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Mars no bar

More is less on Mars. The more data space probes send back, the stranger seems the fourth rock from the sun. Consider one of its greatest mysteries: water, or the apparent absence of it.

india Updated: Mar 20, 2006 01:06 IST

More is less on Mars. The more data space probes send back, the stranger seems the fourth rock from the sun. Consider one of its greatest mysteries: water, or the apparent absence of it. Italian astronomer Giovanni Schiaparelli’s claims of seeing ‘canali’ (Italian for channels) on the Red Planet prompted a mistranslation of ‘canali’ to ‘canals’ by a world excited with the Suez Canal opening. People used it as proof that intelligent life had actually built a canal system on Mars! It even inspired H.G. Wells to pen the War of the Worlds, in 1898, envisioning ‘little green men’ stalking Earth.

Scientists now know that Mars was once a very wet and warm planet. Its oceans presumably disappeared when the planet went through a water cycle and it was cold enough for water to freeze. These cycles of millions of years are caused by the wobble of the Martian axis. As on Earth, the water could have escaped into the atmosphere, or frozen out near the poles and emerged onto the surface in warmer times to cut the sharp channels we now see.

In 2000, Nasa’s Mars Global Surveyor spacecraft spotted hundreds of delicately filigreed gully systems that indicated swimming-pool volumes of water lying entombed underground. The frozen water must have accumulated in winter and evaporated in summer in each hemisphere. Ice doesn’t melt into liquid water on Mars — instead it sublimes, changing directly from solid to gaseous state, like ‘dry ice’ on Earth. But as seasonal swings over centuries evaporated the polar ice caps, it’d have raised the pressure enough to keep water stable in liquid form. In 2002, the Mars Odyssey spacecraft confirmed this when it found tell-tale signs of water ice, in the upper layers of soil in a large region surrounding the south pole.

The presence of so much water (enough to fill an area ten times larger than Uttar Pradesh and Madhya Pradesh put together) means an invaluable resource for manned Mars missions — from providing fuel, oxygen and drinking water to landscaping the planet for human settlement. Since water is a prerequisite for life, these findings also hint at some form of life on Mars. But surface life is unlikely because of the absence of surface water and harsh radiation. A two million-year-old ice slab found by a European probe last year, however, suggests there were wet places beneath the Martian surface before life began on Earth, which could possibly harbour primitive micro-organic life.

All eyes are now on Nasa’s Mars Reconnaissance Orbiter that reached the planet last week to study its composition and search for liquid water beneath the surface using radar sounders. The question of life on Mars may be settled by the end of this decade.

First Published: Mar 20, 2006 01:06 IST