISS-related, and I avoided that because one can conceive
some day, maybe 4 or 5 years hence, where the shuttle will dock with the
ISS as simply a routine part of a larger primary mission. But that's not
really going to happen any time soon. (There are ISS-assembly missions
were some other goals are planned, but not primary ones.)
Bruce
David Blenkinsop
Samuel P. Uselton wrote in message ...
>
>I don't know where the $100 billion for manned space flight over the
>next 10 years came from. Can you give a reference?
I was thinking of the November 23rd, 1998, _Time_ magazine article, where, as I
recall, there was an incredibly wide range of dollars quoted as to what the true
cost of ISS as such might be, from tens of billions to somewhere close to $100
billion. In fact, the Web version of this article is available, it's at
http://cgi.pathfinder.com/time/magazine/1998/dom/981123/space.who_needs_this_2a.html
Notice where the Web article says that the space station is "3 or 5 or 12 times
over budget depending on who's counting the beans", that's using 8 billion for
the initial, early, estimate, apparently, and allowing nothing for inflation. So
what they're saying is that the true cost of the station might be anywhere from
24 billion to 96 billion, I've understood that it takes 10 years or so to
completely build ISS, and there you go. Notice that such a *wide* range of
numbers makes the article sort of a "funny" business, in a way; I'd think the
high end is really some estimate of the total cost of manned space flight,
including any and all shuttle missions remotely to do with ISS during that time?
For another estimate of space station price, try
http://www.reston.com/NASA/watch.html , and scroll all the way down past the
table of STS flights to the link to an _LA Times_ editorial, titled "NASA Needs a
Nudge". Here it says that the total cost of ISS will be $50 billion.
>
>My impression is that the NASA budget has been quite flat recently
>(even though other research oriented agencies finally got some
>increases). I believe it is on the order of $13 billion per year.
>$10 billion per year probably covers *everything* that is even vaguely
>space related (eg EOS) not just manned space flight. There might be
>$3 billion going to the aeronautics programs (the first A in NASA
>after all).
>
Well, we are told that the shuttle is a tremendously expensive vehicle to
operate, so if "shuttle and station" are the definition of manned space flight,
it sounds plausible that those two "vehicles" could account for 10 billion per
year of NASA's budget? I'm no space cost expert, but if the true costs of manned
operations is much less than this, I'd be glad to hear it!
Jorge R. Frank
>
> Samuel P. Uselton wrote in message ...
> >
> >(even though other research oriented agencies finally got some
> >increases). I believe it is on the order of $13 billion per year.
> >$10 billion per year probably covers *everything* that is even vaguely
> >space related (eg EOS) not just manned space flight. There might be
> >$3 billion going to the aeronautics programs (the first A in NASA
> >after all).
> >
>
> Well, we are told that the shuttle is a tremendously expensive vehicle to
> operate, so if "shuttle and station" are the definition of manned space flight,
> it sounds plausible that those two "vehicles" could account for 10 billion per
> year of NASA's budget? I'm no space cost expert, but if the true costs of manned
> operations is much less than this, I'd be glad to hear it!
See http://www.access.gpo.gov/usbudget/fy2000/pdf/nsa.pdf
NASA's total human spaceflight budget for 1999 is about $5.5
billion/year - $3 billion for shuttle, a shade less than $2.5 billion
for ISS. That total will remain fairly flat until ISS assembly is
complete, then the ISS portion drops to around $1.4 billion/year.