Should we go to the Moon? Nasa says we can. Stephen Hawking says we must, in order to survive. Lucy says it would be a really brave thing to do. "You could feel very proud of yourself."
Lucy is a Middlesex schoolgirl I met at Leicester's National Space Centre recently. She was there with a group of nine- and 10-year-old schoolmates who had endured a three-hour coach journey to find out what it takes to be an astronaut. Fast reactions, grace under pressure and the ability to sleep vertically with your head strapped down, to judge from the exhibits. The most exciting of these was a breathtaking simulation of a mission into deep space from a Moon base - idea and images courtesy of Nasa.
Suddenly that is not the wacky, futuristic idea it seemed a week ago. The plans have been published for a permanent base on the Moon by 2020, as a launch pad for deeper space exploration, and that changes everything. Lucy will be in her mid-20s by then, just the right age. For the first time in three decades, children can look into the night sky and say,"It might be me".
Even if it's not likely, the implications of being able to dream at all are immense. Close to where we stood was a replica of an old-fashioned wood-encased television set, showing a hazy black-and-white image of a spaceman bobbing across the lunar surface. It gave me chills. For a moment I was a toddler again, woken up in the night and plonked in front of the telly so that - although I might not remember much - I could say in future that I had seen him: the first man on the Moon. The first person to touch the pale disc that had influenced and enchanted human life since before history. Funding was slashed after the last manned mission, in 1972, but imaginations had been captured. Those young dreamers became scientists whose work transformed communications, medicine and other disciplines. Some are even now working at Nasa.
The space shuttle was a poor substitute for the Moon, because going up for a look around just does not tug the guts in the same way as kicking up lunar dust. Even now, the fantasy almost overcomes my grown-up liberal concerns about going. Spaceheads have an answer to every doubt. Tell them that it costs too much - an estimated £50bn - and they say no, not compared to fighting wars, and anyway the rewards could be even greater in terms of scientific advance. Say the money should be spent on feeding the starving or finding a cure for Aids and they say tell that to the army, or the media moguls, or yourself - anyone who is doing something other than trying to save the world.
Suggest we should be sorting out our own planet before we start cluttering up others and they offer the prospect of helium-3, the potential wonder fuel that could replace both fossil and nuclear fission energy. It may also be why Russia and China are suddenly so enthusiastic about Moon shots too: will Nasa's much-trumpeted desire for international co-operation really last if one of these nations gets to the helium-3 first and claims the right to mine it, for unprecedented riches? And isn't there a military value to sitting up there looking down on us, that nobody is talking about?
Going to the Moon seems fraught with danger, for the rest of us as well as the astronauts. But ultimately there is the Stephen Hawking line, taken at the space centre by a pupil from Twickenham Preparatory School called Alex: "Because of global warming the world is being destroyed, so it would be good if we could find somewhere else to live."
Hearing the lucid, informed arguments of these children who had been so excited by a day thinking about space was a clincher for me. If Moon fever makes science cool for their generation then everyone will benefit. And it really could do that, because for the second time in history there is something amazing to aim for. Lucy and Alex can reach for the Moon, in the belief that they might actually get there.