Hovers and vertical boosters dont work beyond their designated height. Unless there is a surface underneath ,or even water . This is how you scan jago oceans for example. turn ground destabilization off alt+8 in archhud and your ship maintains altitude and you can fly under the water. Or harvest your mu tiles under the water . And water counts .In high atmosphere there isnt any "surface" under hovers . So you can do this with engines facing downwards ,like magic carpet or If your target altitude is more than 1km agg gives more time on hold but more expensive ofc.