Flying toolbox

Kym setting up the RAPPLS system in a modified Squirrel helicopter.
Kym setting up the RAPPLS system in a modified Squirrel helicopter. (Photo: Jan Lieser)
An example of a point cloud produced from LASER pulse data and aircraft position information.

Kym and the Science Technical Support team have developed a helicopter-borne ‘RADAR Aerial Photography Pyrometer Laser Scanner’ (RAPPLS) to assist sea ice scientists to measure the thickness and temperature of sea ice and snow cover. The system was used successfully during the Sea Ice Physics and Ecosystem eXperiment in 2007 and 2012 (Australian Antarctic Magazine 23: 5, 2012) and two voyages to Davis research station in 2008–09 and 2009–10. 

In the nose of the helicopter is the LIDAR (Laser Scanner), GPS and Inertial Navigation System (INS) and the Pyrometer (which measures temperature of the sea ice via Infra-Red radiation). Below the operator is a 50 megapixel medium format digital camera, which takes synchronised photos looking straight down. The camera is mounted in a “bucket” (silver box in photo) in the floor of the helicopter to make sure it has an un-obscured view.

“The INS system records the precise location of the helicopter and camera/LIDAR so that LIDAR data can be matched to the aerial photographs,” Kym says.

“The LIDAR has a rapidly rotating four-facet polygon mirror and fires 10 000 laser pulses per second at the mirror. It then measures the time travelled for each pulse to return from the ground below. The resulting LASER pulse data, along with the aircraft position information, results in a ‘point cloud’ representing the sea ice or object below.”

The high resolution camera is used to measure ice floe sizes, ice types and distribution. It has also been used in aerial survey work to estimate the population of nesting Adélie penguins in the Vestfold Hills.

“The development of the RAPPLS system required modifications and additions to the helicopter, which had challenges with aircraft modification and certification, as well as managing vibration from the main rotor blades,” Kym says.

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