This undated image provided by World View shows World View capsule and balloon spacecraft that will rise to 100,000 feet above Earth for passengers to see the curvature of the planet and the blackness of space. Space tourism companies are employing designs including winged vehicles, vertical rockets with capsules and high-altitude balloons. While developers envision ultimately taking people to orbiting habitats, the moon or beyond, the immediate future involves short flights into or near the lowest reaches of space without going into orbit. (Photo by World View via AP Photo)

A young man with an amputated leg poses for a photograph standing by his broken artificial limb in the rebel-controlled area of Maaret al-Numan town in Idlib province, Syria March 20, 2016. Two university students forced to interrupt their studies have learnt to make and fit hundreds of new limbs in the past four years in opposition-held areas of Syria. A mobile clinic operating from a truck has gone some way to improve access to treatment. While most patients are between 15 and 45, the clinic also helps children and the elderly with replacement limbs. (Photo by Khalil Ashawi/Reuters)

A performer from Cirque du Soleil's show “Quidam” practices backstage before a show at the MEO Arena in Lisbon December 18, 2014. (Photo by Rafael Marchante/Reuters)

A woman protests her eviction from a building she and others invaded about a week ago in the Flamengo neighborhood of Rio de Janeiro, Brazil, Tuesday, April 14, 2015. Police dislodged squatters from the building slated for use as a luxury hotel for the 2016 Olympics in Rio de Janeiro. (Photo by Silvia Izquierdo/AP Photo)

A Myanmar Shiite Muslim devotee runs barefoot over a bed of burning coals as he takes part in a Muharram procession ahead of the Islamic holiday Ashura, in Yangon, Myanmar, October 22, 2015. Muslims across the world are observing Moharram, the first month of Islamic calender, the climax of Moharram is the Ashura festival commemorating the martyrdom of Imam Hussein, a grandson of the Prophet Mohammed in the Iraqi city of Karbala in the seventh century. (Lynn Bo Bo/EPA)

A reveller walks through the streets in the early hours during traditional May Day celebrations in Oxford, Britain, May 1, 2015. (Photo by Dylan Martinez/Reuters)

This Thursday, April 30, 2015 photo shows Lebanese citizens walking on the Corniche, or waterfront promenade in Beirut, Lebanon. This photo was shot through the lowered veil of a niqab, which is worn by some conservative Muslim women. The cloth allows women to follow a strict interpretation of their religious beliefs by preventing others from seeing their faces. (Photo by Hassan Ammar/AP Photo)

Russian Mi-28N from the Berkuty (Golden Eagles) helicopter display team fly in formation during the “Aviadarts” military aviation competition at the Dubrovichi range near Ryazan, Russia, August 2, 2015. The aircraft started dipping down due to back propeller failure and crashed, killing one of two pilots, according to a Reuters photographer and official representatives of the competition. The aviation contest is part of the International Army Games, which are held in Russia from the 1st till the 15th of August with participants from 17 countries, according to organizers. (Photo by Maxim Shemetov/Reuters)