3
Technologies for Research and Observational Instrumentation
A central pillar of the polar research enterprise is the use of instruments and sensors that collect observations within particular physical environments being studied—for example, in the ocean, in the atmosphere, on land, and in, on, and under the ice—and that use the polar environment as a platform for collecting observations beyond Earth’s environment. These instruments and sensors may be fixed or mobile. They may range from a single small handheld device to networks of sensors deployed over vast distances, to large installations comprising numerous sensors. Technological capability essentially drives every aspect of how research instrumentation is used: for example, what variables can be measured and with what precision, accuracy, and frequency; where observations can be collected; and for how long before replacement or maintenance is required.
The first session of the workshop focused on exploring new observational instruments and sensor technologies that are being considered, explored, or implemented across many different areas of polar research. Given the wide array of specific research areas under the umbrella of Antarctic and polar science, this overarching session was divided into three parallel subsessions, grouped by general domain of research: ocean-focused; Earth- and ice-focused; and atmosphere, solar–terrestrial, and astronomy/astrophysics research. Within each of these sessions, a panel of speakers was asked to share examples of cutting-edge developments currently being explored within their particular research community, including insights on how those technological advances have been realized, and to offer thoughts on new advances to help researchers address scientific questions currently constrained by technological limitations.
Before dividing into the parallel sessions, planning committee member Craig Lee, University of Washington, provided a short plenary overview of the “research and development trajectory” of ocean gliders (see Box 2).
OCEAN-FOCUSED RESEARCH
Maaten Furlong, United Kingdom’s National Oceanography Centre, provided perspective on technologies for marine robotics and under-ice operations being developed by the United Kingdom’s National Oceanographic Service. Its operational groups develop underwater gliders, autonomous underwater vehicles (AUVs), remotely operated vehicles, and some uncrewed surface vessels, as well as the associated infrastructure. Its goal is to have close collaboration between the operational development teams and the broader UK marine science community to ensure that they are developing tools that are needed by the community. Furlong’s team focuses on building modular, reusable components that provide significant flexibility and are open
to further development by the broader community. The modular components include pressure-tolerant batteries, power control tubes, software components and operating systems, and a large variety of sensors.
One of Furlong’s team’s biggest challenges has been with the software. The software stack they use includes a web-based, command-and-control system designed to control long-range vehicles (e.g., Slocum gliders, sea gliders, Autosub long range, Autosub 5, and a hover vehicle). Within that system is an automatic piloting framework, which allows other people to develop code to control the vehicles (Harris et al. 2020), and an onboard control system, which is designed to be unified across all of their vehicles. The system is also designed to allow third parties to add back-seat control systems to the platform to effectively extend the vehicle’s capabilities (Munafò et al. 2019).
Their in-house designs include two key classes of vehicles: the Autosub long-range vehicles (relatively slow, low-power, long-range platforms) and the Autosub 5 vehicles (higher powered, short-range) (see Figure 1). They have conducted a few under-ice deployments to date, including one in 2018 under the Filchner ice shelf system. The vehicles and control systems are continually updated, and Autosub 5, the latest generation of high-powered vehicles, was specifically designed for under-ice capabilities. They build redundancy into the system (e.g., two propeller systems), so if any one part fails, it is still possible to recover the vehicle. Key developments coming up in the next few years include updates to the onboard control system and projects looking at building new capabilities into the vehicles.
Britney Schmidt, Cornell University, discussed her group’s work on under-ice robotic tools. The “IceFin” vehicle (see Figure 2) was designed to help scientists better understand processes occurring at ice–ocean interfaces, especially under ice shelves where it is difficult to obtain measurements. This capability is important both for polar exploration and for eventual planetary exploration of ocean worlds beyond the Earth. IceFin is a modular vehicle. It can be separated into seven parts, each with a different purpose. The forward science modules can hold a variety of sensors (e.g., a conductivity-temperature-depth [CTD] sensor, dissolved oxygen sensor, sonar, cameras, and light sources) to do oceanography, map the ice, and avoid collisions. The rear contains directional thrusters that allow vehicle control. A modular science payload can be deployed with different commercial or custom-built instruments (e.g., bathymetric sonar and commercial sensors for pH). Another module holds the custom electronics and batteries (20 lithium-ion batteries) and custom controls that transmit sensor data up a tether. The navigational payload includes a Doppler velocity logger, a laser altimeter, an additional high-definition camera, and a light source. The vehicle can either operate autonomously or be driven live. The navigation and science payloads can be configured to face either up or down to meet different science goals. Schmidt mentioned that some key technological and program needs include better battery options and drills to better access ocean cavities or other places under the ice.
