At the 100 Year Starship Symposium in Houson, I sent out a large number of tweets as @centauri_dreams. That Twitter account is still live, but be aware that my son Miles, who is now working actively with us, has set up a new account solely for the Tau Zero Foundation. You can access @TZFoundation to pick up interesting links and news of the interstellar community. I suspect, for example, that when Miles runs across articles like the one I'm going to be discussing today, they'll appear on Twitter, but he's bound to find a lot of good material that I miss. Yesterday we were looking at distance issues as Larry Klaes discussed the extension of Ithaca, NY's Sagan Planet Walk all the way to Hawaii, where a new 'station' represents Alpha Centauri. Matters of scale are important to convey to the public because getting across the distances involved in interstellar flight is tricky, and various ways of modeling them can provide the needed perspective. Peter Garretson thinks about scale as...

I’m always looking for ways to relate interstellar distances to common objects on Earth, knowing that misunderstandings about the vast scale of the universe are common. Sir John Herschel (1792-1871) talked about dropping a pea off the side of a ship after every mile on an ocean voyage the distance of the nearest star, telling his readers that it would require ‘a fleet of 10,000 ships of 600 tons burthen, each starting with a full cargo of peas.’ Herschel was the first to try to measure the distance to Alpha Centauri, and while his numbers weren’t as accurate as ours, he captured for his era the disconnect between Earthly distances and the heavens. Larry Klaes weighs in this morning with yet another way to study the issue, using an exhibition on the interplanetary scale that has now been extended Herschel-style to the ultimate voyage. By Larry Klaes Since its dedication in 1997, the Sagan Planet Walk has become a landmark feature of downtown Ithaca, New York. The various monuments, or...

Because I utterly lack their skills, I have huge admiration for practical-minded people who can organize things well. Eric Davis’ work as track chair for the ‘Time and Distance Solutions’ track in Houston is a case in point. The challenge is in coping with a key fact of interstellar studies: We are so early in the game that we have not remotely figured out which propulsion method makes the most sense for journeys of this magnitude. Discussing time and distance means culling papers to find a balance of ideas, from what could be near-term (fusion, although it always seems near-term) to highly speculative (antimatter and nanotech). Image: Physicist Eric Davis, a highly visible figure at the Houston conference. Eric nailed the composition of the track, and it was because of that that I stayed in it through the conference. The temptation of getting involved with alternate tracks on ‘Becoming an Interstellar Civilization’ and especially ‘Destinations and Habitats’ was huge, but it was the...

While I didn't see too many technical glitches at the 100 Year Starship Symposium in Houston, I ran into plenty of them in my own attempts to cover the event. The banquet hall where the opening ceremonies were held -- and where the plenary sessions occurred each day -- was impervious to the hotel's WiFi, so that I was unable to use Twitter. Friday's technical sessions in the conference rooms went fine, and I managed to send out a steady stream of tweets from the 'Time and Distance Solutions' track. But halfway through the Saturday sessions, Twitter itself went down. I tried all afternoon to get on, but though my Net connection was strong, Twitter wouldn't come up. Image: Early arrivals setting up at the opening plenary session for the 100 Year Starship Symposium. Everything in order but the WiFi. My experience with US Airways was about the same. The two flights out to Houston were uneventful, but coming back I was on an aircraft that reached new levels of passenger compression. With...

? At left is Mae Jemison, snapped from my seat as she spoke to open yesterday morning's sessions. I couldn't tweet about her comments because the hotel Wi-Fi wasn't working in the room. Several people asked me today why I was still using a ‘netbook’ to take notes and send out tweets from the Houston symposium. It’s an easy answer -- I need a standard keyboard rather than a virtual one, and despite the beauty of tablets like the iPad, I don’t want to carry a separate keyboard around. Besides, my little 10-inch screen Asus serves me well, gives me all the connectivity I need, and runs Linux much faster than the original Windows that it came with (I blew Windows off the hard disk as soon as I bought it and slipped Ubuntu on effortlessly, continually updating it ever since). At $350, which is what it set me back a few years ago, the netbook is a no-brainer for places where I need to make a lot of notes, and if I leave it in a taxi or drop it, the financial loss is minuscule. Image: Mae...

?Bring an umbrella to Houston? I figured it would be unnecessary and left it out of my luggage. Lo and behold yesterday morning it began to rain and it seems to have continued off and on most of the day. That hardly matters when you’re in a huge high-rise hotel, but it’s a good thing it didn’t happen Wednesday night, when I walked all over downtown looking for restaurants. I favor inexpensive ethnic places with interesting menus but also love any place with a decent wine list and crusty bread baked in-house. I walk 3-5 miles each day and get seriously stressed out when I don’t get in the exercise, so I’m hoping the rain will be gone or at least sporadic enough today to let me get out a bit. Houston’s humidity, I must say, did slow down my pace in each journey I’ve taken so far. No time for walking yesterday, though, as I spent all day in meetings re the 100 Year Starship organization and future planning. It was great fun to be with a small group including 100 Year Starship leader Mae...

