Last night a small spacecraft hurled itself through the dusty tail of a comet 240 million miles from Earth and raised the curtain on a weekend of tense theatre for scientists.
Stardust's encounter with comet Wild-2 on the far side of the sun at almost four miles a second - or six times the speed of a rifle bullet - was just the first act in a sequence of distant dramas originally rehearsed in university laboratories and conference rooms.
The second act opens before dawn tomorrow, 100 million miles from Earth, when Spirit, a US robot rover the size of golf buggy, hurtles through the thin atmosphere and bounces to a halt on the parched deserts of Mars, to begin a search for water on the arid planet.
The third act of the drama is revealed later that day when a European spacecraft called Mars Express completes a series of huge elliptical swings around the red planet and settles down to a steady polar orbit which will allow it to probe the secrets of the Martian air and rock.
But even before it starts to send back valuable data, Mars Express has a more urgent role: to make contact with its baby, Beagle 2, the tiny British lander it carried for six months and then pushed gently towards a dusty basin near the Martian equator just before Christmas.
Beagle 2 almost certainly landed on Mars. But it has been stubbornly silent. Its transmitter is too feeble to be detected from Earth and it must relay its call home at fixed times via an orbiting spaceship. Beagle has missed a series of encounters with an orbiter called Odyssey, one of two Nasa missions already in orbit around Mars. But scientists in Britain still hope that Mars Express will be able to make contact, and trigger the start of a new research partnership on the surface of Mars, and far above it.
The invasion is a drama that will last four months for Spirit, six months for Beagle and a Martian year of 687 days for Mars Express. Conversely, last night's thrilling climax to the Stardust story was over in an hour. Comets are - in the imagery of one Nasa scientist - the batter from which the planets were baked. Wild-2 is a relatively new visitor and its ice and dust, preserved for billions of years, could provide answers to a host of questions about planet formation and the emergence of life on Earth.
The spacecraft last night flew to within 190 miles of its huge, icy nucleus. It put up a shield to protect its body from the high velocity buckshot of its coma, and it extended a little tennis racquet-shaped "catcher" made of aerogel to stop and store the speeding particles of comet dust. It will return them to Earth in January 2006.
Spirit, the Martian lander now in the last stages of its journey to Mars, is far bigger than Beagle, and designed to do a different job. Like Beagle it will smash into the Martian atmosphere at around 12,000 m.p.h., slow down and open a parachute.
It will then fire retro rockets and finally inflate airbags to bounce to a halt in a geological formation known as the Gusev crater. (It will be Saturday night in the US, Sunday morning in the UK.) It will be joined on January 25th by a second similar lander, Opportunity, launched three weeks later, and destined for a different stretch of the planet. Both rovers are solar-powered and will "work" by Martian day and "sleep" through the freezing Martian nights. Since the Martian night and day last for 24 hours and 39 minutes, even a successful landing will soon guarantee sleepless nights for mission scientists back in the US.
British and other European researchers have been troubled by sleepless nights since Christmas, when Beagle arrived but failed to make contact.
Mars Express is fitted with a suite of sensors that will probe up to three miles below the Martian surface.
But the first hope is that by Wednesday it will have made contact with Beagle. -(Guardian Service)