The data needed to answer the question was collected by the Lunar Prospector Electron Reflectometer (ER). The data is then processed to derive the electrostatic potential, which is the same thing as the voltage.
This article describes how the ER performs its measurements.
From the article:
I am answering this question in an indirect way. I am looking for a more mathematical formulation (When I asked this question) for converting from Mars Solar Orbital (MSO) coordinate to GEO coordinate or vice versa.
As I exploring for solutions, I found spacecraft spice kernels will help in converting these kinds of coordinate transformations.
In the case of ...
The two images mainly differ in their dynamic range between the darkest and brightest parts of the image.
Here are a few numbers to get started:
the albedo of the Moon varies between 0.1 and 0.3. I.e. the brightest spots are three times brighter than the darkest, given an identical illumination.
photographic cameras do have a range of at least 10 orders of ...