TELSTAR, THE WORLD'S 1ST COMMUNICATIONS SATELLITE

Today, The Grandma has been reading about Telstar, the communication satellite that was launched on a day like today in 1962.

Telstar refers to a series of communications satellites. The first two, Telstar 1 and Telstar 2, were experimental and nearly identical. 

Telstar 1 launched atop of a Thor-Delta rocket on July 10, 1962, successfully relayed the first television pictures, telephone calls, and telegraph images through space. It also provided the first live transatlantic television feed. Telstar 2 was launched May 7, 1963. Telstar 1 and 2 -though no longer functional- still orbit the Earth.

Belonging to AT&T, the original Telstar was part of a multi-national agreement among AT&T (USA), Bell Telephone Laboratories (USA), NASA (USA), GPO (United Kingdom) and the direction générale des Télécommunications (France) to develop experimental satellite communications over the Atlantic Ocean. Bell Labs held a contract with NASA, paying the agency for each launch, independent of success.

Six ground stations were built to communicate with Telstar, one each in the US, France, the UK, Canada, West Germany and Italy. The American ground station -built by Bell Labs- was Andover Earth Station, in Andover, Maine. The main British ground station was at Goonhilly Downs, Cornwall.

The BBC, as international coordinator, used this location. The standards 525/405 conversion equipment (filling a large room) was researched and developed by the BBC and located in the BBC Television Centre, London. The French ground station was at Pleumeur-Bodou. The Canadian ground station was at Charleston, Nova Scotia. The German ground station was at Raisting in Bavaria. The Italian ground station (Fucino Space Centre) was at Fucino, near Avezzano, in Abruzzo.

The satellite was built by a team at Bell Telephone Laboratories that included John Robinson Pierce, who created the project; Rudy Kompfner, who invented the traveling-wave tube transponder that the satellite used; and James M. Early, who designed its transistors and solar panels. 

The satellite is roughly spherical, measures 880 mm in length, and weighs about 77 kg. Its dimensions were limited by what would fit on one of NASA's Delta rockets. Telstar was spin-stabilized, and its outer surface was covered with solar cells capable of generating 14 watts of electrical power.

The original Telstar had a single innovative transponder that could relay data, a single television channel, or multiplexed telephone circuits. Since the spacecraft spun, it required an array of antennas around its equator for uninterrupted microwave communication with Earth. An omnidirectional array of small cavity antenna elements around the satellite's equator received 6 GHz microwave signals to relay back to ground stations. The transponder converted the frequency to 4 GHz, amplified the signals in a traveling-wave tube, and retransmitted them omnidirectionally via the adjacent array of larger box-shaped cavities. The prominent helical antenna received telecommands from a ground station.

Launched by NASA aboard a Delta rocket from Cape Canaveral on July 10, 1962, Telstar 1 was the first privately sponsored space launch. A medium-altitude satellite, Telstar was placed into an elliptical orbit completed once every 2 hours and 37 minutes, inclined at an angle of approximately 45 degrees to the equator, with perigee about 952 km from Earth and apogee about 5,933 km from Earth.  This is in contrast to the 1965 Early Bird Intelsat and subsequent satellites that travel in circular geostationary orbits.

Due to its non-geosynchronous orbit, similar to a Molniya orbit, availability of Telstar 1 for transatlantic signals was limited to the 30 minutes in each 2.5-hour orbit when the satellite passed over the Atlantic Ocean. Ground antennas had to track the satellite with a pointing error of less than 0.06 degrees as it moved across the sky at up to 1.5 degrees per second.

Since the transmitters and receivers on Telstar were not powerful, ground antennas had to be 27 m tall. Bell Laboratory engineers designed a large horizontal conical horn antenna with a parabolic reflector at its mouth that re-directed the beam. This particular design had very low sidelobes, and thus made very low receiving system noise temperatures possible. The aperture of the antennas was 330 m2. The antennas were 54 m long and weighed 340,000 kg.

Morimi Iwama and Jan Norton of Bell Laboratories were in charge of designing and building the electrical portions of the azimuth-elevation system that steered the antennas. The antennas were housed in radomes the size of a 14-story office building. Two of these antennas were used, one in Andover, Maine, and the other in France at Pleumeur-Bodou. The GPO antenna at Goonhilly Downs in Great Britain was a conventional 26-meter-diameter paraboloid.

More information: Space Center Houston

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Rupert Murdoch

VANGUARD TEST VEHICLE THREE, A FAILURE TO LEARN

Today, The Grandma has received the wonderful visit of one of her closest friends, Joseph de Ca'th Lon. Joseph loves History, Anthropology and Science and they have been talking about the Vanguard TV-3, the first attempt of the United States to launch a satellite into orbit around the Earth, whose failure on a day like today in 1957 thwarted the first attempt of the United States to launch a satellite into Earth orbit.

