Asteroid use

Salutations all,

I've been following this thread with interest and while many good
points have been raised.

The possible problems with bringing a large mass into Earth or
Cislunar orbit.

If anybody wants to read some of the very first messages in this list
you will see that I discussed this very problem with Lucio Coelho.
Lucio wanted to deliver finished products from an orbiting O'Neil
colony or raw material from an asteroid mining operation by way of an
unpowered flight/drop from orbit. I pointed out that this may cause
problems with people living on the ground as large massive objects
fell to the ground around them and how a small course change could
cause devastation on the ground. There are ways to get around this
but the important point is I assumed that the goods were
relatively "light" and already in orbit, just minutes from the
ground. Giving little time to act in the case of an intentional
crash. This is not the case with moving masses from say the asteroid
belt to local space. The argument that large masses of raw space
rock and metal would be dangerous and should not be allowed but small
loads of finished products were okay and would be routine, is
absolutely wrong and a case of not thinking or not understanding what
mass is and Newtons second law. Given an average mass of say
3gr/cm^3, about what Eros is, then a large (and very regular cube, to
help the maths) rock of 1km on a side would mass about
3,000,000,000,000 kg or 3 billion metric tonnes. If this is 5% metal
(a not unreasonable assumption, in fact the same sized mass could
come in at 7-8 billion tonnes and run to 95% metal) it represents a
large part of the worlds needs for years to come, depending on which
metal. If this mass was to impact with the ground at a speed of say
40 Km/sec then you have a global problem, the victim would suffer and
so would the aggressor. Even if they were prepared to suffer as well
it is still hard to do. Suppose I have the ability to move this kind
of mass and arrange the money to launch a project to do it. I draw
up plans and set out the detail and then I announce my intension, any
objections would be made then. Your neo-luddites and green eco-
warriors start legal action to stop me and the US Supreme Court
issues an injunction to stop me, sitting here in my office in
Australia, I laugh myself silly, after picking myself up off the
floor I call my launch site in French Guiana and make sure that
nothing is wrong. They tell me that they just need the parts from
South Africa and we can go. Which court do they go to next? A
nation state on the other hand can appeal to the world court and they
could stop me, I am assuming all parties in fact obey the law. With
my fight plan in place and observers from any interested or worried
parties on board we set off. Arriving we begin to move the rock,
here we have a choice of small nudges and a long time line or larger,
more expensive nudges and a shorter time line. We wait for a few
years and then make the final corrections and start to slow it down
to orbital speed to place the rock into the orbit where I want it and
everybody is happy with it. If I was aiming for L4 and changed my
mind at the last moment and decided to teach the world a lesson, I
would need the equivalent of thousands/millions of shuttles pushing
my rock for hours/days in order to make this move or make the changes
years before and give the world time to come out and fix the
problem. On the other hand the small loads of rock attached to light
sails would require a less effort to change course at the last
moment, a LOT less, a million times less. I feel safe with big
rocks, little rocks make me a little uneasy.

Next, Mars Vs Asteroid.

Sorry Marcel, you have the cart before the horse. You have a couple
of problems, first, the delta V needed to move a rock from the main
belt to Mars orbit is more than what is needed to move about in the
belt. The hook here is the time needed to move about the belt but
this is offset by the fact that you could manage to have lots of
rocks on the move at once and so could arrange a steady supply of raw
material to a given point, Ceres if you like or any other rock that
takes your fancy. A few times you have mentioned that Mars has all
the materials needed to build a base so you could live off the land
while building your infrastructure. What can you obtain from the
Martian (I'm not sure about Marsian, I have never heard it before, is
it something new?) resources that you can not get from asteroids or
comets? Answer, nothing! Your other big problem is a legal one,
forget your ignorant masses the problem is in a few UN treaties, they
stop you from claiming any celestial body. You start digging up Mars
to build your bases and you will find researchers running around
yelling for blood. They will point to you contaminating the
environment and ruining the research possibilities. Now the same
holds true for any asteroid but is not as big a problem, there is
only one Mars but lots of rocks, also if I start to change it, how
much of a change is needed before it is no longer a natural object
but a manmade one? Do I just have to melt the surface or is more
needed? It's a lot easier to change a small rock than it is to
change a small planet, enough to consider it artificial.

Mars will no doubt play a large part in the future of space but the
only reason for it to play the central part is because the people
running things want it that way, not because it's better, they just
think it is and won't pull their heads out of the sand. Mars should
go though the research phase and that should be followed by the
development phase, that is where we take advantage of the fact that
the universe has seen fit to put all of that mass in one convenient
place, making it easy to turn it into other things for us.

By the way, in reference to a comment made in an earlier post, living
in a mine is not a bad thing, there are a number of places in
Australia where this is what people do, the surface is much too hot
for comfort so the population have moved underground into very nice,
comfortable houses cut from the rock, very safe, very pleasant, I
have spent time in one, albeit a short time.