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)

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)

Demonstrators take part in a protest against U.S. President Donald Trump in Glasgow, Britain February 20, 2017. (Photo by Russell Cheyne/Reuters)

Journalists interview a girl, member of the Cryophile amateurs winter swimmers club, after bathing in the ice waters of the Yenisei River, during the celebrations for the upcoming Christmas and New Year, in Krasnoyarsk, Russia, December 23, 2017. (Photo by Ilya Naymushin/Reuters)

A girl gets her arm sketched with a body paint tattoo depicting the traditional Dandiya dance, ahead of Navratri, a festival when devotees worship the Hindu goddess Durga, in Ahmedabad, India, September 25, 2016. (Photo by Amit Dave/Reuters)

An aerial view taken on September 11, 2020 shows the Buddhist temple Wat Samphran (Dragon Temple) in Nakhon Pathom, some 40km west of Bangkok. Wat Samphran is a popular tourist destination with visitors coming to see the huge dragon figure curling around a pink cylindrical building next to the Buddha statues and places of worship of the traditional Buddhist temple complex. (Photo by Mladen Antonov/AFP Photo)

Volunteers skin western diamondback rattlesnakes during the 2021 Rattlesnake Roundup at the Nolan County Coliseum in Sweetwater, Texas on March 13, 2021. The town of Sweetwater holds the largest rattlesnake roundup in the world, launched in 1958 with the sole purpose of getting rid of rattlesnakes, killing an average of 5,000 pounds of snake each year. (Photo by Paul Ratje/AFP Photo)

Migrant children run away from clashes with Mexican National Guards after their group crossed the Suchiate River on foot from Guatemala to Mexico, on the riverbank near Ciudad Hidalgo, Mexico, Monday, January 20, 2020. More than a thousand Central American migrants hoping to reach the United States marooned in Guatemala are walking en masse across a river leading to Mexico in an attempt to convince authorities there to allow them passage through the country. (Photo by Santiago Billy/AP Photo)