Via Solar Array to the Outer Planets

by Paul Gilster on April 27, 2006

New Scientist is covering the work of Rudolph Meyer (UCLA), who envisions a vehicle that sounds for all the world like a cross between a solar sail and an ion engine. And in a way, it is: Imagine a flexible solar panel a solid 3125 square meters in size, and imagine this ‘solar-electric membrane’ weighing no more than 16 grams per square meter, far lighter than today’s technology allows. I’ll be anxious to see the paper when it’s published in Acta Astronautica, but the gist of the design seems to be this: the solar membrane would power an ion engine array which, conventionally enough, draws xenon ions through a powerful electric grid to create thrust.

The membrane, stabilized by additional ion engines at the corners, could reach remarkable speeds. Meyer talks about 666,000 kilometers per hour — that’s one year to Pluto, and an obvious invitation out into the Kuiper Belt. No show stoppers here, but clearly a design heavily dependent on advances in thin film arrays. I always listen to Geoffrey Landis (NASA GRC) about such matters; he is, after all, the man Robert Forward declared to be his successor in interstellar studies. And Landis is quoted as saying of Rudolph’s idea, “…the extremely high-energy ion-propulsion vehicles he proposes may be a practical alternative technology for future missions to the edge of interstellar space.”

The article is by Paul Marks, “Will a flying carpet take us to Pluto?” in New Scientist (29 April 2006), available here but only for subscribers.

Update: Geoffrey Landis was kind enough to forward the complete text of his comments to New Scientist (the magazine quoted only the last sentence). Landis wrote: “Professor Meyer suggests an interesting thought-experiment about what may be possible in the future. The solar array needed for his mission requires reducing the mass of solar arrays by several orders of magnitude from existing technology. Much development work, including our work at NASA Glenn, has been addressed at reducing the weight of space solar arrays by adapting thin-film technologies to high-efficiency photovoltaic technology, and the performence he quotes, although extremely agressive, may be possible in the future. If this can be achieved, the extremely high energy ion-propulsion vehicles he proposes may be a practical alternative technology for future missions to the edge of interstellar space.”

How aggressive is Meyer’s idea? Landis notes in his accompanying message that Meyer is quite optimistic about the weight of his solar-electric membrane — “…he was assuming that they could get the performance of single crystal cells, with the weight of a solar sail.” But that’s the kicker, and if it can be achieved the idea may be practicable.

{ 6 comments }

ljk May 2, 2006 at 14:08

Does the paper say how long it would take this probe to
reach the speed of 666,000 KPH?

And would this be fast enoughy that it would require some
kind of shield to keep the solar panels from being penetrated
by space debris?

Administrator May 2, 2006 at 15:58

I haven’t seen the paper yet, but plan to go through it once it runs in Acta Astronautica. So far I’m going off the New Scientist story and Geoffrey Landis’ comments. Re shielding, I would suspect a mission like this wouldn’t require extra protection against dust particles, etc., but I’m not the guy to comment. I’ll see if the matter is addressed in the paper itself.

ljk May 2, 2006 at 20:47

Some other questions to ponder that I have read elsewhere:

How long will it take this vessel to reach that top speed?

And how and how long will it take to slow down or even
stop?

Administrator May 3, 2006 at 15:22

All good questions, and I doubt they’ve been worked out. As far as I know, Meyer contemplates no specific missions, but I would think the initial use of something like this would be a fast spacecraft to the Kuiper Belt with no deceleration involved, the aim being to get into totally unexplored space as quickly as possible. As to getting up to speed, that one, too, may have to await an examination of his upcoming paper, and I’ll pass along any info I can find about it.

rgclark May 8, 2006 at 16:48

Some recent advances in thin-film nanotube sheets might make this *currently* feasible:

From: Robert Clark
Date: Sun, May 7 2006 6:39 pm
Email: “Robert Clark”
Groups: sci.astro, sci.physics, sci.space.policy, sci.energy
Subject: New solar sail proposal might win one of NASA’s Centennial Challenges near term.
http://groups.google.com/group/sci.astro/browse_frm/thread/9395b183e9ed24b9/

Bob Clark

Administrator May 9, 2006 at 13:43

Very helpful set of links. Thanks!

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