Nasa scientists say they have a found a landing site on Mars for the Polar Lander probe to touch down on the Red Planet later this year. The probe, designed to search for water in the form of ice or vapour on the Martian surface, will come down softly on the fine dust of “gentle, rolling plains” in a target area 198km (124 miles) long by 19km (12.4 miles) wide near the planet’s south pole.