Magellan line of sight acceleration profile data record (LOSAPDR)
The Magellan LOSAPDR files contain results from processing of radio tracking data.
The Doppler shift of radio transmissions along the line-of-sight from
the spacecraft to the receiver on the Earth is measured, and splines
are fitted to the Doppler residual
values resulting from spacecraft orbit solutions. Analytical differentiation of
spline results is then interpreted as local accelerations, from which the size and
location of mass anomalies can be inferred. The image above shows the free-air
gravity field of Venus as determined from cycle 4 and 5 Doppler data.
More information about this image is available in the
Note that this image is NOT on the CD-ROM, which contains
LOSAPDRs stored as ASCII tables, one file per orbit.
Each row in the table contains times,
Doppler residuals, spacecraft position and velocity information, and
inferred spacecraft acceleration.
The Planetary Data System (PDS) has written the LOSAPDR products onto CD.
One CD-ROM volume has been produced for cycle 4 and 2 CD-WO volumes have been
produced covering cycles 4-6. These are available from NSSDC.
These data are also available on-line at
the PDS Geophysics Subnode.
Ordering the LOSAPDR CD-ROM - NSSDC CD-ROM Catalog
More information on the LOSAPDR CD-ROM - NSSDC Master Catalog
Detailed information on the Cycle 4 LOSAPDR CD
PDS Geosciences Node
PDS Geophysics Subnode
NSSDC Planetary Sciences Home Page
Dr. David R. Williams, firstname.lastname@example.org
NSSDC, Mail Code 690.1
NASA Goddard Space Flight Center
Greenbelt, MD 20771
NASA Official: Ed Grayzeck, email@example.com
Last Updated: 30 December 2004, DRW