It's been a long wait, but finally Solar Impulse 2 is ready to continue its round-the-world trip. The sun-powered aircraft had been stuck in Hawaii since July due to battery damage sustained in previous flights. Repair works stopped pilot Bertrand Piccard from completing the next leg in 2015, but that doesn't matter -- speed has never been the focus. It's all about distance, and proving what can be done with clean energy sources.
Solar Impulse 2 took off from Abu Dhabi in March 2015 and has since made stops in Oman, India, Myanmar, China and Japan. It's a single-seater aircraft -- Piccard and colleague André Borschberg have been taking turns in the cockpit. Borschberg broke the record for the longest-duration solo flight last summer, after captaining the Impulse 2 for four days, 21 hours and 51 minutes. Now it's Piccard's turn, as he completes a shorter dash to Mountain View in California. The journey should take a few days, finishing up on Saturday -- provided there are no complications, of course.
You can use the Solar Impulse website to keep up with Piccard's progress. The tracker includes some crucial statistics such as the plane's altitude, distance and battery percentage. To fly, Impulse 2 has 17,248 solar cells powering four lithium batteries, which then drive a slew of motors and propellers. Surplus energy collected in the day is then used to keep the aircraft moving through the night. "Every morning you have the suspense of knowing how much energy is left in batteries," Piccard explains. "Then, with the sunrise comes the virtuous cycle of perpetual flight."