got almost excited when I saw this in the latest update from Spacedaily, at least till I read the article :(
http://www.spacedaily.com/news/ssp-03b.html
New York - Aug 11, 2003 - Energy policy is in the news again, with debates in Congress, statements from presidential candidates, consternation over our dependence on the Middle East for oil, and a California recall election traceable in part to energy supply problems for that state. Use of energy, whether fuel for transportation, electrical energy running the internet, or the destructive energy released in weapons, is central to our economy and security.
> got almost excited when I saw this in the latest update from
Spacedaily, at least till I read the article :(
>
It was a pleasant surprise to see that it was written by Arthur
Smith, a frequent contributor to this list.
If you're reading this Arthur, my complements on a well written,
fact filled, and informative article.
I do admire your advocacy efforts on behalf of the SPS concept.
If only more people would get on the bandwagon.
TangoMan
Thanks to both - Brett, what was the source of the disappointment?
No, we can't do it tomorrow, and yes, reductions in launch cost
(or in mass launched per kW) are essential - but the argument
was mainly to try to raise awareness that this is close to
feasible over the next decade or so, and we really should be investing
a lot more money in it. Now, can we get some politicians interested?
My dissapointment relates to two points which were not in the article.
1) the use of materials from the moon or asteroids to build the
satellites (as opposed to sending power from the moon) and
2) the use of Solar Thermal via mirrors and a Barton or Stirling engine,
as opposed to PV
maybe I am just being picky :)
Brett
> My dissapointment relates to two points which were not in the article.
> 1) the use of materials from the moon or asteroids to build the
> satellites (as opposed to sending power from the moon) and
be launched from Earth (by sending manufacturing equipment instead of
the final components). I think both options deserve study - unfortunately
the NASA SSP group did ignore this, with the limited funding they had.
I still haven't seen a concrete proposal for use of lunar or
asteroid resources that allows a utility scale plant to be built (under
$10 billion for several GW power). If you know of one I'd be very
interested.
> 2) the use of Solar Thermal via mirrors and a Barton or Stirling engine,
> as opposed to PV
I did mention PV in one spot, but mostly referred to generic
"solar electric power systems"; again I think both deserve
study, right now I believe solar thermal and PV systems are
comparable in price for terrestrial use, but perhaps larger
scale space systems would be quite different; I haven't
seen mass per kW numbers for the thermal approaches either, so
if you have references on that it would be useful.
Thanks for the comments!
Arthur
Just noticed I made a typo in my last email, should have been a Brayton
engine,not Barton.
Coincidentally while googling for something I came across this, has
anybody by any chance read it ?
>
>>My dissapointment relates to two points which were not in the article.
>>1) the use of materials from the moon or asteroids to build the
>>satellites (as opposed to sending power from the moon) and
>>
>I mentioned Criswell - this is a way to lower the mass required to
>be launched from Earth (by sending manufacturing equipment instead of
>the final components). I think both options deserve study - unfortunately
>the NASA SSP group did ignore this, with the limited funding they had.
>
>I still haven't seen a concrete proposal for use of lunar or
>asteroid resources that allows a utility scale plant to be built (under
>$10 billion for several GW power). If you know of one I'd be very
>interested.
>
Concrete - no. only the info from The High Frontier, SSI and other bits
and pieces rehashed on the web.
hmm Criswell and power from the moon, I wonder if that website that
debunked this by saying the cables would get crossed is still up. lol.
Personal preference/bias, would much prefer to use moon material and
build satellites in orbit, than use ones based on the ground on the moon.
>>2) the use of Solar Thermal via mirrors and a Barton or Stirling engine,
>>as opposed to PV
>>
>I did mention PV in one spot, but mostly referred to generic
>"solar electric power systems"; again I think both deserve
>study, right now I believe solar thermal and PV systems are
>comparable in price for terrestrial use, but perhaps larger
>scale space systems would be quite different; I haven't
>seen mass per kW numbers for the thermal approaches either, so
>if you have references on that it would be useful.
