NSF Press Release on the Completion of Deep Drilling at WAIS Divide, Antarctica
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The deep drilling at WAIS Divide, Antarctica has come to a close. It took eight field seasons to prepare the remote field camp, to drill the 3,405 meter deep ice core (the longest ice core in U.S. history), and to collect the 285 meters of valuable replicate core (see story above), but we did it. On February 5, the National Science Foundation (NSF) released a press release celebrating this historic accomplishment. In case you didn't see the press release, it is available at http://www.nsf.gov/news/news_summ.jsp?cntn_id=126761&org=NSF&from=news.
Replicate Coring Ice Drilling Technology is Successful
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For the first time, significant innovations in ice drilling engineering are providing scientists with replicate ice cores from targeted depths and directions in the ice sheet!
The newly developed, state-of-the-art Replicate Ice Coring System was deployed in December 2012 to re-enter the 6.5-inch diameter deep borehole at WAIS Divide, Antarctica, and successfully allowed the researchers to drill through the wall of the 3,405 meter deep parent borehole and collect a total of 285 meters of additional core from five of the most interesting time periods in the WAIS Divide climate record.
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SolidWorks rendering identifying the main sections of the replicate ice coring system sonde.
The Replicate Ice Coring System is capable of retrieving additional ice cores from specific depths on the uphill side of the main (parent) borehole. The Replicate Coring technique, developed and tested by the IDDO engineers as part of the Deep Ice Sheet Coring (DISC) Drill, is a key advance, because it allows scientists to take samples from specific levels of a parent borehole without impeding the hole itself, leaving the parent borehole open for future logging of information.
The Replicate Ice Coring System collects additional ice at depths of interest by deploying into an existing borehole and then deviating from it. The drill uses two steering actuator sections to tilt itself in the parent borehole by applying sidewards force against the borehole wall. In the first step of the process, the broaching cutter head is deployed to the target depth. Using the actuators, the drill is tipped to the high ("up hill") side of the borehole to engage the cutters. Ice is removed in repeated passes of approximately 15 meters in the up-stroke. In the second step of the process, a milling head is deployed and creates a landing for the coring head. In the third step of the process, a coring head removes a 20 mm kerf and allows a 108 mm diameter core to enter the core barrel. Two meters of core are removed per trip. The coring is repeated until all of the desired replicate ice from the target depth is obtained.
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The Replicate Ice Coring System builds on the existing infrastructure of the DISC Drill and thus requires substantial logistics and infrastructure support. However, the design and engineering behind the system is such that it can be scaled down for use with smaller, more agile drilling systems as well. The downhole portion of the DISC Drill, the sonde, was significantly modified to meet the requirements of steering out of the parent hole. The major components of the replicate sonde are described below.
Cable Interface Section The existing cable interface section of the DISC Drill provides the connection to 4km of fiber optic cable.
Upper Actuator Section The upper actuator section steers the drill, and with the anti-torque levels extended keeps the drill from spinning during cutting operations.
Instrument Section The instrument section provides power and communications to operate the drill.
Lower Actuator Section The lower actuator is identical to the upper actuator, but is configured with discs on the levers to provide smooth navigation.
Pump/Motor Section The pump/motor section has a powerful pump for chip transport and contains the cutter motor.
Lower Sonde The lower sonde includes chip barrels that collect the chips that are cut during coring, a core barrel to collect the core, and the coring head. The lower sonde can be assembled in multiple configurations to meet the needs of the different stages of the replicate coring process.
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The actuator section of the replicate sonde is shown. Photo: Chris Gibson, UW-Madison, IDDO.
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The broaching head of the replicate sonde is shown. Photo: Chris Gibson, UW-Madison, IDDO.
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The replicate sonde with the milling head is shown. Photo: Chris Gibson, UW-Madison, IDDO.
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The coring head with the first replicate ice core ever taken from the "uphill" side of an ice core borehole is shown. Photo: Jay Johnson, UW-Madison, IDDO.
