1958.1.31 The launch of first US made artificial satellite EXPLORER 1

The first US artificial satellite, EXPLORER Ⅰ, successfully launched and carried by Jupiter-C.

Jupiter-C included four boosters. At the forth stage, the length was 2.3 meters with cylinder diameter of 0.152 meters and total weight of 13.97KG. It was equipped with radiation measurer and satellite temperature controllers. According to data transmitted on February 3, 1958, the amount of radiation on the orbit did not exceed 12 times that on the earth.