Boloworlds

Living in deep space presents any number of problems, but one of the more
serious ones is the lack of gravity on small bodies like asteroids and comet
cores. One idea might be to nudge two bodies on mutual intercept courses
with a very small net delta vee between them. When they get close enough,
throw a line from one to the other and secure it with shock-absorbing
arrangements on both ends. With carefully chosen parameters and a bit of
fiddling, the two should go into an eventually circular orbit around a
common center of mass. If there is a marked difference in the relative
masses, each will have a unique gravity gradient induced by centrifugal
force.

Of course, if the objects are rubble piles, it will be necessary to build
net bags around them first, with anchor points on each bag.

Many twiddly bits here, of course, starting with the parameters for
rendezvous. Not only will they have to be put into close proximity to one
another, but their relative spins will have to be brought to a reasonably
close match for the arresting gear to manage without becoming overstressed
or hopelessly twisted.

This can't be an original idea. Has work been done on this already?
References appreciated!


Jim McCauley

"Jim McCauley" wrote in message t...
Living in deep space presents any number of problems, but one of the more
serious ones is the lack of gravity on small bodies like asteroids and comet
cores. One idea might be to nudge two bodies on mutual intercept courses
with a very small net delta vee between them. When they get close enough,
throw a line from one to the other and secure it with shock-absorbing
arrangements on both ends. With carefully chosen parameters and a bit of
fiddling, the two should go into an eventually circular orbit around a
common center of mass. If there is a marked difference in the relative
masses, each will have a unique gravity gradient induced by centrifugal
force.

Of course, if the objects are rubble piles, it will be necessary to build
net bags around them first, with anchor points on each bag.

Many twiddly bits here, of course, starting with the parameters for
rendezvous. Not only will they have to be put into close proximity to one
another, but their relative spins will have to be brought to a reasonably
close match for the arresting gear to manage without becoming overstressed
or hopelessly twisted.

This can't be an original idea. Has work been done on this already?
References appreciated!

This could be an original idea, and I can't imagine anyone doing any
work on it.
References:
http://near.jhuapl.edu/eros/sum.html
"433 Eros is one of the largest and best-observed near-Earth
asteroids. Discovered independently by Gustav Witt (Germany) and
August H.P. Charlois (France) in 1898, Eros accounts for nearly half
the volume of all near-Earth asteroids."
...
"The gravity on Eros is very weak but enough to hold the NEAR
Shoemaker spacecraft. Depending on where they stood, a 200-pound
person on Earth would weigh about 2 ounces on Eros."


Having two Eros size asteriods wouldn't create much gravity. Though
the graviational attraction between two Eros size rocks would be quite
significant, they could orbit each other without needing any
"arresting gear" and this attractive force would dwarf the strength of
very thick and strong cables. Trying to change the direction of the
vectors these size rock with "arresting gear" would similar to trying
to move a train with some string. Having the two rocks slowly graze
one another would probably put them into some kind orbit around each
other.

Now I imagine you were thinking of smaller rocks than Eros. Let's say
one had a rock 1 km in diameter and this rock had a "moon" say 50
meters in diameter and it was in a close orbit [say, 20 km from larger
rock]. You could use your "arresting gear" to bring moon closer to
larger rock. You could match the rotation of the 1 km rock to the
orbit of the moon and could bring the moon nearer the 1 km diameter
rock so that the cable was under tremendous tension- depending on how
strong your cable was you could get these rocks spinning fairly fast.
You could then mine the big rock and sling off the mined material-
which would slow down the spin, but could increase the spin pulling
the moon closer. I think this general idea has been thought of and
some work done on it.
Hmm, didn't see specifically mentioned he
http://www.permanent.com/a-mining.htm
Maybe somewhere else.

"Jim McCauley" wrote in message
...
Living in deep space presents any number of problems, but one of the more
serious ones is the lack of gravity on small bodies like asteroids and
comet
cores. One idea might be to nudge two bodies on mutual intercept courses
with a very small net delta vee between them. When they get close enough,
throw a line from one to the other and secure it with shock-absorbing
arrangements on both ends. With carefully chosen parameters and a bit of
fiddling, the two should go into an eventually circular orbit around a
common center of mass. If there is a marked difference in the relative
masses, each will have a unique gravity gradient induced by centrifugal
force.

Of course, if the objects are rubble piles, it will be necessary to build
net bags around them first, with anchor points on each bag.

Many twiddly bits here, of course, starting with the parameters for
rendezvous. Not only will they have to be put into close proximity to one
another, but their relative spins will have to be brought to a reasonably
close match for the arresting gear to manage without becoming overstressed
or hopelessly twisted.

This can't be an original idea. Has work been done on this already?
References appreciated!


Jim McCauley

Here on earth we already have big trouble lifting a submarine from
the bottom of the sea. Try imagine what it would take to lift a
50 flore building and then realize that the force such a weight is
creating is still nothing compared to two 100m asteroids spinning
around each other to create g-forces. It seams so much easier to
build artificial structures with far less mass, than using asteroids.

And if you have the technology to move two asteroids to each
other, why not reduce their relative speed to zero first, then attach
the line and finaly let them spin? Gives a lot less stress.

Wim Dekker