Former Swiss astronaut and Solar Impulse's chief of test flight operation Claude Nicollier rides a vintage military bicycle next to the solar-powered HB-SIA prototype aircraft after a test flight at Payerne airport April 18, 2011. [Photo/Agencies]

Solar Impulse's Chief Executive Officer and pilot Andre Borschberg performs a low altitude go-round procedure with the solar-powered HB-SIA prototype aircraft during a test flight at Payerne airport April 18, 2011. [Photo/Agencies]

Solar Impulse's Chief Executive Officer and pilot Andre Borschberg steers the solar-powered HB-SIA prototype during a test flight at Payerne airport April 18, 2011. [Photo/Agencies]

Solar Impulse's Chief Executive Officer and pilot Andre Borschberg goes through procedures in the cockpit of the solar-powered HB-SIA prototype aircraft before a test flight at Payerne airport April 18, 2011. [Photo/Agencies]