NASA's New Horizons Team watches the Pluto flyby (8 images)

Members of the New Horizons science team react to seeing the spacecraft's last and sharpest image of Pluto before closest approach later in the day, Tuesday, July 14, 2015 at the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland. The spacecraft was launched nine years ago and traveled 3 billion miles. NASA Photo by Bill Ingalls/UPI

Pluto nearly fills the frame in this image from the Long Range Reconnaissance Imager (LORRI) aboard NASA's New Horizons spacecraft, taken on July 13, 2015, when the spacecraft was 476,000 miles (768,000 kilometers) from the surface. This is the last and most detailed image sent to Earth before the spacecraft's closest approach to Pluto on July 14. The color image has been combined with lower-resolution color information from the Ralph instrument that was acquired earlier on July 13. The spacecraft was launched nine years ago and traveled 3 billion miles. NASA Photo/UPI

The silhouettes of Associate Administrator for the Science Mission Directorate John Grunsfeld, New Horizons Principal Investigator Alan Stern of Southwest Research Institute (SwRI), Boulder, CO., Glen Fountain, New Horizons Project Manager, APL, and Cathy Olkin, Co-investigator, Ralph instrument, SwRI are seen during a media briefing Monday, July 13, 2015 at the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland on July 13, 2015. The closest approach was in July 24, 2015. The spacecraft was launched nine years ago and traveled 3 billion miles. NASA Photo by Bill Ingalls/UPI

Members of the New Horizons science team react to seeing the spacecraft's last and sharpest image of Pluto before closest approach later in the day, Tuesday, July 14, 2015 at the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland on July 14, 2015. The spacecraft was launched nine years ago and traveled 3 billion miles. NASA Photo by Bill Ingalls/UPI