Digest Number 509

>
> Message: 4
> Date: Thu, 19 Dec 2002 12:01:58 -0500
>
> Well, that's quite a demo. If funds were available for it, then yes, it
> could really open the lunar frontier in a major way.
>
> But frankly, I'd settle for something much, much less in the near-term. If
> there were a small but growing research base at Malapert Mountain that
> "lived off the land" in the sense of providing its own radiation
> shielding, its own oxygen for refueling of descent/ascent craft, and
> providing for a few other mass-intensive needs with local resources, then
> I'd be a happy camper. If small robotic factories for producing
> low-grade solar cells arrived at Malapert Mountain 5 years before the
> first human, that'd be o'k with me too.
>
> Dream big or dream small. I guess I'm dreaming small.
>
> Ron
> ******

> _________

Ron the ability to raise funding correlates more to the ROI, than to the amount of money requested, it also correlates to the
intagible "giggle factor".

$ 10 billion with an ROI of 100:1 would be easier to raise than $1 billion with no ROI.

What is the ROI for bootstrapping ?

>
> Message: 5
> Date: Thu, 19 Dec 2002 12:44:03 -0500
>
> Smaller transmitter and receiver sizes are practical with higher
> microwave transmission frequencies, although that requires higher
> quality antennas also. The typical frequency Charles is probably
> assuming is 2.5 GHz, but there's nothing particularly special about that
> number, other than FCC regulations and atmospheric considerations,
> neither of which apply to the Moon. At 250 GHz, the two would need to be
> only 1/10 the diameter (see
> http://www.spacefuture.com/archive/a_few_things_you_occasionally_wanted_to_know_about_wireless_power_transmission.shtml
> for example).
>
> Also, the transmitting antenna does not need to be a single continuous
> object of several hundred meters or kilometers across - rather several
> transmitting antennas can work together in "phased array mode" to
> produce a single main beam lobe at the receiving location.
>
> In other words, I believe the demo could be quite a bit smaller than
> Charles suggests.
>
> Arthur
>

Good points Arthur, I had not really thought about that.

Yes, since the Moon has no atmosphere, optimization criteria becoem different. We would want to minimize the size of the
transmit antenna and rectenna, so we would want to use the highest frequencies where the DC to RF and RF to DC efficiencies are
still up in the 90's %. At some point as the frequencies transition from Microwave to Infrared, the conversion efficiency
starts to drop off rapidly.

Lasers are not much use, because the rectenna would simply be PV arrays are low conversion efficiency.

I wonder what would be the highest useful frequency. Anybody know ?