?A few words before a long day begins. I’m in meetings all Thursday here in Houston as the 100 Year Starship Symposium gets going, having slept well last night on the gigantic bed provided by the Hyatt. The travel day was uneventful. I had decided to make this a non-digital flight as much as possible so as to get through security with less difficulty. That meant the laptop went in a checked bag, the Kindle stayed home, and for the plane I took an actual book, one with pages that you turn by hand, a cover, and an index in place of a search engine. So much for my plans - everything was going great until a couple of coins in my pocket set off the alarms and I got patted down. Image: Yesterday afternoon's view from my room. The Hyatt Regency has a rotating restaurant on its 31st floor. Despite Calvin Trillin's famous exhortation never to eat in a restaurant that rotates, I found the food quite good, including a spectacular glass of Cloudy Bay Sauvignon Blanc from New Zealand. Nice view,...

I'm on my way to Houston for the 100 Year Starship symposium, and I should be airborne before this clicks into visibility through the wonders of automation. I'm involved in meetings all day Thursday and then into regular symposium activities for the rest of the weekend, about which I'll be reporting next week and to a certain extent from the site itself. Last year in Orlando I wound up sending out more tweets than blog posts from the actual venue and this year I've decided to more or less play it by ear, seeing what opportunities arise and how best to convey them. If you're following me on Twitter as @centauri_dreams, be advised that I don't know how much I'll be tweeting, but feel free to 'unfollow' me as needed if you start getting more than you bargained for. You can always sign back up again after the symposium. What I've learned over the years is that I'm not good at multitasking, and my priority has to be getting accurate notes from the various workshops and technical sessions...

Making Progress on Star Trek Physics is Marc Millis' foray into crowdsourcing, a just announced project on Kickstarter. For those new to the concept, Kickstarter allows the general public to make donations to projects that are described on the site. A deadline is established and so is a minimum funding goal -- if the goal is not reached by the deadline, no funds are collected. $275 million have been raised for various Kickstarter projects thus far and Millis is hoping to catch this wave in support of a new book on breakthrough propulsion concepts that is aimed at a broad, general audience. Centauri Dreams readers will recall that Millis and Eric Davis co-edited 2009's Frontiers of Propulsion Science, published by the AIAA. The first compilation on topics Millis analyzed as head of NASA's Breakthrough Propulsion Physics project, Frontiers was lengthy (22 individual essays in 739 pages) and written specifically with a graduate-level and professional audience in mind. The new project...

The 100 Year Starship 2012 Public Symposium begins next week, with the recently announced news that former president Bill Clinton will serve as honorary chair for the event. I'm not sure whether a US president has ever spoken about starships before, but what Clinton said was this: "This important effort helps advance the knowledge and technologies required to explore space, all while generating the necessary tools that enhance our quality of life on earth." The symposium takes a decidedly multi-disciplinary theme, with speakers on topics ranging from engineering to ethics, philosophy, the social sciences and biology. Our recent discussions about experimenting with self-enclosed ecosystems flow naturally into the upcoming event in light of the range of topics to be covered. In addition to the speakers and scientific papers, four workshops have been announced. Let me pull some excerpts on the workshops directly off the 100 Year Starship page: Workshop 1: Research Priorities for the...

Long journeys by spaceship are a staple of science fiction, but we know all too little about how to sustain a human habitat in a hostile environment. Experiments in closed ecosystems simply reveal how much work will have to go toward this subject before we can talk about moving out into the Solar System, much less sending missions outside of it. One experiment in this direction was Bios-3, conducted at the Institute of Biophysics in the Russian city of Krasnoyarsk. John Allen, himself deeply involved with the later Biosphere 2 project, called Bios-3 "something of a clandestine legend to the handful of people actually working on closed life systems." The thought behind Bios-3, which was completed in 1972, was to develop closed ecosystems that could support a crew of up to three in a 315 cubic meter space that would be divided into four areas, one designated for the crew, the others for growing food sources, with xenon lamps acting as the light source and power supplied by a nearby...

As we've had increasing reason to speculate, travel to the stars may not involve biological life forms but robotics and artificial intelligence. David Brin's new novel Existence (Tor, 2012) cartwheels through many an interstellar travel scenario -- including a biological option involving building the colonists upon arrival out of preserved genetic materials -- but the real fascination is in a post-biological solution. I don't want to give anything away in this superb novel because you're going to want to read it yourself, but suffice it to say that uploading a consciousness to an extremely small spacecraft is one very viable possibility. So imagine a crystalline ovoid just a few feet long in which an intelligence can survive, uploaded from the original and, as far as it perceives, a continuation of that original consciousness. One of the ingenious things about this kind of spacecraft in Brin's novel is that its occupants can make themselves large enough to observe and interact with...