L5 regolith processing vs beamed power?

[Jay Lewis]

Someone on Linkedin wants to launch raw mass to L5 for processing but I suspect its much easier to beam power down and only launch finished good.  

My improession is the moon doesn't have a stable orbit due to the earth and sun, but even with expensive station keeping it should be a much easier problem than beaming power from GEO thrugh air to earth due to much less distance and atmosphere.

We have barely demonstated 1KW at 1KM so maybie its a temporary step until that matures?

[Keith Henson]

If you go back almost 50 years to the early Space Manufacturing Conference papers (they are online but expensive from the AIAA), and read the papers from Tom Heppenheimer, regolith was to be launched off the moon to a location near L2. Actually somewhat inside of L2 to compensate for the impact of packages of regolith. Tom described the impacts at the "catcher" as being like a stream of 18th-century cannon balls. When the catcher got full, it moved over to L5 using a rotary pellet launcher, throwing away some of the regolith for reaction mass. The mass driver location on the moon was very specific to take advantage of an "achromatic" orbital path, where small variations in the mass driver exit velocity still got the payload to the target. The mass driver switching in those days was SCRs. They had a fair amount of jitter in switching time and, as a result, variation in the exit velocity. Modern insulated gate power transistors are faster and more consistent.

You might be able to find those volumes in a library. I had two of the first 3 and found the missing one for sale, perhaps on eBay,.

Launching finished parts off the moon is an alternative, but the acceleration is brutal for a reasonable length mass driver. You also have to figure out a way to catch the parts or include rocket engines and guidance in each one.

An alternative that was not available in those days is a moving cable lunar elevator out through L!. It has to hang down in Earth;s gravity far beyond L!. If you make it 190,000 km long, dropping payloads off the end puts them in a Hohmann transfer orbit to GEO.

It is a complex set of tradeoffs.

Keith

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[Opener of the Way]

I would be very enthusiastic to publish a short article on this topic at L5News.substack.com 

To view this discussion visit https://groups.google.com/d/msgid/power-satellite-economics/CAPiwVB5BrW0kreCEnwBzO25Nq3avJkxoYX9RiMSUk9CQQaeamQ%40mail.gmail.com.

[Keith Henson]

Do it with my blessings

Keith

[Greater Earth]

Jay,

You can read  Heppenheimer's book 'Colonies in Space' on the NSS website.

nss.org

Colonies in Space, by T. A. Heppenheimer

Cover illustration by Don Dixon courtesy Stackpole Books Complete online book by T. A. Heppenheimer Table of ContentsColor PlatesChapter 1 – Other Life in Space

🔗 https://nss.org/colonies-in-space-by-t-a-heppenheimer/

 

Chapter (6) which is related to the mass driver is here:

nss.org

Colonies in Space: Chapter 6 – The Moon-Miners

Colonies in Space: Chapter 6 – The Moon-Miners Chapter 6 – The Moon-Miners 

🔗 https://nss.org/colonies-in-space-chapter-6-the-moon-miners/

 Arthur

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[Jay Lewis]

Skimming these and other things the roadmap of TRLs for all the steps are still so low no one can make a business case for either aproach.  So scientists need to keep nudging them along with baby SBIRs for another decade or two.  

For beamed power I can see applications in LEO today but the moon is still mostly for science so by the time regolith processing of any kind is happening beamed power should already be up the capability curve. 

This could be like EVs where we had electric cars before gas cars, but plentify gas drove that development much faster and it took a century for EVs to start getting enough investment to catch on.  My prediction is even if its cheaper to launch regolith to process at L% than to beam power down eventualyy, for now beaming power is probably going to be capable much sooner.