David Hill: Let mankind ever continue to reach for the sky

It's nearly a year since the morning of Jan 16, 2002 when the space shuttle Columbia lifted off from Kennedy Space Centre into a pellucid Florida sky. It had been a long wait for the 22-year-old craft, delayed for 10 months while missions deemed more important flew up to the International Space Station.

Sixteen days later, of course, halfway through its re-entry, Columbia ripped apart, scattering debris and the bodies of its seven crew over Texas. Almost instantly some commentators resurrected the claim that manned space exploration is too dangerous, too irrelevant. We shouldn't be putting money and lives into such far-fetched projects.

Manned space missions are dangerous. You have rocket engines firing at 110 per cent of design capability, and an environment implacably hostile to human survival. But are such missions significantly more perilous than search-and-rescue flights, United Nations peacekeeping or liberating (some say) Iraq?

Answer: yes, in some cases. Yet danger isn't seen as sufficient reason to stop those other commitments. And remember the US has had just three fatal accidents in over 40 years of manned space flight. Two of those involved space shuttles - which have made nearly 120 other, successful missions. That's a pretty fair record.

Systems and people have indeed fallen short. Nasa's inquiry into the Columbia disaster found the same problems of faulty checks and overconfidence that sent Challenger to its doom 17 years earlier.

With Challenger it was a cracked sealing ring on one of the booster rockets, coupled with an insistence on launching in spite of freezing weather that pushed equipment past its limits. With Columbia it was falling insulation hitting the shuttle's wings, plus mission control's bland, blind belief that there was no problem.

After Challenger's crew died, criticisms of manned space flight's supposed irrelevance were widespread. The same happened after Commander Rick Husband and his six fellow astronauts were killed on Columbia.

It is true that unmanned space missions are cheaper. An unmanned interstellar probe could weigh as little as 10 tonnes, while a manned spaceship might weigh 100,000 tonnes.

Unmanned missions have achieved some outstanding results. Look at the Spirit Mars lander and the Stardust comet dust collector. (Don't look at the non-doing Beagle 2 on Mars. Beagle 2 appears to be ... a dog.)

It' s true also that when unmanned missions fail, at least no people die with the machine. But a human presence on missions adds dimensions of flexibility, focus and initiative which no computer can yet provide - and which bring special results.

Technology developed on manned space shuttle missions has been applied to mechanical hearts, blood serum research, fire-resistant foam, artificial limbs, fishing-reel lubricants, head injury problems, computer joysticks and earthquake effects on soil. I could multiply that list 50 times.

But such practical benefits aren't the main reason why manned space missions must continue. It's vital for the human race that, in the words of the great philosophical treatise Star Trek, people should boldly go where nobody has gone before.

Our species seems to need challenges that take it to its limits and beyond its immediate needs. Accepting these challenges defines and advances us. Manned space missions are such a challenge. Like all others, they can become debased and tainted, but that doesn't invalidate their initial purpose.

If the too-dangerous, too-irrelevant argument had been heeded 50 years ago, Hillary wouldn't have climbed Mt Everest. If it had been heeded 250 years ago, Cook would never have reached New Zealand. You can argue the pros and cons of both those feats, but would you really prefer that they had never happened?

Manned spaceflight has meant Russians and Americans working side by side, plus Indians and Pakistanis, French and Germans sharing missions. It involves our scientists at our universities, at Mt John near Tekapo and the Carter Observatory in Wellington.

How many other areas of human endeavour have seen such international co-operation? A poignant feature of Columbia's fatal mission is that one of its experiments, unbecomingly called Gobs (Growth of Bacteria in Spaceflight) was jointly developed by an Israeli medical researcher and a Palestinian biology student.

And if none of those arguments convinces you of the need to keep humans in space, how about this: in two or three billion years, a much shorter length of time than our planet has existed so far, the sun will exhaust its supply of hydrogen, begin burning helium and swell into a giant red star incinerating the inner planets.

Somewhere around the same time our moon, which is creeping away from us a few centimetres each year as Earth's rotation slows, will break free of our gravitational tug and drift off into space. The effects on our planet's tides, climate and life-forms could be cataclysmic.

By the time these unfriendly moments come, if the human race still exists and hopes to keep existing, it will need to have found its way through space to some other home, either on the moons of Jupiter, Saturn or Uranus or beyond our solar system.

"Fantastic risks are justified only by fantastic journeys," wrote Pulitzer Prize-winning journalist Charles Krauthammer, and such a fantastic journey, with its matching risks, inexorably faces humanity.

If you see the ultimate end of human activity as being to secure a future for those who come after us, then our far-off descendants won't thank us for having turned our backs on the chance - the obligation - to take our next steps in manned space flight.