There’s a little spot on Mars, fairly close to the equator, that a few Phoenix kids know better than their own back yards. Ten students from Madison No. 1 Elementary School scoured an 11- by 34-mile patch of the Red Planet for signs of water. But they didn’t use just any old picture of Mars for their research. They studied an image shot especially for them by a camera on NASA’s 2001 Mars Odyssey spacecraft.