Telstar 1

Telstar 1 is a defunct communications satellite launched by NASA on July 10, 1962. One of the earliest communications satellites, it was the first satellite to achieve live transmission of broadcast television images between the United States and Europe. Telstar 1 remained active for only 7 months before it prematurely failed due to Starfish Prime, a high-altitude nuclear test conducted by the United States. Although the satellite is no longer operational, it remains in Earth orbit.

History

The idea of relaying information from one point on Earth to another by means of satellites was not new. As early as October 1945, the visionary Arthur C. Clarke published an article talking about it in the specialized magazine ''Wireless World''. His idea was to enable communication between two points which were prevented from direct radio communication by the curve of the Earth, by relaying the information by radio through an orbiting satellite. During the Cold War, the shock caused by the successful launch of the first artificial satellite, Sputnik 1, by the Soviets increased the United States' interest in aerospace research. Soon thereafter, the Americans began their attempts to launch orbital communications satellites for transmitting telephone, radio, and television signals.

In December 1958, the United States successfully launched its first communications satellite, SCORE. Through it, then-President Dwight D. Eisenhower sent a Christmas message to the entire world. However, SCORE stayed in orbit for only a few months, its enormous surface area and very low Earth orbit forcing reentry after only 500 laps around the planet due to aerodynamic resistance. Also, SCORE relied on a passive reflector, which greatly reduced signal strength, since it did not amplify the signal before sending it back to earth.

The Telstar project represented a substantial financial investment to advance satellite communications technology. According to a memorandum dated August 16, 1962, the total expenditure for the Telstar experimental satellite project, as reported by AT&T to Senator Kerr, was approximately $50 million. This figure includes an initial estimate of $45 million as of April 19, 1962, covering the costs of orbiting the Telstar satellite and establishing a fully operational ground station in Andover, Maine. Additional expenses incurred after this date increased the total project costs by $5 million, with the Andover facility alone costing around $10 million and another $4 million for necessary tie-in lines.

AT&T also reported that it had invested $1.4 billion in research and development for the essential components of the communications system, of which over $1 billion was directed towards technology closely related to satellite communications.

Specific launch costs were also covered by AT&T. On February 16, 1962, approximately five months before the July 10, 1962, launch, AT&T made an advance payment to NASA totaling $2,680,982.

Launch

Telstar 1 was launched on July 10, 1962, from the Cape Canaveral Air Force Station, Florida, atop a Delta rocket. Spherical in shape, the satellite had a diameter of and weighed .

Operations

The satellite had a transponder (receiver and transmitter) with a 50 MHz bandwidth that could relay a single television channel or a FDM signal containing multiple telephone calls or datastreams. The two rings of microwave cavities visible around the satellite's middle were the uplink and downlink antennas for the data signal. The satellite received the 6.39 GHz microwave uplink signal from the transmitting ground station through the upper ring of smaller cavities, and transmitted the 4.17 GHz downlink signal back to the receiving ground station through the lower ring of larger cavities. Since the transmitter was very weak, with a radiated power of only 14 watts, and the antenna array was omnidirectional, very large aperture antennas were required at the ground stations to communicate with it. The satellite also had a helical antenna at one end to receive control commands.

A 53-meter terrestrial antenna manufactured by AT&T Corporation, located in Andover, Maine, was used for the transmissions between the United States and Europe. Built in 1961, and used by Telstar 1, it was later used by Relay 1. Telstar 1 operated normally from launch until November 1962 when the radiation from the Starfish Prime high altitude nuclear test detonation affected the command channel, which began to behave erratically. The satellite was continuously switched on to work around this problem. On November 23, 1962, the command channel stopped responding. On December 20, the satellite was successfully reactivated, and intermittent data were obtained until February 21, 1963, when the transmitter failed. The energy used by it was produced by 3,600 solar cells. The satellite relied on an active repeater and magnified signal strength by a factor of a hundred using a travelling wave tube amplifier (TWTA). Thirteen days after the launch, the first live broadcast of a television show between the United States and Europe took place.

Broadcasting

References

External links

Telstar
N2yo.com

Stamps and envelopes related to Telstar I
. National Postal Museum
{{Orbital launches in 1962

Telstar satellites
Spacecraft launched in 1962
1962 in the United States
Derelict satellites orbiting Earth