Vanguard 1

Vanguard 1 is an artificial satellite launched into orbit on March 17, 1958, after the more famous Sputnik 1 and Explorer 1; it is the only one still in orbit and this classifies it as the oldest man-made object in orbit.

It was also the first satellite to install photovoltaic panels, when this technology was still in its infancy and did not have the efficiencies and durations it has today. The batteries have run out and communication with the satellite is no longer possible. It is estimated that it will travel its orbit for 240 years.

As reported by NASA, he had been designated to perform a test after a launch by a three-stage vehicle, to check the effects on an artificial satellite placed on an orbit around the Earth; geodetic measurements were also obtained through the analysis of the entire mission.

It is an aluminum sphere of 16.5 cm in diameter weighing 1.47 kg. It contains a 10 mW mercury battery which allowed transmission on a frequency band of 108 MHz [5] used by the Institute of the International Geophysical Year and another battery with a transmission power of 5 mW on a frequency of 108 , 03 MHz, provided by six solar cell devices (about 5 cm on each side) mounted on the body of the satellite. Six 30cm antennas protrude from the sphere. The transmitter was used primarily for surveying and engineering data; it was also used to determine the total electron content between the satellite and a receiving station on the earth's surface.

The three stages of the Vanguard rocket placed the satellite in an orbit between 654 and 3969 km for a rotation period of 134.2 minutes and an inclination of 34.25 °.

The maximum duration of stay in orbit was estimated at around 2000 years; but it was found that the pressure of solar radiation and the atmospheric brake produced significant perturbations, which in the long run caused a significant decrease in the life span of the satellite causing it to slip to 240 years. Mercury batteries ceased to be operational in June 1958, while solar cell batteries operated until May 1964; the last signal was received in Quito (Ecuador).