Schmidt’s team has scientists and engineers working together on every aspect of these programs, rather than working with an external technology provider in a traditional customer–client relationship. However, she noted that it is a challenge to get support for technology development alongside science funding. Subsequent breakout discussions echoed this theme, with workshop participants noting the value of having science and engineering teams integrated from the outset of a project, to ensure that technology development and science goals advance together in real time.
Samuel Laney, Woods Hole Oceanographic Institution, provided two examples of technological advances using bio-optical sensors to study ice-covered ecosystems over a range of temporal scales. First, he discussed the example of bio-optical sensors on ice-tethered profilers. This involves a vehicle that collects high-resolution vertical profile data as it climbs up and down a cable under the ice (see Figure 3a) to collect data for long-term time series. Simple sensors collect time series of key properties, such as chlorophyll biomass to profile algal biomass and its spatial and temporal variation in the upper ocean (Laney et al. 2014). With a light meter, Laney and his team collected information about the magnitude, timing, and vertical structure of the light field under the ice (Laney et al. 2017). Laney largely uses off-the-shelf sensors (e.g., a chlorophyll fluorometer, optical backscatter sensor, ultraviolet blue fluorescence meter) attached to the profiler. Some key technology issues Laney and his team had to address were optimizing the physical arrangement of sensors to facilitate deployment (e.g., so that it can fit into pre-drilled ice holes) and making it as easy as possible to integrate sensors into the platform with a microcontroller interface (i.e., keeping it “simple and smart” with a simple, low-power microcontroller and interface board).
Second, he discussed an example using a combination of optical and bio-optical sensors on buoys (see Figure 3b) to study polar coastal margins. This system has been used in Alaska’s coastal regions where land-fast ice is breaking up and degrading—an area where ships, gliders, and other vehicles might not be able to go. The challenges were finding miniature sensors that could
survive the rough conditions; adapting and implementing other devices (e.g., an upward-looking acoustic sensor); and building a system that has GPS and Iridium communications built into it. He noted that design considerations should not only incorporate technology for measurements but also should consider the scalability, sustainability, and environmental impact of the technologies being developed.
Clive McMahon, Sydney Institute of Marine Science, discussed the Animal Borne Ocean Sensors (AniBOS) network, endorsed by the Global Ocean Observing System. The AniBOS network is part of an integrated, multipronged approach that uses animals to collect key oceanographic and behavioral information in areas that are difficult for scientists to sample with the traditional technology of ships, gliders, and floats. AniBOS uses miniaturized CTD instruments (shrunk from hundreds of kilograms to ~580 g) that can attach to an animal. These instruments have temperature, salinity, and pressure sensors, and they transmit information through the Argos satellite constellation in near real time. In addition to the core CTD measurements, McMahon’s team has added fluorometry and some information on light to measure chlorophyll-a, which improves their understanding of biological productivity. Additionally, McMahon noted that AniBOS is standardizing its data across networks, for both data recording and distribution (see Box 3 for more details on data standardization). One of the challenges with the miniaturized sensors is miniaturizing the batteries.
Promising paths forward include expanding dissolved oxygen and bathymetry measurements. Their research team faced some early challenges (e.g., with sensor calibration and stability), but McMahon suggested that the community should not be risk-averse, but rather it should be ambitious about trying new approaches.
Seal-borne instruments can also provide useful information both on animal behavior and on the bathymetry of regions where the animals are diving to the bottom. They can address questions of interest to biologists by using sonar instrumentation to observe prey fields—integrating prey fields with the animal behavior to track that both seasonally and relating to changes in water mass.
EARTH- AND ICE-FOCUSED RESEARCH
Terry Wilson, The Ohio State University, discussed developments in autonomous GPS and global navigation satellite systems (GNSS) and seismic instruments, in particular through the Antarctic network of the polar observing network (POLENET). Working with the IRIS-PASSCAL (Incorporated Research Institutions for Seismology Portable Array Seismic Studies of the Continental Lithosphere) Instrument Center and UNAVCO facilities, investigators sought to collect continuous time-series data year-round by developing power and communication systems optimized for long-term polar operations (see Figure 4). As challenges arose, Wilson and her team made incremental changes and improvements to the instruments. For example, they made weather-hardening improvements after extreme winds destroyed some of their
early deployments and caused static that electrically damaged receivers and overcharged the batteries.
Another development that transformed GNSS was the Resolute Polar Receiver, which integrated the Iridium satellite network into the telemetry with the GNSS receiver and significantly lowered the power requirements. In seismic research, there has been a massive reduction in power requirements of sensors and data loggers. Iridium telemetry has advanced over time, but needs remain for further advances that allow full telemetry transfer of field data, Wilson said. In power systems, Wilson and her team have now moved to primary lithium batteries; and lower-cost lithium rechargeable batteries are now being tested and progressing in availability. Advances on all these fronts may allow for more science and reduce logistic requirements for returning to the field for instrument maintenance.
