America’s Mariner 9 yesterday radioed back its clearest pictures of the surface of Mars since going to orbit three days ago. “We are delighted,” scientist Dr. Bruce Murray said as screens at the Jet Propulsion Laboratory here displayed the wavy contour lines of the south polar icecap. The pictures followed a series of virtually blank shots taken as Mariner approached Mars and went into orbit, with the surface almost totally obscured by a great dust storm. The latest picture clearly showed the unique, complex formation of the pole. Dr. Murray said that the pictures resulted from a decision to swing the cameras around slightly and focus on the south pole from a different angle, while experimenting with various coloured filters. The pole had shown up in one picture taken during the first orbit. It is covered with frozen carbon dioxide and one picture appeared to show a cleft in the ice dividing the polar cap into two. “What is exciting to us is that we are going to get a complete map of the frost,” Dr. Murray said. This would be compared with the pictures of the polar icecap taken by the Mariner 6 and 7 fly-by missions in August 1969, which showed the cap at about its full winter extent, and indicated the mechanics of the seasonal changes.
