The LiftPort Lunar elevator

This video is much in the news lately…

I first saw this video at the 2014 ISEC Space Elevator Conference.  Michael Laine, the driving force behind LiftPort, gave a short talk at the conference and showed this video.  I’m not sure if the one now viewable on YouTube is an updated version from the one he showed, but it seems to be the same one I saw.  It depicts the deployment of a Lunar Space Elevator and it’s capability to mine regolith and transport it back to earth (or wherever).  There’s a lot of detail shown but even more detail that’s not shown – but it is a concept video, not an engineering blueprint.

The video shows a probe/pod that is launched from earth to some stationary point from the moon.  Then an anchor (attached to a space elevator tether) is deployed from the probe/pod to the lunar surface.  There it is anchored and then rovers are deployed to dig up regolith, process it (I assume), and then bring it back to the anchor for eventual shipment back to earth.

There has been a fair amount of debate in the space elevator community about the utility / usefulness of a lunar space elevator.  According to the LiftPort website, the Purpose of building a lunar space elevator would be:

The Lunar Space Elevator Infrastructure is going to serve many purposes for the human race. The first and most obvious is the opening up of the Moon for tourism and colonization purposes. LSEI can be built with current materials, but it would not have a lot of throughput. The goal of the study would be to determine a method of increasing transport throughput to enable humans to go back to the Moon. LiftPort’s LSEI architecture provides consistent, safe, and high-volume lunar transportation. Each Ribbon attached to the lunar surface allows for an additional 260 kg of cargo. Built up over time, 5, 10 or 15 such Ribbons allows for human-rated heavy-cargo capacity. By building a complete, reusable, and expandable infrastructure, LSEI can send three astronauts to the lunar surface every four weeks. In addition, the LSEI expands the capabilities of the Deep Space Habitat envisioned by the Global Exploration Roadmap and endorsed by NASA. Accessing the Moon also means accessing the minerals of the Moon. The Moon’s suspected to possess a motherlode of helium3, which many (ourselves included) believe it could be used to energize nuclear fusion reactions and provide vast amounts of energy in a process which avoids the radioactive waste of nuclear fission (the process used in nuclear power on earth currently.)

I would respectfully disagree.  Humanity has already proven (with 1960’s technology!) that it can send people to the moon (and back again).  It will essentially take the same amount of rocket energy to get someone launched from earth to the moon as it would take to launch someone from the earth to a lunar space elevator.  The launch needs are the same – and that’s the big dog on the block.  The landing requirements might be a bit different – landing on the moon versus rendezvousing with a lunar space elevator spaceport, but not by orders of magnitude.  And a rocket can land anywhere on the moon – with a space elevator, you’re tied to one surface point on the moon.  Of course if you pick the right point, maybe that’s all you need.  But the point I’m making here is that a Lunar Space Elevator will not, IMHO, materially improve our ability to send people to the moon…

At the Space Elevator Conference, Michael Laine also mentioned that a Lunar Space Elevator could also be a good precursor to an earth-based elevator, giving us experience in issues we would have to deal with here.  But, again IMHO, it would be unlike an earth-based space elevator in so many ways.  The entire physics of it is different; on earth, the space elevator tether is “held up” by centrifugal force and is held down by gravity (and a clamp at the earth-anchor station) while on the moon, the tether is held up by gravity – assuming it’s pointed towards earth – and centrifugal force would play no role here.  There is no belt of space debris a lunar elevator would have to worry about.  On the other hand, there would be oscillations in the tether which would have to be dealt with, as with an earth-based space elevator, and one would also have to deal with the logistics of an anchor station.  Also, one would need a method to detect deep-space objects which might impact the space elevator and a method to deal with them.  But at the end of the day, I think the issues would be so different that the only important, relevant experience which would be gained would be experience in building and maintaining big structures in space, things that the ISS is already dealing with.

Where I DO think a Lunar elevator might have some value would be as what was shown in the video (and mentioned as a secondary item on the LiftPort website) – launching valuable cargo harvested on the moon (helium-3 ?) and sending it back to earth (or wherever).  A Lunar elevator would certainly be superior to rockets in this regard.  But it might not be the best solution either, a lunar railgun launcher (such as in Robert Heinlein’s The Moon is a Harsh Mistress) might be more efficient.

At the end of the day, I think it’s all going to come down to economics – can a Lunar Space Elevator pay for itself?  Frankly, I’m dubious.  Leonard David, space reporter/author and keynote speaker at last year’s ISEC Space Elevator Conference, told me I should never end a post with the words “Time will tell“, so I won’t write that here, but I think that whether or not a Lunar Elevator will prove to be a viable economic idea will only be determined by future events 🙂