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 woman takes part in a “Brave Run” competition in Minsk October 4, 2015. (Photo by Vasily Fedosenko/Reuters)

Lali carries balloons to sell on a beach in Mumbai, India, Sunday, October 11, 2015. The United Nations General Assembly marks October 11 as the International Day of the Girl Child, to recognize girls’ rights and the unique challenges girls face around the world. (Photo by Rafiq Maqbool/AP Photo)

A tourist stands on the shore of a private beach in Naama Bay, Sharm el-Sheikh, south Sinai, Egypt, Sunday, November 8, 2015. Britain's foreign secretary says airport security in many cities will need to be overhauled if it is confirmed the Russian plane crash in the Sinai was caused by a bomb planted by the Islamic State group or someone inspired by the militants. (Photo by Vinciane Jacquet/AP Photo)

Police react to a suspicious vehicle near La Carillon restaurant following a series of deadly attacks in Paris, November 15, 2015. Thousands of French troops deployed around Paris on Sunday and tourist sites stood shuttered in one of the most visited cities on Earth while investigators questioned the relatives of a suspected suicide bomber involved in the country's deadliest violence since World War II. (Photo by Pascal Rossignol/Reuters)

A eunuch dances during a rally to mark the congregation of thousands of eunuchs from different parts of India, in Jammu, India, Friday, March 13, 2015. The term eunuchs is used in India to describe transvestites, transsexuals and others who identify themselves as neither male nor female but as a member of a third gender. They traditionally survive by begging, dancing at weddings or blessing newborn babies and are frequently subjected to discrimination. (Photo by Channi Anand/AP Photo)

A picture taken with slow shutter speed shows members of the group “The Kattfiller” from Attendorn taking part during the Norddeutsche Championship carnivalesque dance sport in Kassel (Hessen), Germany, 28 February 2016. About 1,100 qualified dancers show in different disciplines their skills. (Photo by Swen Pfoertner/EPA)

Kristina Elekes, 23, races on her ski during the Bikini Race contest held at Arena Platos Paltinis winter resort, near Sibiu city, 275 Km north from Bucharest, Romania, 06 March 2016. Bikini Race is a timed show on the slopes, at the fourth edition, for women dressed only in swimmsuits and some winter accessories. (Photo by Mihaela Bobar/EPA)