Solar Radiation and Energy

Directions: Read the passage and answer the following question.

Passage - I
With only the sun for fuel, eight tiny electric motors lift a huge, remotely controlled airplane off a runway in Hawaii and pull it to more than 80- thousand feet. Planes like this could fly for months on end in the stratosphere. Ray Morgan, president of AeroVironment says, What we're trying to do is create what we call an atmospheric satellite, which operates and performs any of the functions as a satellite would do in space, but does it very close in, in the atmosphere. NASA is funding research with a former cold war spy plane prototype. Dick Swanson of Sun Power, Inc. says of the planes, ... A very light structure, but they still needed a lot of power to keep this thing up at high altitude, so the other piece of the puzzle is a very light weight, and very high performance solar cell. Dick Swanson's solar cell is super efficient and paper thin. Thousands on the wings of the pathfinder generate ten thousand watts. He says, The solar cell converts sunlight into electricity, or as AeroVironment likes to say, the plane is powered by its shadow. This plane is powered by conventional fan jets, and rather than stay in the stratosphere for months at a time, two would fly in shifts sending and receiving phone calls over a city. The pilots on board would be responsible for taking the plane off, going up to the location, where they would be flying around in circles. Before they leave station, a second plane comes up and assumes responsibility for wireless communications, then there's a hand off. Angel Technologies says a fleet of a thousand planes could provide telecommunications for three hundred cities around the world. Sky Station says several fleets of helium balloons, say two hundred fifty over every major city, could also send cell signals from the stratosphere. And if any of this seems far fetched, Consider the incentive. Planes and balloons would cost only a fraction of the fifty million dollar a launch cost of satellites, and give new companies a piece of the multi-billion dollar communications business.

Passage - II
AeroVironment has been flying solar-electric planes successfully for over two decades and is recognized as the world leader in the field. The aircraft developed under this program have proven the viability of solar-electric aircraft for high-altitude flight. Within two years, solar-electric airplanes incorporating energy storage for nighttime flight will be capable of continuous flight for up to six months at a time at altitudes over 60,000 feet. Applications for such aircraft include telecommunications, remote sensing and atmospheric measurement. The first unmanned solar airplane developed under the NASA program, the Pathfinder, flew to 71,500 feet in 1997. A modified Pathfinder, known as Pathfinder-Plus, flew to 82,000 feet, higher than any other propeller-driven aircraft. This record flight was the 39th consecutive successful flight test of the Pathfinder platform.
Building on Pathfinder’s success, AeroVironment built a next-generation aircraft with a 206-foot wingspan, called the Centurion. The wingspan was then further extended to 247 feet, and the aircraft was renamed the Helios Prototype. The Helios Prototype, which successfully completed initial low altitude flight testing at Edwards Air Force Base in 1999, was then equipped with high efficiency solar cells and underwent high-altitude flight testing in the summer of 2001 in Hawaii at the U.S. Navy Pacific Missile Range Facility in Kauai. On August 13, 2001 on its second high altitude flight, Helios flew to 96,863 feet, shattering the world altitude record for both propeller and jet-powered aircraft. In June and July of 2002, SkyTower/AeroVironment, in collaboration with the Japanese Ministry of Post and Telecommunications (CRL/TAO) and NASA, successfully completed several telecom tests in Kauai—the world’s first commercial applications transmitted from over 60,000 feet in the stratosphere.  The final test, a telecom demonstration scheduled for mid-July, provided an opportunity for participants to see this breakthrough technology first-hand. The commercial version of Helios, which is the ultimate evolution of the Pathfinder and Helios Prototype, will incorporate a fuel cell energy storage system to provide power for flying through the night. It will be capable of continuous flight for months at a time at altitudes of 50,000 to 70,000 feet. A full-size fuel cell and electrolyzer energy storage system for the Helios Prototype is now operating in AeroVironment's test facility. As part of the NASA ERAST program, a reduced weight version of this system will be integrated into the Helios aircraft to enable continuous multi-day flight operation.