money is in short supply

On 24.02.2011 02:04, edpell wrote:
> On a NEO there is building material for the taking. Not so here. On a
> NEO there is full time sunlight for energy. Not so here.

Hi Ed,

this is my thinking too. A NEO would be the best and cheapest way to go.
If we can do it by remote control, habitats or spacecraft could be built by
manufacturing the hull of a radiation shielded spacecraft, a cycler or a
habitat
from concrete made of NEO-material.

Lots of asteroid dust might be the main material for concrete production.
Because of the low asteroid gravity, this dust would be easily grabbed
by asteroid miner spacecraft which just are
plunging into the dust layer and then transport those material, for
instance with 1 or two tons each plunge to the
fabrication site near the asteroid.
Fabrication happens near the asteroid, the main source of hull material,
not in the vicinity of Earth.
So there is no need to deflect an asteroid into Earth orbit and only the
material needed for the hull
has to be transported back to Earth.

This (first spacecraft-) hull or parts of the hull in ring-form would
return by remote control to Earth-orbit ,
where the interior of the spacecraft/habitat would be completed by
astronauts.

How would I do this?
Lightweight, self deploying molds with attached ion propulsion and/or
solar-sails with "Roller-Reefing" attitude
control, station keeping and steering would get filled with materials
for concrete production from the NEO.
If water is not available at the production asteroid, it has to be
acquired from other asteroid sources which
are not already burned out through solar heat in the near Sun vicinity.

The molds would be in ring form, each allowing the creation of a - say
1 one-meter-slice of a beton ring with
say 20 meter diameter and 5 meter thickness for radiation shielding.
By rotating the molds in space, the materials are mixed with water, the
molds are heated by the Sun radiation
from the frontside to Sun and by mirrors from the backside to Sun.

As those ring-molds each have their own propulsion, they can join
together after the concrete rings are hardened
and form a columnar body which then will be held together by
carbon-nanotube tows and glued together with concrete.

Regards
Frank

demonstrator-spacecraft of a Solar-Sail-Power-Station (SSPS) for space
based solar power production
see at http://www.solar-thruster-sailor.info/PresentationISSS2010V13.pdf
(12 MByte-PDF-presentation).

This direct-launch-able Power-Station has ample room for daughter units
e. g. asteroid miners and telecommunication and
observation satellites and could transport a complete mission to target
asteroids.
Since it produces also ample energy (solar-cell-area about double of the
ISS, deployed in one single launch)
it can speed up transportation to and from the asteroid substantially by
powering SEP-propulsion.

As solar foils would be available 1.5 micron CORIN polyimide thin film
a-Si:H solar
panels, 168 Watts/m2, which would weigh about 32 kilograms for 3,120
square
meters for a Ariane V-launcher-version of the SSPS-design and produce
in this version 524 kWp DC electricity

This would be enough, to power one DS4G thruster
http://www.nasaspaceflight.com/2006/01/new-ion-engine-test-success/
as a main propuldion drive, which could deliver exhaust speeds of about
210 km/second.
.