Tim Radford
THE Mars Pathfinder lander – the second United States probe to be launched last month – is due to float down by parachute and bounce gently to rest on airbags on the surface of the Red Planet on July 4 1997. It will be the first visit for 21 years, since the Viking lander probes made an initial tentative exploration of Mars and pronounced it dead.
This time things are different. Nasa’s instruments are designed to detect evidence of water, and therefore proof of at least bygone life. Since August, scientists in the US and Britain believe they have identified circumstantial evidence of microbial life in at least two separate Martian meteorites of wildly different ages.
Martian exploration has a long history – the Soviet Union launched its first attempt in 1960 – but now the stakes are higher.
Russia’s latest attempt crashed in the Pacific with several international experiments on board on November 18. It followed the successful launch of Mars Global Surveyor, a new version of Nasa’s Mars Observer, which suddenly went silent as it reached Mars in 1992.
With precedents like these, Nasa took no chances. It delayed a launch once because of the weather, and a second time because of a computer glitch.
When Pathfinder arrives, the landing petals of the spacecraft will unfold, two ramps will slide down, and a six-wheeled, 10kg rover called Sojourner will beetle down and begin examining the nearby rocks, relaying information back to Earth. Two months later the Global Surveyor will arrive and begin a series of orbits around the Red Planet.
Japan will launch its Planet B mission to Mars in 1998. There will be one more Nasa surveyor and one more lander, followed possibly by two more landers on the Martian ice cap in 1999. More missions are planned by Nasa after 2000. The ultimate goal is a human landing.
* Twenty years ago, the Viking missions produced tantalising images of the surface of Mars, including the notorious “Face of Cydonia”.
Planetary scientists called it an “artefact” – a trick of light and angle. UFO-watchers firmly believed otherwise. They saw the face, and other features mapped by Viking, as evidence of an ancient civilisation, perhaps wiped out in the cataclysm which stripped away the Martian oceans and atmosphere.
For 20 years scientists have shaken their heads. All the evidence from Viking showed that Mars was inhospitable to life.
But this year, United States and British scientists identified evidence of microbial life in meteorites known to have come from Mars. But Pathfinder and Mars Global Surveyer will not look specifically for signs of life, or lost civilisations, but for evidence of water on the planet. Signs of water would increase the possibility of life on Mars.