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)

An injured national guard officer is carried away by comrades outside the parliament building in Kiev, Ukraine, August 31, 2015. Nearly 90 people were wounded and several of them were in a serious condition on Monday after several explosive devices were thrown from crowds in front of the Ukrainian parliament building in Kiev, the interior minister said in a Tweet. (Photo by Valentyn Ogirenko/Reuters)

South Korean actress singers Tiffany (R) and Seohyun react in front of an official camera on the red carpet during 2015 Mnet Asian Music Awards (MAMA) in Hong Kong, China December 2, 2015. (Photo by Bobby Yip/Reuters)

People carrying red umbrellas march through downtown Skopje, Macedonia, marking the International Day to End Violence against s*x Workers, Thursday, December 17, 2015. A group of s*x workers, supported by members of non-government organizations, rallied Thursday demanding rights for the s*x workers and destigmatization of their profession. The banner reads: The Stigma Kills. (Photo by Boris Grdanoski/AP Photo)

An athlete dressed as a clown jumps into the Mediterranean sea as he takes part in the Copa Nadal in the Spanish port of Barcelona in Barcelona, Spain, Sunday, December 25, 2016. The Copa Nadal (Christmas Cup) is a traditional swimming competition that takes place in Barcelona every December 25th, where participants swim 200 meters in the open sea in the port of Barcelona. (Photo by Manu Fernandez/AP Photo)

Christie Brinkley and Ashley Graham pose after Lifetime's American Beauty Star Season 2 Live Finale at Manhattan Center on March 27, 2019 in New York City. (Photo by Mike Coppola/Getty Images for Lifetime)

Rian Johnson, left, director of the upcoming film “Knives Out”, takes a picture of cast member Ana de Armas as they are introduced onstage during the Lionsgate presentation at CinemaCon 2019, the official convention of the National Association of Theatre Owners (NATO) at Caesars Palace, Thursday, April 4, 2019, in Las Vegas. (Photo by Chris Pizzello/Invision/AP Photo)

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)