A handful of images define humanity's 50-year-old history of space exploration: a blue Earth rising over the plains of the Moon, as seen from the Apollo 8 capsule; the glowing disk of the Sombrero galaxy, the most popular image ever taken by the Hubble Space Telescope; the desolate orange-red Martian desert photographed by the US robot vehicle Spirit; a collage of images of Jupiter, Saturn and their multicoloured moons sent back by the Galileo and Cassini probes; and the sight of Buzz Aldrin standing, defiantly and optimistically, on the lunar surface in 1969.
The intriguing point, of course, is that only one of these images has a man in it. The rest are notable for their lack of humanity and were mainly taken by instrument packages launched to carry out scientific work on behalf, and instead, of men and women. These photographs tell us one thing: when it comes to space research, robots rule. This point was reinforced recently by two very different interplanetary events. At the beginning of June, the seven-person crew of the space shuttle Atlantis completed a 14-day mission to the £100 billion (Dh725 billion) International Space Station, a flight that cost around £500 million (Dh 3,623 million) but raised absolutely no public interest whatsoever until tail-fin damage was spotted, raising momentary fears that the craft might burn up during re-entry, as its sister ship Columbia did in 2003.
At the same time, the tiny US lander Phoenix's struggle to test samples of Mars's clumpy soil for signs of water - and possibly life - has been one of the year's most absorbing scientific endeavours. The spacecraft's automated shovel has just uncovered samples of a mysterious white material a few inches under the Martian surface. These have now been shown to be made of ice. The matrix of life, water, has been detected, unequivocally, at the Martian north pole.
The contrast between the two missions could not be more striking. A small automated scoop, sticking out the side of an unmanned probe, is doing better science, and making more headlines, than a giant, vastly expensive orbiting laboratory filled with humans. The question is: why? How come humans in space look banal today? Where did the magic and the mystery go? There are a range of answers to these questions, but all focus on one underlying theme: astronauts have become boring because the only tasks that they can carry out in space today are tedious ones. They bob around a space station that has been built for a political — not a scientific — purpose and are present merely to bolt together modules flown aloft in the space shuttle: the zero-gravity equivalent of assembling an Ikea furniture kit.
Of course it can be tricky to make space lively and entertaining. It is like a refrigerator that has just been ransacked by Homer Simpson: cold and empty. Nevertheless, it has provided its thrills in the past. Apollo astronauts used to run around on lunar rovers and drill out rock samples, eye-catching activities that also had a scientific purpose. And on occasions when images were missed, the reasons often proved intriguing.
There are no photographs of Neil Armstrong on the Moon because Aldrin, miffed that had to be the second human to step on the lunar surface, wouldn't take - or, to be precise, was 'too busy' to take - any pictures of his commander. Thus our only image of the first Man on the Moon is a reflection of him in Aldrin's helmet. The trouble is that after America reached the Moon, its space chiefs couldn't think of anywhere else to send humans - and still can't. They built a space shuttle that was supposed to make space travel cheap and routine, but which has turned out to be a death trap.
In fact, putting men in space and then on to the Moon was largely an historical accident, as historian Gerard deGroot explains it in his recent book Dark Side of the Moon: The Magnificent Madness of the American Lunar Quest. "It didn't make sense financially, as previous voyages of exploration had," he writes. "But for a brief moment in the 20th century, money didn't matter. The Cold War was not the time for accountants; the important thing was to score points against the Russians, and to do so was priceless."
In other words, manned spaceflight had no real function beyond propaganda and has gained little since then. Even worse, it is vastly more expensive than launching unmanned probes and so diverts money from really challenging projects: to build orbiting telescopes that could pinpoint life-supporting planets that orbit distant stars, or to survey the ice-capped oceans of Jupiter's moons, which could also support primitive life.
And yet. And yet. Robot probes may excite, but a future in which space exploration is solely dependent upon them would be a tame one. For all its faults, the firing of men and women into space has some value. It lets our species know it is capable of meeting the ultimate challenge - that it will one day be able to leave its place of birth. And there are genuine, pragmatic reasons for doing so, as Stephen Hawking has pointed out. He maintains that the ability of men and women to leave our planet may - in the end - provide our species with its only hope of survival if environmental catastrophe overtakes the Earth, a prospect that is becoming less and less remote as our population heads towards seven billion and beyond.
"Life on Earth is at the ever-increasing risk of being wiped out by a disaster such as sudden global warming, nuclear war, a genetically engineered virus or other dangers," says Hawking. "I think the human race has no future if it doesn't go into space. It won't survive the next 1,000 years. There are simply too many accidents that can befall life on a single planet". This argument raises a moral issue, of course. Does our species deserve a second chance? If we foul up our place of birth so badly, do we then have the right to settle on other worlds and to start to pollute them?
In the meantime, America - along with Russia and Europe, a fledgling space power that is growing slowly in stature - faces the basic challenging of justifying the costs of maintaining a human presence in space. Rocket flight has brought undoubted advantages. We can watch live TV images from round the world, make cheap international calls; get accurate short-term weather forecasts; and monitor the impact of climate change on our world thanks to satellites. None of these activities require the presence of men and women in orbit, however. So we are left with a dilemma: if we wish to develop any expertise in manned space flight, we have to do that by exploiting that great orbiting Ikea kit, the International Space Station, until something better comes along - which hopefully it will do in the near future.
Robin McKie is science editor of The Observer.