Wilson emphasized that data from these autonomous networks are potentially useful for many research areas—for example, tectonics, ice-sheet dynamics, atmospheric and oceanic studies, and geospace weather. However, further improvements in communications and power systems would benefit all of these applications. For instance, GNSS interferometric reflectometry could have multiple applications, but this requires an array of sites capable of high-rate data collection, which in turn requires better communications and power infrastructure.
There are opportunities to leverage more science with “plug and play” power and communications that could accept a wide array of instruments. Two examples of possible advances on this front include (1) augmenting GNSS
sites with absolute gravity sensors to make measurements to resolve uncertainties in ice mass change and (2) distributed acoustic sensing using fiber-optic cables that provide seismic data. There are also opportunities to better leverage developments happening in related fields—for example, developing seafloor geodesy technologies, both to look at subduction zone hazards and also possibly to study crustal motion beneath Antarctic ice shelves.
Pedro Elosegui, Massachusetts Institute of Technology, discussed how scientists studying glacier dynamics in dangerous, highly crevassed polar regions have thus far relied primarily on instrument deployment from helicopters and ships. Although gathering valuable data, the logistics requirements of such efforts are expensive, risky, and difficult. To scale up these systems to cover more of Antarctica or Greenland, simpler solutions are needed, he said.
The new technology approach that Elosegui’s team is developing is to put geophysics sensors (e.g., high-quality broadband seismometer, geodetic-class GNSS receiver) on a new deployment platform—a “seismo-geodetic ice penetrator” (SGIP) that can be air-dropped from either LC-130 aircraft or helicopters into inaccessible regions of Antarctica where in situ observations are critically needed. When the SGIP impacts the ice, it separates into two components: the forebody lodges into the ice where it collects observations while the top part (the flare, with a GPS/Iridium antenna) operates continuously to stream science and engineering data to the Internet, allowing near-real-time data monitoring. Ultimately, the vision is for these air-dropped instruments to deploy as a broad network covering various ice shelves around the perimeter of Antarctica. Many other sensors could potentially be placed in this platform to collect additional observations where most needed.
Fernando Rodriguez-Morales, University of Kansas, Center for Remote Sensing Ice Sheets (CReSIS), discussed how aircraft and uncrewed aerial vehicle (UAV)-based remote sensing is used to advance ice and snow research in Arctic and Antarctic settings (see Figure 5). Multiple radar frequencies can be used to measure different snow and ice features and penetrate different levels of the ice column. Lower frequencies can penetrate to the bedrock while higher frequencies penetrate to a lesser depth but can accommodate wider bandwidth, which means finer resolution and more ability to resolve the internal structure of the ice closer to the surface. For sea ice, this allows for the measurement of the thickness of the snow cover, which affects how ice grows and melts.
One key technology development is the ice and snow radar sounders that operate on two bounds of the frequency spectrum. These technologies have evolved over many decades, starting with pioneering work performed in the post–World War II era. A research hub emerged at the University of Kansas starting in the 1960s and, since then, researchers around the world have developed many new instrument concepts. Long-term investments from the National Aeronautics and Space Administration (NASA) and National Science Foundation (NSF) grants that resulted in the PRISM project and the CReSIS Science and Technology Center, combined with the leadership and hard work of many people, have built unique interdisciplinary expertise to develop these systems.
CReSIS’s work encompasses the development of instruments custom-fitted for aircraft, facilities to test technologies before field deployment, field computing facilities to produce preliminary results when data are collected, software to process these data, and channels to disseminate results to the wider science community. CReSIS ensures significant involvement of students across this spectrum of work, from initial design to data processing. An NSF Science and Technology Center for Cold Ice Exploration (COLDEX, formed in 2021) focuses on developing and using radar technology to determine the age of ice in Antarctic settings to help pinpoint the optimal sites for ground-based work. Other current lines of development work include (a) putting instruments on long-endurance UAVs that can fly for days and can reach inaccessible areas and (b) working with smaller UAVs that have shorter endurance and lower payload capacity but are less expensive and easier to operate.
Mary Albert, Dartmouth College, discussed technologies being developed by the U.S. Ice Drilling Program (IDP), which is a collaboration among Dartmouth College, the University of Wisconsin, and the University of New Hampshire. The program’s cooperative agreement with NSF has run for more than 10 years. Its mission is to serve science communities that need either a shallow or a deep core of ice, a core of rock from under shallow ice, or a hole through the ice sheet. It conducts integrated annual planning with these communities to identify science goals and the drilling technology and operational support needed. This integrated science planning drives technology innovation and development, Albert said.
