|Space & Planetary Applications
magnetometers have been used for some years aboard orbiting and
interplanetary spacecraft to measure magnetic fields. Some examples:
- The outstanding accuracy
and stability of helium magnetometers were demonstrated by the
lamp-pumped Low-Field Vector Helium Magnetometer, used on past
planetary missions, and also on the Ulysses spacecraft (launched in
1990), now in polar orbit around the sun.
- The Cassini-Huygens
spacecraft, launched in 1997 and due to arrive at Saturn and its moon
Titan in 2004, uses a Vector/Scalar Helium Magnetometer (V/SHM),
provided by the Jet Propulsion Laboratory (JPL), to measure magnetic
fields. The scalar-mode control electronics for this instrument were
designed by Polatomic.
Miniature Vector Laser Magnetometer for Earth Science Applications (NASA /Glenn Research Ctr.)
Miniature Vector Laser Magnetometer (MVLM) is being developed by
Polatomic for NASA’s Earth Sciences Technology Office (ESTO) to measure
the Earth’s magnetic field from spacecraft in Earth orbit. The Earth’s
magnetosphere protects the Earth from incoming radiation from space,
and can be separated into an internal field arising from sources within
the solid earth, and an external field component, which is driven by
interactions with the solar wind and solar radiation. Data from the
measurement of these fields allow for estimation of the internal
dynamics of the Earth’s core, the structure and dynamics of the
lithosphere and crust, and the interaction between the Earth’s field
and the solar wind – a possible influence on Earth’s climate.
Self-Calibrating Vector Magnetometer for Space Applications (NASA / JPL)
Self-Calibrating Vector Magnetometer (SVM) technology represents a
substantial advance in the state of the art of helium magnetometer
design. Magnetic field measurement instruments aboard spacecraft
traditionally require two different types of sensors – a fluxgate
magnetometer to provide vector field measurements, and a scalar
magnetometer to provide scalar measurements and also to calibrate the
fluxgate magnetometer. With the SVM, Polatomic plans to provide all
these functions in a single magnetometer containing one helium cell.
For calibration and scalar measurements, either Optically-driven Spin
Precession (OSP) or Magnetically-driven Spin Precession (MSP) will be
used. For vector measurements, the SVM will use a Bias Field Nulling
(BFN) procedure, which employs tri-axial coils surrounding the cell.