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Dr. Lewis Fraas, Friday, 4-27-12 April 26, 2012

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Dr. Lewis Fraas, Friday, 4-27-12


Guest:  Dr. Lewis Fraas.  Topic:  Mirrors in space for affordable solar electric power.  You are invited to comment, ask questions, and discuss the Space Show program/guest(s) on the Space Show blog, https://thespaceshow.wordpress.com. Comments, questions, and any discussion must be relevant and applicable to Space Show programming. Transcripts of Space Show programs are not permitted without prior written consent from The Space Show (even if for personal use) & are a violation of the Space Show copyright. We welcomed Dr. Lewis Fraas to the program to discuss his MiraSolar Satellite Concept for mirrors in space for solar electric power.  I have posted two of his presentation papers and slides on The Space Show blog for your review.  You can find more about his concept by visiting his website, http://jxcrystals.com/lendrupal.  At his website, go to the lower right corner for links to MiraSolar.  As our discussion addressed common topics throughout our 90 minute program, I’m writing this summary without regard to program segments.  We started our discussion by asking Dr. Fraas to provide us with an overview of his mirrors in space concept.  This he did, drawing from time to time upon comparisons with space solar power concepts placing their satellites in GEO while the mirrors would be in LEO around 1,000 km.  Dr. Fraas made comparisons with SSP and mirrors in space throughout our 90 minute discussion.  We talked about optics and physics as well as the power generating size of the ground stations used in his concept, comparing those to nuclear power plants and other power generating facilities.  I believe you will find the power comparisons most interesting.  We spent a considerable time going over the launch and project economics as well as due diligence from a mostly economic perspective.  As you will hear, there are some blanks yet to be filled in but since this project is a decade or so out in the future, it is challenging to project values and costs that far into the future, let alone what launch vehicles we will have along with their flight, payload, and price characteristics.  Another important part of the discussion focused on ground stations.  Dr. Fraas zeroed them out of the economics when the ground station was built for or was being used for terrestrial solar as the mirrors in space project can make use of the same station.  In cases where the mirrors program needs its own ground station, those costs would be factored into the total project costs.  Listeners asked about environmental issues, an EIR and its challenges. Dr. Fraas made a point of being clear that this was an international project, not just focused on the U.S.  He also suggested that there was a possibility of limiting or restricting U.S. regulations down the road but that other countries might be more interested in mirrors in space, including China, Japan, and India. We had an interesting discussion about the U.S. and the space progress being made in other countries.  Tony asked a series of questions pertaining to using more not fewer mirrors for terrestrial solar farms.  He also wanted to know the launch price that made the project viable.  Dr. Fraas referred to NASA and other studies and cited two reference launch prices.  See what you think when you hear this discussion.  Another topic dealt with radiation at the orbit Dr. Fraas discussed. Here, we talked about the inner Van Allen belt and thanks to a listener, we got some info on debris issues at the desired orbit.  Don’t miss this discussion.  As we heard, it might be advantageous to shift the orbit to 1200 KM for debris mitigation purposes.  Another discussion topic addressed competition with always improving terrestrial forms of energy under development and in the process of coming on line.

You can email Dr. Fraas for more information at lfraas@jxcrystals.com.  Please post your comments/questions on The Space Show blog and I will be sure to call them to the attention of our guest.

1.  Mirrors in Space for Low-Cost Terrestrial Solar R1

2.  38PVSC paper 4th draft Fraas



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2. Kevin Horton - July 11, 2012

I just finished listening to Dr. Fraas’ Space Show appearance. His concept is very interesting, but I am far from convinced that it is practical. It certainly merits study, and possibly a proof of concept satellite launch.

The satellite mass estimates appear to only consider the mass of the membrane that forms the mirror. But, many other elements are needed to create a working satellite:

structure to support the membranes,
superstructure to join the individual mirrors into a single satellite,
pointing mechanisms,
attitude control,
orbital manoeuvring capability to offset the perturbation from sun bouncing off the mirrors (i.e. solar sail thrust),
command and control antennae,
solar arrays to power the satellite,

It seems to this non-space expert that the mass of the membrane could end up being less than half the mass of the total satellite.


1. Is there any evidence or credible analysis that address what percentage of the surface of any given membrane would be on the same plane? It seems like that with a very thin film, subjected to sun pressure, perturbations from pointing, etc that some portion of the membrane would not be perfectly flat, which would cause some of the reflected sun to hit the earth outside the target ground solar station.

2. I would expect there would be some orbital perturbation from the thrust created by the sun reflecting from these large mirrors – solar sail effect. How much manoeuvring capability will be required to offset the effect of these orbital perturbations?

