On March 6, 1986, the Soviet Union's Vega 1 spacecraft flew by Halley's Comet. Vega 1 was the first of five missions to fly by Halley's Comet in the same month. This fleet of spacecraft has been called the "Halley Armada." Because Halley's Comet only comes around once every 75 years, space agencies around the world took advantage of this once-in-a-lifetime opportunity. Before Vega 1 went to the comet, it first flew by Venus to drop off a lander. It then used Venus to perform a gravitational assist maneuver, which put it right on track to fly by Halley's Comet.