After its successful inaugural Paris-to-Brussels flight last year, the Solar Impulse solar-powered aircraft will attempt to fly all the way to Morocco in May or June of this year, a journey almost ten times the distance, and its furthest flight and as a close as it has yet come to a trial run of its round-the-world flight planned for 2014.

To recap briefly on the engineering marvel that is the Solar Impulse, the aircraft has the wingspan of Airbus A340 at 63.4 m (208 feet) but with only the weight of a family car (1600 kg/ 3527 pounds). Solar cells, some 12,000 of them, are built into the wing, providing pollution-free renewable power to four 10-hp electric motors. But they also charge 400 kg (882 lb) of lithium batteries which can keep the Solar Impulse in the air at night.

The night-flying capabilities of the Solar Impulse will be tested in what is to be the aircraft's longest-distance flight to date, expected to take 48 hours. However, there is a scheduled stop at Madrid to switch pilots.

It's hoped the flight will allow Solar Impulse pilots and founders Bertrand Piccard and André Borschberg to gain in experience with the technicalities of long-distance flight, including cooperation with international airports and adapting to air traffic flows.

Earlier this month Borschberg completed a 72-hour non-stop simulated flight in a full-size mock-up to test the human stresses of continuous flying. "Thanks to a careful management of the rest periods I was able to maintain optimum vigilance throughout the flight," Borschberg said as he emerged from the simulator (in what I can only imagine was a pre-prepared statement). "We learnt a great deal about the practical management of life on board."

The forthcoming flight appears to be sponsored at least in part by the Moroccan Agency for Solar Energy which intends to have built five solar power installations generating 2 GW of solar power by 2020. But as long-standing fans of the Solar Impulse we couldn't resist an update on what is another fascinating paragraph in what's still the first chapter of the book of green aviation.

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