[AR] Re: space based solar
- From: Jordan Trewitt <Jordan.Trewitt@xxxxxxxxxxxxxxxx>
- To: "arocket@xxxxxxxxxxxxx" <arocket@xxxxxxxxxxxxx>
- Date: Tue, 19 Mar 2019 02:23:24 +0000
I just want to see what the radiators will be like on either laser or microwave
transmission satellite. Even if it operates at 50% efficiency (may have
mentioned 65%) as the paper claims, that's still a megawatt of radiators (this
assumes 100% duty cycle though).
-Jordan
________________________________
From: arocket-bounce@xxxxxxxxxxxxx <arocket-bounce@xxxxxxxxxxxxx> on behalf of
Bill Bruner <bill@xxxxxxxxxx>
Sent: Monday, March 18, 2019 11:32:10 AM
To: arocket@xxxxxxxxxxxxx
Subject: [AR] Re: space based solar
Powersats have their own area problem, in that they need big rectennas
This assumes microwave transmission to the surface.
Laser transmission would be more compact (and would likely require less upmass).
Please see this 2009 paper<
https://e-reports-ext.llnl.gov/pdf/372187.pdf> from
Lawrence Livermore National Lab, which posits a laser downlink system that gets
a megawatt into orbit with a single Falcon 9 launch.
Lasers have their own eye safety, thermal and arms control issues - but mass
savings might still make them preferable to microwaves.
Bill Bruner, Col., USAF (ret.)
New Frontier Aerospace
bill@xxxxxxxxxx<
mailto:bill@xxxxxxxxxx>
925-456-4553
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On Mon, Mar 18, 2019 at 10:22 AM Henry Spencer
<hspencer@xxxxxxxxxxxxx<
mailto:hspencer@xxxxxxxxxxxxx>> wrote:
On Mon, 18 Mar 2019, James Fackert wrote:
I think the case for space based as more cost effective than terrestrial
plus storage is far from "closing"... (there are a lot of roofs begging
for solar...)
The total of *all* the roofs isn't anywhere near enough to power an
industrial city, especially in areas that don't get a lot of winter sun.
To say nothing of the size and cost of the storage system needed.
(Powersats have their own area problem, in that they need big rectennas...
but at least they don't care about weather and don't need storage, and
they don't need nearly as *much* area.)
but if someone actually steps forward and wants to pony up the -cash-
for lifts to space, I bet SpaceX would accept the work. It is just not
viewed as very likely, and not part of the business plan...
You might be surprised. For one thing, remember that Musk wants to sell
lithium batteries to all the people who need storage -- that may not be
part of SpaceX's business plan but it is part of *his* business plan, and
powersats would compete with it. (This also requires taking his views on
space-based power with a grain of salt -- he has business reasons for
bad-mouthing the idea.)
And for another, it's not unheard-of for people to decline to pursue
potentially-lucrative business because they strongly dislike something
about it. Long-established publicly-traded companies are usually run by
committees of beancounters, who basically don't dislike anything strongly
enough to pass up a sale. But here we're dealing with one guy with a lot
of clout in his companies, and that's a less predictable case. If he
decides that he's not just skeptical, but actively opposed, SpaceX could
easily say "no sale".
Henry
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