The Ivanpah Solar Electric Generating System is seen in an aerial view on February 20, 2014 in the Mojave Desert in California near Primm, Nevada. The largest solar thermal power-tower system in the world, owned by NRG Energy, Google and BrightSource Energy, opened last week in the Ivanpah Dry Lake and uses 347,000 computer-controlled mirrors to focus sunlight onto boilers on top of three 459-foot towers, where water is heated to produce steam to power turbines providing power to more than 140,000 California homes. (Photo by Ethan Miller/Getty Images)

An Olympic Airways airplane stands on the premises of the former Athens International airport, Hellenikon June 16, 2014. For about six decades Hellenikon was Athens' only airport but it closed down in 2001 to make way for a newer, more modern airport before the city hosted the 2004 Olympic Games. After languishing for years as a wasteland of crumbling terminals, Hellenikon is set for resurrection as a glitzy coastal resort. Lamda Development, controlled by Greece's powerful Latsis family and leading a consortium of Chinese and Abu-Dhabi based companies, has big dreams for the area since signing a 915 million euro deal for a 99-year lease in March 2014. (Photo by Yorgos Karahalis/Reuters)

In this photo taken Wednesday, November 26, 2014 attack dogs and their handlers apprehend a “rhino poacher” center, after alighting from a helicopter into water, in a simulation exercise showing training at an academy run by the Paramount Group, near Rustenburg, South Africa. The course prepares canine units to find firearms or contraband, track suspects in the undergrowth and abseil in harnesses from helicopters in pursuit of poachers. Dogs and handlers learn to trust each other and fine tune a relationship balancing control and aggression. (Photo by Denis Farrell/AP Photo)

A muddied family photograph sits on a hallway stairwell in an apartment block on March 17, 2011 in Kensennuma, Japan. Residents were allowed back to their homes today and began the massive cleanup operation caused by a 9.0 magnitude strong earthquake that struck on March 11 off the coast of north-eastern Japan. The quake triggered a tsunami wave of up to 10 metres which engulfed large parts of north-eastern Japan. The death toll has risen past 5000 with at least 8600 people still missing. (Photo by Chris McGrath/Getty Images)

Doctor Boaz Zissu of the Bar Ilan University shows the inscription on a 2,000-year-old ossuary at the Rockefeller Museum on June 30, 2011 in Jerusalem, Israel. The Israel Antiquities Authority have confirmed the credibility of the ancient ossuary, otherwise known as a stone chest in which to store bones, as bearing the name of a relative of the high priest Caiaphas from the New Testament. Laboratory tests have come back saying that the inscription with the name of “Miriam daughter of Yeshua son of Caiaphas, priest of Maaziah from Beth Imri” is both “genuine and ancient”. (Photo by Uriel Sinai/Getty Images)

James Castrission, “Cas” and Justin Jones “Jonesy” ski across an ice staking rink with two “You Can” patients on August 2, 2011 in Sydney, Australia. In 75 days, the Aussie adventure pair will attempt to cross 2,200 kilometres of Antarctic ice to the South Pole and back on foot to raise money for youth with cancer. The journey will require the two to trek with all the supplies for approximately three months of walking. Cas and Jonesy became the first to kayak unassisted over 3,300 kilometres from New Zealand to Australia in 2008. (Photo by Ryan Pierse/Getty Images)

Two of 20 skulls to be taken possession of by a delegation from Namibia stand on display at a ceremony at Charite hospital on September 30, 2011 in Berlin, Germany. The skulls are from Herero and Nama tribespeople taken by German colonial forces between 1904 and 1908, when the Germans violently suppressed an uprising in what was then German Southwest Africa, which is today's Namibia, and in the process killed tens of thousand of Herero and Nama. German scientists at the time took the skulls back to Berlin to demonstrate the racial superiority of Europeans over black Africans. Many Namibians demand a formal apology from the German government. (Photo by Sean Gallup/Getty Images)

An immigrant from Mali rests at the Greek-Macedonian border before an attempt to flee to Macedonia May 13, 2015 village of Idomeni in Kilkis prefecture May 13, 2015. Hundreds of mostly Afghan, Syrian, and African immigrants cross daily from Greece into Macedonia on their way to northern European countries; most of them are turned back by Macedonian border guards. (Photo by Yannis Behrakis/Reuters)