A few examples of drilling technologies that have been developed through the IDP include the Agile Sub-Ice Geologic (ASIG) Drill, Ice-Enabled Winkie
Drills, the Foro 3000 Drill, and the 700 Drill (see Figure 6). The ASIG Drill can retrieve rock cores from beneath 700 meters (m) of ice and the Ice-Enabled Winkie Drills collect rock cores beneath 100 m of ice. Both drills have been tested, used, and proven successful at multiple sites in Antarctica, and both drills will be used in Greenland in 2023. The Foro 3000 Drill, which can drill up to a 3,000-m ice core, will be deployed next year at Hercules Dome, Antarctica—a site that may help to better understand past episodes of ice sheet collapse. The 700 Drill, which can capture up to 700 m of ice, will be used in alpine sites where scientists need to hand carry the equipment up mountains.
In recent decades, the imperative has been to make drills lighter, leaner, and more agile, to help make deployment in Antarctica and Greenland more feasible. The IDP has facilitated a lot of work between engineers and ice-core researchers to explore these needs. Given that faster, smaller drills mean less
ice collected, scientists have developed new methods to conduct analyses using less ice. One can find more details on the next steps and community recommendations for future technology needs in the latest IDP long-range science plan, Albert said.1 See Box 4 for further discussion on drilling technology opportunities.
ATMOSPHERIC, SOLAR-TERRESTRIAL, AND ASTRONOMY/ASTROPHYSICS RESEARCH
Gijs de Boer, University of Colorado Boulder, gave an overview of recent efforts to use remotely piloted aircraft at high latitudes to collect observations of complex, heterogeneous atmospheric and cloud processes. Work on this technology has advanced through partnerships at the University of Colorado, the National Oceanic and Atmospheric Administration (NOAA), the National Center for Atmospheric Research, and private industry. The platforms used are typically small, uncrewed aircraft systems (UAS drones) that are electrically powered, 1–2 m across, and can fly for up to 2.5 hours. de Boer discussed three types of platforms: the Raven, the Data Hawk, and the Helix Copter (see Figure 7).
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Small UAS are a useful technology to provide new perspectives on the lower atmosphere and its interactions with the surface. These systems can measure a variety of atmospheric, thermodynamic, and kinematic variables using sensors to monitor temperature, pressure, humidity, wind, and turbulence. Flown at low altitudes, the Helix also has sensors to look at solar irradiance and a camera system to map the terrain being flown over. de Boer shared several examples of the types of vertical profiling measurements and imagery collected. These observational platforms can distinguish between open ocean, ice, and melt ponds on the ice (features that are finer scale than the grid size of most models), and thus they can help characterize spatial variability and how that affects the energy transport among different parts of the Earth system.
Taneil Uttal, NOAA, discussed a new platform developed by researchers with the NOAA Physical Sciences Laboratory: the Atmospheric Surface Flux Station, which was used for the 2019–2020 Multidisciplinary Drifting Observatory for the Study of Arctic Climate (MOSAiC) Expedition (see Figure 8). This station collects measurements of surface energy balance in an environment of moving sea ice. The researchers’ goal was to carefully measure all separate components of the surface energy balance—incoming and outgoing shortwave energy, incoming and outgoing longwave energy, and sensible and latent heat fluxes—to better understand the transfer of heat and energy from the atmosphere onto land, snow, or ice surfaces. Such observations help scientists understand the atmospheric contribution to ice melt, ocean mixed-layer warming, photochemistry, biological energy sources, and coupling processes.
Their challenge was to build a system that could operate for a full annual cycle on the Arctic sea ice, including the particularly challenging times in the middle of winter (i.e., extreme cold) and in summer (i.e., when ice is moving and breaking apart). Because of the large horizontal inhomogeneity in these environments (including melt ponds, refrozen melt ponds, first-, second-, and
multiyear ice), they needed multiple systems that were portable, able to handle diverse terrain, and able to run autonomously. A key innovation was to deploy sensors on a sled-based platform with a methanol fuel cell power system. They incorporated numerous sensors that one normally puts on towers for measuring surface energy budget fluxes (e.g., an Iridium/GPS, radio antenna and cameras, and instruments for measuring surface meteorology, broadband radiometers, sky and surface brightness, temperature, and surface height as a proxy for snow depth). The sensors were designed to run autonomously over a variety of different kinds of surfaces and could be quickly moved and redeployed when threatened by ice ridges and leads. They originally deployed the platforms 10–20 km from the main ship to see how they drifted around on different ice types. One sensor was left on site when the ship needed to exit the main floe for personnel transfers. Uttal noted that a key challenge was timely data processing and product development.
