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 mine detection rat is given banana as a reward after successfully identifying an inactive mine on July 2, 2015 in Siem Reap, Cambodia. The Cambodian Mine Action Center (CMAC) working with the Belgian NGO APOPO has recently begun testing the feasability of using large mine detection rats from Tanzania to help clear fields of mines and unexploded ordnance in one of the most bombed and mined countries in the world. (Photo by Taylor Weidman/Getty Images)

A Hindu priest waits to perform prayers next to Tejas, India's first locally-built Light Combat Aircraft (LCA), before its induction into the Indian Air Force at the Hindustan Aeronautics Limited (HAL) Airport in Bengaluru, India, July 1, 2016. (Photo by Abhishek N. Chinnappa/Reuters)

Jennifer Oeser of Germany competes in the Women's Heptathlon Long Jump on Day 8 of the Rio 2016 Olympic Games at the Olympic Stadium on August 13, 2016 in Rio de Janeiro, Brazil. (Photo by Alexander Hassenstein/Getty Images)

A P-51 Mustang named “Charlotte's Chariot” from the Southern Heritage Air Foundation flies past a cloud of smoke and fire from a nearby battle reenactment during the Wings Over Houston Airshow in Houston, on Saturday, November 1, 2014. Battle reenactments are part of the yearly show held at Ellington Airport. (Photo by Kar Hlava/AP Photo/Bay Area Citizen)

Men help a woman affected by tear gas used by National Police officers to disperse a demonstration of supporters of Fanmi Lavalas political party in the streets of Port-au-Prince, Haiti, November 22, 2016. (Photo by Andres Martinez Casares/Reuters)

A man and a dog bathe in a fountain during celebrations of Paratroopers' Day in Moscow' s Gorky Park on August 2, 2017. Russia' s Airborne Troops (Blue Berets) celebrate their professional holiday on the Day of Elijah the Prophet, their Patron. (Photo by Stanislav Krasilnikov/TASS)

St Andrews University students skinny dip in the sea as May Day celebrations in St Andrews, Scotland on April 30, 2017. Hundreds of revellers ditched their clothes and bravely jumped into the bitterly cold North Sea. (Photo by Alamy Stock Photos)