With dreams of building a spacecraft within the next 100 years that can reach the stars, a group of enthusiasts has been plotting exactly how we might get there, as Sidney Perkowitz reports.

An alien spacecraft scouting out Earth's scientific prowess last September may well have zeroed in on NASA's Kennedy Space Center in Florida. But the aliens might have learned more if they had flown some miles west to the 100 Year Starship Study (100YSS) conference in Orlando. There they would have seen that human space technology is limited, but in observing the event's hundreds of attendees – from ex-astronauts and engineers to artists, students and science-fiction writers – the aliens would also have encountered humanity's adventurous, stubborn, mad and glorious aspiration to reach the stars.

Maybe this desire to literally travel to the stars by spaceship arises because these distant suns have always seemed to offer a high and remote plane of existence. Aristotle in fact placed the fixed stars furthest from Earth – the centre of his cosmology – and nearest the Prime Mover that causes cosmic motion. The phrase "sic itur ad astra", or "thus one goes to the stars" – from the Roman poet Virgil – refers to reaching divinity or immortality. But another phrase – "per aspera ad astra", or "through hardships to the stars" – reminds us that they are not easy to reach, except in science fiction that sidesteps the difficulties caused by the vast distances the journeys would entail.

Now, with the exploration of the solar system by the US space agency NASA and others well under way, and with the discovery of hundreds of exoplanets orbiting distant stars, it may be time to contemplate the next great jump outwards.

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