The pilots of Solar Impulse 2, the first solar-powered plane to attempt to circumnavigation the globe, just crossed their “point of no return.” Faced with the choice of flying for five days and nights over the Pacific Ocean, too far from any continent or island to make an emergency stop, or abandoning their mission, they chose today to fly.
The plane’s huge wings, silver with solar cells, are stretched out over the open ocean south and east of Japan, and it’ll be another four days before pilot André Borschberg sees the landmass of Hawaii on the horizon.
(A live video from inside the cockpit is accidentally reminiscent of Star Wars, both for the orange flight suit and the Darth Vader breathing soundtrack.)
The flight is long because the plane is slow. At maximum altitude it can fly at just 140 km/h. A Boeing 474, which is much bulkier but has a smaller wingspan, can travel more than six times as fast.
Rather than burning up the tons of jet fuel per hour that propels a normal plane, the Solar Impulse 2 uses nothing but energy from the suns rays, which it collects through more than 17,000 solar cells on its wings, fuselage and tail, and stores in lithium polymer batteries that together make up over a quarter of the aircraft’s overall weight.
When it flies at night, it has to rely entirely on those batteries to keep the plane aloft. Borschberg, meanwhile, will catch sleep in short, 20-minute bursts.
And so far, it’s working. The plane has already completed seven legs of its 12-leg trip, from Abu Dhabi in March to Nagoya, Japan, where it departed today.
Bertrand Piccard, the other pilot behind the project, and the first person to fly round the world in a hot air balloon, is watching this leg from the ground. He will follow the plane’s progress via a barrage of data-collecting instruments, sleeping in short bursts like his colleague, and hope sun keeps shining.