A prototype battery-powered plane, called Greased Lightning or GL-10 is pictured flying at NASA's Langley Research Center in this undated handout photo obtained by Reuters May 1, 2015. The plane, which has 10 engines and can take off like a helicopter and fly efficiently like an aircraft, is currently in the design and testing phase. (Photo by Reuters/NASA)

A model wears a floral head dress as she promotes a chain of garden centres at the Royal Horticultural Soceity's Chelsea Flower Show in London, Britain, May 18, 2015. (Photo by Toby Melville/Reuters)

Uniformed participant dance during a mass rally and parade in the capital's main ceremonial square, a day after the ruling party wrapped up its first congress in 36 years by elevating him to party chairman, in Pyongyang, North Korea, May 10, 2016. (Photo by Damir Sagolj/Reuters)

Ng Sin Nee (L) and Lee Shin May (R) from Malaysia take pictures with the panoramic view of the city from the Sky Box at KL Tower, the world's seventh tallest telecommunications tower, in Kuala Lumpur on May 24, 2016. Officially opened on May 20, the Sky Box has been the latest attraction for tourists arriving to the Malaysian capital. It stands 300 metres above ground and can fit six people at any one time, and offers spectacular views of the Kuala Lumpur skyline, including the iconic Petronas Twin Towers. (Photo by Mohd Rasfan/AFP Photo)

Attendants prepare to fill glasses for delegates before the opening session of the Chinese People's Political Consultative Conference at Beijing's Great Hall of the People, Thursday, March 3, 2016. The more than 2,000 members of China's top legislative advisory body convened their annual meeting Thursday, kicking off a political high season that will continue with the opening of the national congress on Saturday. (Photo by Mark Schiefelbein/AP Photo)

Caoimhe Cooburn-Gray poses for a picture on St. Patrick's day in Dublin, Ireland March 17, 2016. Saint Patrick's Day is a cultural and religious celebration held on 17 March, the traditional death date of Saint Patrick (c. AD 385–461), the foremost patron saint of Ireland. Celebrations generally involve public parades and festivals, céilithe, and the wearing of shamrocks, as well as green or orange attire. (Photo by Clodagh Kilcoyne/Reuters)

A performer wearing costumes walk on stilts before a show during a lantern fair at the beginning of Chinese Lunar New Year, in Xi'an, Shaanxi province, February 11, 2016. (Photo by Reuters/Stringer)

A Chinese man wears a mask to protect against pollution as he waits at a red light while commuting to work in heavy smog on December 8, 2015 in Beijing, China. The Beijing government issued a 'red alert' for the first time since new standards were introduced earlier this year as the city and many parts of northern China were shrouded in heavy pollution. Levels of PM 2.5, considered the most hazardous, crossed 400 units in Beijing, lower than last week, but still nearly 20 times the acceptable standard set by the World Health Organization. The governments of more than 190 countries are meeting in Paris to set targets on reducing carbon emissions in an attempt to forge a new global agreement on climate change. (Photo by Kevin Frayer/Getty Images)