Test pilot Markus Scherdel of Germany attempts to land in the Solar Impulse's solar-powered HB-SIA prototype airplane during a test flight at Payerne airport April 11, 2011. The Solar Impulse HB-SIA, which has 12,000 solar cells built into its 64.3-meter (193-foot) wings, is a prototype for an aircraft that its creators hope will carry out its first circumnavigation of the globe from 2012. [Photo/Agencies]

A woman sits in a lawn chair watching planes land at Ronald Reagan National Airport in Washington D.C. April 11, 2011. [Photo/Agencies]