Aeronautics and Space engineer at France's Compagnie Maritime d'Expertises, or Comex, Arnaud Prost (C) meets with a jogger as he tests on the ground the “Gandolfi 2” underwater training suit for spacewalk, on January 20, 2016 in the calanques region (rocky inlets) of Marseille. The underwater training suit “Gandolfi 2”, developed with the European Space Agency (ESA), is designed for training astronauts underwater to simulate space gravity for the astronaut's extravehicular activities (EVAs). (Photo by Boris Horvat/AFP Photo)

A reveler wearing sheepfur costume is seen in front of a bonfire on which they burn a coffin symbolizing winter during the closing ceremony of the traditional carnival parade in Mohacs, 189 kms south of Budapest, Hungary, 07 February 2016. The carnival parade of people, the so-called busos, dressed in such costumes and frightening wooden masks, using various noisy wooden rattlers is traditionally held on the seventh weekend before Easter to drive away winter, and is a revival of a legend, which says that ethnic Croats ambushed the Osmanli Turkish troops, who escaped in panic seeing the terrifying figures during the Turkish occupation of Hungary. (Photo by Tamas Soki/EPA)

In this photograph taken on February 18, 2016, Pakistani children ride on swings in the predominantly Pashtun Korangi District of Karachi. In a rundown district of Karachi, Rabia balks at a neighbour's proposal to vaccinate her children, demonstrating one of the biggest hurdles to eradicating polio in Pakistan by the end of the year: confused and frightened parents. (Photo by Asif Hassan/AFP Photo)

A general view of the ghost town of a former Soviet military radar station near Skrunda, Latvia, April 9, 2016. (Photo by Ints Kalnins/Reuters)

People walk during a polluted day in Shenyang, Liaoning province, March 31, 2016. (Photo by Reuters/Stringer)

In this May 1, 2016 photo, a reluctant donkey is alternately pushed and pulled and enticed with carrots toward town hall in order to be dressed for the costume competition at the annual donkey festival in Otumba, Mexico state, Mexico. Otumba was an important donkey market during Spanish colonial times, standing at the crossroads of major roads leading to Mexico City, where the beasts pulled heavy loads and carried travelers. Today, however, farmers use tractors and pickup trucks, and the donkey population is in decline. (Photo by Rebecca Blackwell/AP Photo)

A vendor sleeps at his vegetables shop at a main market in Colombo, Sri Lanka May 31, 2016. (Photo by Dinuka Liyanawatte/Reuters)

An elderly man uses a fan to shade himself from the sun as he walks in a public park in Beijing, Tuesday, June 7, 2016. Thursday marks the Duanwu Festival, a public holiday in China celebrated with outdoor activities including dragon boat races. (Photo by Mark Schiefelbein/AP Photo)