A massive explosion on Mars millions of years ago blasted into orbit rocks that have landed on Earth during recent decades, University of California at San Diego chemist Kurt Marti said today. Marti claims that he has confirmed that a 40-pound meteorite that landed in Nigeria in 1962 was a piece of the distant planet. He explained that gas bubbles trapped inside the meteorite were matched with the atmosphere that the U.S. Viking spacecraft found on Mars in 1976. Marti said further testing showed that the meteorite was wandering in space for about three million years before it landed on Earth. Another meteorite that was found in Antarctica 10 years ago also had the chemical signature of the Martian atmosphere, according to Marti, whose findings are being published in tomorrow's edition of the journal Science.