LUMELITE-4: connect ships beyond the coast

LUMELITE-4 launched on April 22, 2023 aboard India’s PSLV-C55 with TeLEOS-2. NUS developed the small satellite platform, while A*STAR’s Institute for Infocomm Research developed its experimental VHF Data Exchange System, or VDES, payload. The project sought to extend maritime data exchange beyond the reach of coastal infrastructure and explore applications such as vessel tracking and two-way messaging.

The existing Automatic Identification System, AIS, broadcasts vessel information such as identity, position, course and speed. VDES develops a broader data-exchange approach around maritime VHF communications. The launch announcement describes intended advantages and experiments; those aims should not be read as proof that every ship already has compatible equipment or that one small satellite supplies continuous global service.

A ship-to-satellite exchange requires a working ship terminal, usable radio geometry, the satellite payload and a path to the intended recipient. A return message adds requirements in the other direction. Receiving one vessel report demonstrates one part of that chain. Demonstrating a two-way application requires evidence that an appropriate message can also reach its destination through the return path.

Imagine a fictional test sending one hundred numbered reports during a contact and receiving ninety-six without error. The observed delivery fraction is ninety-six percent for that test. It does not reveal the delay of each message or prove the same fraction under heavy traffic. Those questions need timestamps, load information and additional observations. Several useful performance measures can describe the same communications experiment.

A two-way maritime exchange

NUS engineers described checking initial ground contact and solar-panel deployment after launch. Those checks provided evidence that the spacecraft had begun operating; they were separate from watching the rocket rise. The university’s May 2024 account marked LUMELITE-4’s first year in orbit. Neither a launch photograph nor an anniversary alone replaces measurements of a particular maritime service’s reliability and latency — open definition.

The program joins university platform engineering with a specialized radio payload and possible ground-network applications. Its lessons extend beyond shipping: distinguish the hardware that carries a signal, the protocol that gives it structure and the service people actually receive. An application becomes useful when the entire path works under relevant operating conditions, and its stated performance should be tied to measurements with an explicit scope.