Stardust is the first U.S. mission launched to robotically obtain samples in deep space and return them to Earth. Stardust is the first NASA mission dedicated to exploring a comet. Comets are leftover materials that formed of the planets and the Sun more than 4.5 billion years ago.
Comets contain many of the organic materials thought to be essential for the origin of life.
In the early Solar System, comets bombarded the planets, repeatedly and often. The space object that struck Earth 65 million years ago, causing the dinosaurs to become extinct, may have been a comet. Comet Wild 2, the destination of Stardust, almost collided with Jupiter in 1974, causing its orbit to be deflected closer to the Sun. It will take several hours to fly through the coma - the cloud of dust and gas coming off the comet's nucleus. It will fly through the part of the coma ahead of the comet nucleus.