Solar Impulse 2, a solar-powered plane piloted by Bertrand Piccard of Switzerland, flies over the Golden Gate bridge in San Francisco, California, U.S. April 23, 2016, before landing on Moffett Airfield following a 62-hour flight from Hawaii. (Photo by Jean Revillard/Reuters/Solar Impulse)





Solar Impulse 2, a solar-powered plane piloted by Bertrand Piccard of Switzerland, flies over the Golden Gate bridge in San Francisco, California, U.S. April 23, 2016, before landing on Moffett Airfield following a 62-hour flight from Hawaii. (Photo by Jean Revillard/Reuters/Solar Impulse)





Solar Impulse 2, a solar-powered plane piloted by Bertrand Piccard of Switzerland, flies over the Golden Gate bridge in San Francisco, California, U.S. April 23, 2016, before landing on Moffett Airfield following a 62-hour flight from Hawaii. (Photo by Jean Revillard/Reuters/Solar Impulse)





Solar Impulse 2, a solar-powered plane piloted by Bertrand Piccard of Switzerland, flies over the Golden Gate bridge in San Francisco, California, U.S. April 23, 2016, before landing on Moffett Airfield following a 62-hour flight from Hawaii. (Photo by Jean Revillard/Reuters/Solar Impulse)





Solar Impulse 2 flies over San Francisco on Saturday, April 23, 2016. The solar-powered airplane, which is attempting to circumnavigate the globe to promote clean energy and the spirit of innovation, arrived from Hawaii after a three-day journey across the Pacific Ocean. (Photo by Noah Berger/AP Photo)





Solar Impulse 2 flies over San Francisco before landing at Moffett Field on Saturday, April 23, 2016. (Photo by Noah Berger/AP Photo)





Solar Impulse 2 flies over San Francisco, Saturday, April 23, 2016. (Photo by Noah Berger/AP Photo)





Solar Impulse 2 flies over San Francisco, Saturday, April 23, 2016. (Photo by Noah Berger/AP Photo)





This April 9, 2016 photo provided by Bertrand Piccard via Global Newsroom shows Piccard taking a selfie on board Solar Impulse 2 during a test flight over the Pacific Ocean. The solar-powered airplane on an around-the-world journey had traveled 80 percent of the way from Hawaii to California by Saturday, April 23. The aircraft's destination on this leg of the journey is Mountain View, Calif., at the southern end of San Francisco Bay. (Photo by Bertrand Piccard/Global Newsroom via AP Photo)





Solar Impulse 2 flies over the Golden Gate Bridge in San Francisco, Saturday, April 23, 2016. (Photo by Noah Berger/AP Photo)





Solar Impulse 2 flies over San Francisco, Saturday, April 23, 2016. (Photo by Noah Berger/AP Photo)





Solar Impulse 2 flies over San Francisco, Saturday, April 23, 2016. (Photo by Noah Berger/AP Photo)





Solar Impulse 2 flies over San Francisco, Saturday, April 23, 2016. (Photo by Noah Berger/AP Photo)





Solar Impulse 2 flies over San Francisco, Saturday, April 23, 2016. (Photo by Noah Berger/AP Photo)





Solar Impulse 2 flies over the Golden Gate Bridge in San Francisco, Saturday, April 23, 2016. (Photo by Noah Berger/AP Photo)





Solar Impulse 2 lands at Moffett Field in Mountain View, Calif., after crossing the Pacific Ocean on Saturday, April 23, 2016. The solar-powered airplane landed in California on Saturday, completing a risky, three-day flight across the Pacific Ocean as part of its journey around the world. (Photo by Noah Berger/AP Photo)





Swiss pilot Bertrand Piccard (R) reacts together with alternate pilot Andre Borschberg after landing Solar Impulse 2, a solar-powered plane, on Moffett Airfield in Mountain View, California, U.S. April 23, 2016, following a 62-hour flight from Hawaii. (Photo by Jean Revillard/Reuters/Solar Impulse)