… one giant leap for Earthlings, who are exploring Mars with interactive technology, write Mail & Guardian Reporters
THE first stage of the invasion of Mars reached a climax on Sunday when a robot scout rolled its six little wheels down a ramp and parked itself on Martian soil. But the events of this week have shown it was not Mars that was being colonised: as it dominated airtime, filled newspaper inches and proliferated in websites, the red planet seized the popular imagination of Earth’s inhabitants and built an empire in cyberspace.
Already, a number of unremarkable-looking boulders are becoming household names – Barnacle Bill, Yogi, Wedge and Scoobie Doo, among others – as people all over the world examine them on the Internet or in the local media.
The names may be silly, and the Nasa scientists filled with an enthusiasm that seems rather boyish, but there is nothing trivial about what those rocks can teach us. Apart from giving scientists crucial information about Mars itself, they could resolve the debate about whether life once existed on its now-barren landscape. And from there, it’s a short step to the rather incredible theory that perhaps life here came from there – in other words, that we’re all Martian.
The robot rover, called Sojourner after the African-American civil-war heroine Sojourner Truth, has already presented evidence from the rough-surfaced rock Barnacle Bill that shows that Mars is much more Earth-like than scientists previously thought.
Although the rover is not designed to take rock samples, it is capable of doing onboard analysis of geological structures as it goes. Using a combination of x-rays and radioactive beams that are “squirted” out at the rocks, Sojourner can measure the internal components of geological structures. Its data is then beamed back to the waiting scientists on Earth, who almost immediately turn it into soundbites for the eager public.
Analysis of Barnacle Bill reveals clear evidence of repeated melting and reheating, suggesting it has been cooked and cooked again within the Martian crust. This implies that the red planet remained hotter longer than researchers suspected.
“This is a real surprise,” said Hap McSween, a geologist from the University of Tennessee. “We were not expecting to see rock of this composition.”
Barnacle Bill, to the researchers’ surprise, appears to contain a good deal of quartz – a common mineral on Earth. Previously, they thought Mars would be almost entirely basalt – the most common type of volcanic rock on Earth. Quartz rises to the top when basalt is cooked repeatedly, like cream rising to the top of unhomogenised milk.
Bill is also loaded with the element silicon, and “so much silicon demands that it has quartz,” said McSween. In some ways, Barnacle Bill is similar to rocks found in the South American Andes.
Researchers talked delightedly this week of the overall variety of rocks at the landing site of their spacecraft, Pathfinder. “This site is really a rock festival,'” Sweeny said, in the joke-speak that has become the hallmark of the Pathfinder team’s communications style. They also talked of “rock stars” and “red heaven”.
The other major issue for the life-on-Mars theory is water. It’s hard to believe the barren, arid and rusting terrain seen in the Pathfinder images was ever under water. But there are clues for geological eyes. A white semi-circle in front of the bear- shaped rock called Yogi looks like the remains of an ancient puddle of standing water, the kind of place where ancient Martian pond scum might have found a home.
The most ancient surfaces on Mars show the remains of lakes, suggesting that water flowed on the surface at one time. The rocky plain where Pathfinder sits was clearly the site of great floods. But, according to Pathfinder chief scientist MatthewGolombek, they occurred in the period between one billion and threebillion years ago – long after the formative years and possibly at a time when the temperatures were too cold for water to remain liquid for very long.
Pathfinder geologists selected the spacecraft landing site, the Ares Vallis, because it appeared to be an ancient flood plain – the new images erased any lingering doubts. In fact, the water gushed forth at a rate equal to the flood that filled the Mediterranean sea, said geologist Michael Malin, a consultant to the mission. Water probably flowed from horizon to horizon, he said.
One of the “mysteries that puzzle scientists”, as South African nuclear physicist Dr Kelvin Kemm says, is exactly what occurred to cause Mars’s water to vanish dramatically. One plausible theory is that Mars experienced a major collision with a meteorite, similar to the one that some theorise wiped out the dinosaurs here on earth. The force of the asteroid stripped away the atmosphere of Mars, resulting in a rapid cooling, the surface water either evaporating or flowing to the poles.
Some scientists believe that there is a strong likelihood that there is still liquid water present on the planet. There is a huge amount of frozen water – in the form of ice-caps – on both poles of Mars. Kemm says major changes occur to these ice caps between summer and winter: “the ice caps advance and retard by some 300km”. What this implies is that when the caps are melting, rivers must be flowing. And, somewhere on the planet, perhaps under the apparently sterile surface, life may still flourish.
Pathfinder is just one part of a decade- long Nasa project – called the Mars Surveyor programme – to explore the red planet. The aptly named Pathfinder, which cost about $150-million to develop, is the voortrekker of the programme, blazing a trail for other space craft to follow. And there is already one hot on its tail: a second craft, Global Surveyor, is on its way and due to arrive in Mars’s atmosphere in early September this year.
While Pathfinder and its mini-explorer Sojourner are charged with gathering data from the planet’s surface, Global Surveyor will not be landing: it will remain in Mars’s orbit, and photograph every metre of the planet over the period of one Martian year (about two Earth years), including getting a closer look at the controversial sphinx-like “face” originally photographed by the Viking craft 21 years ago. Eventually, the information from Surveyor will help scientists decide on landing sites for future spacecraft.
Pathfinder is the first mission in 20 years to overcome a jinx known at Nasa as the great galactic ghoul. Since 1976, when the Viking landers returned 50 000 photographs, there have been six launches to Mars. Four were lost and one has yet to arrive.
Unlike Venus, which is closer to Earth than Mars, but is reminiscent of hell with temperatures of 600 C and sulphuric acid for rain, Mars is relatively hospitable to human life. Although the atmosphere is very thin – about a hundredth of Earth’s – there is air, temperatures vary between a manageable 30 C and -130 C, and the length of a Martian day (or “sol”) is conveniently close to the 24-hour Earth day. This makes Nasa’s ambition to have a permanently manned Mars space station within the next decade possible.
ENDS