Image of Explorer 38.
|Manufacturer||Goddard Space Flight Center|
|Launch mass||602 kg (1,327 lb)|
|Start of mission|
|Launch date||4 July 1968, 17:26:50UTC|
|Launch site||Vandenberg SLC-2E|
|Semi-major axis||12,221.0 kilometers (7,593.8 mi)|
|Perigee altitude||5,832.8 kilometers (3,624.3 mi)|
|Apogee altitude||5,867.8 kilometers (3,646.1 mi)|
|Argument of perigee||191.2321°|
|Epoch||3 July 2018|
Explorer 38 (also called as Radio Astronomy Explorer A, RAE-A and RAE-1) was the first satellite to study radioastronomy. Explorer 38 was launched as part of the Explorers program, being the first of the 2 satellites RAE. Explorer 38 was launched on 4 July 1968 from Vandenberg Air Force Base, California, United States, with a Delta J rocket.
Explorer 38 measured the intensity of celestial radio sources, particularly the Sun, as a function of time, direction and frequency (0.2 MHz to 20 MHz). The spacecraft was gravity gradient oriented. The spacecraft weight was 602 kilograms (1,327 lb), and average power consumption was 25 W. It carried 2 750 feet (230 m) long V-antennas, one facing toward the Earth and one facing away from the earth. A 120 feet (37 m) long dipole antenna was oriented tangentially with respect to the earth's surface.
The spacecraft was also equipped with one 136 MHz telemetry turnstile. The onboard experiments consisted of four step-frequency Ryle-Vonberg radiometers operating from 0.45 MHz to 9.18 MHz, two multichannel total power radiometers operating from 0.2 MHz to 5.4 MHz, one step frequency V-antenna impedance probe operating from 0.24 MHz to 7.86 MHz, and one dipole antenna capacitance probe operating from 0.25 MHz to 2.2 MHz. Explorer 38 was designed for a 1-year minimum operating lifetime.
The spacecraft tape recorder performance began to deteriorate after 2 months in orbit. In spite of several cases of instrument malfunction, good data were obtained on all three antenna systems. The small satellite observed for months the "radio sky" in frequencies between 0.2 MHz and 9.2 MHz, but it was subjected to the continuous radio interference coming from our planet, both natural (aurorae, thunderstorms) and artificial.
Explorer 38 has 4 antennas deployed in orbit:
The scientific experiments are:
The following results are reported in 1971: