Hydrogen-powered high flier

The Global Observer, an unmanned airborne vehicle (UAV) that is designed to stay aloft for up to 7 days at an altitude of up to 65,000 feet while carrying a 400-pound payload, had its first flight last month. The launch from Edwards Air Force Base in California marked the beginning of a test program that will result in a week-long flight in the stratosphere using liquid-hydrogen fuel.

"We successfully completed Global Observer's historic first flight on August 5 and its second flight on August 19,” Bob Curtin, AeroVironment’s vice president of business development, told TechNewsDaily.

“In both flights [the aircraft] employed batteries to fly for more than one hour at a maximum altitude of approximately 4,000 feet above mean sea level. These first two flights satisfied the team's objectives for demonstrating and gathering data on aircraft control, handling, communications and structural performance."

Unmanned platforms like the Global Observer that operate above 50,000 feet combine the capabilities of satellites with the flexibility of aircraft for persistent intelligence, surveillance and reconnaissance (ISR) missions. The aircraft is being developed by AeroVironment under a joint concept technology demonstration (JCTD) sponsored by several U.S. agencies under the direction of the Special Operations Command.

Hydrogen powered

Ultimately, the Global observer will be powered by a liquid-hydrogen-fueled propulsion system. AeroVironment had explored the use of solar power for the aircraft , but determined that liquid hydrogen propulsion was the best solution for a high-altitude, long-endurance UAV. Solar power today is not sufficient to support continuous operation beyond the tropics during winter.

The Global Observer has a 175-foot wingspan and weighs less than 10,000 pounds. It has a modular composite airframe, which enables it be transported by a cargo aircraft, and an internal-combustion engine modified to burn hydrogen that drives a generator to produce electricity to power the UAV’s four propellers. Hydrogen was chosen because it has three times the energy of conventional fuel. When in operation, the aircraft produces no carbon emissions.

"Global Observer is being developed to address the need for an affordable, persistent platform that can provide seamless communications and ISR over any spot on the globe for as long as required,” Curtin said. “Swapping orbits every 5 to 7 days, a two-air vehicle system would maintain uninterrupted coverage in a manner similar to a geosynchronous satellite, but about 2,000 times closer to the earth's surface."

A new frontier

Compared to conventional aircraft, the Global Observer requires fewer takeoffs and landings, which translates into lower cost. And unlike satellites, it can easily be repositioned, the technology can be upgraded and the payload can be switched.

Aerovironment Chairman and CEO Tim Conver believes that the Global Observer can open the stratosphere for practical use just as airplanes opened up the lower atmosphere for use and satellites made operating in space possible.

AeroVironment is best known for small, unmanned aircraft such as the RQ-11 Raven . The Raven, which weighs 4.2 pounds and can stay aloft for 90 minutes, has been used extensively by U.S. troops in Afghanistan for surveillance.

IBM Scientists Create Tiniest 3-D World Map

IBM scientists working across three countries have created the smallest-ever 3D map of the world -- so tiny that 1,000 maps could fit on a grain of salt.

The map, measuring 22 by 11 micrometers, is scratched out on a polymer surface. Every 8 nanometers corresponds to 1,000 meters of altitude -- so Mount Everest would be about 64 nanometers high. The map is composed of 500,000 pixels, each measuring 20 nanometers square. The patterning process could conceivably be used for nano-scale electronics and medical devices.

The breakthrough was in how the scientists decided to build the map. IBM scientist Urs Duerig says in a company video that his "a-ha" moment was in realizing he could make 3-D shapes by removing material rather than adding to it.

A tiny silicon tip attached to a cantilever is heated as it approaches a polymer substrate. Force and heat chip away at the polymer, yielding the desired shapes. It took two minutes and 23 seconds to build the 3-D map of Earth.

"It's like the ancient Egyptians chiseled their stuff into stone plates. Here we have the analogue, but on the nano-scale," he said.