Challenger was launched off Fremantle, WA, on 5 November 2016 (Photo: Charitha Pattiaratchi)


Challenger glider, where RU now?

The underwater glider ‘RU29’, recently renamed ‘Challenger’, is on a journey from Fremantle, WA, to Galle, Sri Lanka. It departed Australia on 5 November and left Australian waters sixteen days later. Challenger is now in international waters.

This glider mission is a joint project between Rutgers University in the USA and the IMOS Ocean glider Facility, which is operated by The University of Western Australia (UWA). The project is part of the Global Challenger Mission. The mission aims to cover a distance of 6,200 km and, if successful, will set a new world record for distance covered by an ocean glider in a single journey.

On its way to Sri Lanka, Challenger is sending data back to the lab via satellite and being made available through the Global Telecommunications System (GTS). GTS is run by the World Meteorological Organization  to share atmospheric and ocean data globally. Challenger's position can be tracked via the IMOS Ocean gliders Facility website or via the Rutgers University site. Near real time data can also be accessed through the IMOS Ocean Current website (see ID N=198). Measurements of temperature and salinity at depths up to 1000 m are available in near real time.

Challenger is expected to take about 8–10 months to make the long journey, arriving in Sri Lanka in September–October 2017. The data gathered by Challenger will enable scientists to see how conditions in the Indian Ocean have changed over time. Temperature and salinity at specific depths and locations recorded by Challenger will be compared with measurements taken up to 40 years ago. These comparisons will help scientists to predict ocean conditions and their impact on climate.

The glider was released in the Perth canyon with a plan to travel west along 32oS. The Perth canyon is a region where strong ocean eddies are found.

Professor Chari Pattiaratchi of UWA, and leader of the IMOS Ocean glider Facility, is following the progress of Challenger.

“Challenger encountered a strong clockwise eddy and was swept southwards but is now back onto the planned track,” said Professor Pattiaratchi.

“Recent data have indicated that although the glider is well offshore of the Leeuwin Current influence, it is still trying to navigate across a line of ocean eddies,” he said. (see map, right)

The data collected during the period it was within the eddy indicated that the density contours changed by more than 100m within the eddy when compared to outside the eddy.

Underwater gliders, like their airborne namesakes, are not propelled by an engine. Movement through the water is achieved through changes in buoyancy. By alternately reducing and expanding their volume, gliders can descend and ascend through the ocean using very little energy. In addition to controlling ascent and descent, rudders on the glider enable its direction to be changed. The glider can descend to 1,000 metres and then rise to the surface to transmit the data obtained. Challenger is piloted by remotely by a group led by Rutgers University including those from UWA. 

IMOS Ocean gliders Facility Leader, Professor Chari Pattiaratchi, explains what the Challenger mission is about in this video.

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Map showing Challenger's position in a series of ocean eddies offshore Western Australia (Image: IMOS OceanCurrent)