Scientists interested in using the DISC Drill in the future need to work with the Ice Drilling Program Office - Science Advisory Board to formulate their plans and to ensure that their science is articulated in the Long Range Science Plan, which is updated annually each spring. The current schedule for the DISC Drill is as follows:
Dec 2012 - Jan 2013: Replicate coring at WAIS Divide, Antarctica
Dec 2013: Disassemble and pack DISC Drill at WAIS Divide
Nov 2014 - Jan 2015: Disassemble arch and prepare for traverse back to McMurdo Station
Nov 2015 - Jan 2016: Traverse DISC Drill from WAIS Divide to McMurdo Station
Feb 2016: Retrograde DISC Drill to CONUS via vessel
May 2016: DISC Drill arrives in Madison, WI
May 2016 - Nov 2017: Inspect, re-build, re-design and replace drill system components if necessary
Given the anticipated schedule above, the DISC Drill could be ready for shipment to the field again in late 2017. For the latest information and schedule for the DISC Drill, visit: https://icedrill.org/equipment/deep-ice-sheet-coring-drill
Replicate Coring System Characterization Testing Underway
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After review of data collected during the previous Antarctic field season and in preparation for the 2012-2013 WAIS Divide field season, IDDO has designed and fabricated a sophisticated test set-up to determine the root causes of shortcomings experienced by the Replicate Coring system. During the third quarter, IDDO was able to complete a major portion of a "sonde-in-the-borehole" test of the Replicate Coring System to determine drill sonde deflection, to verify the mechanical system analyses and to measure force at cutter head for given set points. This will assist IDDO engineers in making system modifications necessary to successfully collect replicate core during the next field season. The root cause of the intermittent instrument section faults witnessed in the field and during the system test in Madison was identified; the fix is designed and is currently being implemented. Troubleshooting of actuator motors, pressure testing of motor sections and modifications of instrument section circuit boards and LabVIEW software modifications were all successfully completed. System testing and modifications will continue into the Fourth Quarter. The large DISC Drill winch motor was also successfully repaired, rebuilt and returned to IDDO.
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Replicate coring system testing in Madison, WI.
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Cooling jacket for replicate coring instrument section.
This season's maiden voyage of the DISC Drill's Replicate Coring capability proved to be both challenging and enlightening. While no core was obtained, IDDO engineers gained a great deal of insight into the process of creating a deviation for replicate coring. A new borehole camera proved valuable in assessing the results of the deviation effort. The video and operating data are being analyzed to aid in the modification to replicate components in order to improve chances of success during the upcoming replicate coring production season. IDDO has held several internal design reviews and, in addition, IDPO led an external review of Replicate Coring modifications held in Madison on March 27-28. Dr. George Cooper, Emeritus Professor at U.C. Berkeley and Dr. Alfred Eustes, Associate Professor at Colorado School of Mines participated as external reviewers. The effort to carefully review and analyze the recent field season experience has led to the design of tests and test fixtures needed to improve the replicate coring system.
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The Replicate Coring System's milling head with cutters. Photo courtesy of Jay Johnson.
IDDO completed the bench testing of replicate coring components prior to their being shipped to WAIS Divide. In addition, IDDO designed and built a new inclinometer control board with greater accuracy for positioning the sonde in the borehole for replicate coring, developed a bumper for the broaching cutter head to protect the borehole during the lowering and raising of the drill sonde, and designed and built a downhole camera system. IDDO conducted field-testing of the replicate coring system at WAIS Divide in January 2012, and the system will be used for production drilling at WAIS Divide during the 2012-13 field season.
IDDO completed fabrication and bench testing of the DISC Drill's Replicate Coring System, and plans to conduct field-testing of the system at WAIS Divide in the latter part of the 2011-2012 Antarctic field season. Production drilling with the replicate coring system at WAIS Divide is planned for the 2012- 2013 Antarctic field season.
For the latest news regarding 2011-2012 WAIS Divide field season progress, visit: https://waisdivide.unh.edu/
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Testing of the Replicate Coring System in the lab.
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Close-up view of the Replicate Coring System actuator section.
If you are preparing a NSF proposal that includes any kind of support from IDP, you must include a Letter of Support from IDP in the proposal. Researchers are asked to provide IDP with a detailed support request six weeks prior to the date the Letter of Support is required. Early submissions are strongly encouraged.
The U.S. National Science Foundation Ice Drilling Program (IDP) is a NSF-funded facility. IDP conducts integrated planning for the ice drilling science and technology communities, and provides drilling technology and operational support that enables the community to advance the frontiers of science.
