Espionage

Ears in the sky

By listening for radio and radar signals, a new generation of satellites can track human activity, both licit and illicit

IN THE MIDDLE of last year, Ecuadorians watched with concern as 340 foreign boats, most of them Chinese, fished just outside the Exclusive Economic Zone (EEZ) around their country’s westernmost province, the Galapagos Islands. The law of the sea requires such vessels to carry GPS-based automatic identification systems (AIS) that broadcast where they are, and to keep those systems switched on. Some boats, however, failed to comply. There were more than 550 instances of vessels not transmitting their locations for over a day. This regular radio silence stoked fears that the boats concerned were sneaking into Ecuador’s waters to plunder its fish.

Both local officials and China’s ambassador to Ecuador denied this, and said all the boats were sticking to the rules. In October, however, HawkEye 360, a satellite operator based in Virginia, announced it had detected vessels inside Ecuador’s EEZ on 14 occasions when the boats in question were not transmitting AIS (see map). HawkEye’s satellites could pinpoint these renegades by listening for faint signals emanating from their navigation radars and radio communications.

HawkEye’s satellites are so-called smallsats, about the size of a large microwave oven. They are therefore cheap to build and launch. HawkEye deployed its first cluster, of three…