When the ESA’s Proba-V was launched on May 7, its main mission was to map land cover and vegetation growth across the entire surface of the Earth every two days. But the miniaturized ESA satellite is also casting its gaze higher, to test whether it is possible to track aircraft continuously from space. Proba-V has now shown this is indeed possible, by becoming the first satellite to pick up aircraft tracking signals from space.

Automatic Dependent Surveillance – Broadcast (ADS-B) is set to replace radar as the primary tracking technology for aircraft worldwide. ADS-B offers numerous advantages over radar, including greater accuracy due to the fact it relies on GPS, which will allow aircraft to fly closer together in congested airspace. It also broadcasts information on the aircraft, including speed, position and altitude.

And because it is a broadcast technology, ADS-B signals can be received not only by air traffic control on the ground, but also by other aircraft in the air. Proba-V has now shown these signals can also be detected from space, making it possible to monitor aircraft in remote areas and over oceans. While ADS-B stations are cheaper to deploy than ground-based radar, they are still not economically feasible for many remote areas and aren’t possible across expanses of ocean. Space-based monitoring would overcome these problems.

Although the ADS-B signals are relatively weak, Proba-V's experimental receiver was able to record over 12,000 ADS-B messages within two hours at an altitude of 820 km (510 miles) without any need to upgrade existing aircraft equipment. The German Aerospace Center (DLR), which is overseeing the experiment, now plans to see how many aircraft can be observed and, because different sized aircraft are assigned different signal strengths, which types of aircraft can be detected.

“Space-based ADS-B monitoring holds a lot of potential in terms of security and safety – including search and rescue for airspace not covered by ground-based surveillance,” says Toni Delovski of the DLR. “Filling in these gaps has obvious value. Moreover, it may allow aircraft to traverse regions with decreased separation between them and on more efficient routes, boosting overall traffic capacity while cutting fuel consumption and carbon dioxide emissions.”

Source: ESA