A new instrument is used to study the inner workings of Greenland’s glacier mills by riding the currents inside a glacier’s moulin. The West Greenland Moulin Explorer instrument was deployed into a tubular shaft to autonomously record temperature, pressure, 3D acceleration, and location. It is built with a slightly positive buoyancy in order to assist in recovery.
The unit is made up of several components. A 3-axis MEMS (microelectromechanical systems) accelerometer with 0.001-g resolution forms the base of the unit. A pressure transducer is added that is capable of withstanding 500 psi (≈3.4 MPa), and surviving down to –40 °C. An Iridium modem sends out data every 10 minutes. The location is traced by a GPS (Global Positioning System) unit. This GPS unit is also used for recovery after the mission. Power is provided by a high-capacity lithium thionyl chloride D-sized battery. The accelerometer is housed inside a cylindrical, foot-long (≈30 cm) polyvinyl chloride (PVC) shell sealed at each end with acrylic. The pressure transducer is attached to one of these lids and a MEMS accelerometer to the other, recording 100 samples per second per axis.
This work was done by Alberto E. Behar, Jaret B. Matthews, and Hung B. Tran of the Jet Propulsion Laboratory; Konrad Steffen, Dan McGrath, and Thomas Phillips of the University of Colorado Boulder; and summer students Andrew Elliot, Sean O’Hern, Colin Lutz, Sujita Martin, and Henry Wang for NASA’s Jet Propulsion Laboratory. For more information, download the Technical Support Package (free white paper) at www.techbriefs.com/tsp under the Mechanics/Machinery category. NPO-46514
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Instrument for Analysis of Greenland's Glacier Mills
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Overview
The document discusses an innovative instrument designed for analyzing the Moulins of Greenland's glaciers, which are critical for understanding the dynamics of ice sheets and their contribution to global climate change. Moulins are narrow tubular chutes that facilitate the drainage of surface meltwater to the glacial bed, influencing water storage, pressure, and glacier movement. Given the challenges of studying these features directly due to their inaccessibility and the harsh conditions, the development of a specialized instrument is essential.
The proposed solution involves designing and fabricating a robust unit capable of withstanding extreme temperatures of -20°C and pressures of up to 500 psi, as it may operate at depths of 400 meters below sea level. The instrument is constructed with a cylindrical chassis to ensure buoyancy and stability while navigating through the water currents within the Moulin. Key components include an accelerometer, a pressure transducer, a GPS unit with a satellite modem link, and an antenna, all housed within a sealed cylindrical PVC shell. The accelerometer records 3-axis acceleration data at a high resolution, while the pressure transducer measures the water pressure, providing critical data on the conditions within the glacier.
The instrument operates autonomously, logging data for 10 to 15 hours as it travels through the glacial river before surfacing to transmit its GPS coordinates for recovery. This novel approach allows scientists to gather real-time data on the flow of water through Moulins, enhancing the understanding of glacier dynamics and the effects of climate change on Greenland's ice sheet.
The document emphasizes the significance of this research in the context of global warming, as monitoring the reduction of Greenland's ice sheet is vital for predicting future sea-level rise and climate impacts. The development of this instrument represents a significant advancement in glaciology and environmental science, providing a means to study previously inaccessible areas of glaciers and contributing to the broader understanding of climate change effects on polar regions.
In summary, the document outlines the design, functionality, and importance of a novel instrument for studying Greenland's glacier Moulins, highlighting its potential to advance scientific knowledge in the face of climate change.
