Using Concrete to build space ships...

> So ok, now I would use your proposal and mix it with mine.
>
> I would send out robotic crafts, solar sail carrier space ships
> carrying fleets of prospector crafts which mine the asteroid and
> bring the ore to the processing facilities in space.
>
> You would have near to free transportation due to the solar sails
> and wouldnt have to provide for human life support and transport.
>
> The reason that I proposed molds to be filled in free space with
> concrete was that I thought it could be done with ease remote
> controlled through robots (were space ships are robots also here).
>
> Frank

Ay Carumba!!

How is this different than your original proposal?

Now you're going to find an asteroid that has a profile close to a
cycler orbit, and you're still going to mine the material and send
it back to Earth. What's the point?

Let's pretend we're building an old-fashioned sailing ship on Earth.

I say find a good harbor for a shipyard and make sure it has lots of
timber, flax, and hemp nearby. Build the ship there.

You're saying to put the shipyard in Denver, Colorado. Go to Seattle
and bring the timber back to Denver. Go to Lincoln, Nebraska and
bring hemp and flax back to Denver. Build the ship. Then transport
the ship to Los Angeles to launch it.

Why go to an asteroid that is in an orbit close to that of a cycler
and send the material back to Earth-Sun L1 and then have to relaunch
it back to the cycler orbit?

Where are all of those solar sails going to come from? Do you have
any idea of the limitations solar sails impose on your scheme?

http://www.etext.org/Zines/Quanta/sailing.html
"If a square metre of a perfectly absorbing material is put in
direct sunlight above the atmosphere, and the light hits it
perpendicularly to the surface, it feels a force of 4.7
micronewtons, or roughly one two thousandth of the weight of a paper
clip at the Earth's surface. A perfectly reflecting material would
feel double that force. Compare this to the three space shuttle main
engines (SSMEs), each of which generates 1.67 meganewtons of thrust
at sea level, and 2.1 meganewtons of thrust in vacuum. Even a
100,000 square metre sail would not generate a millionth the thrust
of a single SSME, though it would be a square as long on edge as
three football fields."

Look here for more detailed analysis:
http://www.inspacepropulsion.com/tech/sails_missionapps.html
http://www.inspacepropulsion.com/tech/sails_physics.html

Let's look at your 200,000 tonne cycler again.

KE = 0.5 mv^2 ------> 0.5 * (200,000,000 kg)(4,300 m/s)^2 = 1.85 *
10^15 Joules

As per the above quote, 1 m^2 of sail equal 4.7 micronewtons of
force. Put another way 212,750 m^2 of sail area will produce 1
newton of force.

A joule = 1 newton meter.

How many square meters of solar sail are you going to need to haul
200,000,000 kg of material to L1? Then you have to launch the cycler.

You do the math :)

If you seek to avoid having life-support for the construction crew
on the asteroid, how is that any different than having life-support
for your crew stationed at L1?

TangoMan