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Magnetometer/Electron Reflectometer (MAG/ER)

NSSDCA ID: 1996-062A-05

Mission Name: Mars Global Surveyor
Principal Investigator:Dr. Mario H. Acuna


The magnetometer/electron reflectometer (MAG/ER) experiment is designed to: (1) establish the nature of the magnetic field of Mars; (2) develop appropriate models for its representation; and, (3) map the Martian crustal remanent field to a resolution consistent with the Mars Global Surveyor orbital altitude and ground track separation. The presence and nature of a magnetic field on Mars will provide evidence of a liquid core, which will in turn constrain models of the internal composition, evolution, and dynamics.

The experiment consists of two separate subsystems: the magnetometer (MAG) and the electron reflectometer (ER). The instruments are mounted on a boom extending from the spacecraft body. The magnetometer subsystem consisted of two triaxial fluxgate magnetometers. The dual magnetometer technique, similar to instruments developed for other missions (e.g., Voyager and Magsat), allowed the real-time estimation of the spacecraft-generated magnetic field and provided redundancy for the in situ magnetic field measurements. Each magnetometer makes measurements in three orthogonal directions over the range +/-16 nT to +/-65,536 nT, over 7 ranges, varying by a factor of 4. The data are measured at 12 bits/sample. The electron reflectometer is a symmetrical quadspherical electrostatic analyzer with a field of view of 360 by 14 degrees. the ER can measure 1 eV to 10 keV with a resolution delta-E/E of 0.25.

The electronics consist of a 80C86 microprocessor with a 16 kbyte memory. The instrument can measure from 2 to 16 magnetic vectors/s Available data rates are 324, 648, and 1296 bits/s

Alternate Names

  • MAG/ER
  • MarsGlobalSurveyor/MAG/ER
  • urn:nasa:pds:context:instrument:mgs.mag

Facts in Brief

Mass: 5.4 kg
Power (avg): 4.6 W
Bit rate (avg): 1.296 kbps

Funding Agency

  • NASA-Office of Space Science (United States)


  • Planetary Science: Fields and Particles

Additional Information

Questions and comments about this experiment can be directed to: Dr. David R. Williams



NameRoleOriginal AffiliationE-mail
Dr. Mario H. AcunaPrincipal InvestigatorNASA Goddard Space Flight Center

Selected References

  • Acuna, M. H., et al., Magnetic field and plasma observations at Mars: Initial results of the Mars Global Surveyor mission, Science, 279, No. 5357, 1676-1680, doi:10.1126/science.279.5357.1676, Mar. 1998.
  • Acuna, M. H., et al., Magnetic field of Mars: Summary of results from the aerobraking and mapping orbits, J. Geophys. Res., 106, No. E10, 23403-23417, Oct. 2001.
  • Mitchell, D. L., et al., Probing Mars' crustal magnetic field and ionosphere with the MGS Electron Reflectometer, J. Geophys. Res., 106, No. E10, 23419-23427, Oct. 2001.
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