The oldest artificial satellite still remaining in Earth orbit is Vanguard 1, a United States scientific satellite launched back in March 1958. Designed primarily to test the launch capabilities of a three-stage rocket and evaluate the effects of the space environment on a satellite, it successfully fulfilled its active scientific mission before communications ceased decades ago. Because of its high-altitude orbit, Vanguard 1 experiences minimal atmospheric drag, allowing the tiny spherical spacecraft to remain in outer space, where scientists calculate it will continue orbiting our planet for centuries to come.