Vanguard TV-3, also called Vanguard Test Vehicle-Three, was the first attempt of the United States to launch a satellite into orbit around the Earth, after the successful Soviet launches of Sputnik 1 and Sputnik 2.

Vanguard TV-3 was a small satellite designed to test the launch capabilities of the three-stage Vanguard and study the effects of the environment on a satellite and its systems in Earth orbit. It was also to be used to obtain geodetic measurements through orbit analysis. Solar cells on Vanguard TV-3 were manufactured by Bell Laboratories.

At its launch attempt on 6 December 1957, at Cape Canaveral Air Force Station, the booster ignited and began to rise, but about two seconds after liftoff, after rising about 1.2 m, the rocket lost thrust and fell back to the launch pad. As it settled the fuel tanks ruptured and exploded, destroying the rocket and severely damaging the launch pad.

The Vanguard 1A satellite was thrown clear and landed on the ground a short distance away with its transmitters still sending out a beacon signal. The satellite was damaged, however, and could not be reused. It is now on display at the National Air and Space Museum of the Smithsonian Institution.

The exact cause of the accident was not determined with certainty, but it appeared that the fuel system malfunctioned. Other engines of the same model were modified and did not fail.

More information: NASA

The history of the Vanguard TV-3 project dates back to the International Geophysical Year (IGY). This was an enthusiastic international undertaking that united scientists globally to conduct planet-wide geophysical studies. The IGY guaranteed free exchange of information acquired through scientific observation which led to many important discoveries in the future.

Orbiting a satellite became one of the main goals of the IGY. As early as July 1955, President Dwight D. Eisenhower announced, through his press secretary, that the United States would launch small, unmanned, earth-circling satellites as part of the U.S. participation in the I.G.Y.

On 9 September 1955, the United States Department of Defense wrote a letter to the secretary of the Navy authorizing the mission to proceed. The US Navy had been assigned the task of launching Vanguard satellites as part of the program. Project Vanguard had officially begun.

The payload of the TV-3 was very similar to the later Vanguard 1. It was a small aluminium sphere, 16.3 cm in diameter and with a mass of 1.5 kg. It carried two transmitters: a 10-mW, 108-MHz transmitter powered by a mercury battery, and a 5-mW, 108.03-MHz transmitter powered by six solar cells mounted on the body of the spacecraft.

Using six small aerial antennae mounted on its body, the satellite primarily transmitted engineering and telemetry data, but the transmitters were also used to determine the total electron content between the satellite and the ground stations.

Other instruments in the satellite's design included two thermistors, which were used to measure the satellite's internal temperatures for the purpose of tracking its thermal protection's effectiveness.

Although the satellite was damaged beyond reuse capability during the crash, it was still transmitting after the incident.

The Vanguard TV-3 utilized a three-stage launch vehicle known as the Vanguard designed to send the satellite into orbit around the Earth. The fins were removed from the rocket as a way to reduce the drag and instead, the launch motor was mounted in gimbals which allowed it to pivot and direct its thrust for steering. The second and third stages of the rocket were also gimballed.

As designed, the first stage would cause the rocket to rise under the thrust of burning liquid oxygen, ethanol, gasoline and silicone oil which would propel the vehicle to a velocity of 6,400 km/h, lifting the satellite through the denser layers of the atmosphere in 130 seconds. Next, the second stage would burn its fuel, carrying it away from stage one motor and tanks.

More information: Smithsonian National Air and Space Museum

The satellite would rise to an altitude of 480 kilometres above the earth. The flight path had been programmed to tilt from a vertical into a more horizontal course. Then, the third stage would take over to provide spin and the final boost, shoving stage three into orbit at 29,400 km/h.

The satellite would slowly disengage from the third-stage rocket, where at this speed it would fall toward Earth at the same rate the earth's surface curves away from it. As a result, the satellite's distance from the earth would remain about the same.

At launch on 6 December 1957 at 16:44:34 GMT at the Atlantic Missile Range in Cape Canaveral, Florida, the booster ignited and began to rise but about 2 seconds after liftoff, after rising about a meter, the rocket lost thrust and began to settle back down to the launch pad.

As it settled against the launch pad the fuel tanks ruptured and exploded, destroying the rocket and severely damaging the launch pad.

The Vanguard satellite was thrown clear and landed on the ground a short distance away with its transmitters still sending out a beacon signal. The satellite was damaged, however, and could not be reused. It is now on display at the Smithsonian Air and Space Museum.

More information: NASA

 All of us know today the value of communications satellites,
weather satellites, resources satellites...

Rusty Schweickart