Definition
A surveillance system in which ADS-B Out signals transmitted by aircraft are received by a constellation of low-earth-orbit satellites rather than by ground-based receivers. The satellites relay the position, altitude, velocity, and identification data to air traffic control, providing surveillance coverage over oceans, polar regions, deserts, and other areas where ground stations cannot be installed.
Plain English
It is the same position-reporting signal aircraft already transmit, but picked up by satellites instead of ground antennas. This lets controllers track aircraft over oceans and remote areas where no ground equipment exists.
Context Anchor
Seen in discussions of aircraft tracking, oceanic routes, remote-area operations, and modern air traffic surveillance.
Derivation
‘Space-based’ simply means the receivers are in orbit rather than on the ground. The qualifier exists because regular ADS-B was originally designed around ground-based receivers, so the space-based version had to be named distinctly.
Why Pilots Care
Improves safety by enabling ATC tracking on flights over water or wilderness where traditional radar is unavailable.
Intuition Check
Space-Based ADS-B does not mean the aircraft gets its ADS-B position from space. The aircraft broadcasts its ADS-B signal, and satellites receive that signal from above.
Example Sentence 1
Thanks to space-based ADS-B, controllers over the North Atlantic can now see aircraft positions almost continuously instead of waiting for voice position reports.
Example Sentence 2
Operators equip aircraft with ADS-B Out to take advantage of space-based coverage in remote regions.