>
Going from a very rusty memory from reading The High Frontier five years
ago (borrowed from the State Library) O'Neill leaned towards thermal (or
is my memory horribly mistaken?) over PV. (does my feeble memory
remember this quote correctly ? "Need more power ? build a bigger mirror")
I don't have any data on the relative pricing of PV and PT.
I do however have a link that some may find interesting, At the local
uni (Australian National University) they have a dedicated section for
solar power - both thermal and pv. ( http://solar.anu.edu.au/ )
as part of their work they have built what they call "The Big Dish" (
http://engnet.anu.edu.au/DEpeople/Keith.Lovegrove/STG/facilities.html )
which is a 400m^2 paraboloidal dish solar concentrator. The Big Dish is
meant to be just one of many in a larger plant, all feeding to a Thermal
engine. Unfortunately because it is built for use on the Earth's
surface, and because of the need to face directly at the sun, The whole
asssembly is rather heavy. The page lists 50 tons for the foundations
and 19 tons for the dish, though I am not sure which parts are
considered "dish" for the purposes of weight. It is quite impressive to
stand next to, though it really doesn't seem very big.
Consider however that PT basically consists of a mirror and the engine.
Consider also that later this year the planetary society will be
launching an inflatable mirror, that is 600m^2 in area, and weighs 100kg
into orbit ( http://www.planetary.org/solarsail/index2.html and
http://www.planetary.org/solarsail/missions/planetary_solar_sai.html )
Also note that last year (I think it was - or was it earlier this year)
NASA mentioned the idea of an inflatable station out towards the moon.
If - and a big If - you could build an inflatable Parabolic Dish shaped
mirror,(obviously larger than either 400m^2 or 600m^2 for that matter,
as you would need a lot more energy than that size system would supply)
using a similar material to that used on Cosmos, you could lower the
mass requirements for an SSPS significantly, which would leave the main
mass in the Thermal Engine and any support structure. Something to think
about at any rate.
>Thanks for the comments!
>
> Arthur
>
you're welcome :)
Brett
Message Sounds related to this research: http://science.nasa.gov/newhome/headlines/msad03mar99_1.htm It would be sort of interestingif it worked out that SPS was economical for a Mars base before it was economical for Earth. Interestingly, this article attributes the idea of using Martian CO2 for manufacture of return propellant to our very own Gerard O'Neill, saying that Zubrin subsequently promoted it. I think most people are of the understanding Zubrin originated the idea, and this is the only article I've ever found attributing the original concept to O'Neill.
Mike Combs
Coincidentally while googling for something I came across this, has
anybody by any chance read it ?
http://gltrs.grc.nasa.gov/cgi-bin/GLTRS/browse.pl?1992/E-7581.html
I hadnt read this Mars beamed power solution. However, I am part of a student team researching using SPS for Mars missions. We only started this past April as part of a design competition for the European Space Agency. The report was due to the ESA at the end of July and you can visit at http://silmarillion.thebackofthemoon.com/Silmarillion-Project-University-of-Waterloo.pdf. Wed be happy to receive any feedback since we are only just beginning our research into this area. Hopefully well be able to make time with school to continue to explore the concept. We do have plans for physical testing and computer modelling, but thus far, all our research has been reviewing other literature.
"Combs, Mike" wrote: Sounds related to this research: http://science.nasa.gov/newhome/headlines/msad03mar99_1.htm It would be sort of interestingif it worked out that SPS was economical for a Mars base before it was economical for Earth. Interestingly, this article attributes the idea of using Martian CO2 for manufacture of return propellant to our very own Gerard O'Neill, saying that Zubrin subsequently promoted it. I think most people are of the understanding Zubrin originated the idea, and this is the only article I've ever found attributing the original concept to O'Neill.
Regards,
Mike Combs
Coincidentally while googling for something I came across this, has
anybody by any chance read it ?
http://gltrs.grc.nasa.gov/cgi-bin/GLTRS/browse.pl?1992/E-7581.html
> Interestingly, this article attributes the idea of using Martian
CO2 for
> manufacture of return propellant to our very own Gerard O'Neill,
saying that
I heard this idea from my mothers boyfriend back in 75'. I was in jr
high. He was a Bell Labs Mathematician and a L5 Society member
I don't know wear Dr Z was back then.
Jeffrey