| NSF Org: |
OCE Division Of Ocean Sciences |
| Recipient: |
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| Initial Amendment Date: | August 23, 2018 |
| Latest Amendment Date: | November 4, 2019 |
| Award Number: | 1829670 |
| Award Instrument: | Continuing Grant |
| Program Manager: |
Kandace Binkley
kbinkley@nsf.gov (703)292-7577 OCE Division Of Ocean Sciences GEO Directorate for Geosciences |
| Start Date: | August 15, 2018 |
| End Date: | July 31, 2022 (Estimated) |
| Total Intended Award Amount: | $272,362.00 |
| Total Awarded Amount to Date: | $276,362.00 |
| Funds Obligated to Date: |
FY 2019 = $121,987.00 FY 2020 = $4,000.00 |
| History of Investigator: |
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| Recipient Sponsored Research Office: |
500 EL CAMINO REAL SANTA CLARA CA US 95050-4776 (408)554-4764 |
| Sponsor Congressional District: |
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| Primary Place of Performance: |
CA US 95050-4345 |
| Primary Place of
Performance Congressional District: |
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| Unique Entity Identifier (UEI): |
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| Parent UEI: |
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| NSF Program(s): | OCEAN TECH & INTERDISC COORDIN |
| Primary Program Source: |
01001920DB NSF RESEARCH & RELATED ACTIVIT 01002021DB NSF RESEARCH & RELATED ACTIVIT |
| Program Reference Code(s): |
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| Program Element Code(s): |
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| Award Agency Code: | 4900 |
| Fund Agency Code: | 4900 |
| Assistance Listing Number(s): | 47.050 |
ABSTRACT
Five decades of scientific ocean drilling have created more than 113-cased boreholes in the ocean. Such legacy boreholes have been drilled into a range of seafloor geologic settings and many of these boreholes are deep enough that natural geothermal gradients have warmed the boreholes to temperatures in the range (60-200 degrees C). Within this temperature range reactions pathways between seawater and basalt change, affecting how the basaltic crust ages through the dissolution of primary minerals and the precipitation of different minerals as veins, for example. This combination of dissolution and precipitation changes the characteristics of the ocean crust that ultimately affects how the crust is subducted and the potential for large destructive earthquakes. This temperature range also spans the thermal limits of microbial life, based on experiments (122 degrees C), theoretical calculations (150 degrees C), and anecdotal evidence (180 degrees C). However the scientific drilling community currently lacks the ability to collect such warm pristine borehole fluids because electronics fail at such temperatures. This project will solve this sampling problem by first testing shape memory alloys, which are metal alloys that can change their shape and length at a specific temperature that is a function of the alloy composition and fabrication process. Then a water sampling system will be developed that utilizes the properties of shape memory alloys to trigger the collection of boreholes fluids. The first deployment of the newly fabricated system will occur in July 2019 when the scientific drilling program re-enters a legacy borehole that is ~200 degrees C at the base of the hole. The broader impacts of this project will provide the scientific community with a new sampling system for collecting borehole fluids at elevated temperatures. Such a sampling system is not limited to oceanic boreholes, but could be used within the thousands of existing continental boreholes. This new high temperature fluid sampling system will allow the community to explore new directions in understanding hydrothermal processes. Hydrothermal processes and the thermal limits of life are exciting topics that engage the public. More specifically the proposed work will include the development of a hands-on module for a week-long summer day camp (ssrovcamp.org) for rising 3-5th and 6-9th grade students and students involved in the undergraduate marine education program at Santa Clara University. Combined, over 300 students were engaged in one of these two programs in 2018.
The crux of this project is to design and fabricate a fluid sampling system for high temperature 60-200 degrees C borehole applications in oceanic and continental settings. The project will build on a Provisional Patent to design and fabricate standard titanium syringe-like fluid capture systems that are triggered by a novel mechanism. This mechanism will use shape memory alloys, given that such alloys change shape at a particular temperature. The sampling system will be modular in design to allow a suite of samples to be collected on a single lowering, each sampler collecting fluid at a specific temperature depending on the particular shape memory alloy that is used in that sampler. This system will be designed to be deployable from oceanic drilling vessels, continental drilling rigs, and submersibles/remotely operated vehicles (ROVs).
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
PUBLICATIONS PRODUCED AS A RESULT OF THIS RESEARCH
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PROJECT OUTCOMES REPORT
Disclaimer
This Project Outcomes Report for the General Public is displayed verbatim as submitted by the Principal Investigator (PI) for this award. Any opinions, findings, and conclusions or recommendations expressed in this Report are those of the PI and do not necessarily reflect the views of the National Science Foundation; NSF has not approved or endorsed its content.
Over the past 50 years, more than 100 cased deep-sea boreholes have been drilled into the seafloor in order to study a range of scientific phenomena. Many of these boreholes are deep enough that the Earth?s natural geothermal gradients have warmed the water in these holes to temperatures of up to 200 degree C. This provides a unique opportunity to explore the thermal limits of microbial life through sampling of the water in these boreholes. This is challenging, however, due to the very narrow diameter of these holes and the pressures found at the depths of interest. In particular, it is difficult to develop a cost-effective sampling system using conventional electronics given the need to provide capable cooling systems.
An innovative alternative for temperature-based sampling is to use Shape Memory Alloys (SMA) as a trigger device for a purely mechanical water sampling system. Wires, springs, and similar metallic components made from SMA materials have an interesting property in that they change their mechanical shape when raised above a temperature setpoint. The ?activation? temperature depends on chemical make-up of the alloy, and shape changes can include processes like contraction or shrinkage of a wire.
Exploiting this characteristic of SMAs, the project team has designed and manufactured a number of high-temperature borehole fluid samplers that use SMA mechanisms design to trigger samples at a variety of temperatures in the 50-200 degree C range. Testing has shown that designs have a sampling repeatability on the order of 0.5 degrees C, and the samplers are narrow, long tubes capable of fitting into a borehole. Samples will be returned for analysis in the lab.
The team hopes to deploy a dozen of these samplers as part of a probe that will be inserted into a borehole during a 2023 expedition through the International Ocean Drilling Program. By choice of the SMA alloy blend of the trigger mechanism, each sampler can be configured to sample borehole water at specific points based on their temperature. Analysis of the water, once returned to a laboratory environment, allows study of the marine environment as a function of temperature. This provides a low-cost and simple way to explore how marine geochemistry and microbial activity vary as a function of temperature, and within the borehole environment, these studies can be conducted over a wide range of temperatures. Among other studies, there is specific interest in using this sampler to identify microbial activity at temperatures above 130 degrees C, which is the near the upper thermal limit of life as we know it on Earth.
Use of this SMA-based triggering technology may have other temperature-based sampling applications. The purely mechanical design offers possible advantages in terms of packing volume, cost, and risk. The development team is exploring extensions for water-tight samplers and samplers for lower temperature applications.
Last Modified: 08/18/2022
Modified by: Christopher A Kitts
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