Build a maritime information chain

MDASat-1a, MDASat-1b and MDASat-1c launched together on Transporter-3 on 13 January 2022. The Cape Peninsula University of Technology built the three 2U CubeSats, with SANSA supporting the program. Their maritime purpose built on ZACUBE-2’s radio work: collect ship transmissions and help deliver useful information about activity at sea. The satellites were one part of an information system, alongside ground reception, processing and the people using the results.

Maritime domain awareness means developing an informed picture of activity in a marine area. It does not mean that one satellite can see every vessel at every moment. Radio reports depend on transmissions and successful reception; an optical image depends on a different sensing process. A useful operational picture combines evidence while retaining each observation’s time, location and limitations.

Consider an invented ship report generated at 09:00, received by a satellite at 09:01, downloaded at 09:08 and displayed after processing at 09:10. The information is ten minutes old when a reader sees it. One minute of that interval precedes satellite reception, seven precede ground delivery and two precede display. The age of the observation is not the same as the duration of a radio contact.

For a time-sensitive application, improving only the display cannot eliminate delay earlier in the chain. Engineers must examine acquisition, onboard handling, downlink scheduling and ground processing together. A timestamp should identify what it measures: the ship’s report time, the reception time or the product’s publication time. Replacing an old observation time with the latest display time creates false freshness.

Information age follows the observation

In January 2022, CPUT reported receiving beacons from all three spacecraft and exchanging commands and telemetry. The same update said the data link was not yet commissioned. This is an important engineering distinction: basic contact can verify parts of the spacecraft without demonstrating the complete path from a ship’s transmission to a useful delivered product.

A fictional service requirement might ask for correctly decoded, time-stamped reports delivered within ten minutes for a defined test area and interval. Its test must examine the final product against known inputs. Counts of launched satellites, received beacons or attractive map markers cannot substitute for that test. The requirement also needs a stated coverage scope, so an unobserved area is not mistaken for an empty sea.