Stefan Dobrovolny of Austria and Inigo Munoz Elorza of Spain (R) stand in front of a quad bike during a simulated Mars mission on Tyrolean glaciers in Kaunertal, Austria, August 7, 2015. The Austrian Space Forum is sending some of its researchers to practice weight-less walking in spacesuits on a glacier which resembles the terrain on Mars. (Photo by Dominic Ebenbichler/Reuters)

A Chinese future bride has her friends playing with her dress during a pre-wedding photoshoot in front of the Eiffel tower in Paris, France, August 28, 2015. As young Chinese become wealthier, they take abroad the tradition of taking their wedding photos days before they are married, rather than on their wedding day. (Photo by Philippe Wojazer/Reuters)

A street cleaner demonstrates his martial arts skills in front of a closed shop near Beijing's Tiananmen Square September 2, 2015 as the capital prepares for tomorrow's parade. (Photo by Damir Sagolj/Reuters)

A selection of prizewinning images from the Take a View 2016 photography awards. Here: Finding Gold, taken in Wast Water in Cumbria, which won the Great Britain #OMGB “Home of Amazing Moments” award. (Photo by Mark Gilligan/PA Wire)

The People of Mah Meri tribe at home at Pulau Carey village on December 03, 2016 in Selangor, Malaysia. The Mah Meri people are one 18 tribes of Orang Asal (indigenous people) living in west Malaysia. The Mah Meri are know for thei wood carvings and also for the richness of their songs and dances. (Photo by Yuli Seperi/Sijori Images/Barcroft India)

Women in yukatas, or casual summer kimonos, take their selfie in front of paper lanterns during the annual Mitama Festival at the Yasukuni Shrine, where more than 2.4 million war dead are enshrined, in Tokyo, Japan July 13, 2017. (Photo by Kim Kyung-Hoon/Reuters)

A woman stands in front of graffiti depicting Venezuela's late former President Hugo Chavez, right, and revolutionary hero Simon Bolivar, in downtown Caracas, Venezuela, Wednesday, October 25, 2017. (Photo by Rodrigo Abd/AP Photo)

Brazil's synchronised swimmers Luisa Borges (front) and Maria Eduarda Miccuci perform during a training session at the Rio Olympic Park in Rio de Janeiro, Brazil, April 7, 2016. (Photo by Pilar Olivares/Reuters)