Update 6/24: The Solar Impulse 2 plane continued to make history on Thursday when it landed in Seville, Spain after completing a 71-hour, 6,000-kilometer (3,728-mile) transatlantic crossing from New York—all without using a single drop of gasoline. Bertrand Piccard piloted the 15th (and most recent) leg of the solar plane's circumnavigation of the globe which started in Abu Dhabi in March 2015. Organizers had originally hoped to land in Paris, in a nod to Charles Lindbergh's historic 1927 journey, but poor weather meant the plane was diverted to Seville instead. While spending three days alone in a tiny cockpit over open ocean is not for everyone, Piccard seems to have enjoyed it: a post on the Solar Impulse 2's official blog described the journey as "A beautiful flight that has countlessly left Bertrand in awe at the vast expanse of the Atlantic Ocean—encountering oil tankers, islands, whales, icebergs, and an abundance of water." With 90 percent of the around-the-world journey behind them, the team will now chart their return to Abu Dhabi, taking into account the weather as well as security concerns in the Middle East. Egypt or Greece will likely be the next stop—after spending a few days to celebrate in Seville, of course.
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4/25/2016: When a plane landed in Mountain View, California on Saturday just before midnight, it was cause for celebration around the world. After all, this was no ordinary flight: The plane, the Solar Impulse 2, spent nearly three days in the air on its 2,810-mile, 62-hour flight from Hawaii, did not use a single drop of gasoline, is powered entirely by the 17,000 solar cells covering its 236-foot wingspan, and only weighs about as much as an SUV. Yet this leg of the journey is part of a greater mission to be the first plane to circumnavigate the globe using nothing but solar energy. The two Swiss aviation explorers behind the project, André Borschberg and Bertrand Piccard, have been taking turns in the cockpit for over a year now, as they try to prove the feasibility of zero-emission air travel.
The project has not been without setbacks: after setting off for circumnavigation in Abu Dhabi in March 2015, the plane experienced frustrating delays in Asia, caused by poor weather over the Pacific and was grounded and under repair for ten months in Hawaii, after the plane's batteries overheated on the record-breaking five-day stretch from Japan to Hawaii. But while the timeline has been pushed because of the mechanical delay (the entire trip was originally supposed to take only five months), Piccard and Borschberg remain committed to the project. "It's a new era. It's not science fiction. It's today," Piccard told CNN after Solar Impulse 2 landed in California. "It exists and clean technologies can do the impossible."
Beyond the remarkable technological achievement of clean air travel, the trip is a feat of human endurance. Piccard and Borschberg take turns piloting different legs of the trip (Piccard was at the controls for the most recent leg), where they are confined to a 135-cubic foot, unheated cockpit for days at a time. The pilots sleep for 20-minute stretches, and use tactics such as meditation and breathing exercises to stay focused. They eat meals especially prepared for the trip by Nestlé and—to answer an obvious question—the toilet is built into the seat. "“It’s very interesting how the human mind can adapt to this type of new situation," Piccard told Wired. The physical toll that each journey takes makes it all the more epic when the plane, after days in the sky, comes in to land:
To complete the journey, Piccard and Borschberg plan to cross North America, complete a transatlantic hop, and make their way across the Middle East, back to Abu Dhabi, by the end of the summer. While the pilots are trying to prove that solar travel is possible, there are several limitations that throw shade, so to speak, on the idea of solar-powered commercial travel—the most obvious being the carrying capacity of the aircraft. The Solar Impulse 2 has the wingspan of a Boeing 747 in order to hold thousands of solar cells, but it can only carry a cabin for one. Additionally, as evidenced by its lengthy flight-times, the plane crawls along at around the speed of a Toyota Corolla—between 20 and 90 miles per hour. It also needs clear, sunny days, because of its reliance on solar energy: In fact, the plane drops from a daylight altitude of 28,000 feet to 5,000 feet at night, in order to conserve energy.
But there are advantages to being able to keep an aircraft in the skies for lengthy periods of time—currently, the only reasons the Solar Impulse 2 has to land are bad weather or for the pilots' health (and sanity). The team is currently developing an unmanned version of the plane that—much like modern airships—could theoretically stay in the sky for months and be used to track weather patterns, patrol skies, or serve as mobile antennae to supply Internet access to remote or underdeveloped parts of the world. So, even if it is unlikely that we will be lining up at JFK to board a solar-powered jumbo jet anytime soon, the flight does mark a bright step toward aviation innovation that takes air travel's giant carbon footprint into account.
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This article was originally published on April 25. It has been updated.