3. How will the mirrors be controlled to ensure each mirror is illuminating the correct spot on earth? If there are multiple mirrors, each independently controlled, it would seem impossible to have any kind of control feedback based on observations of the location of the centre of the illuminated area vs the target location.

4. How many times per hour will each satellite require its mirrors to be turned to point at a new ground solar station? How long will it take the membranes to settle out after the perturbation from this repointing?

Lewis Fraas - July 11, 2012


You are asking a lot of good relevant quesstions. I will begin to answer as follows:
1.) Regarding the satellite weight, I did assume a weight twice that of the L’Garde solar sail satellite incudding mirror film. However, a mirror satellite building block really does need a prelimianry design. I have teamed with L’Garde to start this design activity. I have an accepted paper on this topic to be presented at AIAA meeting in Jan 2013.
2.) Keeping the mirrors flat is important. I have calculated the radiation pressure and I have a design where this looks manageable.
3.) Regarding steering the mirrors, I plan on 250 m mirrors as building blocks and moment of inertia and slew rate are comparable to alpha gimble on International Space Station.
If you send me an e-mail at lfraas@jxcrystals.com, I can send you more detail.
Thank you for your interest.

3. Lewis Fraas - June 9, 2012


First with regard to clouds, the terrestrial sites would presumably be chosen in sunny locations like near San Diego or San Antonio or Cairo or Sydney, etc. The assumption is that they are being built as economical terrestrial solar sites where clouds are minimal.

With regard to the beam moving form target site to target site, yes, but each mirasolar satellite consists of multiple mirror elements which might be sequencially moved so that there might be moon light at an in-between location for 30 seconds rather than a flash of 1 sun for a fraction of a second.

Finally, with regard to time over the ovean, yes there is time over the ocean. That is included in my calculation and the idea is still 10 times more economical than the Space Power Satellite with microwave beaming. You do understand that these are in sun synchronous orbit. You should look at the full paper for a detailed comparison between this concept and the SPS.

See http://jxcrystals.com/publications/PVSC_38_Manuscript_Fraas_5-9-12.pdf

4. pritchie - May 10, 2012

Interesting idea.

First some operational questions:

1. Given your essentially building big solar sails, won’t you need some kind of propulsion on the satellites to keep them in the desired orbits?

2. The paper states that the weight of each satellite is going to be 1600 MT. That implies very large scale orbital construction. You will either need to include costs for developing robotic construction techniques or a certain # of human space flights to perform the construction.

3. Your launch cost estimates feel low. The LEO number isn’t quite right given your going to a polar orbit. Also, the quoted cost for the Falcon Heavy is to 200km, not 1000km. The exact figure is anyones guess but $2000/kg might be a better number…

Second, on the economics:

There is going be a crossover point from where it becomes cheaper to build satellites vs expanding the ground based infrastructure.

Your paper quotes the price of $2.2/w (DOE projection for 2016). To be viable your satellites need to cost less than that or you’re better off just expanding the ground based infrastructure.

That’s a tricky number to calculate but it’s largely dependent on the size of the existing infrastructure. Thus, until the ground based plants exist to support the satellites the economics don’t work out. But once they do, funding should be relatively easy to raise from the owners of the plants + you would have a powerful lobby to help push through any regulatory issues…

5. Alistair - May 4, 2012

good points. Even gimballing the mirrors would result in a quick, and bright flash across large areas. I would think some sort of shutter mechnism would work. Problem arises when said mechanism fails, or worse yet, the satellite loses all control and tumbles. You’d have a beam moving around wildly. Some robust failure modes could mitigate it, but it’s not fool proof.

Still, it was an interesting discussion. The lunar orbit might be a better location to prove this technology, especially since you get nearly 15 days of darkness each lunar cycle, not to mention the deep craters that could use some decent illumination and/or power.

6. Andy Hill - April 30, 2012

An interesting discussion but Id like to raise a couple of points.

First a draw back to beaming sunlight would be any clouds blocking the light and reducing the light able to be collected. This is not a problem for systems that use microwaves.

Secondly, depending on the focus of the beam, how quickly would it disperse outside the ground station? Would there be an area in semi-daylight around them?

Also what about when the beam tracks across country between stations? It would be like having a flashlight shone at any house in its path and while you reduce this by crossing open water wherever possible it would be very difficult to remove this problem completely.

A final problem is the mirror orbit which due to the Earth’s rotation would move its relative position making the time it would be able to beam to any one station minimal. Without having floating stations at sea there will be a lot of time when the mirror would be unusable.

An interesting concept but I cant see this being anymore doable than space based solar power.

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