Solar Sails: Remembering Carl Wiley

by Paul Gilster on March 11, 2014

If you’re interested in solar sails and find yourself in California, a stop by UC Riverside’s Tomás Rivera Library should be worth your time. There you will find the Carl A. Wiley collection on solar sails, containing books, manuscripts and various other materials related to sail technologies. Wiley was an aeronautical engineer who wrote the first detailed article on solar sails to reach a wide audience. Evidently concerned about the venue — Wiley’s article had been accepted by John Campbell’s Astounding Science Fiction, which some of his colleagues might not have taken seriously — he chose to write under the pseudonym ‘Russell Saunders.’

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Finding Wiley’s papers at Riverside is perhaps no surprise, given that this is the home of the Eaton Collection of Science Fiction & Fantasy, ‘the largest publicly-accessible collection of science fiction, fantasy, horror and utopian literature in the world.’ Pulp magazine enthusiasts like myself will note that the archive houses full runs of many pulp titles, along with movie scripts, almost 100,000 science fiction fanzines and over 100,000 hardback and paperback books, along with a growing list of manuscripts and papers from authors in the field.

Wiley’s connection with science fiction may have been tenuous, though I suspect he was a regular reader. But editor Campbell loved the sail concept, and “Clipper Ships of Space” appeared in Astounding’s May, 1951 issue. Wiley wrote with a straightforward style for an audience accustomed to much wilder ideas than the momentum of photons pushing a sail up to speeds suitable for interplanetary missions. He notes in his first paragraph that while science fiction had been full of ‘warp drives’ and other exotica, few writers had really explored near-term alternatives to rockets. It seemed time to do so, and as Wiley had been studying these matters throughout the 1940s, he was the right man for the job. His second paragraph reads as follows:

I intend to propose another method of propulsion in a vacuum which is based on present day physics. I will show that in many ways this drive is more practical than the rocket. In order to prove my point I will have to use a certain amount of mathematics. This will permit those who wish to, a chance to check my assertions. The rest may follow my verbal argument which I hope will be fairly coherent without the mathematics.

Wiley had a lot more on his plate in 1951 than solar sails, and we can get a bit of insight into his use of a pseudonym when we put his life at that time into context. He was working at Goodyear Aircraft Corporation (later Lockheed Martin), which despite its history with airships like the USS Akron, had turned to aircraft production during World War II, building the tail assembly for the B-26 Marauder bomber. As the war ended and the Cold War emerged, Wiley led the effort to improve aerial reconnaissance through the development of Synthetic Aperture Radar (SAR), his breakthrough coming at just about the time his solar sail article appeared in Astounding.

Wiley’s work would result in the first synthetic aperture patent just three years later. It was a real breakthrough for aerial reconnaissance considering that higher-resolution radar was needed to see smaller objects at higher altitudes, and Wiley’s relatively detailed imagery could be created with an antenna that was 1/100th the size of the more traditional antennae such details would demand. He called his method Simultaneous Buildup Doppler and saw it lead to decades of further development including live SAR technologies in the cockpit — the imaging radar for the SR-71 Blackbird grew out of all this, capable of identifying objects 30 feet in diameter up to 100 miles away from a height of more than 80,000 feet while traveling at Mach 3.

This Lockheed Martin overview of Synthetic Aperture Radar remembers Wiley as ‘a brilliant if eccentric engineer,’ a term evidently chosen because of his enthusiasm for space technologies like the sail, considering that the following sentence refers to Wiley’s article in Astounding. But over the years we’ve seen Wiley become a part of deep space lore, particularly now that solar sails have become an operational reality. It’s certainly true that he was not the first to discuss solar sails openly — J. D. Bernal had written about space sailing, and Konstantin Tsiolkovsky worked on it in the 1920s. Thinking about their possibilities goes back to Kepler’s day. But few engineers in the 1950s were serious about flying without propellant, which is why I’ll turn tomorrow to the work of two others who deserve our thanks.

