NASA Dryden News Releases

NASA Schedules SR-71 Flights Over SouthWest

Jan. 21, 1994

Release: 94-2

NASA plans to fly an SR-71 aircraft over areas of eastern California, Arizona and New Mexico Jan. 25 at supersonic speeds in support of an experiment for a commercial program developing a satellite-based instant wireless personal communications network called the IRIDIUM system.

The aircraft will be flying at a speed of about 2200 mph -- three times the speed of sound -- at an altitude of up to 75,000 feet.

The experiment is being conducted by Motorola's Satellite Communications Division, Chandler, Ariz. It is part of ongoing work to test prototype equipment for the IRIDIUM system which is being developed to permit any type of telephone transmission -- voice, data, FAX, paging -- to reach its destination anywhere on Earth, at anytime of the day or night. The system is expected to become operational in 1998.

The flight path includes Arizona because the IRIDIUM system is being designed and tested in Arizona. New Mexico is included because the SR-71 has a very large turn radius that takes it over that state during the mission.

Two flights are scheduled Jan. 25 for the experiment, with departures from NASA's Dryden Flight Research Center, Edwards, Calif., planned at 9 a.m. and 12 p.m. (PST). Two SR-71 flights were flown last Dec. 22 for the Motorola experiment, but different flight paths were used on that mission.

Geographical areas under the SR-71 during the mission will include Owens Valley, Calif.; the southeast portion of Nevada east of Las Vegas; the southwest portion of Arizona west of Phoenix; the southern portion of Arizona south of Tucson; western New Mexico west of Truth or Consequences; and central Arizona north of Phoenix and south of Springerville. As the aircraft returns to California it will fly over the eastern Mojave Desert north of Twenty Nine Palms.

People on the ground along an approximate 30-mile wide flight path under the aircraft may hear a mild to moderate sonic boom as the aircraft passes overhead.

The SR-71 is being used for these experiments to simulate some of the communications conditions expected to occur with spacecraft when the IRIDIUM system is in operational use.

The SR-71 is the world's fastest and highest flying aircraft. A former U.S. Air Force reconnaissance aircraft, it is used by NASA in a variety of research projects that call for a high speed, high altitude platform.

Sonic booms are created by air pressure any time an aircraft exceeds the speed of sound. Much like a boat pushes up a bow wave as it travels through the water, an aircraft pushes air molecules aside in such a way they are compressed to the point where shock waves are formed. This shock wave expands downward from the aircraft in a cone that spreads across the landscape along the flight path. The sharp release of pressure, after the buildup by the shock wave, is heard as the sonic boom.

Several factors influence the intensity of sonic booms -- weight, size and shape of the aircraft or vehicle, plus its altitude, attitude, flight path, and weather or atmospheric conditions.


Note to Editors: For further information on the Motorola experiment contact Stephanie Nowack at (602) 732-2012.

For additional information on the SR-71 aircraft, contact Don Nolan, (805) 258-3447 or

Color photographs of the SR-71 are available from the Dryden Public Affairs Office, (805) 258-3449

These photos also are available on the World Wide Web via Internet at address: /centers/dfrc/Gallery/Photo/index.html