NASA explains the secret weapon for its audacious Mars sample mission Chris Davies - Dec 22, 2020, 1:12pm CST NASA’s mission to take the Perseverance rover to Mars may be ambitious in its own right, but even that pales in comparison to the US space agency’s incredible plan to bring samples of Martian rock back to Earth. While Perseverance will join Curiosity, Sojourner, Spirit, and Opportunity as permanent residents of Mars, the samples the rover collects of soil and rock there are intending to make a return journey. Of course, getting stuff from Earth to Mars – while challenging in itself – does at least have the collected expertise of NASA and its commercial partners to count upon. Bringing samples back in the opposite direction, though, is far trickier. While Curiosity and the other rovers have beamed images and scientific data back through their data connections with Earth, you can’t do that with physical soil samples.