In January of this year, Vietnam announced plans for a ground station that could downlink high-resolution imagery from Indian satellites as they pass overhead. Vietnam now has a view of its immediate area from space in near real-time. The ground station is another chessboard move in the increasingly contested control and sovereignty over certain maritime areas between China and several Asian nations. But it also highlights the political nature of who has ground stations for other nation’s satellites.
In 2003, China abruptly shut down a space control station in the small Pacific nation of Kiribati, shortly before China’s first astronaut launch. The decision was made shortly after Kiribati established diplomatic relations with Taiwan, ruffling feathers in Beijing. The United States, in turn, refuses to allow its extensive space tracking assets in Australia to be used for Chinese space missions. But this does not stop European space tracking antennas in Australia from being used for this purpose.
Nations regularly try to spy on satellite transmissions with ground antennas, but cannot always decrypt the signals they send. Like scrambled pay TV, you can pick up the transmission but it’s pointless to watch. Nor can they legally control those satellites, although cyberwarfare will certainly involve such attempts at hijacking control in times of war.
Most nations on Earth do not operate weather satellites, but these nations can still download data with their own antennas. International agreements on weather monitoring actually encourage the sharing of this data for civilian purposes. The images are good enough to spot approaching storms but not detailed enough to see tanks or aircraft. Getting high-resolution images of military value is a different question. [fold]
But you don’t really need your own antenna. A credit card will do. Commercial image companies will sell images of almost anywhere, to almost anyone, provided that their own host government approves it. Sales embargoes can sometimes be more effective than dismantling dishes. The initial search phase for the lost Malaysia Airlines flight MH370 employed extensive use of satellite imagery. Much of this was carried out by US commercial satellites at Australia’s request so these images arrived on Earth through ground stations that were not on Australian soil.
Some space tracking antennas are carried aboard large ships, which are deployed in international waters shortly before critical missions are launched. China has a large fleet of vessels for this purpose. Apart from being able to move them in ways that cannot be done with land-based antennas, the tracking ships are immune from territorial control issues.
One way countries get around the dilemma of chokepoints on the ground is to get satellites to talk to other satellites above them. This technique is extensively used by military and intelligence-gathering satellites. The 'relay' satellites then channel the telemetry to ground stations in secured locations.
Photo courtesy of Flickr user .fresside.