Combine radar and ship reports

RCM 2, like the other constellation members, carries radar and a receiver for the Automatic Identification System, or AIS. Radar detects reflected energy. AIS receives information broadcast by participating vessels. Combining the two can connect a detected object with a reported identity and movement, but the sensors do not measure the same thing.

AIS messages include changing position and motion information as well as separately transmitted identity and voyage information. The Australian Maritime Safety Authority explains that position reports may arrive before a vessel’s name. A blank label in a display therefore does not necessarily mean that no vessel exists or that its operator is concealing an identity.

A bright radar feature also needs interpretation: sea conditions, viewing geometry and target characteristics influence detection. Treat an unmatched detection as a candidate requiring follow-up. Missing, delayed or inaccurate reports are reasons to check the evidence, not sufficient proof of illegal activity.

In an original example, an AIS position is recorded ten minutes before the radar observation. A vessel moving steadily at 12 knots travels 12 nautical miles per hour. Ten minutes is one sixth of an hour, so the expected travel is 2 nautical miles, about 3.7 kilometres. Comparing the old reported position directly with the new radar location could create a false mismatch.

Advance the reported position using its time and motion, then consider uncertainty. A turn, acceleration or poor position fix can change the prediction. Where several detections are nearby, an apparently close match may still be ambiguous. The goal is an evidence-based association, not forcing every dot to accept a name.

The calculation assumes constant speed and direction. It is a teaching example, not an operational vessel-tracking result. Keep acquisition time separate from the time a website or ground service receives and displays a message.

Align radar and a reported position

Radar can help locate oil-related surface anomalies because a slick can change the small waves and electrical properties that affect the return. But an observed pattern is not a complete history of how it formed. Weather, other surface conditions and additional observations matter when testing a proposed explanation.

The preserved NASA photograph shows a natural oil seep near Santa Barbara, California. It is a visible-light comparison from another research project, not an RCM radar observation. Its purpose here is to demonstrate a real alternative origin for oil: observing a slick does not automatically establish a ship discharge.

An analyst investigating a suspected spill would seek compatible observations, environmental context and independent confirmation. A nearby AIS report may identify a possible association, but proximity alone does not establish responsibility. Communicate what was detected, which explanation fits, and what remains unresolved.