25/04/2016 07:09 BST | Updated 24/04/2017 06:12 BST

Solar Impulse Again in the Air - Bertrand Piccard 'Happy Icarus'

Thursday, April 21, on the World Earth Day, the majestic airplane Solar Impulse took off silently from Hawaii to California for a three day ocean crossing. In the tiny cockpit sits the solar pioneer Bertrand Piccard. Throughout the flight you can see and hear Piccard on the Internet

Bertrand Piccard and André Borschberg will take turns to Solar Impulse commands. While Borschberg, a former military pilot, is the aviation mind of the project, Bertrand Piccard is the charismatic visionary. The Piccard is a Swiss dynasty of three generations of "savant-urier" (scientists and adventurous). After Earth had been explored by extension, the Piccards dedicated themselves to explore the vertical dimension. Auguste (1884-1962) was perhaps the man with the greatest vertical range, from 17 000 meters of altitude in his air balloon (1930) to 4000 meters depth in his bathyscaphe Trieste (1950). Jacques (1922-2008) was the man who dove deeper into the ocean, to 11 000 meters, with the bathyscaphe Trieste (1960). While Auguste and Jacques explored the planet to know him, Bertrand explores the planet to protect it. Psychiatrist, practitioner of yoga and hypnosis, Bertrand Piccard faces not only the external material constraints, but especially he touches the inner dimension of the individual and of the human species. What limits can a man reach while flying lonely and precarious for 100 hours over oceans and continents? What ecological boundaries humankind must not exceed, if we want prosperity and fairness for ten billion people, without devastating the planet?

Departed from Abu Dhabi on March 9, 2015, Solar Impulse had to make a one year stop on Hawaii, for changing the damaged batteries. Before that, he covered 20 000 km in eight legs, by 250 hours of flight, using 5600 kWh of solar electricity. During the day the sun's energy in part feeds the plane's engines and partly accumulate in two ways: by charging the batteries and by climbing at high altitudes. At night the plane glides toward lower altitudes and uses battery power. After California, the plane will touch New York, Europe and finally the place from which it started, Abu Dhabi. This is a Mecca of renewable energies, home to Masdar City, the solar town designed by Sir Norman Foster, and to Irena, the International Renewable Energy Agency.

Solar Impulse is the world's largest civilian aircraft and the lightest: 72-meter wide and 2 tons in weight. With the same wingspan the Airbus 380 weights 500 tons. 100 is the number of millions of euro that the entire project costed, and the it is also the speed of Solar Impulse in km/h. 8 HP is the average power of its electric motors, fed by 200 m2 of photovoltaic panels. 8 HP was also the power of the engine of Wright Flyer, the first powered aircraft to take off in 1903, opening the era of mass aviation which has seen the air traffic double every 15 years since the 70s. On the one hand, safety, affordability, and number of passengers increased continuously, with large human benefit. On the other hand, however, there was another dramatic increase: the overall consumption of energy and the environmental damage caused by burning fossil fuels in the aircraft engines. It's just to exhort by example to abandon fossil fuels and switch generally - not necessarily in aviation - to the energy of the sun, that the Solar Impulse project was started in 2003.

Most probably photovoltaic panels will never power transport aircrafts. The experience acquired by Solar Impulse will serve at most to the develop automated solar aircrafts. With a fleet of these aircrafts, for example, Facebook considers a project for a global internet coverage. Yet Solar Impulse was born not for the sake of the technique, but for the wide dissemination of an idea: humankind can and must accelerate the energy transition towards renewable energies. What better than an epic solar flight around the world for inspiring and exciting millions of people?

For this reason the project has invested significant resources in "Future is clean", a worldwide campaign to collect signatures and rise awareness with the endorsement of official initiators such as Kofi Annan, Mikhail Gorbachev, Achim Steiner (Director of UNEP, the United Nations Program for the Environment), Doris Leuthard (Swiss environment minister), Richard Branson.

According to the greek myth, Icarus dared to fly too near the sun on wings of feathers and wax. The latter melted and he fell into the sea. "Icarus 2.0" could be the name of the Solar Impulse sky adventure. Or perhaps "Happy Icarus", in a sunny version of Albert Camus motto: "The fight to the summit is enough to fill a man's heart. One must imagine Sisyphus happy. "