Acceleration, Reconnection, Turbulence and Electrodynamics of Moon's Interaction with the Sun

NASA has been studying the region around the Earth that protects us from the solar wind – a flow of charged particles coming from the Sun. This protected region is called the magnetosphere. Earth’s Magnetosphere 2

Earth’s magnetosphere – [pronunciation: the second syllable sounds like “neat” and not “net”] Magnetic fields exist throughout all of interplanetary space. The magnetosphere is the region within which the magnetic field generated by Earth is dominating over all other magnetic fields generated by, e.g., the Sun. 3 Credit: Peter Reid 2007

Charged particles in the solar wind can be damaging to people if they are exposed, but luckily the Earth is protected from them. However, in planning for future space travel, high-energy charged particles is an ever- present concern. Lunar Base Design Lab; by ©Thiago Ceballos,

THEMIS A group of five satellites, called the NASA THEMIS Mission, was launched in These special satellites help scientists to unlock the mystery of how Earth's magnetosphere stores and releases energy from the Sun and generate aurora. THEMIS spacecraft and Earth; Credit: dailygalaxy.com 5

FROM THEMIS TO ARTEMIS In 2010, THEMIS scientists had the opportunity to repurpose two of the satellites on a new mission to study the interaction between the Moon and the solar wind. Using the small amount of remaining fuel, and taking advantage of the Moon’s gravity, they sent two of the satellites on a two-year journey from Earth’s orbit into lunar orbit. ARTEMIS trans-lunar trajectories in the ecliptic plane. The coordinate frame here rotates such that the Sun is always to the left. The red line shows the P1 trajectory; the blue line shows the P2 trajectory. The Earth is at the center of the figure, and the Moon’s orbit is shown in gray. The blue dots are the Sun-Earth L1 and L2 Lagrange points, the gray dots are the Moon and the Earth-Moon L1 and L2 points at a particular epoch 6 Credit: Emmanuel Masongsong, UCLA 2013

FROM THEMIS TO ARTEMIS To learn more about how two of the THEMIS satellites became ARTEMIS, check out this interview with scientist Daniel Cosgrove on: How to Recycle a Spacecraft And then watch this video: ARTEMIS Trajectory Movie ARTEMIS is an excellent example of reusing valuable materials for a new, innovative mission. 7

The two repurposed satellites are now orbiting the Moon, helping scientists to understand what happens on the Moon as it passes through the Earth’s magnetosphere, since it doesn’t have one of its own. ARTEMIS Mission Credit: NASA. ARTEMIS 8

ARTEMIS MISSION As the Moon orbits the Earth, it moves into and out of the Earth’s magnetosphere. What happens to the Moon when it is within Earth’s magnetosphere? What happens to the Moon when it is outside of Earth’s magnetosphere? These are some of the mysteries scientists are using ARTEMIS to solve! Credit: Leitha Thrall, UC Berkeley