ARTEMIS Spacecraft Will Fly As Low As 60 Miles Above The Lunar
Surface
Two small NASA probes that had been used to study space weather
now are orbiting the moon to study its interior and surface
composition.
The spacecraft, called Acceleration, Reconnection, Turbulence
and Electrodynamics of the Moon's Interaction with the Sun
(ARTEMIS), began their journey away from Earth's orbit in July
2009. The first spacecraft entered lunar orbit on June 27, and the
second on July 17.
Engineers used complex orbit maneuvers to relocate the
spacecraft to their new locations. The journey required many
gravity assists from the moon and Earth and used minimal amounts of
fuel. The probes will now approach the moon's surface to within
sixty miles once per orbit. The data will provide scientists with
new information about the moon's internal structure for the next
seven to 10 years.
"This is a good example of how additional science can be
achieved with the innovative use of existing spacecraft," said Dick
Fisher, director of Heliophysics for NASA's Science Mission
Directorate in Washington. "The quality of the original design and
construction of the spacecraft creates a double win: a new research
opportunity for the space science community with no additional cost
to the nation's taxpayers."
Both spacecraft were previously in areas called the Lagrangian
points, areas on either side of the moon, where the moon and
Earth's gravity balance perfectly. These locations were ideal spots
to study Earth's distant magnetic field and how the solar wind,
made up of ionized gas known as plasma, flows past the moon and
tries to fill in the vacuum on the other side. The ARTEMIS mission
was made possible by repurposing two spacecraft that would
otherwise have ceased operations in 2010. The spacecraft were part
of NASA's Time History of Events and Macroscale Interactions during
Substorms (THEMIS) mission launched in 2007.
"From their new orbits about the moon, ARTEMIS will collect
important data about the moon's core, its surface composition, and
whether it contains pockets of magnetism," said Dave Sibeck,
ARTEMIS and THEMIS project scientist at NASA's Goddard Space Flight
Center in Greenbelt, Md. "ARTEMIS also will provide information
needed to understand the moon's magnetic environment in space and
its relationship to events near Earth."
The THEMIS mission consisted of five identical spacecraft that
studied the magnetic environment around Earth, the aurora, and how
these are affected by the sun. The other three THEMIS probes
continue their original science mission. Substorms are atmospheric
events visible near the poles as sudden increases in the brightness
of the aurora. The findings from the mission may help protect
commercial satellites and humans in space from the adverse effects
of particle radiation.