The NASA Extreme Environment Mission Operations (NEEMO) 21 mission began on July 21 as an international crew of aquanauts splashed down to the undersea Aquarius Reef Base, located 62 feet below the surface of the Atlantic Ocean in the Florida Keys National Marine Sanctuary. The NEEMO 21 crew will perform research both inside and outside the habitat during a 16-day simulated space mission. During simulated spacewalks carried out underwater, they will evaluate tools and mission operation techniques that could be used in future space missions, including journeys to Mars. (Photo by Karl Shreeves/NASA)

A participant with a face painted as popular Mexican figure “Catrina” attends the Day of the Dead event at a National house for Mexican fans in central Moscow, a host city for the 2018 FIFA World Cup, Russia June 29, 2018. (Photo by Sergei Karpukhin/Reuters)

A woman cools off from the extreme heat from an opened fire hydrant in Brooklyn, New York on July 2, 2018. The highest temperature reached 35 degrees Celsius in New York City on Monday as a result of a prolonged heat wave. (Photo by Shannon Stapleton/Reuters)

England fan celebrates on top of an ambulance after England' s win over Sweden in the Russia 2018 World Cup quarter- final football match, in London on July 7, 2018. (Photo by Henry Nicholls/Reuters)

Ministry of Defence handout photo of Chinooks from RAF Odiham as they take part in the Royal Air Force flypast over central London to mark the centenary of the RAF on Tuesday, July 10, 2018. (Photo by SAC Pippa Fowles (RAF)/PA Wire)

A reveller perches on a public hire bicycle outside a bar in Shoreditch, the weekend before new licensing rules come in to effect across Hackney on July 28, 2018 in London, England. Hackney Council has voted to introduce strict new licensing rules which will see “core” curfews in place for new venues as well as extending the “Special Policy Area”, within which licenses are granted only in exceptional circumstances. (Photo by Jack Taylor/Getty Images)

Amy Winehouse's father Mitch Winehouse (C) mother Janis Winehouse (L in white) brother Alex Winehouse (R) and former boyfriend Reg Traviss (2nd R) look at floral tributes left at her house by fans on July 25, 2011 in London, England. (Photo by Gareth Cattermole/Getty Images)

A person poses on the track during a fashion competition at the Durban July horse racing event in Durban, South Africa July 1, 2017. (Photo by Rogan Ward/Reuters)