NASA reveals finalists for next New Frontiers robotic mission: Saturn's moon Titan or Rosetta spacecraft's comet

The field for NASA's next New Frontiers mission is narrowing. Officials announced the two finalists for a new robotic explorer mission -- one that would send a spacecraft to bring samples of the comet 67P/Churyumov-Gerasimenko to Earth, and another to explore Saturn's moon Titan. The two mission concepts, CAESAR and Dragonfly, detailed in a NASA briefing Wednesday, beat out 10 other proposals to explore solar system targets including a basin on the moon; the surface of Venus; and Enceladus, the icy ocean world that also circles Saturn. "The New Frontiers program is really the premier program for our principal investigators and indeed it's one of the most difficult programs to be selected for," said Jim Green, director of the Planetary Science Division at NASA Headquarters in Washington. NASA only selects about two of these medium-class missions every decade, he added.