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JGS March 11, 2014 at 11:22

Love the slide rule on that cover!

don wilkins March 11, 2014 at 12:49

It is wonderful to remember those who have dreamed a future of hope. I would love to be as “eccentric” as Carl Wiley.

Michael March 11, 2014 at 15:24

I am still dubious about using lasers for propulsion other than ignition processes. They are not very efficient yet ~30 % for CO2 lasers. They diverge badly and have little thrust and are hard to vary their output.

A particle beam is slightly more efficient ~35 %, can be made very narrow and self collimating at very high velocities, the output can be varied to the speed of the craft much more easily and even radioactive materials could be used to splatter the crafts film and allow fission fragment propulsion further out.
In the latter case the radioactive waste from a fission reactor which we don’t want anyway could be used, perhaps some of the stable decayed material could be used to increase the size of the sail as acceleration takes place, dirty but it gets us moving.

Adam March 11, 2014 at 16:34

Bernal, from memory, didn’t write about solar-sails, but J.B.S.Haldane did, in “The Final Judgement”, as the means of interplanetary travel by the Venusian colonists. He was getting his ideas from Tsander’s pioneering work. Bernal’s “The World, the Flesh and the Devil” discussed spaceflight.

Randy Chung March 11, 2014 at 16:36

Michael, how do you make a self collimating particle beam? Any references would be greatly appreciated.

Adam March 11, 2014 at 17:14

Bernal on solar sailing…

Failing this, a form of space sailing might be developed which used the repulsive effect of the sun’s rays instead of wind. A space vessel spreading its large, metallic wings, acres in extent, to the full, might be blown to the limit of Neptune’s orbit. Then, to increase its speed, it would tack, close-hauled, down the gravitational field, spreading full sail again as it rushed past the sun.

Describes the perihelion maneuver long studied by Greg Matloff quite well. Seems my memory has misrepresented Bernal after all.

Christopher Phoenix March 11, 2014 at 19:07

The Carl A. Wiley collection on solar sails sounds pretty interesting, would love to see that sometime. His article for Astounding was, I believe, the first to spread he concept of the solar photon sail to a popular audience. Well, at least to the popular audience who read Astounding. Later science fiction stories like Cordwainer Smith’s The Lady Who Sailed the Soul and Think Blue, Count Two were probably inspired be his discussion of the solar sail, though the Cordwainer tales tended to exaggerate the solar sail’s capabilities to an unjustified extent.

Moving past his thinking on solar sails, his work as an engineer on synthetic aperture radar is quite interesting. I’ll have to read more about his life and work. You always manage to dig up fascinating topics, Paul, keep up the good work!

Michael March 12, 2014 at 4:45

@Randy Chung March 11, 2014 at 16:36

‘Michael, how do you make a self collimating particle beam? Any references would be greatly appreciated.’

I can find no references, I have combined what little I know about relativity and electro-dynamic theory, but it might be out there somewhere.

Let say two electrically neutral particles are travelling in parallel very close to one another and slowly. There will be gravitational and electro-dynamic forces between the particles such as the van der Waal force (with the right atoms it is larger). Ordinarily it would take a long time for the two particles to eventually come together, gravity first and then the van der Waal force.
Now if we increase the speed of the particle to approaching light speed they gain energy/mass equivalence that is thousands of times greater than the rest mass and so they will be attracted towards each other faster.

In effect we would have a beam of particles that would tend to want to stay together rather than disperse due to these forces.

I also see you are a researcher on I4IS, so am I although comms’ is a little slow.

