NASA will either sample a comet or visit Saturn's moon Titan

Saturn's third-largest moon Dione can be seen through the haze of its largest moon, Titan, in this view from NASA's Cassini spacecraft. Credit: NASA / JPL-Caltech / Space Science Institute

NASA has selected two finalists for the New Frontiers space program:

Why it matters: Both concepts will receive further design funding and one will eventually launch, possibly in the mid 2020s. Thomas Zurbuchen, associate administrator for NASA's Science Mission Directorate in Washington, D.C, told Scientific American's Lee Billings, "These are tantalizing investigations that seek to answer some of the biggest questions in our solar system today."