NASA ERAST Program

[1] According to NASA, "ERAST was a multiyear effort to develop the aeronautical and sensor technologies for a new family of remotely piloted aircraft intended for upper atmospheric science missions.

The JSRA was based on NASA's Space Act Agreement Authority, which permitted flexible teaming, cost-sharing and intellectual property sharing to maximize collaboration for rapid technology development progress.

Additional technologies considered by the ERAST Alliance include lightweight materials, avionics, aerodynamics, and other forms of propulsion suitable for extreme altitudes and duration.

[1] In 1988, NASA decided to obtain a HALE UAV named "Perseus" to deal with these problems, designating the effort the Small High-Altitude Science Aircraft (SHASA) program.

[7] The NASA Pathfinder, Centurion, and Helios aircraft were a series of solar- and fuel cell system-powered UAVs, which AeroVironment, Inc. developed the vehicle under the ERAST program.

Solar photovoltaic cells mounted on the top of the wing produce up to 7,200 watts, powering the aircraft's six electric-driven propellers, as well as the suite of scientific instruments.

With its engine at first augmented by a single-stage turbocharger, the ALTUS II reached an altitude of 37,000 ft during its first series of development flights at Dryden in August, 1996.

In October of that year, the ALTUS II was flown in an Atmospheric Radiation Measurement (ARM-UAV) study in Oklahoma conducted by Sandia National Laboratories for the Department of Energy.

After major modifications and upgrades, including installation of a two-stage turbocharger in place of its original single-stage unit, a larger fuel tank and additional intercooling capacity, the ALTUS II returned to flight status in the summer of 1998.

The goal of its development test flights was to reach one of the major ERAST Level 2 performance milestones, to fly a gasoline-fueled, piston-engine remotely piloted aircraft for several hours at an altitude at or near 60,000 feet.

The Digital Array Scanned Interferometer (DASI) was operated from the Pathfinder in the summer of 1997, acquiring imaging interferometric data of the Hawaiian Islands.

The Scaled Composites Proteus aircraft was flown as a surrogate UAV controlled remotely from the ground, although safety pilots were aboard to handle takeoff and landing and any potential emergencies.

In April 2003, a second series of flight demonstrations focusing on "non-cooperative" aircraft (those without operating transponders), was conducted in restricted airspace near Mojave, California., again using the Proteus as a surrogate UAV.

Proteus was equipped with a small Amphitech OASys 35 GHz primary radar system to detect potential intruder aircraft on simulated collision courses.