The magnetic fields measured by the MAG will be a combination of the Earth's
magnetic field (35,000 nano Teslas), the field carried from the Sun by the
solar wind (approximately 10 nano Teslas), and the Moon's field, which is
extremely weak (approximately 1,000 nano Teslas) compared to that of the
Earth. The magnetic field at the lunar surface is also affected by local
deposits of magnetic material. The instruments are copies of detectors that
are on board the Mars Global Surveyor spacecraft, launched in December 1996,
with some modifications to adapt them for a spinning spacecraft. The triaxial
fluxgate magnetometer is a standard device that is also used to measure
magnetic fields on Earth. "Triaxial" means that it includes sensors
to measure the strength of the field in three different directions. This
enables scientists to determine not only the maximum strength of the field
but also the direction it points.
Image courtesy of Lockheed Martin
The "fluxgate" is an electric coil through which the magnetic
field passes. By measuring the variation of the current passing through
the coil, the MAG determines the strength of the magnetic field. It can
measure magnetic fields as weak as one-millionth of the strength of the
Earth's magnetic field.
* The Magnetometer is mounted on a boom 8.5 feet (2.6 meters) away from
the spacecraft, in order to isolate it from the magnetic fields generated
by the spacecraft's own electronics.
Go to Magnetometer / Electron Reflectometer
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