Tom March 12, 2014 at 5:13

The most beautiful of pipe dreams. One day this will not be a pejorative term.
We’re almost 60 years away from ‘Sputnik’ , even 5 Centuries from Copernicus and we are still just beginning our manned journeys into Outer Space.
I have a feeling, an intuition, that a part of our being actually lives in the Cosmos. We are incomplete.
Given the risks… I’d take the voyage of a solar sail craft.
I’m nothing like the caliber of humans who do field expeditions to Greenland, the Antarctic or the ISS. I was a soldier once and a long haul over-the-road trucker…30 years of my life in those 2 professions.
Trade 1000 miles a day for 1 million a day… I could go anywhere between the Sun to Ceres. Make it 10 million a day, and all the way to Neptune.
What would an unskilled passenger do? Arrive!
A hermit at the distance of Pluto.
How human descendants will marvel at my frozen mummy in the millennium to come… its not vanity… its ingraining into people that getting to the planets & stars is the struggle for life.
And the Sun to your back with the farthest stars as your course has a poetic ring to it.

Ron S March 12, 2014 at 13:02

Michael: “Now if we increase the speed of the particle to approaching light speed they gain energy/mass equivalence that is thousands of times greater than the rest mass and so they will be attracted towards each other faster.”

No. Their relative velocity remains ~zero.

Brett Bellmore March 12, 2014 at 17:01

“‘Michael, how do you make a self collimating particle beam? Any references would be greatly appreciated.’”

Parallel currents attract, basic electrodynamics. A charged particle beam constitutes a parallel current. Unfortunately, it only constitutes a parallel current in the presence of a background of charged particles that aren’t moving with it, in a complete vacuum it would not see it’s own magnetic field.

So it would only self-focus thanks to interactions with the interstellar medium, and that is tenuous enough the self-focusing effect would be rather weak. Not like a particle beam in the atmosphere, which can whip around like a high pressure hose. The problem, though, is that the charged particles would be repelling each other, and any self-focusing would have to overcome that. I don’t see that happening.

I think relying on gravitational interactions might be more promising, with neutral particles. No repulsion to overcome, if very well collumated to begin with, even a little gravity could make the difference.

Eniac March 12, 2014 at 23:14

Michael: Particle beams diverge FAR worse than lasers, and they do not “self-focus”.

Michael March 13, 2014 at 17:13

@Eniac March 12, 2014 at 23:14

‘Michael: Particle beams diverge FAR worse than lasers..’

Particle beams have divergences that are comparable with lasers or better and can be narrowed into very tight beams down to 10′s of nanometres or less

If anyone is interested in particle beams this make a good if somewhat long read.

http://www.fieldp.com/freeware/cp_beams_text.pdf

and a little more on the subject.

http://adweb.desy.de/~rossbach/uni/cern.pdf

@Ron S March 12, 2014 at 13:02

Michael: “Now if we increase the speed of the particle to approaching light speed they gain energy/mass equivalence that is thousands of times greater than the rest mass and so they will be attracted towards each other faster.”

No. Their relative velocity remains ~zero.’

If there is no relative velocity between them then they are collimated/parallel.

@Brett Bellmore March 12, 2014 at 17:01

‘Parallel currents attract, basic electrodynamics. A charged particle beam constitutes a parallel current. Unfortunately, it only constitutes a parallel current in the presence of a background of charged particles that aren’t moving with it, in a complete vacuum it would not see it’s own magnetic field.’

No, the electro-magnetic field permeates all of space, what will happen is that the coulomb forces between the charged particles in the beam will want to defocus the beam but as they approach the speed of light the magnetic field component (created by the moving charge) starts to counter it out ultimately equalling it, so no defocusing or very little occurs.

‘So it would only self-focus thanks to interactions with the interstellar medium, and that is tenuous enough the self-focusing effect would be rather weak.’

Collisions and electromagnetic interactions with particles in space would be an issue tending to scatter the particles but the particles that do get through to a sail will pack a lot more momentum than a photon.

Ron S March 13, 2014 at 20:12

Michael: “If there is no relative velocity between them then they are collimated/parallel.”

Try again. You seem to have totally missed my point about your fundamental error regarding relativistic physics.

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