Exploring Antarctic subglacial lakes with RECoverable Autonomous Sonde(RECAS):Design and first field tests

Conducting scientific drilling on subglacial lakes and obtaining samples of subglacial lake water holds great significance in unraveling the formation and evolution of Antarctic subglacial lakes and early Earth's life forms.Despite various approaches to access and directly sample subglacial water and sediments,clean access and exploration of subglacial lakes remain challenging.To address this concern,Jilin University has developed the RECoverable Autonomous Sonde(RECAS)prototype.This technology enables sampling and in-situ detection of subglacial lake water while being isolated from the surface,thus minimizing the risk of pollution.Laboratory tests,including downward and upward drilling,long-running,remote-control,and cold-environment assessments,were conducted to validate the sonde's principle and functionality.During the 38th Chinese National Antarctic Research Expedition,CHINARE(2021–2022 season),the RECAS prototype underwent testing on the flank region of Dalk glacier,10 km from Zhongshan Station in Antarctica.Three boreholes with depths of 200.3,183.2,and 133.5 m were successfully drilled,with the refrozen meltwater sealing the boreholes during the process.Approximately 600 mL of melted water samples were collected from each hole.Throughout the drilling tests,all systems of the RECAS prototype performed within the expected ranges.