It’s surprising but gratifying that we can now talk about the ‘interstellar community.’ Just a few years back, there were many scientists and engineers studying the problems of starflight in their spare time, but when they met, it was at conferences dedicated to other subjects. The fact that the momentum has begun to grow is made clear by the explicitly interstellar conferences of recent memory, from the two 100 Year Starship symposia to the second Tennessee Valley Interstellar Workshop. Icarus Interstellar is mounting a conference this August in Dallas, and the Institute for Interstellar Studies plans its own gathering this fall in London.
Of course the Internet is a big part of the picture — Bob Forward and his colleagues could use the telephone and the postal service to keep in touch, but the energizing power of instant document exchange and online discussion was in the future. All this was apparent in Huntsville for the Tennessee Valley event, from which I have just returned. There was an active Twitter channel open and video streaming of the talks, and although I had little time to answer them, I was getting emails from many interested parties who couldn’t attend. Getting copies of papers and presentations after the conference closed can be managed in hours on the Net.
Starflight challenges not only everything we know about propulsion but also our understanding of human nature. If we are seriously considering human travel to such distant destinations, we are looking at decades of travel time at a bare minimum, or the possibility of a generation ship in which people live their lives entirely aboard the craft, which could take hundreds or even thousands of years to reach its destination. Astronaut Jan Davis, who gave the keynote in Huntsville, talked about the various problems of even short duration spaceflight based on her own experience of multiple Shuttle missions.
Image: Rockets dominate the Huntsville skyline in this shot I took from the Calhoun Community College on the final night of the workshop.
Some of these issues are well identified, including the lack of privacy and the loss of muscle and bone mass due to prolonged weightlessness. The privacy issue balances oddly with a sense of isolation, Davis said, as you are cut off from all aspects of your normal life. “You hear a lot of voices, but they’re not the voices you take for granted every day. I missed my dog. I missed sounds like wind, waves hitting the shore. You’re busy, but you’re also isolated.” As medical officer on her two flights, Davis trained on emergency procedures in case a crewmember became incapacitated. The main issue was to stabilize a patient long enough that he or she could be swiftly returned to Earth.
The conclusion from all this is that humans are adapted for Earth, not space, yet they have key advantages over robotic systems, including the ability to discern, judge and learn on a fine-grained basis. Swiftly changing conditions in an on-board experiment she was managing led Davis to alter the schedule on the fly, making changes that would have been difficult for the current generation of robotics. The astronaut sees a combination of the two paradigms as the most likely possibility for long-term missions, perhaps aided by medical breakthroughs in hibernation that would allow the crew to spend most of a long mission in stasis while automatic systems ran the ship.
Robert Hampson (Wake Forest University) extended thinking in this direction by talking about what we need to learn about the human brain before we can contemplate long-duration spaceflight with an interstellar reach. Hampson is an associate professor of physiology and pharmacology with a passion for neuroscience and biology. Given what we know today about risk factors like stroke, epilepsy and Alzheimer’s disease, he notes that if we launch 100 people on a 100 year journey, 25 of them will be incapacitated by the time they arrive even if we can extend their lifetimes significantly. Interstellar flight, then, demands that we learn to predict and prevent degenerative diseases, keeping the brain healthy through entertainment and intellectual stimulation.
One way to do that is with a direct human/machine interface, a kind of TiVo wired into the brain. Hampson told the audience that to fix the brain for long-duration spaceflight, we have to find a way to interface with it, and that means we have to understand its language and coding. It’s a challenge that demands the help not just of the medical community but of mathematicians, physicists and engineers. As to the hibernation that Jan Davis talked about, Hampson asks how much we know about brain activity during hibernation. Is an astronaut under hibernation for fifty years going to have a fifty-year long dream?
I’m jumping around in the schedule here to tie thematic ends together, so I’ll add that my own talk, called “Slow Boat to Centauri,” got into long-duration mode by discussing worldships and how they could sustain themselves along the way. The idea was to show how many resources are available between the stars, suggesting as many space researchers have that our expansion might not involve a direct mission to another star, but rather a step-by-step progression of colonies that gradually moves the human sphere outward. Gradual exploration like this might take thousands of years.
We can all hope for fast propulsion, but suppose the engineering is intractable. Would we still go to the stars if limited to speeds much less than ten percent of c? One-tenth of one percent of lightspeed gets you to Alpha Centauri in about 4300 years, which is also (very roughly) the extent of human history in terms of recoverable documents and written language. A worldship moving at this speed, in other words, recapitulates the human historical experience aboard a craft that would have to be engineered to be a living world, a vast O’Neill cylinder with propulsion.
The right kind of worldship — and Gordon Woodcock (L5 Society) worked through the engineering problems of creating such a vessel in a first-day talk — would have to be one large enough to sustain a population of thousands in conditions that were eminently livable, the complete antithesis of the cramped quarters Jan Davis experienced aboard the Shuttle. We’re all on a worldship of our own, following our star in its 230 million year journey at 220 kilometers per second around the galaxy, so perhaps a livable worldship engineered by the future Kardashev type 1 civilization we hope to grow into would be an acceptable interstellar ark.
Image: A worldship designed to hold generations of humans, as imagined by space artist Adrian Mann.
Putting the speed issue in perspective, one tenth of one percent of the speed of light is 300 kilometers per second, compared to the 17 kilometers per second that our fastest deep space probe, Voyager 1, has attained. There are ways of moving that fast that we can calculate today, but the engineering needed to produce a worldship — and the vast issues raised by creating a closed-loop ecology aboard the craft — demand a multi-disciplinary approach that takes us into biology, philosophy, sociology and the humanities as well as physics. The long-term perspective needed for such thinking was frequently discussed in Huntsville, about which more on Monday.