Two recent questions and their answers have raised a further question.

In [Are there laws about how close military aircraft can fly to passenger jets, and are they enforced?](https://aviation.stackexchange.com/questions/13856/are-there-laws-about-how-close-military-aircraft-can-fly-to-passenger-jets-and), we learned that "the military can get as close to other aircraft as they damn well please, through a procedure called Military Assumes Responsibility for Seperation of Aircraft, or MARSA".

In [Why are there NASA branded F/A-18s?](https://aviation.stackexchange.com/questions/14251/why-are-there-nasa-branded-f-a-18s) we see a picture of closely flying planes, and a comment notes "NASA is a civilian agency".

Do the NASA planes fly under MARSA rules or another set of rules for civilian agencies? Are there other non-military agencies that fall under this rule too?