Launched via space shuttle in May 1989, the long-delayed Magellan space probe reaches the planet Venus after an unusually long voyage (15 months) and begins an orbital insertion maneuver. Where most missions to Venus have reached the planet in only a few months, Magellan has had to make do without the more powerful Centaur liquid-fueled booster stage, resulting in a journey of a year and three months. (The Centaur upper stage had been cancelled after the Challenger disaster because it was felt that carrying an additional liquid-fueled rocket in a shuttle cargo bay was too risky.) Magellan is placed into an elliptical orbit, completely circling Venus every three hours, where it will conduct high-resolution radar mapping of the surface at the closest point in its orbit, and transmitting the resulting data to Earth while furthest from Venus. The first phase of the mapping mission will last through 1991.