Twin Artemıs Probes To Study Moon İn 3-D

On Sunday, July 17, the moon will acquire its second new companion in less than a month. That's when the second of two probes built by the University of California, Berkeley, and part of NASA's five-satellite THEMIS mission will drop into a permanent lunar orbit after a meandering, two-year journey from its original orbit around Earth. The first of the two probes settled into a stable orbit around the moon's equator on June 27. If all goes well, the second probe will assume a similar lunar orbit, though in the opposite direction, sometime Sunday afternoon. The two spacecraft that comprise the ARTEMIS mission will immediately begin the first observations ever conducted by a pair of satellites of the lunar surface, its magnetic field and the surrounding magnetic environment.

"With two spacecraft orbiting in opposite directions, we can acquire a full 3-D view of the structure of the magnetic fields near the moon and on the lunar surface," said Vassilis Angelopoulos, principal investigator for the THEMIS and ARTEMIS missions and a professor of space physics at UCLA. "ARTEMIS will be doing totally new science, as well as reusing existing spacecraft to save a lot of taxpayer money."

"These are the most fully equipped spacecraft that have ever gone to the moon," added David Sibeck, THEMIS and ARTEMIS project scientist at the Goddard Space Flight Center (GSFC) in Maryland. "For the first time we're getting a unique, two-point perspective of the moon from two spacecraft, and that will be a major component of our overall lunar research program."

The transition into a lunar orbit will be handled by engineers at UC Berkeley's Space Sciences Laboratory (SSL), which serves as mission control both for THEMIS (Time History of Events and Macroscale Interactions during Substorms) and ARTEMIS (Acceleration, Reconnection, Turbulence, and Electrodynamics of the Moon's Interaction with the Sun).

"We are on our way," said Manfred Bester, SSL director of operations. "We're committed."

What makes the auroras dance?

The five THEMIS satellites (or probes) were launched by NASA on Feb. 17, 2007 to explore how the sun's magnetic field and million-mile-per-hour solar wind interact with Earth's magnetic field on Earth's leeward side, opposite the sun. Within a year and a half, they had answered the mission's primary question: Where and how do substorms in the Earth's magnetosphere – which make the auroras at the north and south poles dance – originate?