On this day, 67 years ago, on March 17, 1958 (January 28, 1958 in the lunar calendar), the U.S. Navy successfully launched the Pioneer-1 satellite into Earth orbit. On March 17, 1958, following the launch of the first artificial satellite, Explorer 1, the second American artificial satellite, VANGUARD1, was also successfully launched. Pioneer-1 is a small earth-orbiting satellite with a shell made of aluminum alloy with a diameter of 15.2 centimeters and a weight of only 1.47 kilograms. It is used to test the launch capabilities of a three-section rocket vehicle. The design is expected to maintain a service life of nearly 1000 years, and will be powered by solar cells in orbit to continuously transmit data back to the Earth for nearly three years. This scientific satellite has successfully proved that the shape of the Earth is not exactly round, but rather like a pear.