Source: New Zealand Defence Force (NZDF)
A low-cost floating reflector to enable space-based synthetic aperture radar to detect people lost at sea is being developed by University of Auckland scientists in collaboration with the New Zealand Defence Force (NZDF).
The device could be a lifesaver in the Pacific and help New Zealand keep watch over its vast search and rescue region, covering 30 million square kilometres of water.
Vice Chief Defence Force, Rear Admiral Mathew Williams, and senior University leaders observed the latest phase of the Synthetic Aperture Radar for Search and Rescue (SAR4SaR) research programme at Omaha, north of Auckland.
“Finding a raft or small boat in the open ocean is like looking for a needle in a haystack,” said Tom Dowling, a University of Auckland scientist who is leading the project in conjunction with Defence Science & Technology (DST).
“But we aim to make the needle so shiny that it can’t be missed,” Dr Dowling said.
Small enough to fit in a small boat – even below the seat of a canoe – the device is popped open to float on the sea, reflecting electromagnetic energy back to satellites passing overhead. An artificial intelligence tool would be scanning radar data to detect the call for help.
“This innovation could be especially relevant for parts of the Pacific where many people rely on simple boats and lack access to high-end emergency gear,” said David Galligan, the director of DST, the Devonport-based scientific arm of the NZDF.
“But fishers often go to sea with limited safety and communications equipment. When problems arise, they can find themselves adrift on the open ocean.”
In experiments done earlier this year, reflectors were tested for their durability and detectability from the air and space.
In tests staged from HMNZS Canterbury near the subantarctic Campbell Island, prototypes remained visible to satellites in stormy seas with gusts of 50-knot winds – more than 90 kilometres per hour.
During the week-long experiment at Omaha, the reflectors were put through a series of trials that confirmed their detectability, durability and ease of deployment.
The device’s effectiveness is made possible because of the advent of low-orbiting satellites.
Working in the University Space Institute’s fabrication facility, Dr Dowling and University engineer Ella Fasciana created prototypes in a variety of shapes – square, diamond, wedge – from materials available at local home improvement stores: aluminium foil, plastic sheeting, gaffer tape and tarpaulins.
The geometric configuration of adjoining aluminium surfaces focuses the energy of the radar signals and bounces it back to space, providing a distinctive signature for identification.
Reflectors won’t replace contemporary emergency alerting systems, such as Emergency Position-Indicating Radio Beacons or Satellite Emergency Notification Devices. But they would be a boon for people who can’t afford such devices and a back-up for those who can.
When small vessels go missing in the Pacific, the responsibility for coordinating the search often falls to New Zealand because this country is responsible for a zone extending from the mid-Tasman Sea, halfway to Chile, and from the South Pole almost up to the Equator.
In 2023/24 New Zealand’s Rescue Coordination Centre conducted 489 search and rescue operations.
In many cases, search and rescue involves deploying long-range maritime patrol aircraft, such as the Royal New Zealand Air Force’s P-8A Poseidon, operated by No. 5 Squadron.
While these aircraft are vital for conducting extensive search and rescue operations, their use comes with significant operational costs. Each mission places considerable demands on both resources and the aircraft themselves, contributing to increased maintenance needs and airframe fatigue.