Andrew Gerrard, New Jersey Institute of Technology, spoke about space weather observing systems deployed in the polar regions, which have been developed through broad community efforts. Space weather is fundamentally tied to Earth’s magnetic field lines, which terminate in the northern- and southernmost regions. In the north is the Arctic Ocean (a difficult place to gather observations), but in the south, the Antarctic continent provides a place for scientists to deploy instrumentation to study these systems and advance space weather prediction capabilities. There is an array of different stations deployed for geospace monitoring in the Antarctic—including crewed stations at McMurdo, South Pole, and Palmer; a network of Automated Geophysical Observatory (AGO) stations (which have been running since the mid-1990s); and a network of stations operated by Virginia Tech.
The crewed stations have an array of sophisticated space weather instrumentation, but three stations can only offer a rough snapshot of space weather conditions for the entire region. Thus, Gerrard and his group developed remote instruments for wider deployment to gain a better handle on the synoptic-scale conditions. Compared to the crewed stations, these autonomous units run on lower power and lower data bandwidth. They contain instruments such as fluxgate magnetometers, radio receivers, GPS receivers, and relatively simple all-sky–type instruments, typically single-band, fixed-filter–type imaging systems. Data are transmitted via Iridium.
The systems typically run on a combination of solar and battery power, 15 watts or lower, whereas the AGO stations use a combination of solar, wind, and battery to run at about 400 watts. Much of the current technological development focus is on making more robust systems that can last longer without requiring servicing. By working with teams of engineers, Gerrard and his group have developed better receivers, lower noise characteristics, and increased data processing.
Gerrard emphasized that the biggest challenge the geospace community faces is constraints on actually deploying instrumentation in deep-field locations. There is a need to consider how flight resources are used, other options for getting into the deep field (e.g., automated traverses), and opportunities to maximize international collaborations. He emphasized that these platforms used by the geospace community often have power and data bandwidth to
spare, which can be used to house other instruments and thus help other research communities as well.
Aya Ishihara, Chiba University in Japan, discussed some of the challenges involved in the development of sensors for the South Pole neutrino telescope projects: IceCube (currently in operation) and IceCube-Gen2 (in the design stage). The IceCube installation is located near the South Pole station, buried in the ice about 1.45–2.45 km deep. The observatory covers more than 1 km3 in volume. IceCube consists of more than 5,000 glass-enclosed digital optical modules, each containing photomultiplier tube (PMT) sensors that are used for detecting a very dim light, called Cherenkov radiation, which is a signature of neutrinos. The sensors employed need to be cutting-edge in their ability to collect highly precise, accurate measurements of photons but also robust with an expected operational lifetime of more than 20 years.
IceCube has collected many groundbreaking observations, and a next-generation neutrino detector for the South Pole—IceCube-Gen2—is currently being designed. This will be a much larger installation, with a volume of 8 km3. There will be larger horizontal spacing between detector holes but less volume per hole, which raises new challenges of maximizing the photon sensitivity within each hole, which has led to a new elongated photo sensor design with PMTs that can see in multiple directions.
For this more complex IceCube-Gen2 system, the sensor modules must satisfy the same requirements for robustness and long lifetime—they must be unbreakable and must be operational at low temperatures (−10ºC to −40ºC). They must have low power consumption and low data bandwidth, in part because power and communication must occur via a very long (2.5 km) copper cable. Ultimately, Ishihara and her team hope to use fiber-optic cable or wireless transmission—technologies that are common in our daily lives but not yet confirmed to be robust enough for deep ice operations. Testing and development are ongoing.
Another challenge is that the ice in which the observatories are built is slowly moving. To understand the fine details of the ice flow occurring over the IceCube-Gen2 deployment site, Ishihara and her team need to monitor the distortion of ice by the underlying bedrock below 2,500 m. It is anticipated that it will be feasible to do this monitoring using the optical light sources in the detector modules, but ice flow information outside the detector area may only be obtainable using radar-sounding observations. The IceCube work requires numerous collaborations across scientific disciplines and national programs. Ishihara and her team are trying to use observations from European Space Agency airborne radar soundings, ground penetrating radar, and other sources of information.
Johanna Nagy, Washington University in St. Louis, discussed the technology used in telescopes in Antarctica—both on the ground at the South Pole and flying around the continent on stratospheric balloons launched from near McMurdo Station. These telescopes are measuring microwave radiation in what is known as the cosmic microwave background (CMB), an echo of the hot dense plasma that filled the universe in the early moments after the big bang.
