New Moons Rising - GPS Declassified: From Smart Bombs to Smartphones - page 19

Vanguard's Legacy
Project Vanguard experienced another letdown when the tv- 3bu backup rocket
broke up ifty-seven seconds into its flight, on February 5, 1958 . 103 Coming on
the heels of the triumphant Explorer I launch five days earlier, the rocket fail-
ure brought a less intense public reaction. Success finally came on March 17,
1958, when Vanguard I, a “test”-size satellite, soared into orbit aboard the tv- 4
launch vehicle. Altogether, over a period of about four years, Project Vanguard
developed a new three-stage rocket, designed and built an accurate worldwide
tracking system, and placed three satellites, weighing three, twenty-one, and
fifty pounds, respectively, into orbit in fourteen launch attempts, eleven of
which carried satellites. While the public's memory is forever tied to the tv- 3
fireball, the program surpassed its original goals: to place a scientific satellite
in an orbit around the earth, to prove that it was in orbit, and to use the satel-
lite to conduct a scientific experiment in the upper atmosphere.
Although Vanguard I was not first into orbit, it exceeded expectations, start-
ing with longevity. Sputnik I succumbed to orbital decay and burned up on
reentry after three months. 104 Sputnik II lasted 162 days. 105 Explorer I trans-
mitted signals for almost four months and orbited until 1970. 106 Vanguard I
transmitted signals for more than six years and is still orbiting Earth in a highly
stable orbit. 107 Predictions for how long it will remain in orbit range from two
hundred to two thousand years. The satellite's long life, combined with Mini-
track's accuracy, yielded surprisingly significant scientific findings, given its
modest instrumentation. Orbital studies revealed, among other things, that
Earth is not a perfect sphere but ever so slightly pear-shaped and that the upper
atmosphere is far denser than previously thought. 108
Longevity also describes Minitrack, which spawned several generations of
ground tracking systems. By the fall of 1957, when Sputnik I reached orbit,
Minitrack ground stations had been constructed at numerous sites around the
globe, including at Blossom Point, Maryland; Fort Stewart, Georgia; Havana,
Cuba; Quito, Ecuador; Lima, Peru; and Antofagasta and Santiago, Chile. 109
This north-south line of stations, located roughly along the seventy-ifth merid-
ian of longitude and with overlapping, fan-shaped reception patterns extend-
ing skyward, created an “electronic fence” to capture each overhead pass of
the satellite. Tracking stations transmitted all data by teletype to Washington
dc for processing by an ibm 704 mainframe computer, which calculated and
plotted each orbit. 110