Happy birthday to you,

happy birthday to you,

Happy birthday dear Sputnik,

happy birthday to you.

Last week (October 4) marked the 50th anniversary of the launching of Sputnik I. The scientific purposes of Sputnik I were to measure the density of the upper atmosphere, the propagation of radio waves in the upper atmosphere, and the density of meteorites in low orbit.

Sputnik wasn't a large or complicated satellite by today's standards: 185lb, 23 inches in diameter, with 4 antennae ranging from 8 to 10 feet long. Sputnik I was polished smoothly enough that it appeared as a 6th magnitude object in the night sky (dimly visible on a clear night), and it emitted a regular series of radio beeps. These last two properties brought the space race into prominence. The satellite itself only lasted a couple of months, but it's effects are still being felt today.