The Acceleration, Reconnection, Turbulence, and Electrodynamics of
the Moon’s Interaction with the Sun (ARTEMIS) mission is a spin-off from
NASA’s Medium-class Explorer (MIDEX) mission THEMIS, a five identical
micro-satellite (hereafter termed “probe”) constellation in high altitude Earth-orbit
since 17 February 2007. By repositioning two of the five THEMIS probes (P1 and
P2) in coordinated, lunar equatorial orbits, at distances of ~55-65 RE geocentric
(~1.1-12 RL selenocentric), ARTEMIS will perform the first systematic, two-point
observations of the distant magnetotail, the solar wind, and the lunar space and
planetary environment. The primary heliophysics science objectives of the
mission are to study from such unprecedented vantage points and inter-probe
separations how particles are accelerated at reconnection sites and shocks, and
how turbulence develops and evolves in Earth’s magnetotail and in the solar wind.
Additionally, the mission will determine the structure, formation, refilling, and
downstream evolution of the lunar wake and explore particle acceleration
processes within it. ARTEMIS’s orbits and instrumentation will also address key
lunar planetary science objectives: the evolution of lunar exospheric and sputtered
ions, the origin of electric fields contributing to dust charging and circulation, the
structure of the lunar interior as inferred by electromagnetic sounding, and the
lunar surface properties as revealed by studies of crustal magnetism. ARTEMIS is
synergistic with concurrent NASA missions LRO and LADEE and the anticipated
deployment of the International Lunar Network. It is expected to be a key element
in the NASA Heliophysics Great Observatory and to play an important role in
international plans for lunar exploration.