Effect On Satellite Orbits
The lunar mascons alter the local gravity in certain regions sufficiently that low and uncorrected satellite orbits around the Moon are unstable on a timescale of months or years. This acts to distort successive orbits, causing the satellite to ultimately impact the surface.
The Luna-10 orbiter was the first artificial object to orbit the moon and it returned tracking data indicating that the lunar gravitational field caused larger than expected perturbations presumably due to 'roughness' of the lunar gravitational field. The Lunar mascons were discovered by Paul M Muller and William L Sjogren of the NASA Jet Propulsion Laboratory (JPL) in 1968 from a new analytic method applied to the highly precise navigation data from the unmanned pre-Apollo Lunar Orbiter spacecraft. This discovery observed the consistent 1:1 correlation between very large positive gravity anomalies and depressed circular basins on the moon. This fact places key limits on models attempting to follow the history of the moon's geological development and explain the current lunar internal structures.
At that time, one of NASA's highest priority "tiger team" projects was to explain why the Lunar Orbiter spacecraft being used to test the accuracy of Project Apollo navigation were experiencing errors in predicted position of ten times the mission specification (2 kilometers instead of 200 meters). This meant that the predicted landing areas were 100 times as large as those being carefully defined for reasons of safety. Lunar orbital effects principally resulting from the strong gravitational perturbations of the MASCONS were ultimately revealed as the cause. William Wollenhaupt and Emil Schiesser of the NASA Manned Spacecraft Center in Houston then worked out the "fix" that was first applied to Apollo 12 and permitted its landing within 163 meters of the target, the previously-landed Surveyor 3 spacecraft.
Read more about this topic: Mass Concentration (astronomy)
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