The groundbreaking experimental aircraft known as Solar Impulse 2 has met an untimely end. According to a National Transportation Safety Board report, the completely solar-powered plane crashed into the Gulf of Mexico during an autonomous test flight on May 4. While there were no injuries or fatalities, the wreck of the Solar Impulse marks an unfortunate end for one of the most impressive and inspirational planes in aviation history.
Solar Impulse was first conceptualized in 2003 by Bertrand Piccard, the grandson of Swiss deep sea pioneer Auguste Piccard and the son of Jacque Piccard, the first person to reach the Mariana Trench. Piccard never intended the vehicle for commercial use, but instead envisioned it as a way to raise awareness for sustainable energy by building the first solar-powered plane capable of circumnavigating the globe. The first iteration, Solar Impulse 1, completed its inaugural test flight in 2009 followed by multiple additional trips over the next few years.
Construction on Solar Impulse 2 began in 2011. Even with a 232-foot wingspan that made it wider than a Boeing 747, the completely carbon-fiber frame ensured the plane only weighed about 5,100 lbs, making it about as heavy as a standard SUV. The 130-cubic-foot, nonpressurized cockpit included oxygen reserves and additional environmental equipment to enable a pilot to travel long distances at a maximum altitude of 39,000 feet. According to sUAS News, a total of 17,248 photovoltaic solar cells offered a peak power output of 66 kW to four electric motors and four lithium-ion batteries weighing nearly 1,400 lbs. Basic autopilot technology also allowed its sole occupant to sleep in 20 minute intervals.
Solar Impulse 2 completes inaugural flight
Solar Impulse 2 made history in 2016 as the first fixed-wing, entirely solar-powered plane to circumnavigate the Earth. The feat was accomplished over the course of 16.5 months, with Piccard alternating piloting duties with Foundation co-founder André Borschberg and making 17 stops along the route. Solar Impulse 2 cruised at a ground speed between 31 and 62 mph, relying on the slower pace during evening portions of the trip.
In 2019, the Solar Impulse Foundation announced the sale of Solar Impulse 2 to Skydweller Aero for an undisclosed sum. The Spanish–American company’s plans were very different from the plane’s initial purpose. Instead of focusing on its solar capabilities, Skydweller hoped to pursue its military-related surveillance potentials, which included “carrying radar, electronic optics, telecommunications devices, telephone listening, and interception systems.”
After supplying numerous modifications, Solar Impulse 2 completed its first autonomous flight in Spain in 2023. The first entirely uncrewed, autonomous flight took place at Stennis International Airport near Bay St. Louis, Mississippi, the following year. At the time, Skydweller also confirmed its larger goal was to develop and supply a fleet of uncrewed, solar-powered planes capable of nonstop flight at latitudes between Miami (26°N) to Rio de Janeiro (23°S). These near-continuous operations would involve military and commercial contracts, allegedly at a much lower cost than current satellite options. The overhauled flagship aircraft reportedly crashed after losing power while flying over the Gulf of Mexico on May 4.
“We learned through social media about the crash of the Skydweller solar drone,” Piccard and Borschberg wrote in a statement provided to Popular Science. “The Solar Impulse team is saddened by the loss of an important technological flagship.”
Skydweller representatives did not respond to Popular Science at the time of writing. According to the Swiss news outlet SWI, part of Solar Impulse Foundation’s original sales contract with Skydweller stipulated the aircraft would eventually return to Switzerland for installation in the Swiss Museum of Transport in Lucerne.
“Very often when we speak of protection of the environment, it’s boring,” Piccard told Popular Science in 2013. “The first airplane [had] the technology of 2007. The second airplane [had] the technology of tomorrow.”
