NASA Assigns Two Spacecraft To New Moon Study Mission
July 10, 2013

NASA Assigns Two Spacecraft To New Moon Study Mission

April Flowers for - Your Universe Online

After successful completion of their science objectives earlier this year, two NASA spacecraft have been assigned a new mission to study how solar wind electrifies, alters and erodes the moon's surface. The data collected could reveal valuable information for future explorers and give planetary scientists a hint of what's happening on other worlds around the Solar System.

The new mission's name is ARTEMIS, or Acceleration, Reconnection, Turbulence and Electrodynamics of Moon's Interaction with the Sun. ARTEMIS will use two of the five in-orbit spacecraft from NASA's older THEMIS (Time History of Events and Macroscale Interactions during Substorms) mission.

The THEMIS mission was originally launched in 2007 as NASA's first five-satellite mission. The unique constellation of the spacecraft provided scientists with data to help resolve the mystery of how Earth's magnetosphere stores and releases energy from the sun by triggering geomagnetic substorms.

"Using two repurposed satellites for the ARTEMIS mission highlights NASA's efficient use of the nation's space assets," said Dick Fisher, director of the Heliophysics Division in NASA's Science Mission Directorate.

The ARTEMIS mission will measure solar wind turbulence on scales never before attempted by previous missions. Solar wind is a stream of charged particles emitted from the upper atmosphere of the sun, which travels at speeds of up to 1 million miles an hour and sometimes causes storms in Earth's magnetosphere.

"ARTEMIS will provide a unique two-point view of the moon's under-explored space environment," said Vassilis Angelopoulos of the University of California, Los Angeles (UCLA), principal investigator of the THEMIS mission. "These two spacecraft are headed for an incredible new adventure."

The two outer THEMIS spacecraft, using spare on-board fuel and a set of complex orbit maneuvers over the course of more than a year, have moved into their initial positions to begin the ARTEMIS mission. One ARTEMIS spacecraft reached the L2 Lagrange point on the far side of the moon on August 25, 2012, while the other spacecraft reached the L1 Lagrange point on the Earth-side of the moon on October 22.

A Lagrange point is sort of a gravitational parking space for spacecraft, as the gravity of the Earth and moon balance there. "ARTEMIS is going where no spacecraft have gone before," said Manfred Bester, Mission Operations manager from the University of California at Berkeley, where the spacecraft are operated. "We are exploring the Earth-Moon Lagrange points for the first time."

The spacecraft will spend six months at the Lagrange points before moving closer to the moon. Initially, the spacecraft will be approximately 62 miles from the surface of the moon, but will eventually move closer. The spacecraft will investigate how the solar wind impacts a rocky world when there's no magnetic field to protect it from a point-blank range.

Earth, as opposed to the moon, is protected from direct solar wind contact by its magnetic field. The moon, on the other hand, is exposed because of its lack of global magnetism.

Part of NASA's series of low-cost, rapidly developed missions in the Explorers Program, ARTEMIS is a joint effort among NASA's Goddard Space Flight Center in Greenbelt, Maryland; NASA's Jet Propulsion Laboratory in Pasadena, California; the Space Sciences Laboratory at Berkeley; and UCLA.

The remaining three THEMIS spacecraft will continue to study substorms that are visible in the Northern Hemisphere as a sudden brightening of the Aurora Borealis, otherwise known as the Northern Lights.