The next asset I would propose........
Aerostats.
These are lighter than air lift vehicles without a crew that remain tethered to a location.
Uses include
- high altitude antennas for greater broadcast and reception range.
- Radio relay for two ground stations over great or elevated terrain, such as mountainous terrain.
- Radar coverage for military and civil aircraft tracking.
- mobile radar coverage by changing the fixed location on a regular basis.
- Radar coverage during unusual weather or storm seasons such as hurricanes or tornadoes. (placed around the perimeter of a storm area or raised in the aftermath).
- long range and ultra long range video surveillance with multiple, all weather, pan/tilt/zoom cameras.
- Navigation beacons similar to the Loran system to guide emergency and relief aircraft.
- long duration air sampling platform for ionizing radiation and chemical warfare agents.