Rhino poaching has been on the rise in the past few years. In South Africa and other regions where rhinos run, poachers have been killing or darting rhinos with tranquilizers for their horns.
Rather than adorning walls, many horns are ground up into medicines, sold mostly in Southeast Asia. A possible — yet controversial — way to stop poaching may be rhino ranches, where the horns are harvested for sale and the animals are allowed to grow new ones.
Robert Siegel talks to retired Navy Captain Don Walsh about the attempt by movie director James Cameron to take a submersible capsule to the bottom of the Mariana Trench — the deepest spot on Earth. Walsh says it will be a combination of science and adventure, because Cameron is a storyteller and dedicated amateur explorer. Walsh made a 1960 dive to the same trench.