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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This article first appeared in the May, 2010 issue of NASA Tech Briefs Magazine.

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