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Clementine S-Band Transponder Doppler Gravity Experiment

NSSDCA ID: 1994-004A-08

Mission Name: Clementine
Principal Investigator:Dr. Eugene M. Shoemaker


The Clementine gravity experiment used measurements of perturbations in the motion of the spacecraft to infer the lunar gravity field. Clementine was equipped with an S-band microwave transponder and 2 S-band omni-directional high-rate antennas which were used for tracking by the NRL tracking station in Pomonkey, Maryland, and the NASA Deep Space Network. The frequency of the S-band transmission was measured every 10 sec., and the Doppler shift would give the relative velocity of the spacecraft towards or away from the Earth. Accelerations were calculated from changes in the velocity, and after accounting for the orbit, relative motions of Earth and Moon, and Earth and solar gravity, these accelerations are converted to lunar gravity effects on the spacecraft. The calculated lunar gravity field can be used to model subsurface lunar structure. The Pomonkey station could measure the velocity to an accuracy of 3 mm/s, while the Deep Space Network stations could acheive about 0.3 mm/s. Tracking was not possible on most of the lunar farside (120 to 240 long., -45 to 45 lat.), when the Moon was between the spacecraft and the Earth. In all, over 361,000 observations were made, approximately 57,000 at less than 1000 km altitude.

Alternate Names

  • Clementine Radio Science
  • Clementine/ClementineS-BandTransponderDopplerGravityExperiment
  • urn:nasa:pds:context:instrument:clem1.rss

Facts in Brief

Mass: 8.27 kg
Bit rate (avg): 128 kbps

Funding Agencies

  • Department of Defense-Department of the Navy (United States)
  • NASA-Office of Space Science (United States)


  • Planetary Science: Geology and Geophysics

Additional Information

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



NameRoleOriginal AffiliationE-mail
Dr. Paul D. SpudisDeputy Team LeaderLunar and Planetary
Dr. Eugene M. ShoemakerTeam LeaderUS Geological Survey
Prof. Jacques E. BlamontTeam MemberCNRS, Service d'Aeronomie
Mr. Merton E. DaviesTeam MemberRand Corporation
Dr. David E. SmithTeam MemberNASA Goddard Space Flight
Dr. Daniel N. BakerTeam MemberUniversity of
Mr. Thomas C. DuxburyTeam MemberNASA Jet Propulsion
Dr. Bonnie J. BurattiTeam MemberNASA Jet Propulsion
Dr. Carle M. PietersTeam MemberBrown
Mr. Charles H. ActonTeam MemberNASA Jet Propulsion
Mr. Eric EliasonTeam MemberUS Geological
Dr. Alfred S. McEwenTeam MemberUS Geological
Dr. Paul G. LuceyTeam MemberUniversity of

Selected References

  • Lemoine, F. G. R., et al., A 70th degree lunar gravity model (GLGM-2) from Clementine and other tracking data, J. Geophys. Res., 102, No. E7, 16339-16359, doi:10.1029/97JE01418, July 1997.

Other Clementine Information at NSSDCA

Clementine overview

Other Sources of Clementine Data/Information

Clementine Gravity and Topography Data

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