The Solar Impulse prototype, now in Madrid after visiting Morocco, will head out tomorrow July 17 for either home in Payerne, Switzerland, or if weather is bad, Toulouse. If they go, you can follow the action live from inside the cockpit. Once home the prototype is to rest in its hangar while its bigger brother is constructed for the world flight in 2014. The main spar of that aircraft–that is 28 feet longer than the spar of the prototype now flying–failed a test while the prototype was returning from Morocco, and now the schedule for the world flight is uncertain.
UPDATE: Solar Impulse is safely on the ground at its home in Switzerland.