This picture taken on January 6, 2018 shows macaque monkeys looking at a man's camera during snowfall at Wulongkou Nature Reserve in Jiyuan in China's central Henan province. (Photo by AFP Photo/China Stringer Network)

A horse is ridden out of the River Eden after being washed on the first day of the Appleby Horse Fair on June 7, 2018 in Appleby, England. The fair is an annual gathering for Gypsy, Romany and travelling communities. The event has existed under the protection of a charter granted by James II since 1685 and it remains one of the key meeting points for these communities. Around 10,000 travellers are expected to attend the event who traditionally come to buy and sell horses and it offers an opportunity for the traveller community to come together to celebrate their heritage and culture. (Photo by Ian Forsyth/Getty Images)

A visitor looks at a Soviet-made «Zaporozhets» retro car, which was converted into an aquarium at a small and medium business exhibition in St. Petersburg, Russia on December 5, 2018. (Photo by Anton Vaganov/Reuters)

“What created this unusual hole in Mars? The hole was discovered by chance on images of the dusty slopes of Mars' Pavonis Mons volcano taken by the HiRISE instrument aboard the robotic Mars Reconnaissance Orbiter currently circling Mars”. (Photo by NASA/JPL/University of Arizona)

Stefan Dobrovolny of Austria and Inigo Munoz Elorza of Spain (R) stand in front of a quad bike during a simulated Mars mission on Tyrolean glaciers in Kaunertal, Austria, August 7, 2015. The Austrian Space Forum is sending some of its researchers to practice weight-less walking in spacesuits on a glacier which resembles the terrain on Mars. (Photo by Dominic Ebenbichler/Reuters)

This photo provided by NASA shows a full moon rising behind the United Launch Alliance Atlas V rocket with NASA's Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft onboard at the Cape Canaveral Air Force Station Space Launch Complex 41, Sunday, November 17, 2013, Cape Canaveral, Florida. NASA's next Mars-bound spacecraft, the Mars Atmosphere and Volatile Evolution, or MAVEN, is the first spacecraft devoted to exploring and understanding the Martian upper atmosphere. (Photo by Bill Ingalls/AP Photo/NASA)

This artist's scoreboard displays a fictional game between Mars and Earth, with Mars in the lead. It refers to the success rate of sending missions to Mars, both as orbiters and landers. Of the previous 39 missions targeted for Mars from around the world, 15 have been successes and 24 failures. For baseball fans, that's a batting average of .385. The United States has had 13 successes out of 18 attempts, or a “batting average” of .722. NASA's Curiosity rover, set to land on the Red Planet the evening of Aug. 5, 2012 PDT (morning of Aug. 6 EDT), will mark the United States' 19th attempt to tackle the challenge of Mars, and the world's 40th attempt. (Image by NASA/JPL-Caltech)

This February 7, 2018, photo shows João Lousada, a flight controller for the International Space Station, wearing an experimental space suit during a simulation of a future Mars mission in the Dhofar desert of southern Oman. The desolate desert in southern Oman resembles Mars so much that more than 200 scientists from 25 nations organized by the Austrian Space Forum are using it for the next four weeks to field-test technology for a manned mission to Mars. (Photo by Sam McNeil/AP Photo)