CMB observations are an incredibly useful tool for cosmologists to learn about the history and nature of the universe. For instance, observations of the
CMB allow for mapping of the microwave radiation across the sky, looking at frequencies near 150 gigahertz. Small differences in the temperature and the linear polarization across the sky can allow for precision measurements of key properties of the universe. To advance cosmology research, it is necessary to build instruments able to make more sensitive measurements, particularly of linear polarization.
The South Pole, one of the highest and driest sites on Earth, allows high atmospheric transmission for microwave light and very low atmospheric emission, with very stable observing conditions. It is one of the best spots on Earth for deep-field observations. For all those reasons, the South Pole is home to the BICEP (Background Imaging of Cosmic Extragalactic Polarization)/Keck series of telescopes, as well as the South Pole Telescope, and it is proposed for future experiments such as CMB-S4.
Nagy noted two particular areas of technology development that the community is excited about for advancing CMB measurements. The first transformative development relates to cryogenic cooling technology. Roughly a decade ago, telescopes at the South Pole switched from using helium for cooling to pulse-tube mechanical cryocoolers. But mechanical coolers raise concerns about vibrations during operation and performance over different tilt angles as the telescope changes position. Pulse-tube cryocoolers offer a huge advantage, given the expense and logistical difficulties of having a constant supply of liquid helium at the South Pole, and then keeping the telescope cold over extended periods. Commercial vendors are developing cryocoolers for a variety of applications, and CMB researchers identified commercial models suitable for telescope operations. With no need to make space for giant liquid helium tanks, receivers can be packed closer together, building more sensitivity into the instrument. However, pulse-tube cryocoolers still consume a lot of power; lower-power cryocoolers would be transformative for both balloon-borne and ground-based experiments.
The second example discussed by Nagy was new telescope designs that have higher optical throughput and sensitivity, equivalent to several current telescopes. This could potentially transform the research landscape because deploying more copies of existing telescopes increases the demand for infrastructure for transportation, construction, and operation. The new telescope has 85 individual optics tubes, each with a detector that measures light in two different frequency bands. The new design allows for a huge increase in the sensitivity of a single instrument. Taking advantage of the sensitivity requires careful control of systematic errors. One approach being tried is a 5-m monolithic mirror that avoids diffraction that results from gaps between the smaller mirror panels that previous instruments have used. Such technology advances will enable CMB telescopes to significantly increase their sensitivity while being as efficient as possible in deploying and operating at the South Pole.
LIFE STUDIES RESEARCH
Only ~1 percent of viruses known on the planet today have been sampled and sequenced. This is an area for improvement, as noted by Arvind Varsani,
Arizona State University, who discussed how technology developments are advancing research on viral dynamics in polar ecosystems. Scientists have long studied viruses from the perspective of disease agents and pathogens but the role of viruses at population and ecosystem levels has barely been studied (Sommers et al. 2021). One of the biggest challenges in understanding the diversity, distribution, and dynamics of viruses is the genomic properties of viruses themselves. A key tool to study viruses, sequencing technologies have greatly evolved (Shendure et al. 2017; see Figure 9). However, sequencing in the field presents unique challenges (e.g., larger instruments are intended for core facilities and smaller, more complex instruments require onsite technical assistance).
One current cutting-edge technology is nanopore-based systems, which can be small, portable, and affordable ($1,000–$3,000). These systems have a bacterial nanopore tethered to an enzyme (e.g., helicase) that unwinds nucleic acid to assess the bases and electric charges. Based on that, molecules can be sequenced. One challenge is the high error rate when a single molecule is sequenced; the molecule must be resequenced multiple times to bring the error rate down. There is also a challenge with the signal-to-noise ratio because viruses interact with a variety of organisms and the genomes are relatively small. There are ways to improve that signal-to-noise ratio, but because different viruses have varying properties, it is important to tailor the approach to the ultimate research goal. Varsani and colleagues have developed a framework to assess which approaches should be used in which context (Sommers et al. 2021). There have been significant recent advances in studying viral dynamics of marine systems (e.g., the Tara Oceans project; Roux et al. 2016), but relatively little comparable research has been done in terrestrial ecosystems. The rapid field sequencing capabilities available today are a game-changer for this sort of research, Varsani said.
Sarah Johnson, Georgetown University, expanded the discussion on biological sequencing. Traditionally, people doing biological sequencing have relied on large, high-fidelity “workhorse” technologies (e.g., Illumina iSeq/NextSeq/MySeq sequencers). Now, much smaller instrument technologies are being developed that offer new options for biologists working in Antarctica to do in situ analyses. iSeq instruments are only about a cubic foot in volume. Although not designed to be used outside, iSeq instruments are highly portable, lightweight, easy to use, and relatively low cost.
