An interstellar movement has been brewing for the past sixty or so years among physicists and engineers who have taken a serious look at what it would take to get to the stars. Their work is not based on wishes but on physics, and while they are aware of the intractable distances to reach even the nearest star (4.2 years at the speed of light itself), they have continued to study how to send spacecraft on such epic journeys. Organizations have emerged -- DARPA's 100 Year Starship, Icarus Interstellar, the Tau Zero Foundation -- whose members call to mind physicist Robert Forward's injunction: "Travel to the stars is difficult but not impossible." Centauri Dreams readers know all this, but at least on the basis of Adam Frank's op-ed Alone in the Void, many readers of The New York Times do not. A professor of physics and astronomy himself (University of Rochester), Frank is well versed in the problems of distance and time and understands how difficult it will be to send humans to the...

Galileo Galilei makes a brief appearance in the news this morning with word that several copies of his books, including two examples of the Sidereus Nuncius, have turned out to be forgeries. The latter, whose title is usually translated as Starry Messenger, was the first scientific presentation on observations made with a telescope, and contains Galileo's early work on the Moon and the moons of Jupiter, among other things. One Marino Massimo De Caro, currently under arrest for massive thefts from the Girolamini Library in Naples, may have had connections with the forgeries, which are worrisome news for those of us who like to poke around in ancient manuscripts and for anyone interested in the history of science. News of the manuscripts also puts me in mind of a paper by Danielle Briot (Observatoire de Paris), which uses Galileo in quite a different context. Briot became interested in the life and work of Ary Sternfeld (1905-1980), a prolific writer on science and a researcher who may...

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...