The first solar powered flight to navigate the world ended with the touchdown of the aircraft Solar Impulse in Abu Dhabi.
The plane landed where the landmark 25,000-mile flight started more than 12 months ago.
During that time and 16 touchdowns as the pilots circumnavigated the Earth at an average speed of between 28mph and 56mph depending on height and wind speed.
Not all the journey was bright and cheerful.
The start was delayed months by faulty batteries, a pilot fell ill in Cairo and bad weather disrupted flight plans.
Nevertheless, the primary objective was accomplished – to fly a solely solar powered aircraft around the world to prove the task could be done.
Sun rays of hope
But think of the Solar Impulse as a prototype rather than a production version.
The plane collected the sun’s rays in close to 17,250 cells that powered four electric driven propellers. At night, energy stored in four batteries that recharged during day time flight took over.
In order to collect enough solar power, the plane’s wing span was 236 feet.
Weight was kept to a minimum. While a conventional large airliner may come in at 400 tonnes before loading with fuel, passengers and cargo, Solar Impulse weighs a mere 2.5 tonnes.
The risk is buffeting by crosswinds on take-off and landing could blow her off course, so teams of runners and cyclists were available to keep the plane on the runway when powering up and down.
Endurance records for pilots
During the flight, the two-man crew logged 500 flying hours. As a single seater, only one was on watch flying the plane solo.
The flight over the Atlantic and Pacific oceans, which took 70 and 118 hours respectively and accounted for around a third of all flying time.
Crossing the Atlantic non-stop was a first for a solar powered aircraft, while the time taken to fly over the Pacific was a record for the duration of a solo flight.
The flight was sponsored by more than 40 companies and organisations. The main sponsor was the Abu Dhabi government’s Masdar clean energy company. The mission cost is estimated at more than $100 million.