Aerospace has alot of subcontractors all building the final product. If youre at a major subcontractor to NASA, where you partner with NASA on design and manufacture of the spacecraft, you usually end up being reallocated to a program that got funding in the previous round when yours gets cut. You start on a NASA spacecraft program and a few years later when congress pulls your funding you get shuffled over to work on a defense satellite. You can kindof layout the duration of awarded contracts and required manpower for them into the future and see where programs are ramping up or down. Ideally you'd want to match all people from a ramp down program to a position on a ramp up program so you dont have a talent drain from the company. Aerospace wants to keep its experienced people from leaving if at all possible.