VANGUARD 1
This satellite belongs to the United States navy developed by the US navy research laboratory. It was launched on March 17, 1958. It holds the record as the world’s oldest satellite that is still in orbit. The expected life time of this spacecraft was about 240 years. The main mission of this satellite is to study the earth science. It is the first satellite to be powered by the solar energy from the sun. For this purpose the satellite has six solar cells mounted on the outer surface. The spacecraft is spherical in structure and weighs about 1.47 kilograms. There are six short antennas used to transmit the data observed in the space. This tracking data was used to study about the shape of the earth. It also determines the total electron content between the space and the ground stations. This satellite lost the communication slowly and the final data received at May 1964 but it is still in the earth’s orbit.