Just a reminder of something you probably understand, but the UM is a massive undertaking. We are questioning very fundamental theories of the scientific establishment and that means we have to cover every field of science: geology, astronomy, physics, biology, etc. We have to do this because every field of science connects to almost every other field. What I’m saying is, thank you for your question, and we regret that we could not fit the answer in Volume I. So instead we actually cover this subject in Volume III of the UM: The Universe System as it relates more to physics and the universe.
But since you asked, I would be happy to give you a general answer! The Gravitational Constant, G, is a proportion that shows up in Newton’s equation of gravity. Henry Cavendish devised an experiment to find G back in the year 1798 using a device that used pendulums and big metal spheres to measure the gravitational attraction between the spheres. From his experiment, he calculated a density of the Earth to about 5.5 grams per cubic centimeter. Other scientists noticed this number was close to the density of iron, hence the iron core theory. From there, G was derived to be about 6.6 x 10^-11 with the subsequent units. UM researchers have replicated this experiment and have found that air resistance actually has an appreciable effect on the pendulum, something that Cavendish did not account for. His experiment needs to be redone in a vacuum so that the air doesn’t slow down the movement of the pendulum.
Even though this number has been ‘established’, there is another number that is usable and even preferred in space technology. That is called the Gaussian Gravitational Constant, k. It was derived by Carl Fredrich Gauss based on the average orbital period of the Earth. This number does not require a specific mass of a celestial body, and is in fact the number that satellite scientists will use in their formulations and space missions.
So, in essence, space missions successfully work because scientists use the right proportions for the mass of planets and asteroids, even though the specific mass isn’t accurately known.
I hope that answers your questions. Let me knew if there was something you want me to further expound.
Have a great day!