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Transporting liquids and gases across the moon



 
 
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  #12  
Old February 10th 04, 08:12 PM
Mike Combs
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Default Transporting liquids and gases across the moon

"Alex Terrell" wrote in message
om...

An excellent story it is. I also pointed out a few months ago that you
could actually use this system to transfer energy.


Thanks.

Yes, which would be nice given that solar energy might be more constantly
available at the poles than at other latitudes.

However, I'm a little worried about the accuracy requirement. If a
cargo hits the side of an L1 catcher, it explodes at about 20m/s,
doing little damage. But these ones will come in at about a km/s. I
wouldn't like to underwrite the receiving infrastructure.


Granted, pointing would be VERY important. O'Neill talked about use of
electrostatic plates downrange of his lunar mass-driver for fine-tuning of
trajectory. Some of these spaced at wide intervals along the path would
probably be a good idea.


--


Regards,
Mike Combs
----------------------------------------------------------------------
We should ask, critically and with appeal to the numbers, whether the
best site for a growing advancing industrial society is Earth, the
Moon, Mars, some other planet, or somewhere else entirely.
Surprisingly, the answer will be inescapable - the best site is
"somewhere else entirely."

Gerard O'Neill - "The High Frontier"


  #13  
Old February 10th 04, 08:35 PM
Bill Bogen
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Default Transporting liquids and gases across the moon

"Mike Combs" wrote in message ...
"Alex Terrell" wrote in message
om...
There are reasons why it's advantageous to have a main lunar base at
low latitude, and a water mining base at the poles.

But how could cargo be transported bewteen the two.


I wrote a short SF story where I had a mass-driver and an "anti-mass-driver"
tossing filled and empty buckets of ice back and forth between a polar mine
and an equatorial station.

http://members.aol.com/howiecombs/tnbttbt.htm

The advantage of such a system would be the lack of need for infrastructure
between the two points.

A few years later, someone at the Space Studies Institute was discussing
just such an "anti-mass-driver".


Yep, an elegant system. But it might be cheaper, if ice were the only
thing being transported, to fling ice cubes using a ground-based
rotating tube or sling. A passive catcher at the other end would
accumulate the icecubes. No need to make or recycle buckets, no need
to maintain two mass-drivers. A 30 meter radius sling spinning at
1000 rpm would do it. Maybe use a laser slightly downrange to zap the
icecubes and tweak their trajectories.

My favorite general-purpose lunar transport system, though, is still
the rotavator, a spinning polar-orbital tether cartwheeling around the
Moon, touching down near equator and poles. The acceleration could be
gentle enough for passengers as well as cargo and it could also be
used to ship people/cargo to and from Earth. We'd need small rocket
vehicles to rendezvous with the bottom end of the tether.
  #15  
Old February 11th 04, 09:27 PM
Alex Terrell
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Default Transporting liquids and gases across the moon

(Bill Bogen) wrote in message . com...
  #16  
Old February 11th 04, 09:35 PM
Lex Spoon
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Default Transporting liquids and gases across the moon

How about a sort of four legged kangaroo transport truck, that jump up
and down on the moon surface?

A can imagine now, a truck with four pogo sticks. Perharps also with a
little bit assistances with retro rockets.

Jumping up and down has been a proved method on traveling on the moon.
LOL!


Oh heck, this might actually be practical. First time I've heard of this
idea. Doesn't use reaction mass, can travel rough terrain. I wouldn't
want to ride in one tho.



The programming is extremely challenging. Otherwise walking and
hopping have some nice improvements over rolling. Imagine going down
the highway and your car has the option to hop over someone instead of
ramming into them. Imagine if a pothole was nothing, and it took a
2-3 foot ditch before you got even close to worrying about it.

But again, the programming is tough. Insects are much better at
walking and hopping than computers, these days.



-Lex



  #17  
Old February 12th 04, 07:16 AM
Allen Meece
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Default Transporting liquids and gases across the moon

There are reasons why it's advantageous to have a main lunar base at low
latitude, and a water mining base at the poles.
Those reasons, whatever they might be, are probably not enough to ignore the
advisability of placing the base near the water supply, just as we've been
doing here on earth for twenty-seven million years, for obvious reasons.
Another advantage of placing the base at the poles is that there would be
more hours of sunlight available to provide for solar power. It would also be
more cheerful as well as providing more visibility for working than enduring
two-week-long pitch-black nights.
^
//^\\
~~~ near space elevator ~~~~
~~~members.aol.com/beanstalkr/~~~
  #19  
Old February 12th 04, 05:00 PM
Bill Bogen
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Posts: n/a
Default Transporting liquids and gases across the moon

"Mike Combs" wrote in message ...
"Alex Terrell" wrote in message
om...

An excellent story it is. I also pointed out a few months ago that you
could actually use this system to transfer energy.


Thanks.

Yes, which would be nice given that solar energy might be more constantly
available at the poles than at other latitudes.

However, I'm a little worried about the accuracy requirement. If a
cargo hits the side of an L1 catcher, it explodes at about 20m/s,
doing little damage. But these ones will come in at about a km/s. I
wouldn't like to underwrite the receiving infrastructure.


Granted, pointing would be VERY important. O'Neill talked about use of
electrostatic plates downrange of his lunar mass-driver for fine-tuning of
trajectory. Some of these spaced at wide intervals along the path would
probably be a good idea.


A few problems... unless your payload is moving at orbital velocity
(1679 m/sec), it must be lofted at some angle above the horizontal and
so will not be hugging the surface within the reach of electrostatic
plates for very long. Maybe lasers would be a better way to tweak the
trajectories. An off-target one kilogram payload would hit with the
same energy as one ton moving at 100 miles/hour. And given that the
trip takes about 27 minutes, you'd have a lot of payloads doing a lot
of damage while you 'fine-tuned' the trajectories.
  #20  
Old February 12th 04, 11:39 PM
Ian Stirling
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Default Transporting liquids and gases across the moon

Lex Spoon wrote:
How about a sort of four legged kangaroo transport truck, that jump up
and down on the moon surface?

A can imagine now, a truck with four pogo sticks. Perharps also with a
little bit assistances with retro rockets.

Jumping up and down has been a proved method on traveling on the moon.
LOL!

snip
The programming is extremely challenging. Otherwise walking and
hopping have some nice improvements over rolling. Imagine going down
the highway and your car has the option to hop over someone instead of
ramming into them. Imagine if a pothole was nothing, and it took a
2-3 foot ditch before you got even close to worrying about it.


It's not only that, but it's also got problems energetically.

While there is no inherent reason you can't regeneratively recover
the energy from moving the legs, it's many orders of magnitude
more complex than a wheel.

A wheel only needs a simple bearing, and uses rotational symmetry
to generate the force to move the contact surface backwards and
forwards.

A leg needs multiple actuators all able to cycle at high rates, and
the ability to swing the leg rapidly and accurately and exert high
forces.

If the control system goes out on a wheel, then you carry on
going in the same direction.

If it goes out on a leg, you fall over pretty much immediately.
 




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