Micro Gravity and A Space Elevator?

On 2020-06-10 16:43, David Spain wrote:
On 2020-06-10 8:40 AM, Niklas Holsti wrote:
Yes, but you also have to take into account that as the cab rises, it
gains "orbital" velocity, which counteracts the gravity. The effect of
the "orbital" velocity increases until it exactly balances gravity
when the cab reaches the geosynchronous altitude.

Are objects inside the cab of the space elevator near the "space" end
undergoing any form of microgravity?

Yes, see above.


OK that makes sense and is totally interesting.

Is this an interesting way to get artificial gravity on a space station
'on the cheap' without rotation?

It is certainly a way to get any desired apparent gravity from one-gee
to zero-gee, without a centrifuge. Building "stations" at various
altitudes along the elevator of course increases the stress on the
elevator cable a little.

But I wouldn't call a space elevator "cheap" :-)

--
Niklas Holsti

niklas holsti tidorum fi
. @ .

On 2020-06-10 1:06 PM, Niklas Holsti wrote:

But I wouldn't call a space elevator "cheap" :-)


Good point. Plus it relies on unobtainium for the cable. I've heard
carbon nano-tubes *might* be strong enough. But haven't seen them laid
out in 36,000 km long "cables" either.

Dave

On Wednesday, June 10, 2020 at 2:01:52 PM UTC-4, David Spain wrote:
On 2020-06-10 1:06 PM, Niklas Holsti wrote:

But I wouldn't call a space elevator "cheap" :-)

Good point. Plus it relies on unobtainium for the cable. I've heard
carbon nano-tubes *might* be strong enough. But haven't seen them laid
out in 36,000 km long "cables" either.

Nothing even remotely approaching obtainium is on the horizon for a space
elevator for Earth.

It would be possible for the Moon today, given its much lower gravity. Given
its very slow rotation, a geosynchronous anchor would not work, but they could
use one of the Moon's LaGrange points.

On 2020-06-10 2:16 PM, Scott Kozel wrote:

It would be possible for the Moon today, given its much lower gravity. Given
its very slow rotation, a geosynchronous anchor would not work, but they could
use one of the Moon's LaGrange points.


You're thinking a fuel depot? Water pumped up from the surface to the
anchored depot at L1 or L2? Micro-gravity available when docked?

Dave

On Wednesday, June 10, 2020 at 2:28:39 PM UTC-4, David Spain wrote:
On 2020-06-10 2:16 PM, Scott Kozel wrote:

It would be possible for the Moon today, given its much lower gravity. Given
its very slow rotation, a geosynchronous anchor would not work, but they could
use one of the Moon's LaGrange points.

You're thinking a fuel depot? Water pumped up from the surface to the
anchored depot at L1 or L2? Micro-gravity available when docked?

I wasn't advocating or opposing a Moon space elevator, just saying that it is
technologically feasible with today's materials.

I read somewhere that a Mars space elevator is technologically feasible with
today's materials, but I am not sure about that.

On Jun/10/2020 at 18:35, Scott Kozel wrote :
On Wednesday, June 10, 2020 at 2:28:39 PM UTC-4, David Spain wrote:
On 2020-06-10 2:16 PM, Scott Kozel wrote:

It would be possible for the Moon today, given its much lower gravity. Given
its very slow rotation, a geosynchronous anchor would not work, but they could
use one of the Moon's LaGrange points.

You're thinking a fuel depot? Water pumped up from the surface to the
anchored depot at L1 or L2? Micro-gravity available when docked?

I wasn't advocating or opposing a Moon space elevator, just saying that it is
technologically feasible with today's materials.

I read somewhere that a Mars space elevator is technologically feasible with
today's materials, but I am not sure about that.

An Earth space elevator is technologically feasible with today's
material. See for instance
space.nss.org/wp-content/uploads/2000-Space-Elevator-NIAC-phase1.pdf
that's a little old, but materials available 20 years ago should be
available now. It would be too expensive, but technically, it is doable.
Costs estimates in that report are of $40B (page 11.4), but I would say
the author is a little optimistic, not ridiculously so, but a little
optimistic.

On Mars, I'm not sure how one would solve the problem caused by the low
orbiting moons but I think it would be doable. Anyway, for the time
being, the traffic from Mars surface to Mars orbit is too low to justify
the cost, whatever that cost would be :-)


Alain Fournier

On 2020-06-10 7:46 PM, Alain Fournier wrote:

An Earth space elevator is technologically feasible with today's
material. See for instance
space.nss.org/wp-content/uploads/2000-Space-Elevator-NIAC-phase1.pdf

Interesting, will take a look, thanks. Reformatted for one-click...

https://space.nss.org/wp-content/upl...IAC-phase1.pdf

Dave

Allow me to refresh your memory:

On 2020-06-10 7:46 PM, Alain Fournier wrote:
On Jun/10/2020 at 18:35, Scott Kozel wrote :
On Wednesday, June 10, 2020 at 2:28:39 PM UTC-4, David Spain wrote:
On 2020-06-10 2:16 PM, Scott Kozel wrote:

It would be possible for the Moon today, given its much lower
gravity.Â* Given
its very slow rotation, a geosynchronous anchor would not work, but
they could
use one of the Moon's LaGrange points.

You're thinking a fuel depot? Water pumped up from the surface to the
anchored depot at L1 or L2? Micro-gravity available when docked?

I wasn't advocating or opposing a Moon space elevator, just saying
that it is
technologically feasible with today's materials.

I read somewhere that a Mars space elevator is technologically
feasible with
today's materials, but I am not sure about that.

An Earth space elevator is technologically feasible with today's ---- emphasis mine
material. See for instance
space.nss.org/wp-content/uploads/2000-Space-Elevator-NIAC-phase1.pdf
that's a little old, but materials available 20 years ago should be
available now. It would be too expensive, but technically, it is doable.
Costs estimates in that report are of $40B (page 11.4), but I would say
the author is a little optimistic, not ridiculously so, but a little
optimistic.

On Mars, I'm not sure how one would solve the problem caused by the low
orbiting moons but I think it would be doable. Anyway, for the time
being, the traffic from Mars surface to Mars orbit is too low to justify
the cost, whatever that cost would be :-)


Alain Fournier

On 2020-06-10 2:01 PM, David Spain wrote:
On 2020-06-10 1:06 PM, Niklas Holsti wrote:

But I wouldn't call a space elevator "cheap" :-)


Good point. Plus it relies on unobtainium for the cable. I've heard
carbon nano-tubes *might* be strong enough. But haven't seen them laid
out in 36,000 km long "cables" either.

Dave


https://figshare.com/articles/Growth...bution/2393992

Just need to scale this process up by a factor of 72E6 meters in length.
No quite so much in diameter.... :-)

Dave