An American flag flutters on a young tree stripped of bark after a massive tornado passed through the town killing at least 116 people May 24, 2011 in Joplin, Missouri. The tornado that ripped through the town of about 50,000 people May 22, is being called the deadliest single tornado in the U.S. in 60 years. (Photo by Julie Denesha/Getty Images)

Tourist Police sit in the shade on a road leading to the Coptic Cairo area on May 27, 2011 in Cairo, Egypt. Protests in January and February brought an end to 30 years of autocratic rule by President Hosni Mubarak who will now face trial. Food prices have doubled and youth unemployment stands at 30%. Tourism is yet to return to pre-uprising levels. (Photo by Peter Macdiarmid/Getty Images)

Yuan Zi, a male giant panda and Huan Huan, a female giant panda, share their life inside their enclosure at Zoo Parc De Beauval on January 25, 2012 in Beauval, France. A pair of giant pandas which have been loaned to the zoo by China, where they hope the pair will reproduce and help boost the world's dwindling panda population. (Photo by Franck Prevel/Getty Images)

Residents (R to L) Luiza, Janubie, Leiticia and Lucas sit beneath an overpass near their houses in an impoverished area in the unpacified Complexo da Mare slum complex, one of the largest “favela” complexes in Rio, on March 18, 2014 in Rio de Janeiro, Brazil. (Photo by Mario Tama/Getty Images)

Vintage wine bottles dated from 1946 lay down in the wine cellar of the Massandra winery near Yalta, 28 March 2014 (Yalta is a resort city on the north coast of the Black Sea in the Autonomous Republic of Crimea, a territory recognized by a majority of countries as part of Ukraine and incorporated by Russia as the Republic of Crimea). Massandra winery has one of the largest wine collections in the world. (Photo by Sergei Ilnitsky/EPA)

A man photographs the main engines of the space shuttle orbiter Discovery on display at the Udvar-Hazy Smithsonian National Air and Space Annex Museum in Chantilly, Virginia August 28, 2015. Shuttle Discovery had 27 years of service and flew 39 times before being retired in 2011. (Photo by Gary Cameron/Reuters)

A policewoman wipes her tears as she stands in front of metal caskets containing the bodies of Special Action Force (SAF) police who were killed in Sunday's clash with Muslim rebels, at Villamor Air Base in Pasay city, metro Manila January 29, 2015. Philippine President Benigno Aquino urged legislators on Wednesday not to abandon a plan for autonomy for Muslims to end a decades-old insurgency after the clash in which dozens of people were killed, saying doing so would dash hopes for peace. (Photo by Romeo Ranoco/Reuters)