Boeing Delta II 7000 Series Rocket Kicks Off The New Millennium At Cape Canaveral
With The Successful Launch Of An Air Force Global Positioning System Satellite

By Cliff Lethbridge

CAPE CANAVERAL AIR FORCE STATION, FL (January 30, 2001) - A Boeing Delta II 7000 Series (model 7925) rocket successfully launched the NAVSTAR GPS IIR-7 satellite at 2:55 a.m. EST today from Launch Pad 17A. This was the first launch of the New Year and the first launch of the New Millennium at the Cape. Launch was delayed about 12 minutes to rectify a last-minute technical glitch which cropped up in the final minutes of the countdown.

Due to a rare combination of wind speed and direction, only a handful of security and safety personnel on Cape Canaveral Air Force Station were able to view the launch outside. A brisk on-shore wind flow caused all non-essential Cape personnel to be ordered indoors before launch. Even members of the news media who wished to view the rocket as it lifted off the pad were required to evacuate the Cape about 30 minutes before launch to prevent missing the event entirely.

NAVSTAR GPS IIR-7 is a replacement satellite in the Air Force Global Positioning System (GPS), a 24-satellite constellation designed to allow military forces to determine their location anywhere in the world with tremendous accuracy. There are currently 30 GPS satellites in orbit, including spares. The satellite launched today is destined to replace one of the original operational GPS satellites launched in 1989. Each GPS satellite circles the Earth approximately every 12 hours at an altitude of about 11,000 miles and transmits continuous signals.

Ground users can use the GPS constellation to determine their location to within a few feet and the time to within one-millionth of a second. GPS receivers were originally built for use on military ships, aircraft and land vehicles. Hand-held receivers were also built for use by ground troops. The technology eventually made its way into the civilian commercial marketplace, although initially the U.S. military scrambled the GPS signal so that civilian receivers were not as accurate as military receivers. However, the Air Force recently decided not to scramble GPS transmissions, effectively making civilian receivers as accurate as military receivers.

Each GPS satellite has a useful life of about 7.5 years. The GPS constellation is controlled from the GPS Master Control Station (MCS), operated by the 50th Space Wing's 2nd Space Operations Squadron at Falcon Air Force Base, Colorado. The GPS-dedicated ground support system consists of five monitor stations and four ground antennas located around the world. The monitor stations use GPS receivers to track the navigation signals of all the GPS satellites. Information from the monitor stations is then processed at the MCS and used to update the navigation messages sent from the GPS constellation.

Copyright © 2001 by Spaceline, Inc.