# [extropy-chat] Space elevator numbers III

Keith Henson hkhenson at rogers.com
Thu Feb 15 17:41:17 UTC 2007

```snip

>I'm trying to launch 1-100 kg sized packets, preferrably in a
>rapid-firing sequence somewhere from the lunar north pole just fast
>enough to reach escape velocity and then be captured by Earth.

Taking "rapid fire" as one per second, my analysis says 3 Mw/kg.

So do you need the power of 1, 10, or a 100 locomotive engines?

At a kw per square meter, and 25% efficiency, 3 Mw is 12,000 square
meters.  At a kg/square meter for PV cells and support that's 12 metric
tons.  (Or 120, or 1200).

A useful number to consider is the energy payback time for PV
cells.  That's from one to three years.

http://www.oilcrisis.com/netEnergy/EnergyPayback4PV_NREL.pdf

So if your landed package on the moon was able to provide a kw of power and
*all* of that was fed into making more PV cells, to get up to a Mw would
take 10 doubling times (2**10 ~ 1000), that's 10-30 years.

>It might or might not require an aerobraking corridor for capture
>and/or orbit circularization. This should work, but I'd rather
>not do the math.

Sorry, but you really do need to do math and not just on orbital calculations.

Keith

> > to launch it too?  And how are you going to collect it?
>
>
>Not collect, this is supposed to unfold into um-thin PV
>platforms somewhere in Earth orbit, which do realtime
>phased array beamforming, tracking rectenna ground stations.
>There should be several such platforms in line of sight
>in order that the target illumination is semi-steady.
>
> > http://en.wikipedia.org/wiki/T._A._Heppenheimer
> > >
> > >Power alone is not alone a motivator, since this leaves you
> > >with a teleoperated industry basis which can grow exponentially.
> >
> > To do what?
>
>
>To disassemble parts of the Moon and the planetoids into an
>optically dense circumsolar computational node cloud, as
>habitats for a solid-state civilization.
>
>
>--
>Eugen* Leitl <a href="http://leitl.org">leitl</a> http://leitl.org
>______________________________________________________________
>ICBM: 48.07100, 11.36820            http://www.ativel.com
>8B29F6BE: 099D 78BA 2FD3 B014 B08A  7779 75B0 2443 8B29 F6BE
>
>
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