NASA Logo, National Aeronautics and Space Administration
NASA Space Science Data Coordinated Archive Header

Synthetic Aperture Radar (SAR)

NSSDC ID: 1989-033B-01
Mission Name: Magellan
Principal Investigator: Dr. Gordon H. Pettengill

Description

The purpose of this experiment was to obtain radar images, combined with altimetry and radiometry measurements, over the majority of Venus' surface. The radar sensor unit was contained in a single unit of overall dimensions 1.27 x 0.76 x 0.30 m. The radar system used the 3.7 m diameter high-gain antenna for synthetic aperture radar (SAR) observations and radiometry. A smaller, fan-beam antenna was used for the altimetry measurements. The antennae operated at a wavelength of 12.6 cm and shared common electronics. Between SAR bursts, pulses from the altimeter were transmitted toward the planet's surface. Radiometer data were also interleaved between the SAR bursts by having the high-gain antenna in a passive mode during which it measured the amount of radiated thermal microwave energy from the surface. Calibration of the radiometer was performed using an internal source. Thermal noise sources (e.g., the radar sensor, antenna, and cabling) were removed by making physical temperature measurements. The SAR operated at a frequency of 2.385 GHz with a pulse length of 0.0265 ms and a peak output of 325 W. In radar mode, the resolution of the instrument was about 150 m. The resolution of the altimeter was 30 m and the accuracy of the radiometer was 2 K. Mapping took place during a 37.2 minute period centering around periapsis with data transmitted during the time around apoapsis. This resulted in imaging swaths of approximately 25 km by 17,000 km which could then be combined to create a map of Venus' surface. When the radar data was combined with altimeter data, a three-dimensional surface map could be created. The radiometer data were used to determine the electrical conductivity and composition of the surface. Each mapping cycle was designed to allow the surface to rotate by one Venus day (243 Earth days or about eight months) under the spacecraft, thereby imaging a full 360 degrees of longitude in each cycle. Because both experiments required the dedicated use of the high-gain antenna, the first three cycles of operation were dedicated to the SAR with the final cycle dedicated to the gravimetry experiment. The original intent was to provide a map which covered in excess of 70% of the surface. By the end of the first mapping cycle, over 80% of the surface had been mapped. By the end of the second cycle, over 90% of the surface had been mapped at least once. By the completion of the third cycle, approximately 99% of the surface had been mapped by the SAR.

Alternate Names

  • SAR

Facts in Brief

Mass: 15.2 kg
Power (avg): 210.0 W
Bit rate (avg): 806.0 bps

Funding Agency

  • NASA-Office of Space Science Applications (United States)

Discipline

  • Planetary Science: Geology and Geophysics

Additional Information

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

 

Personnel

NameRoleOriginal AffiliationE-mail
Dr. John E. GuestCo-InvestigatorUniversity of London 
Dr. Gerald G. SchaberCo-InvestigatorUS Geological Surveygschaber@usgs.gov
Dr. Franz W. LeberlCo-InvestigatorVexcel Corporation 
Dr. Neon E. ArmandCo-InvestigatorInstitute of Radio Engineering and Electronics, Russia 
Dr. R. Keith RaneyCo-InvestigatorCanada Centre for Remote Sensingkeith.raney@jhuapl.edu
Dr. Gerald SchubertCo-InvestigatorUniversity of California, Los Angelesgschubert@astemis.ucla.edu
Dr. Joseph H. BinsackCo-InvestigatorMassachusetts Institute of Technologyjhb@space.mit.edu
Prof. Sean C. SolomonCo-InvestigatorMassachusetts Institute of Technologyscs@dtm.ciw.edu
Dr. R. Stephen SaundersCo-InvestigatorNASA Jet Propulsion Laboratory 
Prof. Raymond E. ArvidsonCo-InvestigatorWashington Universityarvidson@wunder.wustl.edu
Dr. Kurt L. LambeckCo-InvestigatorAustralian National Universitykurt.lambeck@anu.edu.au
Dr. Alexander T. BasilevskyCo-InvestigatorVernadsky Institute 
Dr. Roger J. PhillipsCo-InvestigatorSouthern Methodist Universityroger@boulder.swri.edu
Dr. Charles ElachiCo-InvestigatorNASA Jet Propulsion Laboratorycelachi@mail1.jpl.nasa.gov
Prof. G. Leonard TylerCo-InvestigatorStanford Universitylen@nova.stanford.edu
Dr. William M. KaulaCo-InvestigatorUniversity of California, Los Angeles 
Dr. John A. WoodCo-InvestigatorSmithsonian Astrophysical Observatoryjwood@cfa.harvard.edu
Dr. Victor R. BakerCo-InvestigatorUniversity of Arizonabaker@pirl.lpl.arizona.edu
Dr. Manik TalwaniCo-InvestigatorHouston Area Research Centermanik@rice.edu
Dr. Dan P. McKenzieCo-InvestigatorUniversity of Cambridgemckenzie@esc.cam.ac.uk
Dr. James W. Head, IIICo-InvestigatorBrown Universityjames_head_III@brown.edu
Dr. Barry E. ParsonsCo-InvestigatorOxford Universitybarry.parsons@earth.ox.ac.uk
Dr. Joseph M. BoyceCo-InvestigatorNASA Headquartersjboyce@higp.hawaii.edu
Dr. Gordon H. PettengillGeneral ContactMassachusetts Institute of Technologyghp@space.mit.edu
Mr. Merton E. DaviesCo-InvestigatorRand Corporation 
Dr. Donald B. CampbellCo-InvestigatorCornell Universitydbc7@cornell.edu
Dr. Lawrence A. SoderblomCo-InvestigatorUS Geological Surveylsoderblom@usgs.gov

Selected References

Pettengill, G. H., et al., Magellan: Radar performance and data products, Science, 252, No. 5003, 260-265, Apr. 1991.

Tyler, G. L., et al., Magellan: Electrical and physical properties of Venus' surface, Science, 252, No. 5003, 265-270, Apr. 1991.

Saunders, R. S., et al., Magellan mission summary, J. Geophys. Res., 97, No. E8, 13067-13090, Aug. 1992.

Pettengill, G. H., et al., Venus surface radiothermal emission as observed by Magellan, J. Geophys. Res., 97, No. E8, 13091-13102, Aug. 1992.

Solomon, S. C., et al., Venus tectonics: An overview of Magellan observations, J. Geophys. Res., 97, No. E8, 13199-13255, Aug. 1992.

Johnson, W. T. K., Magellan imaging radar mission to Venus, IEEE Proc., 79, No. 6, 777-790, June 1991.

[USA.gov] NASA Logo - nasa.gov