NASA's Helios prototype solar-electric remotely piloted aircraft crashed during a checkout flight from the Pacific Missile Range Facility (PMRF) on Kauai, Hawaii, on 26 June. The flying-wing aircraft was being prepared for a record-breaking 40h flight powered by solar energy during the day and at night by a newly developed fuel cell-based electrical system. The aircraft was flying under the guidance of mission controllers from developer Aerovironment and had been airborne about 29min when the mishap occurred. The lightweight vehicle came down in the Pacific west of the PMRF. The cause of the crash is not known. The Helios prototype set a world altitude record for winged aircraft of 96,863ft (29,543m) flying from Hawaii in August 2001.
Source: Flight International