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)

Shoppers walk past crocodiles for sale at a market in Bata on February 3, 2015. Markets in Equatorial Guinea sell a variety of animals including pangolins, monkeys and crocodiles as food. (Photo by Carl De Souza/AFP Photo)

A dog, at the behest of his owner, rides a skatebaord on April 3, 2017 in Berlin, Germany. The dog's owner, who looked like he might be homeless, coaxed the dog to ride the skatebaord and asked passersby who stopped to watch for money. (Photo by Sean Gallup/Getty Images)

Private Harold L. Langhofer edges into the ball-turret, March 9, 1943. Curled in this position, he can turn the turret so that it fires in any direction. The turret can also be swung around so that the hatch opens into the plane, and the gunner can crawl into it while the Flying Fortress is in motion. (Photo by AP Photo)

Young girls dress up in traditional costumes and pose for a selfie at the opening ceremony of the Leishan Miao new year festival in the city of Kaili, Guizhou province, China on November 23, 2015. (Photo by Imaginechina/Rex Shutterstock)

Boys pose with their toy guns as others play on swings, on the first day of the Muslim holiday of Eid al-Fitr, which marks the end of the holy month of Ramadan, in the government-controlled district of Dwelaa in Damascus, Syria July 6, 2016. (Photo by Omar Sanadiki/Reuters)

“Joker” movie production tries to hide Joaquin Phoenix's clown make-up and green hair with umbrella and a long black cloth over his head as he was walking with the help of assistant and bodyguard to the set of “Joker” filming at a Bronx train station on September 22, 2018. (Photo by The Mega Agency)

A Pakistani labourer carries bricks on his back at a construction site at a residential area in Islamabad on March 29, 2017. (Photo by Aamir Qureshi/AFP Photo)