Explorer 3

Explorer 3 was the third satellite of the Explorer program, which was the first and most comprehensive program of satellites and space probes of the United States.

The satellite was launched in the framework of Geophysical Year and should, after the failure of Explorer 2, continue the research of Explorer 1. The instruments were thereby placed in the front part of the fourth stage of the launch vehicle housing. Explorer 3 was spin stabilized and turned approximately 750 times per minute around the longitudinal axis. To send the data of the entire orbit to the ground station, possessed Explorer 3 on a magnetic tape. The data is sent with a 60 milliwatt transmitter to 108.03 MHz and with a 10 milliwatt transmitter at 108.00 MHz for Earth. When two antennas slot antennas and four flexible antennas that unfolded due to the rotation of the satellite and a crossed dipole antenna were served. Energy related to the satellite from a nickel -cadmium battery, which alone accounted for about 40 % of the weight of the payload. This could provide the 60 - milliwatt transmitter for 31 days and the 10 - milliwatt transmitter for 105 days with electricity.

For thermal control surface of the Explorer 3 was white with dark green stripes painted.

Like its two predecessors Explorer 3 was equipped among other things with a Geiger counter to measure cosmic radiation, as well as an apparatus for detecting micro- meteorites.

On June 27, 1958 after about 1160 orbits of the satellite burned up in the atmosphere. A replica can be in the National Air and Space Museum in Washington, DC be visited.

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