Transcripts of 10636_ARTEMIS_H264_1280x720_59

(tone) (Music) Narrator: Launched in 2007, NASA's five THEMIS spacecraft have now successfully completed their two-year mission to determine the cause of geomagnetic substorms. Because they are continuing to work perfectly, NASA is redirecting the outermost two spacecraft to special orbits at and around the Moon. This new mission, which is called ARTEMIS, uses some very complex maneuvers over two years to get both spacecraft into position. Although the spacecraft sometimes move far outside the orbit of the Moon, their every move is carefully orchestrated to ease them into position while using very little of their precious fuel. ARTEMIS 1, in red, had the larger orbit to begin with, so it requires a much more dynamic path to harness its energy. (Music) (Music) For a few months, the spacecraft don't even orbit the Earth or the Moon. Instead, they circle the two locations where the the gravity of the Earth and the Moon cancel out exactly. These spots, just inside and just beyond lunar orbit are known as Lagrange points. NASA has several satellites orbiting one such point between the Earth and the Sun. As the Moon orbits the Earth, it passes in and out of the Earth's magnetic field and the million-mile per hour stream of particles emitted by the Sun known as the solar wind. While in these regions, the two ARTEMIS spacecraft will seek evidence turbulence, particle acceleration and magnetic reconnection, three fundamental phenomena that control the nature of the solar wind's interaction with the Earth's magnetosphere. Finally, in 2011, the ARTEMIS settle into a lunar orbit. (Music) Employing their full complement of instruments and unique vantage points, the spacecraft will study the vacuum the Moon carves out in the solar wind and the processes that eventually fill this lunar wake. (Music) Nearer the Moon, they will observe the effects of surface electric fields, ions sputtered off the lunar surface, and determine the internal structure of the Moon from variations in its magnetic field. These observations will improve understanding of the Sun-Earth connection called space weather, and its interaction with our nearest neighbor in space. (Music) (Beeping)