Guest Physicist Zia Mian on Nuclear Proliferation. Also: Spirit, The Mars Rover is looking for signs of life; Bush announces major space initiative that involves a possible permanent moon base and a human mission to Mars; Nukes in Space? What are the dangers of using Nuclear energy for space exploration?; Did a supernova wipe out life on earth 440 million years ago?; Scientists say global warming could wipe out 1/3rd of life on earth.; The honey-bee genome has been deciphered.