Hotel staff practice self-defence skills after a training session given by team member of Special Weapons and Tactics (SWAT) team, in Hangzhou, Zhejiang province, April 7, 2016. (Photo by Reuters/Stringer)

Athlets run during the women's 3000 meter steeplechase at the International Athletics Meeting in Lucerne, Switzerland, 14 June 2016. (Photo by Alexandra Wey/EPA)

“The banker”. Underwater Sculpture, Museo Subacuático de Arte, Cancun. (Photo by Jason deCaires Taylor/UnderwaterSculpture)

NASA says it could be another 20 years before humans touch down on Mars, but in a sense, the Mars Society has been exploring the red planet for more than a decade – in Utah. Photo: Csilla Orgel, a geologist of Crew 125 EuroMoonMars B mission, makes her way back to the Mars Desert Research Station (MDRS) in the Utah desert March 3, 2013. The MDRS aims to investigate the feasibility of a human exploration of Mars and uses the Utah desert's Mars-like terrain to simulate working conditions on the red planet. Scientists, students and enthusiasts work together developing field tactics and studying the terrain. All outdoor exploration is done wearing simulated spacesuits and carrying air supply packs and crews live together in a small communication base with limited amounts of electricity, food, oxygen and water. Everything needed to survive must be produced, fixed and replaced on site. (Photo by Jim Urquhart/Reuters)

Internally displaced Syrian children who fled Raqqa city stand near their tent in Ras al-Ain province, Syria January 22, 2017. (Photo by Rodi Said/Reuters)

Right wing demonstrators chase a Black Lives Matter protester after a pro-Trump caravan rally convened at the Oregon State Capitol building on September 7, 2020 in Salem, Oregon. The caravan event, billed as the Oregon For Trump 2020 Labor Day Cruise Rally, began in Clackamas and made its way to the Oregon State Capitol in Salem. (Photo by David Ryder/Getty Images)

Two women react to the camera as Nightclub Circus hosts the first dance event, which will welcome 6,000 clubbers to the city's Bramley-Moore Dock warehouse on April 30, 2021 in Liverpool, England. The event is part of the national Events Research Programme which will provide data on how events could be permitted to safely reopen. (Photo by Anthony Devlin/Getty Images)

A soldier supporting anti-government opposition groups carries a rocket-propelled grenade launcher on a street in the Fagah area of Mogadishu, Somalia Sunday, April 25, 2021. Gunfire was exchanged Sunday between government forces loyal to President Mohamed Abdullahi Mohamed, who signed into law on April 14 a two year extension of his mandate and that of his government, and other sections of the military opposed to the move and sympathetic to former presidents Hassan Sheikh Mohamud and Sharif Sheikh Ahmed. (Photo by Farah Abdi Warsameh/AP Photo)