Tuesday, 2 October 2012

Water on Mars has a long history

It was November 1971. The scene at Nasa was a tense one, similar to that of Curiosity's landing back in August. Ground controllers held their collective breath as Mariner 9 approached Mars. If everything went to plan, the spacecraft would make history by being the first manmade object to go into orbit around Earth's neighbouring planet.
Mariner 9 was an octagonal spacecraft just less than a metre and a half across, with four cross-like solar panels sticking out another two metres from its body. Its mission was to map Mars. At the appointed time, the retrorockets fired and Mars' gravity took hold of the spacecraft.
Soon afterwards, data began to flow back to Earth from the cameras. Images built up on the monitor screens line by line but the scientists stared in mounting disappointment. Nothing was visible. The whole planet was engulfed in a dust storm. All the exquisite geology that the spacecraft was meant to see lay buried under a blanket of suspended particles.
All the personnel could do was wait for the dust to settle, and pray that the spacecraft would wait too. Even today spacecraft can be fickle things. Back then, they were positively cranky. They could fail at any time, for any of a thousand different unanticipated reasons. Mariner 8, for example, had been destroyed during its launch.
Time was of the essence as the dust storm raged. Days turned to weeks until the Martian skies finally began to clear in January. As it did, one titanic mountainous peak after another broke through the murk. These were the extinct volcanoes of the Tharsis region.
t is now 40 years since that first observational proof was beamed back to Earth. Every Mars mission since has corroborated the finding and yet new evidence for rivers or lakes still excites us more than anything else. The only news that could trump it would be the discovery of life on Mars.

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