1. They include Becquerel Crater in Arabia Terra, a densely cratered zone in the northern hemisphere, where rock layers can also be seen.

2. FISSION HISTORY 18'6: radioactivity was discovered by Henri Becquerel 1'47: the first UK research reactor started at Harwell 1'4': start of civil nuclear energy in Britain with decision that the next plutonium–producing reactors should generate electricity 1'56: first of four reactors, built at Calder Hall near Windscale in Cumbria, opened by the Queen 1'5': four more at Chapelcross opened. 1'7': Three Mile Island nuclear power plant near Harrisburg, Pennsylvania suffers a partial core meltdown.

3. PM –– Key dates in the history of nuclear power: 18'7: French scientists Marie Curie and Henri Becquerel discover radioactivity. 1'42: Manhattan Project begins, creating top–secret nuclear research and production facilities. 1'51: U.S. reactor creates first usable electricity from nuclear fission. 1'56: France‘s first nuclear reactor goes on line. 1'7': Accident at Three Mile Island in Pennsylvania causes partial meltdown, halting expansion of U.S. nuclear industry and spurring the anti–nuclear movement. 1'86: Reactor at Chernobyl plant in Soviet Union explodes, killing four people immediately and exposing millions to radiation, which reached as far as Sweden and Germany.