VENUS SURFACE GRAVITY MAPS
from Magellan Mapping Cycles 4 and 5
January 30, 1994
This GIF image was made from data supplied by the Magellan Gravity Team at the
Jet Propulsion Laboratory, Principal Investigator William L. Sjogren. The
original data, ID MGN-V-RSS-5-GRAVDR-L2-V1.0, may be obtained from the
Geosciences Node of the NASA Planetary Data System.
FREE-AIR VERTICAL SURFACE GRAVITY MAP (DMGJV40E.B01)
This image of the free-air gravity field was generated at a reference radius of
6051.0 km from a fortieth degree and order spherical harmonic model (MGN40E)
with a grid spacing of one degree. The model was determined using Doppler radio
tracking data from the Magellan spacecraft on cycles 4 and 5 (Sept. 1992 to Nov
1993). There was also an a priori constraint on the coefficient power spectra
of 1.2x10^-5/(n^2), where n is the spherical-harmonic degree of the coefficient.
The largest positive gravity anomalies are associated with Beta Regio (200
milligals, latitude 25N, longitude 281E) and Atla Regio (203 milligals, 2N,
199E), which are topographically high regions. The largest negative anomalies
are all in the lowlands, ranging from -40 to -80 milligals. The amplitudes of
the anomalies are similar to those of the Earth, but unlike those of the Moon
and Mars which are much larger. However, there is almost perfect correlation of
topography with gravity (highs with highs and lows with lows) which is not the
case for the Earth, where some gravity highs occur in the oceans and some
gravity lows occur over continents.
Reference GM = 324858.5578 km^3/sec^2
Reference Gravity Radius = 6051.0 km
Reference Density = 2900 kg/m^3
Reference topographic radius = 6051.839 km