Humanity's long march to other star systems begins with baby steps today, experts say.
Making interstellar travel a reality within the next century or two will require the continued and methodical development of a range of advanced propulsion technologies, as it's unclear at this stage which ones will eventually pan out, said Marc Millis, the former head of NASA's Breakthrough Propulsion Physics Project.
Getting behind one particular technology right now is "like trying to predict who's going to win the Indy 500 when you haven't even built a car yet," said Millis, who has continued his interstellar research activities at the Tau Zero Foundation, which he established. [Gallery: Visions of Interstellar Flight]
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