Editorial: Mars/Once it was the Wet Planet, too Star Tribune

It has been only a century or so since astronomers noted the first suggestions of water on Mars — the trench-like surface features still known, somewhat fancifully, as canals. Since then the clues have come in a trickle: Satellite photos of rock that might have been carved by currents, discovery of a polar ice cap, readings from chemical probes that might or might not point to ancient moisture.