Rapid advances in miniaturization have also led to extremely small nanopore sequencers such as Oxford Nanopore’s MinION, a small, handheld sequencer that weighs only 85 g, is 10 cm long, and draws about a watt of power. These instruments can sequence native DNA to avoid polymerase chain reaction (PCR) bias and can directly sequence RNA. The instrument uses a new type of technology that measures an ionic current as DNA passes through a protein nanopore embedded in a polymer membrane. It is less accurate, but the output is much longer reads (e.g., instead of 300 base pairs, the output is tens of thousands). It is robust and requires low enough power to use in the field. In addition to handheld sequencing instruments, a variety of other associated technologies have been developed in parallel, such as portable cell lysis, microcentrifuges, battery-powered nanophotometer, and offline bioinformatics databases.
These technologies have the potential for maximizing efficiency in the field. For instance, instead of collecting every sample, it is possible to triage specific targets (thus optimizing limited field time) because researchers can immediately assess if a sample has what they are looking for. Researchers can also investigate in real time when they come across unanticipated findings in the field.
These technologies can also protect against catastrophic sample loss (e.g., samples thawing en route back to the United States). Johnson remarked that there is a higher level of security in having all of the field data downloaded to an external hard drive upon leaving Antarctica. A concern when doing transcriptomics is that samples may change, so it is a great benefit to do those analyses as soon as possible after collection. In general, more efficient field operations mean a lower environmental and logistical footprint of the work.
In the breakout discussion moderated by Paul Winberry, Central Washington University, and Sharon Robinson, University of Wollongong, one workshop participant noted that establishing a DNA sequencing laboratory in McMurdo Station would be beneficial. Diane McKnight, University of Colorado Boulder, noted that the new handheld sequencing devices (and related technologies) could be a way to expand connections between research activities. For example, those doing geophysical and drilling work could perhaps help obtain preliminary biological data that could be used by other investigators. This could help address a common challenge that reviewers of funding proposals often question whether it will be a good use of resources to send researchers to a new location if they are unsure that there will be interesting biological data to collect there.
Beth Shapiro, University of California, Santa Cruz, discussed environmental DNA (often called sedimentary or ancient DNA), which refers to DNA that comes from environmental samples rather than an individual living organism. For example, environmental DNA from lake cores comes from organisms living in the lake (e.g., insects, worms, fish, microbes, and plants) or that get blown into or deposited in the lake. In polar environments, sedimentary ancient DNA can be retrieved by sampling ice cores, permafrost cores, or sediment cores extracted from the bottom of a lake. The aim is to develop a robust chronology for these cores to help us understand how old the samples are. Often, the color and texture of cores can also reveal something about the environmental history of the region. For example, layers of whiter and darker lines in
a core are often due to characteristics such as differences in sedimentation or permafrost and tephra layers, which often appear as fine white lines and can indicate a volcanic eruption with a known date.
As soon as cores are removed, they are exposed to potential contaminants; thus, a lot of work goes into ensuring that authentic ancient DNA can be distinguished from DNA that might get onto the surface of these cores after they are extracted. Samples are split open in a special clean room to minimize the possibility of contamination. Understanding how DNA is preserved in the sediment is a significant area for research, Shapiro said. Scientists know that DNA is preserved for at least 100,000 years or longer in some exceptional circumstances, and samples from some sites in the Arctic are older than 800,000 years. In polar regions and cave sites, there can be exceptional preservation of ancient DNA due to the cold and lack of UV radiation exposure. Some samples possibly go back millions of years.
Shapiro shared three different state-of-the-art technologies currently used to extract DNA from samples:
- Metabarcoding uses PCR to target a specific conserved region of the genome.
- Metagenomics approaches sequence everything extracted in the DNA.
- The newest approach, still in development, is to develop “bait sets” that target and extract specific DNA one is interested in (e.g., only fish, seals, or plants) and washes everything else away.
COMMON CHALLENGES ACROSS RESEARCH AREAS
In the final plenary for this session, all workshop participants reconvened to share key ideas that arose in the three parallel sessions and to consider common themes among the groups. For instance, several participants expressed interest in the miniaturization of components and sensors, because smaller components require less power and enable more sensors and instruments to fit on a platform. There is great potential to work with industry partners on such developments; however, such partnerships can often be challenging to build because of the lack of large, profitable markets for specialized research instruments.
