In April, China launched its first tracking data relay satellite to lessen its dependency on ground satellite control and relay stations.

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But like radar technology, ADS-B currently relies on ground stations to relay information, making it useless over remote areas.

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Both spacecraft make use of the US space agency's Tracking and Data Relay Satellite System (TDRSS) to speak to the ground and controllers do not want any conflicts.

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The ground control stations send their commands to Reaper via a fibre-optic link to a satellite relay station in Europe, which bounces them into space and back down to the aircraft.

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