Axel, a research prototype rover for exploring the Moon, Mars and other planets, is remotely driven over rocks as engineers from Jet Propulsion (JPL) and grad students from Caltech (California Institute of Technology) demonstrate its mobile over the steep and rocky grounds of the JPL Mars Yard on January 14, 2009 in Pasadena, California. The rover is capable of descending cliffs or into craters and returning by a cable tethered to its starting point. Development of the Axel rover is a point effort funded by NASA Exploration Systems Mission Directorate (ESMD) and lead by Principal Investigator Issa Newnas and Co-Investigator and Caltech professor of mechanical engineering bio engineering Joel Burdick. (Photo by David McNew/Getty Images)

An image of the popular video game “Angry Birds” is displayed on an iPod Touch on March 18, 2011 in San Anselmo, California. The “Angry Birds” mobile device video game developer Rovio is begnning the process of seeking an initial public offering (IPO). (Photo Illustration by Justin Sullivan/Getty Images)

Facebook CEO Mark Zuckerberg (L) watches a demonstration of the new Facebook video chat during a news conference at Facebook headquarters July 6, 2011 in Palo Alto, California. Zuckerberg announced new features that are coming to Facebook including video chat and a group chat feature. (Photo by Justin Sullivan/Getty Images)

A supporter of the team of Ukraine cheers prior to the Euro 2016 Group C soccer match between Ukraine and Poland at the Velodrome stadium in Marseille, France, Tuesday, June 21, 2016. (Photo by Thanassis Stavrakis/AP Photo)

Russian President Vladimir Putin (C) and Defence Minister Sergei Shoigu (back) attend a reception to honour graduates of military academies at the Kremlin in Moscow, Russia, June 28, 2016. (Photo by Alexei Druzhinin/Reuters/Sputnik/Kremlin)

A conductor (C) collects fares from candy floss sellers as they travel in a tram to a marketplace early morning in Kolkata, India, December 23, 2015. (Photo by Rupak De Chowdhuri/Reuters)

An instructor (C) adjusts the posture of students of flight attendant major during a training session at Anhui Foreign Languages University, in Hefei, Anhui province, China, May 25, 2015. (Photo by Reuters/China Daily)

France fan before the Russia 2018 World Cup Group C football match between Denmark and France at the Luzhniki Stadium in Moscow on June 26, 2018. (Photo by Axel Schmidt/Reuters)