Lessons learned from shallow subglacial bedrock drilling campaigns in Antarctica

We review successes and challenges from five recent subglacial bedrock drilling campaigns intended to find evidence for Antarctic Ice Sheet retreat during warm periods in the geologic past. Insights into times when the polar ice sheets were smaller than present serve as guiding information for modeling efforts that aim to predict the rate and magnitude of future sea level rise that would accompany major retreat of the Antarctic Ice Sheet. One method to provide direct evidence for the timing of deglaciations and minimum extent of prior ice sheets is to extract subglacial bedrock cores for cosmogenic nuclide analysis from beneath the modern ice sheet surface. Here we summarize the lessons learned from five field seasons tasked with obtaining bedrock cores from shallow depths (<120 m beneath ice surface) across West Antarctica since 2016. We focus our findings on drilling efforts and technology and geophysical surveys with ground-penetrating radar. Shallow subglacial drilling provides a high risk, high reward means to test for past instabilities of the Antarctic Ice Sheet, and we highlight key challenges and solutions to increase the likelihood of success for future subglacial drilling efforts in polar regions

Evidence for Quaternary Ice-mass Fluctuations of the West Antarctic Ice Sheet: Interpretations From a Relative Sea Level Reconstruction in the Amundsen Sea and Geophysical Surveys in West Antarctica

Determining the past timing and extent of ice volume changes of the West Antarctic Ice Sheet (WAIS) remains essential for forecasting the rate and magnitude of retreat of the WAIS in the coming decades and centuries. Records of when the WAIS was last smaller than present are sparse and the limited evidence for reduced ice volumes remains a critical gap to address in the paleoclimate community. In this thesis, I examine two lines of evidence of ice volume changes for the WAIS through a relative sea level reconstruction in the Amundsen Sea and from radar observations from field sites across the ice sheet. The relative sea level reconstruction shows that for the Amundsen Sea Sector, ice remained relatively stable for the last 5.5 ka and that the current bedrock uplift rates are an order of magnitude larger than the observed RSL fall during that same period. Conversely, evidence from radar observations collected at sites across the WAIS shows evidence of previous ice surfaces at depths of tens of meters below the modern ice surface and highlight the usefulness of radar studies, that when paired with the collection of ice cores or subglacial bedrock, can provide the timing of readvances. Further, in this thesis I summarize the challenges and successes for the retrieval of subglacial bedrock samples for cosmogenic nuclide analysis from five field campaigns in West Antarctica. This method provides direct evidence for the timing of WAIS retreat during past warm periods but is difficult due to technological and logistical limitations. I focus the findings on drilling efforts and technology and geophysical surveys with ground-penetrating radar and find that 1) a dedicated ground-penetrating radar survey by a practiced geophysicists is necessary given the complex nature of ice near margins, 2) drilling campaigns should start at shallow depths and progress to deeper sites to provide ground truth results for radar surveys and to limit time dedicated to troubleshooting drilling operations, 3) target locations with a clean ice-bedrock interface to prevent drilling complications due to clay overburden, and 4) future drilling campaigns need to balance sites that answer key scientific questions with those that are less challenging to support logistically

Enabling technologies for the subsurface exploration of the solar system

Future robotic exploration missions within the Solar System, focussing on either scientific discovery or the emerging field of In-Situ Resource Utilisation (ISRU), shall require the development of technologies which are capable of exploring to ever-greater depths beneath the planetary surface. In order to achieve these ambitious goals, advances in the existing state of the art in robotic sampling are required. This Ph.D. presents findings on the development of novel solutions within this field. The development of the Ultrasonic Planetary Core Drill (UPCD), a system based upon the ultrasonic-percussive drill technique, was designed with a Mars Sample Return (MSR) objective at the core of the development. Breakthroughs in autonomous control and the robotic assembly of drill strings were required in order to meet the requirements set. The system was tested at Coal Nunatak, Antarctica, in December 2016. A rotary-percussive drilling system for use in extracting subglacial bedrock samples from Earth’s Polar Regions was developed. Making use of technologies devised in the UPCD project, this collaboration with the British Antarctic Survey (BAS) required a low resource approach to the problem in order to ensure compatibility with existing BAS systems and logistical constraints. Building upon technologies developed and confidence generated in previous systems, the subglacial bedrock was industrialised into what became the Percussive Rapid Access Isotope Drill (P-RAID). This system underwent initial field trials at the Skytrain Ice Rise, Antarctica in January 2019 with the intention to further develop the system for full deployment

Workshop on Science Opportunities for a Multidisciplinary Long-Range Aircraft for Antarctic Research: Program and Abstract Volume

Organizing Committee: Bea Csatho, David H. Bromwich, Michael Studinger, Thomas R. Parish, Robin Muench, and Jeff StithOffice of Polar Programs, National Science Foundatio

The Sleeping Giant: Measuring Ocean-Ice Interactions in Antarctica

Global sea level rise threatens to be one of the most costly consequences of human-caused climate change. And yet, projections of sea level rise remain poorly understood and highly uncertain. The largest potential contribution to global sea level rise involves the loss of ice covering all or even a portion of Antarctica. As global atmospheric and ocean temperatures rise, physical processes related to the ocean’s circulation: (i) carry this additional heat into the deep ocean, (ii) transport it poleward via the overturning circulation and (iii) ultimately deliver the heat to the underside of floating Antarctic ice shelves. Enhanced melting that occurs due to warm ocean waters plays an important role in the loss of ice from the continent. Our understanding of the first two steps that bring heat towards Antarctica has increased substantially over the past two decades through improved measurements of air-sea interactions and interior ocean properties (e.g., Argo). Yet, the constraints on the oceanic delivery of heat to Antarctic ice shelves and its impact on melt rates remains critically under-studied. Our inability to constrain the rate of retreat of Antarctic glaciers and how the Antarctic Ice Sheet will behave in a warming climate remains the single most significant reason for the large uncertainty in sea level projections over the 21st century. This problem is the focus of the KISS study, "The Sleeping Giant: Measuring Ocean Ice Interactions in Antarctica," and stands as one of the grand challenges of climate science today