A solar-powered aircraft, potentially capable of cruising for months at a time without a pilot, is currently under development and could soon hit the skies.

The drone is being developed by Skydweller Aero Inc., a US.-Spanish aerospace company that develops ultra-persistent drones for commercial and military applications.

The Skydweller aircraft has a wingspan of 72 meters (236 feet) fitted with 270 square meters (2,900 square feet) of photovoltaic cells that can provide 2 kilowatts of power. Thanks to its flexible payload, it has the potential to perform a range of applications, including telecommunications, geospatial monitoring, data collection, weather forecasting, emergency operations, and surveillance.

The hardy drone is currently in the midst of preliminary flight tests with human pilots. According to a company press release, a crewed test flight in April 2021 potentially broke the world record for the highest altitude reached and sustained by a solar-powered aircraft, cruising at nearly 4,875 meters (16,000 feet).

The end goal is to develop a solar-powered aircraft that can fly without a crew for up to 90 days, the longest continuous solar-powered flight program in history. Flight Global reports that the company hopes to demonstrate the aircraft’s solar-powered, long-endurance flight at some point between the end of 2021 and mid-2022. The media outlet also reports that the company has received a $5 million contract from the US Navy to demonstrate the plane’s capabilities.

"This research and development contract will provide Skydweller the opportunity to further develop their zero carbon solution while advancing technology for national security efforts," a spokesperson for Skydweller Aero said in a statement to IFLScience. 

Skydweller had previously received investment from Leonardo, a billion-dollar Italian aerospace company headquartered in Rome.

The Skydweller craft is a revamp of Solar Impulse, the solar-powered aircraft in which two pilots, André Borschberg and Bertrand Piccard, circumnavigated the globe between 2015 and 2016. Over the course of 16 months, the plane made a 17-legged journey from Abu Dhabi across Asia, cruising over the Pacific to Hawaii and then mainland USA, before stopping off in Spain and Egypt, and eventually back to Abu Dhabi. The longest leg of this total flight was a 7,212 kilometer (4,481 mile) hop from Japan to Hawaii that took 117 hours and 52 minutes.

Three years after this flight was completed, Solar Impulse and Skydweller signed an agreement for the future use of this groundbreaking aircraft. By all accounts, it looks like the new Skydweller craft is effectively the Solar Impulse aircraft kitted out with new technology and software that will make this dream of long-endurance crewless flights possible. 

“Solar Impulse, in this contemplated second life, will continue to illustrate that clean technologies can achieve the impossible while at the same time building a sustainable future," Bertrand Piccard, the Initiator and Chairman of Solar Impulse, said in a statement in 2019. "With Skydweller, the world’s most famous solar-powered aircraft of unlimited endurance will have concrete benefits for the greater good, and all without ever using a single drop of fuel.”

[H/T New Scientist]