NASA says it is extending the international Cassini mission that is touring Saturn and its moons for another two years. The space agency announced the extension Tuesday. Since 2004, the unmanned probe has beamed back about 140,000 images. Its prime mission is slated to end in July. The agency says the $160 million extension will allow Cassini to make 60 more revolutions around the ringed planet and fly by its largest moon, Titan, and four other satellites.