NASA has selected two missions to further explore past targets—Saturn's largest moon, Titan, and the comet 67P/Churyumov-Gerasimenko—as the final candidates for its next billion-dollar robotic spacecraft, the agency announced today. The candidates for the next New Frontiers mission, chosen from a field of 12, will now have until January 2019 to refine their pitches to the agency, with a launch planned by 2025.
The first, Dragonfly, would send a semiautonomous quad-copter to fly between sites on the surface of Titan, which features an Earth-like landscape of rivers and lakes filled with liquid methane. The second candidate, Comet Astrobiology Exploration Sample Return (CAESAR), would capture and return to Earth a sample from the nucleus of 67P/Churyumov-Gerasimenko—a comet previously explored by the European Space Agency's Rosetta spacecraft.
Rather than selecting three final candidates, as it has in the past, NASA opted for a head-to-head competition. "I selected these mission concepts based on their outstanding and visionary science," Thomas Zurbuchen, associate administrator of NASA’s science mission directorate in Washington, D.C., said in a teleconference announcing the finalists. "I didn't start with a number in mind."