Recently I have become interested in model based system engineering (MBSE) and for the past few months have been trying myself at answering the question of what it would take to fly a VLEO remote sensing satellite constellation. The end goal is an online calculator that would spit out a price optimized (very coarse) design for a satellite constellation given a set of business requirements (inspired by one for Orbital Data Centers).
It turns out that one of the mission requirements, the maximum revisit time, has quite huge price implications. That is the worst time it takes for a satellite to capture the entire globe up to a certain latitude. So if it is one week, then it means for that particular location it can take 7 days to get another image.
The parameter is so influential, because it directly affects how many satellites one has to launch and how many launches one has to make for different orbital planes.
While trying to model the revist time, there were many things that I haven’t thought of. Small changes can vastly change the coverage due to orbital alignment and what one could call “resonance” affects due to the phasing of the satellite.
It was fun to really dive deep here and create something that helps with quick evaluation. You can check out the calculator here.
I published the math and derivation in a PDF on research gate.
This is just a subproject. The bigger calculator that will optimize a constellation for cost will follow!