Sub-ice Exploration of an Antarctic Lake: Results from the Endurance Project

The ENDURANCE autonomous underwater vehicle was developed and deployed to explore and map a unique environment: the waters of Lake Bonney in Taylor Valley, one of the McMurdo Dry Valleys of Antarctica. This permanently ice-covered lake presented several unique challenges and opportunities for exploration and mapping with an AUV. ENDURANCE was successfully deployed in 2008 and 2009, completing the rst full synoptic 3-D chemical pro le and high-resolution 3-D geometric mapping of such a body of water. Following the 2008 campaign, several upgrades were made to the vehicle to improve its exploration capabilities. The most signi cant of these was replacement of two battery packs. The improved energy capacity of these batteries coupled with analysis of in-situ transit speed e ciency tests resulted in an almost tripled range of the vehicle. This fact, combined with a longer ber-optic data tether, enabled vastly more ambitious missions during the 2009 campaign. In addition, operational changes were made in 2009, including a super-ballasted mode to enable the vehicle to operate within the super-saline lower lake layers and investigate previously inaccessible areas of the Taylor Glacier face. ENDURANCE successfully navigated in the presence of ice cover and large density gradients including precise approach and negotiation of narrow passageways and demonstrated autonomous melt hole location, position lock and auto recovery on a routine, daily basis. It performed general automated mapping and pro ling surveys, as well as detailed studies of localized phenomena, operating in an extreme, remote, unknown environment. Postprocessing of the data gathered on the two campaigns has made available a never-before-seen level of detail greatly enhancing the understanding of the lake biogeochemistry. The ENDURANCE project has demonstrated new underwater mapping capaFigure 1: ENDURANCE in position over the Lake Bonney deployment melt hole. The drop sonde can also be seen suspended below the vehicle in a partially deployed position as part of the instrument calibration. bilities to enhance the understanding of extreme, unique environments. Many of the characteristics and capabilities of ENDURANCE now successfully demonstrated in complex under-ice settings beneath West Lake Bonney are the types of behaviors that will be needed for sub-ice autonomous probes to Europa, Enceladus, and other outer planet watery moons.