Everything in the seven-minute action-packed entry sequence, starting with the spacecraft hurtling in at over 21,000 km per hour and ending with the six-wheeled robotic rover being lowered by nylon cords to the surface of Mars, went just as planned. Back on the home planet, controllers and mission staff assembled at the famed Jet Propulsion Laboratory in the U.S. jumped up in elation and celebrated when word came through in the form of radio signals that Curiosity, as the rover is called, had indeed landed safely. Soon afterwards, the first grainy picture taken by a camera on the rover came through. The plan is for the car-sized rover to spend the next two years trundling about, looking for indications that Mars could, at least in the past, have supported life. Humans have long been excited by ideas of life that might exist on the neighbouring planet. In the early years of the last century, it was thought that intelligent beings there had constructed a network of irrigation channels. From that, with a bit more imagination, ‘Little Green Men’, who might have designs on Earth, emerged.

But in the years since then, it has become clear that Martians, if they indeed existed, would be microscopic and microbial, rather than the swashbuckling sort found in science fiction. Spacecraft that surveyed Mars from orbit and earlier rovers that wandered its surface have found convincing evidence that although the planet is now dry, liquid water once existed on its surface. Where there is water, there could have been life. Curiosity has been put down in the Gale Crater, which appears to have once held a large body of water. The rover’s instruments will look for more evidence of water and how the environment in the crater changed over time. It will study whether other ingredients needed to support life, such as key chemical elements and sources of energy, were present. If organic molecules are discovered, that might suggest life had existed, assuming that non-biological origins could be ruled out. Perhaps the most exciting possibility is finding unmistakable indications that life in some form still survives somewhere on the planet. India’s Mars mission, which was recently cleared by the Cabinet and is scheduled to be launched at the end of next year, should be able to contribute to such a search by scrutinising the planet’s atmosphere from orbit. There may be methane in the atmosphere, which could have a biological origin. The next logical step in the exploration of Mars will be to bring rock and soil samples back to Earth for detailed analysis. Such an ambitious and costly effort could well be an international one. Only then will the issue of life on that planet be finally settled.

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