People take photos as the ET-94 space shuttle external fuel tank travels through Inglewood to complete its 4,000 nautical mile from NASA's Michoud Assembly Facility in Louisiana to the California Science Center in Los Angeles, California on May 21, 2016. It will be paired with the space shuttle Endeavour in a vertical launch position at the museum. / AFP PHOTO / Mark RalstonMARK RALSTON/AFP/Getty Images

People take photos as the ET-94 space shuttle external fuel tank travels through Inglewood to complete its 4,000 nautical mile from NASA's Michoud Assembly Facility in Louisiana to the California Science Center in Los Angeles, California on May 21, 2016. It will be paired with the space shuttle Endeavour in a vertical launch position at the museum. / AFP PHOTO / Mark RalstonMARK RALSTON/AFP/Getty Images

The ET-94 space shuttle external fuel tank travels through Inglewood to complete its 4,000 nautical mile from NASA's Michoud Assembly Facility in Louisiana to the California Science Center in Los Angeles, California on May 21, 2016. It will be paired with the space shuttle Endeavour in a vertical launch position at the museum. / AFP PHOTO / Mark RalstonMARK RALSTON/AFP/Getty Images

People look on as the ET-94 space shuttle external fuel tank travels through Inglewood to complete its 4,000 nautical mile from NASA's Michoud Assembly Facility in Louisiana to the California Science Center in Los Angeles, California on May 21, 2016. It will be paired with the space shuttle Endeavour in a vertical launch position at the museum. / AFP PHOTO / Mark RalstonMARK RALSTON/AFP/Getty Images

Two women take slefies as the ET-94 space shuttle external fuel tank travels through Inglewood to complete its 4,000 nautical mile from NASA's Michoud Assembly Facility in Louisiana to the California Science Center in Los Angeles, California on May 21, 2016. It will be paired with the space shuttle Endeavour in a vertical launch position at the museum. / AFP PHOTO / Mark RalstonMARK RALSTON/AFP/Getty Images

A police officer looks on as the ET-94 space shuttle external fuel tank travels through Inglewood to complete its 4,000 nautical mile from NASA's Michoud Assembly Facility in Louisiana to the California Science Center in Los Angeles, California on May 21, 2016. It will be paired with the space shuttle Endeavour in a vertical launch position at the museum. / AFP PHOTO / Mark RalstonMARK RALSTON/AFP/Getty Images

An independent searcher looks at a computer as a drone flies during an experimental flight to make searches on the atmosphere, on May 20, 2016 in the Centre of Atmospheric Research (Recherche Atmosphérique - CRA) in Lannemezan in the French Pyrenees. The goal is to test new drones with new weather forecast sensors by flying close to a 60m mast equipped with reference sensors (temperature, humidity, wind) and to exchange experiences in a way to progress in this new area. / AFP PHOTO / REMY GABALDAREMY GABALDA/AFP/Getty Images

TULSA, OK - MAY 21: Solar Impulse 2, the solar airplane of Swiss pioneers Bertrand Piccard and André Borschberg, in preparation for the take off from Tulsa International Airport, Oklahoma, with Andre Borschberg at the controls, on 21 May at 4:22am local time (UTC-5). The plane, which is piloted by Borschberg, is expected to land at Dayton International Airport, Ohio, on the same day at around 11:00pm local time (UTC-4). The flight is part of the attempt to achieve the first ever Round-The-World Solar Flight, the goal of which is to demonstrate how modern clean technologies can achieve the impossible. Christophe Chammartin/ SI2