Pioneer VenusNASA launches the 1,100 pound Pioneer Venus Orbiter, designed to orbit Venus for a year to study the planet’s atmosphere and its interaction with other space phenomena. Though launched separately, the two Pioneer Venus spacecraft will arrive at Venus within days of one another in December 1978. The Orbiter takes radar observations of the cloud-shrouded planet, from which the first surface map of Venus is derived. As with many other unmanned NASA spacecraft designed for relatively short-duration missions, the Pioneer Venus Orbiter outlives its design lifespan, staying fully functional into the 1990s and eventually becoming the only American spacecraft to view Halley’s Comet in 1986.