Also in 2017, for the larger, more expensive New Frontiers competition, NASA considered a Venus mission called Venus In situ Composition Investigations, or Vici, which sought to put two landers on the planet’s surface. It was passed over for Dragonfly, which will send a plutonium-powered drone to fly on Titan, the largest moon of Saturn.In addition, planetary scientists are in the middle of putting together their once-a-decade recommendations to NASA about their priorities. NASA usually undertakes only one flagship mission — a big, ambitious, expensive effort — at a time. A Venus flagship mission under consideration would include two balloons that would float in the atmosphere for a month.