English: This artist's concept of a proposed Mars sample return mission portrays the capture of a collection of Martian samples by a spacecraft orbiting Mars. The samples would have been collected on Mars by a rover and lifted to orbit by an ascent vehicle. After this rendezvous, the orbiter would fire its main thruster to escape Mars orbit and begin a return trip to deliver the sample container to Earth. NASA and the European Space Agency are collaborating on proposals for a mission to gather samples of Martian rocks and bring them to Earth after 2020. This illustration depicts preliminary concepts, not finished design.