2012: The year in space (36 images)

This NASA artist rendering released on January 1, 2012 shows NASA's Gravity Recovery And Interior Laboratory (GRAIL)-A spacecraft entering orbit around the moon. The second GRAIL spacecraft is expected to enter the moon's orbit tomorrow and the two will begin to map the lunar surface. UPI/NASA

NASA's orbiters "Atlantis" (l) and "Discovery" pass within feet of each other on the tow way between the Vehicle Assembly Building and the Orbiter Processing Facility at the Kennedy Space Center, Florida on March 9, 2012. Discovery, complete with the rear cone to enhance its aerodynamic performance for flight, is moving to the VAB where NASA will complete preparations to fly Discovery to the Smithsonian Museum's Steven F. Udvar-Hazy Center at Dulles Airport in Chantilly, Virginia near Washington DC. Atlantis is returning to the Processing Facility to continue modification for display at the Kennedy Space Center Visitor Complex in Florida. UPI/Joe Marino-Bill Cantrell

This undated NASA the south polar region of Saturn's largest moon, Titan, and shows a depression within the moon's orange and blue haze layers near the south pole, captured by the NASA's Cassini spacecraft, December 31, 2011. UPI/NASA