SpaceX’s Dragon spacecraft, March 6, 2014. SpaceX's Falcon 9 rocket and Dragon spacecraft launched from Launch Complex 40 at the Cape Canaveral Air Force Station, Florida, for their third official Commercial Resupply (CRS) mission to the orbiting lab on April 18, 2014. Dragon returned to Earth with a parachute-assisted splashdown off the coast of southern California on May 14, 2014. Dragon is the only operational spacecraft capable of returning a significant amount of supplies back to Earth, including experiments. (Photo by Ron Lin/SpaceX Photos)

A window cleaner passes a lighter to his colleague while rappelling from a new building in Tianjin March 23, 2007. (Photo by Reuters/Stringer)

A couple of monkeys look from inside their cage at a rescue and rehabilitation center in Santiago, Chile, Saturday, November 22, 2014. Elba Munoz who runs the center, says that one of the goals of the Center for the Rescue and Rehabilitation of Primates is to stop the trafficking of the animals. (Photo by Luis Hidalgo/AP Photo)

A truck is seen in a hole after part of the structure of a bridge collapsed into a river in Changchun, Jilin province May 29, 2011. Two truck passengers were injured, while the cause of the accident is still under investigation, local media reported. (Photo by Reuters/China Daily)

Lindsay Heimbach goes airborne while sledding down a hill on Mt. Lemmon December 27, 2008. (Photo by James Gregg/Arizona Daily Star)

A protester uses molotov cocktails against riot police during May Day protests on May 1, 2010 in Athens, Greece. (Photo by Milos Bicanski /Getty Images)

Finia, a visiting student from Hanover, cools off under a water sprinkler in front of the Chancellery on June 10, 2010 in Berlin, Germany. (Photo by Sean Gallup/Getty Images)

Fuse TV VJ's Marianela and Juliya attend the store opening of “Nigo's A Bathing Ape” with Pharrell Williams January 11, 2005 in New York City. (Photo by Paul Hawthorne/Getty Images)