This answer is currently accepted. I believe the physics is wrong, since conservation of angular momentum prevents a satellite from raising its orbit around a spherically symmetric body by using only gravity.
The problem in the answer is the conflation of center-of-mass and center-of-gravity, which are of course are usually not the same position in a gravity gradient, and certainly not blindly interchangeable.
The explanation and equations given there express the central body's contribution only through μ which is G time the mass of the Earth. Without torque, you can't use Earth's gravity to boost the orbit.
I think this site generally regards physical principles like conservation of angular momentum in few-body mechanics problems as given, and within that context, the answer is therefore wrong.
I know this is stack exchange and wrong answers happen and get accepted, but this one is demonstrably wrong based on basic conservation of angular momentum arguments.
I've left several comments there within the long comment chain that exists there, though a key few relating specifically to torque are now missing.
Options I can think of include
- add more comments.
- write an answer that just explains why the other answer is incorrect.
- write a correct answer to the question, and in doing so help make it clear why the other answer is incorrect. (This is hard, but doable)
- with coming up on 10,000 questions here, don't worry about it.