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)

Elaine Vandiver shares a moment with a two-year old alpaca as they touch noses as she washes him at her farm at 1560 Stateline Road Monday, May 11, 2015, in Walla Walla, Wash. (Photo by Michael Lopez/Walla Walla Union-Bulletin via AP Photo)

Russian policewomen dressed in Soviet Army styled uniforms take part in the Victory Day parade in Volgograd on May 9, 2018. Russia marks the 73 rd anniversary of the Soviet Union' s victory over Nazi Germany in World War Two. (Photo by Mladen Antonov/AFP Photo)

Chechen Interior Minister Ruslan Alkhanov greets participants of the military parade to mark the Victory Day in Grozny, Russia, May 9, 2015. Russia marks the 70th anniversary of the end of World War Two in Europe on Saturday with a military parade, showcasing new military hardware at a time when relations with the West have hit lows not seen since the Cold War. (Photo by Reuters/Host Photo Agency/RIA Novosti)

A participant in wingsuit flies above Tianmen Mountain at Zhangjiajie Scenic Spot during the 4th Red Bull WWL China Grand Prix on October 16, 2015 in Zhangjiajie, Hunan Province of China. The 4th Red Bull WWL China Grand Prix will last three days from October 16-18 in Zhangjiajie. (Photo by ChinaFotoPress/Getty Images)

A dancer lets a Russian tourist practice the traditional tannoura dance at a cafe in the Red Sea resort of Sharm el-Sheikh, Egypt November 10, 2015. The fallout from the crash of a Russian Metrojet passenger plane in Egypt's Sinai Peninsula could slash tourism income from Sharm al-Sheikh by half, the head of the region's travel agents' association said on Tuesday. Several airlines have suspended flights to the Red Sea resort since the Oct. 31 crash, which investigators and Western governments believe was likely to have been caused by a bomb. Thousands of Russian and British tourists have been flown home. (Photo by Asmaa Waguih/Reuters)

A visitor poses for a photo with a Crayon Shin-chan model during an exhibition at Joy City in Beijing May 5, 2015. The exhibition, which showcased fifty models of the Japanese cartoon character in different poses and expressions, will run from April 18 to June 22. (Photo by Jason Lee/Reuters)

People dance Tuesday, April 28, 2015, in Baltimore. Maryland's governor vowed there would be no repeat of the looting, arson and vandalism that erupted Monday in some of the city's poorest neighborhoods. (Photo by Matt Rourke/AP Photo)