Sail Concepts

‘Smart Pellets’ and Interstellar Propulsion

July 16, 2014

When Clifford Singer proposed in his 1980 paper that a stream of pellets could be used to drive an interstellar vehicle, the idea emerged at a time when Robert Forward had already drawn attention to a different kind of beamed propulsion. Forward’s sail missions used a beamed laser from an array near the Sun, and […]

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Clifford Singer: Propulsion by Pellet Stream

July 15, 2014

Small payloads make sense if we can extract maximum value from them. But remember the problem posed by the rocket equation: It’s not just the size of the payload that counts. A chemical rocket has to carry more and more propellant to carry the propellant it needs to carry more propellant, and so on, up […]

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Reflections on the LightSail Project

July 10, 2014

I was delighted to see Doug Stetson, the program manager for The Planetary Society’s LightSail effort, quoting Johannes Kepler in last night’s webcast. If you missed the Pasadena event, which took place at the KPCC Crawford Family Forum in Pasadena, CA, you can watch the recorded session here, and I highly recommend it. Kepler’s 1610 […]

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Focus on LightSail-A

July 9, 2014

As Cosmos 1 demonstrated, launching solar sails isn’t always easy. The Planetary Society’s sail perished thanks to a malfunctioning Volna booster not long after launch in 2005. When NASA attempted to launch its NanoSail-D in 2008, a problem aboard the Falcon 1 booster destroyed the craft. And when the agency launched the backup, NanoSail-D2, in […]

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Cosmos 1 in Context

July 8, 2014

We’re coming up on the tenth anniversary of Centauri Dreams, and it doesn’t surprise me even remotely that two of the earliest stories I ever wrote for the site involve solar sails. August 17, 2004’s Solar Sail Test by Japan talks about the Japanese Institute of Space Astronautical Science testing sail deployment strategies, and the […]

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Sailing to Halley’s Comet

July 7, 2014

We have interesting solar sail news coming up later this week, so it seems a good time to lead into it with some thoughts on NASA’s early solar sail work. For the theoretical work for a sail rendezvous with Halley’s Comet was well along in the 1970s, when Louis Friedman, later a founder and executive […]

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The Probe and the Particle Beam

April 2, 2014

For those wanting to dig deeper into Alan Mole’s 1 kilogram interstellar colony probe idea, the author has offered to email copies of the JBIS paper — write him at For my part, writing about miniaturized probes with hybrid technologies inevitably calls to mind Freeman Dyson, who in his 1985 title Infinite in All […]

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Solar Probe Plus: Prelude to ‘Sundiver’?

March 20, 2014

‘Sundiver’ maneuvers are surely the most extreme events to which we could subject a solar sail. To my knowledge, it was Gregory Benford who first came up with the term — he mentions in Fantasy & Science Fiction that he passed the coinage on to David Brin when Brin was working on the book that […]

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From Cosmism to the Znamya Experiments

March 19, 2014

What got me thinking about French influences on early solar sail work in Russia yesterday was the realization that science fiction was much stronger in Europe, and particularly France, in the latter part of the 19th Century than we Americans might realize. Hugo Gernsback to the contrary, the genre did not emerge in 1926 with […]

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Solar Sailing Moves into the Journals

March 13, 2014

I’m just getting started with Chris Impey and Holly Henry’s Dreams of Other Worlds (Princeton University Press, 2013), but glancing through it yesterday reminded me how long it has taken sail hardware to get into space. While Ted Cotter and Carl Wiley hoped for early experiments with sail ideas, we never got them until much […]

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