Reaching for the Stars

Participants—an eclectic mix of engineers,scientists,science-fiction fans,students and dreamers—explored a mix of ideas,including how to organise and finance a century-long project; whether civilisation would survive,because an engine to propel a starship could also be used for a weapon to obliterate the planet; and whether people need to go along for the trip.

“The space programme,any space programme,needs a dream,” said one participant,Joseph Breeden. “If there are no dreamers,we’ll never get anywhere.”

It was Breeden who offered the idea of an engine-less starship. A physicist by training,he had most recently devised equations that forecast to banks how much they were going to lose on their consumer loans. From his doctoral thesis,Breeden remembered that in a chaotic gravitational dance,stars are sometimes ejected at high speeds. The same effect,he believes,could propel starships.

First,find an asteroid in an elliptical orbit that passes close to the sun. Second,put a starship in orbit around the asteroid. If the asteroid could be captured into a new orbit that clings close to the sun,the starship would be flung on an interstellar trajectory,perhaps up to a tenth of the speed of light.

“The chaotic dynamics of those two allow all the energy of one to be transferred to the other,” said Breeden,who came toting copies of a paper describing the technique. “It’s a unique type of gravity assist.”

DARPA,by design,pursues out-of-the-box projects without immediate military use. David L. Neyland,the director of tactical technology at DARPA,who orchestrated the one-year starship study,noted that his agency was founded more than 50 years ago as a response to Sputnik,the Soviet Union’s Cold War satellite coup. And the research and development of technologies that could lead to a starship,he said,would likely create useful military spinoffs.

“The problem of the stars is larger than most people realise,” said James Benford,a physicist who organised sessions on starship propulsion. In 10,000 years,the speed of humans has jumped by a factor of about 10,000,from a stroll (2.6 mph) to the Apollo astronauts’ return from the moon (26,000 mph). Reaching the nearest stars in reasonable time—decades,not centuries—would require a velocity jump of another factor of 10,000.

The space agency has now begun with studies on an ideal fuel for a space reactor,and new nuclear engines could be ready by the end of the decade. As for radioactivity concerns,the reactors would not be started until they reached space. “Space is a wonderful place to use nuclear power,because it is already radioactive,” said Geoffrey Landis,a scientist at the NASA Glenn Research Center in Ohio (and a science fiction author). More advanced nuclear engines could use reactors to generate electric fields that accelerated charged ions for the thrust. Then fusion engines—producing energy through the combining of hydrogen atoms—could finally be powerful enough for interstellar travel.

The $1.1 million one-year starship study—$1 million from DARPA,$100,000 from NASA—will culminate with the awarding of a $500,000 grant to an organisation that will take the torch for further work.KENNETH CHANG