Since the footprint data uses the spheroid GRS1980, can I just define it as NAD1983? I know that NAD1983 uses GRS1980, but I am not sure if I can define this layer as datum-based instead of spheroid-based.
Although some literature suggest similarilties between GRS1980 and NAD1983, defining one for the other may present some practical challenges given that NAD1983 and similar datum-based definitions are often land-based, regional in extent and therefore non-geocentric as opposed to GRS1980 and similar ellipsoids like WGS84 which are global and geocentric.