money is in short supply

Am 24.02.2011 18:50, schrieb Victor Smith:
>
> http://www.solar-thruster-sailor.info/PresentationISSS2010V13.pdf
>
> Interesting paper...did you author it"?
>

Thanks, and yes, I am the author and had the opportunity to present my
design with that presentation, though in a shorter version.
>
> Looks plausible from an investment point of view, as well as workable
> on a practical level. Given the contract that has been entered into
> allowing for the reception of beamed power (by 2013), I hope they can
> get the project finished and that it performs up to spec.
>
They expected to start delivering energy from 2016 on, but their plans
have nothing to do with my design - although I would be happy,
if they gave it a try for a demonstrator SSPS :-) . The advantage of
this design is to get larger deployable solar cell areas into space
in one single launch as the ISS features now - after years of
construction works.

Another advantage is the integration of a highly control-able fuelless
attitude control and station keeping system by Roller Reefing.
As every solar cell array can be used also for solar sailing, it is
obvious to use the roll able thin film solar cells for high precision
attitude control and station keeping too.

> Shouldnt be difficult to get it launched, since it rides up in an
> Ariane V.
>
Unfortunately there are no plans to use my design,
this is just an example to show, how large the deployable solar cell
arrays could get.
So I had to choose a launcher. Every other launcher would be fine too,
but I used
a big one to make my point. A smaller one would allow low cost low Earth
orbit launch,
while the craft would reach the mission orbit with the electric
propulsion system.

> Ill be even happier to see the first one deployed to an asteroid.
>

> I dont quite get your reference to ships diving into the dust layer
> of the asteroid to produce material for your concrete rings.
>
The reference is the presentation. The SSPS is a mothership, able to
take in several daughter units at once, for
instance asteroid miner spacecraft and observation satellites (see page
10 of the presentation, the mothership with 4 daughters in this case).
As the asteroid gravitation is so small, slow (for instance ion
propulsion) acceleration might be enough to get into such an dust layer.

The mining daughter units would carry a scooping container formed like a
scoop which is open on the front side, closed to other sides, or a
container with a releasable lid underneath and accelerate with it
thrusters towards the ground of the asteroid scooping or pressing the
container down and
accelerate backwards after that. The special DTU (double thruster
units)-design allows, that the daughter can slow down, stop or reverse
each turn or acceleration just by switching the thrusters of the used
units, since each DTU-unit carries two thrusters installed opposite to
each other.

Take a look onto the presentation pages 17 and 20, where 3 of several
possible daughter designs are shown.
The container could be strapped to the net of the standard daughter on
page 17.
As the mothership has a docking station in this case of about 28 cbm
volume having say 3 miner daughters, should
be possible - for instance
one scooper, one with press down container and one with a container on
the topside and robot arms to collect
other objects than sand or dust. All containers would use a press out
mechanism too.

Of course observation and communication daughters should be also
available with every operation to allow
remote control by using film and foto data. The mothership could
generate the energy for large bandwidth
to provide quasi life videos with a small time lag for NEOs (much less
than for Mars).

As main material I would prefer dust, because you don't have to grind it
any more.
If needed you just have to do some sorting of material components by
using magnetic and dimagnetic forces,
and filtering techniques.
As this dust might be collision dust, metallic parts should be part of
the material.
Each of those containers of say 1 or 2 cbm volume, would allow to
extract some tons of material depending on the
specific mass with one single landing only.

Then the daughters unload their materials at the construction site,
preferably if this is possible just by pressing it directly
out to the ring-molds.
For the first missions this materials should be brought back to the ISS
for examination and figuring out how to use it
and try space concreting techniques near the ISS.

To auction/ sell some of the materials would be also a good help to
finance the venture.
To sell video material of the first operations to publishing and
licenses to video-gaming companies
(producing a game a la Mars miner now for asteroids), would be of help.

To spread the financing load further it might be a good idea to sell
docking spots at the mother for single daughter units
at the mothership, so a company or an agency can concentrate on the
design of one daughter while another company/
agency provides the mothership.

So an for instance ESA/NASA/JAXA-venture with the participation of
several private companies would be possible and
help spreading financing in this cash strapped times. And it would allow
to install space infra structure and show that
the development is going forward, even though the agencies have not
really much more funds as in former times.

> ..or, for that matter, how you plan to use these rings to build
> spacecraft and habitats,
>
the molds would get filled with the concreting materials and mixed with
water.
They would rotate and use gravitation for mixing as the concrete mixers
on Earth,
just that this would be rotational gravitation.

The opening would be at the inner side of the Ring-Mold instead of on
the upside of an
Earthly mixer-machine. The materials would get pressed out of the
daughter unit through
a pipe into the ring, where the rotation keeps it insides and the
concrete cures.
The arrangement of mirrors would help to hold the correct temperature.
The hull should be diffusion tight, so that the water cannot diffuse out
before the curing
has happened. The ring stays in the mold.

As each mold has it's own thrusters, several of them, already cured can
arrange
themself with those thrusters to a columnar body which get's strapped
together
with CNT-tows from outside. The contact zones of the rings would feature
groves
which get filled with concrete to form a tight connection at the contact
zones.

The lids of the hull would be made with smaller rings or disks mounted
inside the
last ring of each end.
One of those rings could feature also Roller-Reefing for fuelless
attitude control and
power generation for the hull.

> though I suppose a habitat of that diameter (20 meters) might be made
> (kinda small though).
>
Those 20 m hull was not meant to serve as a habitat, rather as a
spacecraft which provides
radiation protection to Mars or asteroid astronauts but also as
demonstrator for larger
bodies, like habitats.

bist wishes

Frank