Pathfinder-Plus on a flight in 1998 over Hawaiian waters.

Pathfinder-Plus flight in Hawaii June 2002

Pathfinder-Plus flight in Hawaii June 2002

Pathfinder-Plus on a flight over Hawaii in 1998.

Pathfinder-Plus on flight over Hawaii.

Pathfinder-Plus flying over the Hawaiian Islands in 1998 with Ni'ihau Island in the background.

Pathfinder-Plus on a flight with the Hawaiian island of N'ihau in the background.

Pathfinder-Plus on a flight over Hawaii in 1998.

Pathfinder-Plus on flight over Hawaiian Islands in 1998.

Pathfinder-Plus on a flight over the Hawaiian island of N'ihau in 1998.

Pathfinder-Plus on a flight over the Hawaiian island of N'ihau in 1998.

Pathfinder-Plus on a flight over the Hawaiian island of N'ihau in 1998.

Sensitive instruments mounted on booms extending forward of the wing measure air turbulence and its effect on the stability of the Pathfinder-Plus solar-electric flying wing.

AeroVironment ground crew check out the operation of the Pathfinder-Plus solar aircraft's electric motors during combined systems tests on Rogers Dry Lake.

Pathfinder-Plus on flight over Hawaiian Islands, with N'ihau and Lehua in the background.

AeroVironment engineers and technicians closely monitor flight data in the ground control station during the Pathfinder-Plus' turbulence measurement flights.

AeroVironment pilot Wyatt Sadler controls the Pathfinder-Plus flying wing from a small console, video and computer monitors in the ground station.

The record-setting AeroVironment/NASA Pathfinder-Plus solar-electric flying wing is enshrined in the National Air & Space Museum's Udvar-Hazy Center in Virginia.

With its sensor booms projecting ahead of the wing, the Pathfinder-Plus solar-electric aircraft soars under a blue sky on a turbulence measurement research flight.

AeroVironment technicians prepare to remove the Pathfinder-Plus solar aircraft from its ground dolly before a turbulence measurement flight from Rogers Dry Lake.

With its sensor booms projecting ahead of the wing, the Pathfinder-Plus solar wing soars under a blue sky on its final turbulence measurement research flight.

The Atmospheric Turbulence Measurement System booms are clearly evident in this view of the Pathfinder-Plus solar aircraft as it flies over Rogers Dry Lake.

AeroVironment crew chief Mark Shipley applies sealing tape to a wing joint on Pathfinder-Plus before it is hoisted into place at the NASM's Udvar-Hazy Center.

The Pathfinder-Plus solar-electric flying wing lifts off Rogers Dry Lake adjoining NASA Dryden Flight Research Center on a turbulence-measurement flight.

As the rising sun dawns over the parched bed of Rogers Dry Lake, AeroVironment's solar-electric Pathfinder-Plus awaits takeoff on its final research flight.

The Pathfinder-Plus solar-electric flying wing lifts off Rogers Dry Lake adjoining NASA Dryden Flight Research Center on a turbulence-measurement flight.

AeroVironment's test director Jim Daley, backup pilot Rik Meininger, stability and controls engineer Derek Lisoski and pilot Wyatt Sadler (clockwise from bottom left) closely monitor systems testing of the Pathfinder-Plus solar aircraft from the control station.

The Atmospheric Turbulence Measurement System booms extend forward from the Pathfinder-Plus solar wing as it soars over Rogers Dry Lake on its final flight.

The Pathfinder-Plus solar aircraft flies past NASA Dryden's space shuttle hangar and shuttle carrier aircraft as it descends for landing on Rogers Dry Lake.

With turbulence-measurement booms projecting ahead of the wing, Pathfinder-Plus soars aloft over Rogers Dry Lake on its final research flight from NASA Dryden.

NASA's Helios Prototype aircraft taking off from the Pacific Missile Range Facility, Kauai, Hawaii, for the record flight. As a follow-on to the Centurion (and earlier Pathfinder and Pathfinder-Plus) aircraft, the solar-powered Helios Prototype is the latest and largest example of a slow-flying ultralight flying wing designed for long-duration, high-altitude Earth science or telecommunications relay missions in the stratosphere. Developed by AeroVironment, Inc., of Monrovia, California, under NASA's Environmental Research Aircraft and Sensor Technology (ERAST) project, the unique craft is intended to demonstrate two key missions: the ability to reach and sustain horizontal flight at 100,000 feet altitude on a single-day flight in 2001, and to maintain flight above 50,000 feet altitude for at least four days in 2003, with the aid of a regenerative fuel cell-based energy storage system now in development. Both of these missions will be powered by electricity derived from non-polluting solar energy. The Helios Prototype is an enlarged version of the Centurion flying wing, which flew a series of test flights at NASA's Dryden Flight Research Center in late 1998. The craft has a wingspan of 247 feet, 41 feet greater than the Centurion, 2 1/2 times that of its solar-powered Pathfinder flying wing, and longer than the wingspans of either the Boeing 747 jetliner or Lockheed C-5 transport aircraft. The remotely piloted, electrically powered Helios Prototype went aloft on its maiden low-altitude checkout flight Sept. 8, 1999, over Rogers Dry Lake adjacent to NASA's Dryden Flight Research Center in the Southern California desert. The initial flight series was flown on battery power as a risk-reduction measure. In all, six flights were flown in the Helios Protoype's initial development series. In upgrading the Centurion to the Helios Prototype configuration, AeroVironment added a sixth wing section and a fifth landing gear pod, among other improvements. The additional wingsp