Dan McManus and his service dog Shadow hang glide together outside Salt Lake City, Utah, July 22, 2013. McManus suffers from anxiety and Shadow's presence and companionship help him to manage the symptoms. The two have been flying together for about nine years with a specially made harness for Shadow. (Photo by Jim Urquhart/Reuters)

Students carry a female trainee who has fallen into a stupor during high intensity training at Tianjiao Special Guard/Security Consultant camp on the outskirts of Beijing December 1, 2013. Former Chinese soldier Chen Yongqing has big ambitions for his bodyguard training school Tianjiao, which he says is China's first professional academy to train former soldiers and others as personal security guards. Chen charges 500,000 yuan ($82,400) a year for each protector as China's rich and famous look to bolster their safety and sense of importance. (Photo by Jason Lee/Reuters)

Todd Bretl specializes in underwater photography, and is able to capture striking photos of aquatic life big and small. His photos of sharks are particularly striking; though he rarely faces hostility from the animals, he tries not to spend too much time looking through his viewfinder and many shots are framed by educated guesses and impeccable timing. What follows are photographs taken over the past several years on trips to the Bahamas and Isla Guadalupe, an island off the coast of the Baja California peninsula in Mexico. (Photo by Todd Bretl)

An American flag is visible in the windows of the cupola aboard the International Space Station. Thanks to a bill passed by Texas legislators in 1997 that put in place technical voting procedure for astronauts – nearly all of whom live in Texas – they have the ability to vote from space through specially designed absentee ballots. To preserve the integrity of the secret vote, the ballot is encrypted and only accessible by the astronaut and the county clerk responsible for casting the ballot. (Photo by NASA)

Marieke van der Meer from the Netherlands works on her sculpture “Flora” at the sand sculpture show in Binz on Ruegen island, Germany, 09 March 2016. With the motto “Fascination Nature”, 50 sand artists have created oversized sculptures. The sculptors use 16,000 tons of special sand that is pressed into big blocks first and then formed. The 7th sand sculpture show on 5,600 square meters of exhibition ground opens on 12 March 2016. (Photo by Ens Buettner/EPA)

A couple wearing masks as a precaution against the spread of the new coronavirus walk on the Malecon seawall at sunset in Havana, Cuba, Monday, August 31, 2020. Cuban authorities will introduce new measures starting tomorrow Tuesday aimed at containing the spread of the coronavirus in Havana among others a curfew from 7 pm until 5 am and no one without special permission will be able to enter or leave the province. The new measures will last at least 15 days. (Photo by Ramon Espinosa/AP Photo)

On September 1, 2004, Chechen militants stormed an elementary school in the town of Beslan in the Russian republic of North Ossetia. They took 1,100 teachers, children, and their relatives hostage, demanding the withdrawal of federal forces from Chechnya as a condition for their release. On September 3, 2004, Russian security forces stormed the building, resulting in a battle in which more than 330 hostages died, including 186 children. Here: A man assists two young hostages who managed to escape from the school building after special forces entered the school in Beslan, North Ossetia, Friday 03 September 2004. (Photo by Yuri Kochetkov/EPA)

Iraqi pro-government forces fire an anti-tank cannon near al-Sejar village, north-east of Fallujah, on May 25, 2016, as they take part in a major assault to retake the city from the Islamic State (IS) group. Iraqi forces, consisting of special forces, soldiers, police, paramilitary-fighters and pro-government tribesmen, launched a major assault to retake Fallujah, the scene of deadly battles during the US occupation and one of the toughest targets yet in Baghdad's war on the Islamic State group. (Photo by Ahmad Al-Rubaye/AFP Photo)