Pilot André Borschberg of Solar Impulse 2 has just reached the “point of no return." On a trip said to take 120 hours Borschberg no longer has the opportunity to fly back to Japan, and must instead wait until Hawaii’s land mass appears within sight. If he succeeds, it will be the longest duration solo fight in aviation history. Not to mention the longest flight powered by solar energy.

Unlike a normal plane that uses tons of jet fuel to keep itself aloft, the Solar Impulse 2 uses energy from the sun, which it collects in 17,000 solar cells on its wings, fuselage and tail and stores in lithium polymer batteries.  At night, the plane will have to rely on that stored solar energy to keep it, and its crew up. Borschberg will use that time to sleep in 20 minute bursts. 

Should he need to bail out, the plane is also equipped with a dinghy, and enough supplies to last him several days until a team will be able to find and rescue him. And if he succeeds, the vessel’s other pilot Bertrand Piccard will take the next leg of the flight. 

Cover: Twitter