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 man walks on the road between Nouahibou and Nouakchott, where three Spanish aid workers were abducted in Mauritania, December 3, 2009. (Photo by Rafael Marchante/Reuters)

Fishermen carry calabashes to attend Argungu fishing and cultural festival at Argungu Town, Kebbi State in northwestern Nigeria, on March 14, 2020. Argungu fishing and cultural festival is one of the oldest and most widely attended festivals in the country dating back many generations, featuring series of water competitions and traditional games. The festival returned after 10 years suspension due to insecurity in northwest Nigeria. (Photo by Pius Utomi Ekpei/AFP Photo)

Israeli police officers are about to push away a demonstrator during a protest against Israel's Prime Minister Benjamin Netanyahu outside his residence in Jerusalem, Israel, early Sunday, August 9, 2020. (Photo by Ariel Schalit/AP Photo)

View of an egg fried on the pavement in Pozo Hondo, Santiago del Estero, Argentina on January 23, 2016, while the real feel was 57 degrees Celsius. Pozo Hondo's Mayor Claudio Nicolau fried an egg on the pavement of the main square of the city Saturday. (Photo by AFP Photo/Stringer)

London Mayor Boris Johnson takes part in a tug of war with members of the armed services to launch the London Poppy Day, outside City Hall, in London, October 27, 2015. London Poppy Day is a street collection event to raise money for serving and retired members of the armed services and their families. (Photo by Stefan Wermuth/Reuters)

Icelandic horses play in their paddock at a stud farm in Wehrheim near Frankfurt, Germany, as a mist rolls in on Thursday, August 5, 2021. (Photo by Michael Probst/AP Photo)

A man dressed in a Halloween costume swims along the coast of the northern Lebanese city of Batroun, on October 28, 2021. (Photo by Ibrahim Chalhoub/AFP Photo)