Science fiction becomes reality
After a flight of 352m miles which cost $2.5bn (€2bn) the robotic explorer Curiosity has landed on Mars.
Many spacecraft have made the same voyage in the past, but this exceeds all of them in importance.
Since the dawn of civilisation -- probably since much earlier, far back in prehistoric times -- humanity has been fascinated by the Red Planet. Before ever such an art existed as science fiction writing, there was keen speculation about its atmosphere, its surface and its imaginary inhabitants.
Early users of telescopes saw what looked like canals designed for transport. They thought they might have been built by beings very like ourselves.
Later, writers unveiled their own ideas of what kind of civilisation might have used them. Edgar Rice Burroughs described adventures in deserts interspersed with decaying cities.
He was right about the deserts, but not the adventures or the cities. We now know that nothing like human life exists on Mars. There are no Martians, red, green or any other colour.
But we do have evidence that water once flowed on the planet's surface. Curiosity has landed in one of the areas where such evidence exists.
Its two-year mission is to seek proof of life -- primitive, microscopic life, but life nevertheless -- outside our own world.
If Curiosity itself is a triumph of engineering, the project is one of the most exciting scientific endeavours of all time.