The group also discussed the importance of sensor stability and reliability, as well as the standardization and interoperability among sensor technologies (see Box 3). The advancing modularity of sensors could be an opportunity for innovative technological development. Even mundane advances (e.g., uniform connectors) could mean that instrumentation could easily be swapped out if something breaks down. However, the standardization of field instruments can be hampered by an industry’s propensity to hold proprietary details of some technologies. Thus, the group highlighted the importance of strategies to help ensure that critical technologies are widely available and readily adoptable.
Another topic discussed among some of the groups was collaborations to facilitate technology developments. It was noted that smaller groups may proceed slower in the development of a particular technology, but they can be agile in switching from one topic to another. In contrast, a larger team that includes engineers and software engineers can move more quickly on a specific topic but may be much slower to transition to a new area of research. Some participants discussed how cross-agency partnerships can be productive for driving technological advances; for instance, the CMB detectors’ development has been a cross-agency effort among NSF, NASA, the National Institute of Standards and Technology, and the Department of Energy.
Other participants acknowledged the benefits of helping scientists and engineers develop close working partnerships, with ongoing opportunities to compare notes and share ideas. However, one group pointed out that sustaining such efforts may require sustained funding for teams and maintaining institutional knowledge.
One group discussed “sacrificial instruments” that are deployed with no expectation of eventual recovery. This approach does help avoid the large logistical burden of returning to the field to retrieve instruments, but leaving them behind itself poses environmental impacts. More broadly, there was much discussion about advances in autonomously operating instruments that require minimal or infrequent servicing, thus reducing the logistical burdens and costs.
Several participants expressed interest in expanding opportunities to test field equipment before polar deployment, as one way to help address the challenge of moving from technology development to operational stages. Many systems in the “proof of concept” phase (i.e., where a single research group develops a new approach to measure something) face barriers to being operationalized and used on a large scale by the broader research community.
Some other categories of development that were discussed include deicing technologies (for everything from drones to telescopes); cryocooling technologies (which could draw lessons from NASA spacecraft); docking technology for AUVs; new (lighter, more agile) ice and rock drilling technologies (see Box 4); and rapid DNA sequencing that can be utilized in the field or at McMurdo Station. Many participants also expressed interest in the opportunities and challenges of expanding the use of solar power for research instrumentation (see Box 5 in Chapter 4).
Several other key ideas were raised in the open discussion that followed the reporting from the three instrumentation breakout groups. One topic was the decisions and trade-offs required in the technology design process. Britney Schmidt suggested that the community should think about the many decisions that go into particular field designs that could have large ramifications for hidden costs. More open conversations about this between scientists and those who provide engineering and logistical support could lead to creative solutions that reduce the logistical impact and footprint of research activities. She noted that there can sometimes be challenges working with commercial companies to build new instruments because there are often special science and logistics requirements the company may not be aware of or know how to address.
One participant offered an engineering perspective on the importance of being intelligent and discerning about the design process. For instance, while everyone wants the perfect battery or other power sources, it can be just as
important to reduce power consumption. Craig Lee echoed this point, noting that ocean glider development maxed out what advances could be made with batteries and then had to focus on improving glider efficiencies. Lee added that effective communication between the logistics operators and researchers can be critical to the ultimate success of efforts to deploy new technology developments.
Robert Clauer, Virginia Tech, added further perspectives regarding tradeoffs in power supply choices, noting that scientists use heavy batteries not necessarily because of a lack of alternative options, but because it is often the most reliable technology and the only option to sustain power over the dark period of Antarctic winter.
Dan Costa said that the polar community is constantly faced with tradeoffs, and must look for a “sweet spot” balance. For instance, regarding the balance between data transmission and energy utilization, there is a trade-off between the costs and benefits of saving and transmitting all of one’s raw data versus filtering and compressing those data streams. In comparing different battery power options (e.g., off-the-shelf systems versus higher-tech, lighter-weight systems), some trade-offs to consider include cost, ease of transport and use in the field, and flight transport restrictions.
The group discussed opportunities to draw from technology developments led by other research communities, for example, from the health care world. Costa remarked that one can now measure numerous parameters of the human body via wearable sensor technologies, and this could potentially be adapted for polar sciences. For example, the heart rate recorders one wears during exercise could be adapted for studying animals in the wild. Similarly, Susan Jewel noted that the field of space medicine is starting to develop “digital twin” concepts that integrate biooptics, biosensors, telecommunications, and other technologies, and there could be an opportunity to harness such approaches for Antarctic research.
Ted Scambos, University of Colorado Boulder, remarked that the polar community is not short on new technology ideas but often lacks places to take ideas for investigation, development, and testing. UNAVCO and IRIS offer the capability to assist people in developing better sensors, particularly for land and ice instrumentation, and there are some equivalent groups within the ocean community. See Chapter 7 for more discussion of this issue.
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