4. Project Echo. The Echo satellite was a large inflated balloon with a highly reflective surface. Satellites of
the Echo type are known as passive satellites, which serve as reflectors or reradiators of electromagnetic energy
and contain no energized electronic circuitry of their own. Orbital altitude varies from 658 to 1,222 miles. On
the same day the balloon was launched, the first two-way-voice link via passive satellite was accomplished.
5. Project Westford. The primary objective of Westford was to place an orbital reflective belt of millions of
tiny dipoles around the Earth. These dipoles return a large percentage of radiation received to the Earth. The
announcement of this project brought a storm of objections from scientists around the world who claimed that
this belt of resonant particles would interfere with both radio and visual astronomical observations. On 4
October 1961, a special panel of the President's Science Advisory Committee reported that no permanent
damage would accrue from such an experiment, and a launch with a payload of 75 pounds of fine copper
dipoles was attempted on 21 October 1961. The experiment failed because the dipoles did not disperse in orbit.
On 12 May 1962, the US Air Force announced that the second Westford experiment package had been launched
and that dispersal was taking place as planned. The final results of this experiment were not announced.
6. Project Advent. Project Advent was a major military satellite communications effort directed at placing a
multichannel active repeater at synchronous altitude. At synchronous altitude the satellite revolved around the
Earth at the same angular speed as the Earth's surface. The satellite, therefore, appeared to hang nearly
motionless above some point on the Earth's surface. This has many obvious advantages of a low- or medium-
altitude nonsynchronous satellite, the most important being that it eliminates many of the technical problems
associated with tracking a satellite moving at high speed across the sky. Difficulties encountered in the booster
program, combined with other complications, caused cancellation of the entire program and the effort was
reoriented into the Defense Communication Satellite Program (DCSP) for DoD. The two "gateway" ground
terminals that were built for the Advent program at Fort Dix, New Jersey and Camp Roberts, California, were
first modified for the SYNCOM program and have since been remodified for the DCSP.
7. Project Telstar. Telstar I satellite was a medium-altitude communications satellite, commercially designed
and launched by National Aeronautics and Space Administration (NASA) to demonstrate the feasibility of
intercontinental communications via satellites. Entirely company-founded by American Telephone &
Telegraph Company (AT&T), the launch was performed by NASA Orbit was achieved on 10 July 1962 and a
live television program was transmitted for the first time between North America and Europe. Trouble
developed in the satellite when ionization caused by high-altitude nuclear testing affected certain parts. A
specially formulated code was used to turn off the power supply long enough for deionization to occur.
Successful operation was restored and continued throughout the remainder of its life. Telstar II was orbited on
7 May 1963. In an attempt to reduce the ionization effects experienced with Telstar I, Telstar II was placed in a
higher orbit (6,702 miles maximum altitude) and employed some evacuated devices. Live color television was
transmitted via Telstar II from the US to France.