Participants climb over a wall at the “Tough Mudder” endurance event series in Arnsberg September 6, 2014. Competitors who took part in the endurance event saw themselves having to overcome various military style obstacles. (Photo by Ina Fassbender/Reuters)

Employees prepare spacesuits at the Russian-leased Baikonur cosmodrome in Kazakhstan on August 19, 2015. Members of the main crew of the 45/46 expedition to the International Space Station ISS, Kazakhstan's cosmonaut Aydyn Aimbetov, Russian cosmonaut Sergei Volkov and Denmark's astronaut Andreas Mogensen from the European Space Agency, are scheduled to blast off to the International Space Station (ISS) on September 2, 2015. (Photo by AFP Photo)

Kristina Elekes, 23, races on her ski during the Bikini Race contest held at Arena Platos Paltinis winter resort, near Sibiu city, 275 Km north from Bucharest, Romania, 06 March 2016. Bikini Race is a timed show on the slopes, at the fourth edition, for women dressed only in swimmsuits and some winter accessories. (Photo by Mihaela Bobar/EPA)

Polar bear twins make their first public appearance with their mother “Freedom” at Ouwehands Zoo Rhenen, in Rhenen, The Netherlands, 19 February 2015. The twins, who were born in November 2014, have not been named because their gender has not yet been determined. (Photo by Bart Maat/EPA)

Indonesian mahouts clean their Sumatran elephant in a river near the zoo in Medan, North Sumatra, Indonesia, 12 December 2014. According media reports, the smallest of the Asian elephants, Sumatran elephant (Elephas maximus sumatrensis) is facing serious pressures arising from illegal logging and associated habitat loss and fragmentation in Indonesia. The population has come under increasing threat from rapid forest conversion to plantations. (Photo by Dedi Sahputra/EPA)

The villas of Marabe Al Dhafra in Abu Dhabi, United Arab Emirates are home to approximately 2,000 people. Located in one of the hottest regions of the world, the record high temperature here is 49.2C° (120.6F°). (Photo by Benjamin Grant/Penguin Random House)

In this February 26, 1962 file photo, Mercury astronaut John Glenn, and his wife, Annie, ride in the back of an open car with Vice-President Johnson during a parade in Glenn's honor in Washington. The Capitol is seen in the background. Glenn, the first American to orbit Earth who later spent 24 years representing Ohio in the Senate, died Thursday, Dec. 8, 2016, at the age of 95. (Photo by AP Photo)

A model presents a creation during a hair styling competition in Minsk, Belarus on November 9, 2017. (Photo by Sergei Gapon/AFP Photo)