The technological challenges of the plane mission are daunting. "The agency must be able to deliver and then fly a planelike craft in an atmosphere that is 1 percent as dense as the atmosphere of Earth," says Kluger. "It's an ambitious undertaking, but NASA has succeeded in meeting challenges like this in the past." Until the plane mission lifts off, NASA is putting its eggs in two more conventional modes of exploring the planet: Within the year, a polar orbiter will be surveying Mars and a lander will arrive to study what lies beneath its surface. Martians, beware: The Earthlings are coming, the Earthlings are coming!
NASA is returning to its aviation roots. The space agency revealed its plan for Mars this week, and it features... a plane. The Martian flyover in a yet-to-be-designed unmanned plane is scheduled for 2003 -- fittingly, the 100th anniversary of the first Wright brothers flight. Symbolism aside, an unprecedented amount of Martian data will be collected. "We are entering a new phase," says TIME science writer Jeffrey Kluger, who notes that the last Pathfinder mission was the first in which the surface exploration of Mars was carried out by a moving spacecraft. The plane mission takes "such mobile exploration to a new level," says Kluger. "It will allow the close study of much more land area and surface features."