Space.com: Since 2004, NASA's Cassini spacecraft has been sampling dust as it orbits Saturn. The vast majority of the dust particles have come from eruptions from Saturn's moon Enceladus, but 36 of the particles have been traced to the interstellar medium. The interstellar dust is believed to have come from the local interstellar cloud—the region of dust and gas that the Milky Way is currently moving through. The interstellar particles stand out from the local dust particles because of their direction and high speed. Both NASA's Galileo and the joint NASA–European Space Agency probe Ulysses have detected interstellar dust before, but Cassini was the first probe able to provide measurements of the concentrations of rock-forming elements in the dust. Although the concentrations matched what was expected, the particles were surprisingly uniform in composition. That uniformity may arise from the dust being destroyed and reformed repeatedly by supernova shock waves.
