Early every year the National Aeronautic Association recognizes some of the most memorable flights of the previous year, and 2001 had a number of unusual and exceptional flights to note. Interestingly, two of the flights that made the list for 2001 were made by aircraft without a pilot onboard. The solar-powered AeroVironment Pathfinder I, or Helios, set an altitude record last summer when it flew to 96,863 feet over Hawaii. At 247 feet, Helios's wingspan is nearly 10 times that of a conventional light plane. Driven by 14 propellers powered by the energy derived from the sun by a vast array of solar panels, Helios is a technology demonstrator for the kind of airplane that could someday make the first powered flight on Mars.