A cloud of black smoke billows out the exhaust pipe of John Robertson's diesel dragster as he runs down the track during the 2015 NHRA Kansas Nationals, Friday, May 22, 2015, at Heartland Park in Topeka, Kan. (Photo by Chris Neal/The Topeka Capital-Journal via AP Photo)

A model of the New Horizons spacecraft is seen at a live television program on NASA television celebrating the spacecraft's closest proximity to Pluto, at Johns Hopkins University Applied Physics Laboratory, site of the mission operations center, in Laurel, Maryland, USA, 14 July 2015. At approximately 7:49 am ET (11:49 am GMT), 14 July, New Horizons was scheduled to be as close to Pluto as the spacecraft will get; about 7,800 miles (12,500 kilometers) above the surface, following a journey of more than nine years and three billion miles. This is the first mission to the Pluto System and the Kuiper Belt. (Photo by Michael Reynolds/EPA)

People are reflected in a shop window as they walk along a street in a shopping district in Tokyo, Japan June 25, 2015. (Photo by Thomas Peter/Reuters)

The Enemy, 1944. With the outbreak of world war two, photojournalism was enlisted in defence of Mother Russia. In this photo by Anatoli Egorov, who was wounded in action, corporal Stepan Vasiljevich Ovcharenko shoots at enemy troops with a machine gun. (Photo by Anatoli Egorov/Lumiere Brothers Center for Photography)

A general view shows smoke and volcanic ashes billowing from volcano Cotopaxi in Pedregal, Ecuador, late 07 October 2015. (Photo by Jose Jacome/EPA)

A massive sand storm cloud is close to enveloping a military camp as it rolls over Al Asad, Iraq, April 27, 2005. (Photo by Cpl. Alicia M. Garcia, U.S. Marine Corps/Reuters/U.S. Department of Defense)

A “nail house”, the last building in the area, sits in the middle of a road under construction in Nanning, Guangxi Zhuang Autonomous Region April 10, 2015. According to local media, the owner of the house didn't reach an agreement with the local authority about compensation of the demolition. (Photo by Reuters/Stringer)

In this July 15, 2015 photo, Nepalese amputee victims Khendo Tamang, left, and Nirmala Pariyar, both 8, share a single pair of shoes at the Bir Trauma Center in Kathmandu, Nepal. After suffering serious leg wounds in Nepal's massive 2015 earthquake that killed and injured thousands, both girls were brought to the Bir Trauma Center in Kathmandu, to receive single leg amputations. Following their surgeries, Nirmala's relentless cheerfulness drew a still very depressed Khendo close and both found an inseparable friendship which has helped their emotional wounds heal. (Photo by Niranjan Shrestha/AP Photo)