Paging back through Kelvin Long’s book Deep Space Propulsion (Springer, 2011) last night, I was reminded that Freeman Dyson had written about his disillusionment with nuclear pulse propulsion methods long after Project Orion was terminated. The passage is in his autobiographical account Disturbing the Universe (Basic, 1981), which caught Long’s attention and led him to reprint it. Here’s a snippet of Dyson’s reflections: Sometimes I am asked by friends who shared the joys and sorrows of Orion whether I would revise the project if by some miracle the necessary funds were suddenly to become available. The answer is an emphatic no... By its very nature, the Orion ship is a filthy creature and leaves its radioactive mess behind it wherever it goes... Many things that were acceptable in 1958 are no longer acceptable today. My own standards have changed, too. History has passed Orion by. There will be no going back. Long speculates that Dyson may simply have been referring to Orion as an...

It had never occurred to me that there was something the Graf Zeppelin and the Saturn V had in common. Nonetheless, a re-reading of Freeman Dyson's paper "Interstellar Transport" confirms the obvious connection: Like the great airships of the 1930s, the Saturn V was huge and carried a payload that was absurdly small. Dyson, writing in 1968 fresh off the end of Project Orion, the rise of Apollo, and the triumph of chemical propulsion, had thought at one time that the US could bypass the Saturn V and its ilk, offering a fast track to the planets at a fraction of Apollo's cost. The Atmospheric Test Ban Treaty of 1963 was a major factor in putting an end to that speculation. I mentioned yesterday that I thought Dyson set about to be deliberately provocative in this piece, that he hoped to reach people who would have been unaware that interstellar distances could conceivably be crossed (thus his choice of Physics Today as his venue). To do that, he had to show that even reaching the Moon...

My time off last week really was refreshing, although it coincided with the same heat wave that has kept the Eastern US under duress for many days now, especially dangerous for those who lost power because of severe storms. Fortunately, I used part of my time to fly to San Jose to participate in Steve Durst's Galaxy Forum (sponsored by the International Lunar Observatory Association), where I spoke on destinations in the outer Solar System and beyond as we make our first tentative steps into the galaxy. It was a good gathering, with lively talk from Seth Shostak, Jon Lomberg, Tony Cardoza (who signs people up to travel on future flights with Virgin Galactic), and Durst himself. It was also a pleasure to meet Centauri Dreams regular Alex Tolley. Blissfully, the temperatures never got out of the low 70s, with a refreshing breeze that made walking around downtown a pleasure. Miles, my older son, lives near San Francisco and the trip was also a wonderful chance to reconnect. I can recall...

Summer in Green Town, Illinois back in 1928 opened like this: "It was a quiet morning, the town covered over with darkness and at ease in bed. Summer gathered in the weather, the wind had the proper touch, the breathing of the world was long and warm and slow. You had only to rise, lean from your window, and know that this indeed was the first real time of freedom and living, this was the first morning of summer." Thus the beginning of Ray Bradbury's Dandelion Wine, which I re-read not long after the author's death. With catastrophic fires in the American west and triple-digit heat along the Atlantic seaboard, summer has indeed come, and so has a brief summer holiday for Centauri Dreams. Although I won't have months ahead of me the way Bradbury's character Douglas Spaulding did, I am looking forward to a week off. This site is now approaching its eighth anniversary and I'm ready for a break, one that will give me time to catch up on reading, do necessary work around the house, and...

We all carry our assumptions with us no matter where we go, dubious extra baggage that can confuse not just our scientific views but our lives in general. That's why it's so refreshing when those assumptions are challenged in an insightful way. Think, for example, of the starship as envisioned by Hollywood. In our times it looks like something produced by the joint efforts of NASA, ESA and other governmental space agencies. No matter how diverse the crew, the model is always based on western culture, the assumptions reflecting our modern ethos. When an assumption is ripe for questioning, along comes a writer like Michael Bishop. Consider the starship Kalachakra, carrying a crew of 990 to a planet in the Gliese 581 system, as envisioned in Bishop's 'Twenty Lights to the Land of Snow,' a novella in the Johnson/McDevitt book Going Interstellar. Most of the crew spends the flight in hibernation using the wonderfully named drug ursidormizine -- thus slumbering 'bear-like' -- but each...

Tau Zero founder Marc Millis is interviewed by Bruce Dorminey in Forbes this week, the logical first question being where interstellar flight ranks on our list of priorities. A case can be made, after all, that we have yet to get humans beyond the Moon, and that while we have managed robotic missions to the outer planets, our technologies need development closer to home. Should a Moon base get our attention, or a Mars mission? Millis argues that pursuing next steps like these should be managed in tandem with the pursuit of more far-reaching advances that force us to look beyond existing methods. Breakthroughs can change everything, and Millis is, after all, the former head of NASA's Breakthrough Propulsion Physics project, which came to an abrupt end in 2002 when a congressional earmark to build a propulsion laboratory in Alabama -- one that cost more than all NASA's BPP research put together -- scarfed up what could have been research money. And as Millis tells Dorminey, we're left...