as these investments will provide U.S. researchers the opportunity to drive research forward without external constraints, maintain leadership positions in the international polar community, support a well-trained future U.S. workforce, and engage as equal decision-making partners in the design and implementation of future international field programs. These investments in U.S. capabilities will strengthen U.S. scientific, workforce development, and economic interests both nationally and abroad.

NSF may need to consider trade-offs between vessel capabilities. To assist NSF in this effort, the committee classified capabilities needed by the U.S. researchers on USAP or partner vessels as Critical or Important for each of the science drivers (Table 6-1). The justifications for these classifications are expanded in the sections below. Where appropriate, the text references back to the more comprehensive justifications provided in Chapters 3, 4, and 5.

Polar Class 3 Icebreaking Capabilities

A Polar Class 3 (PC3) icebreaker for access into winter ice cover and to coastal areas is Critical for studies on sea level rise, global heat and carbon budgets, and changing ecosystems (see Chapters 3, 4, 5; Table 6-1). Specifically, a PC3 icebreaker would enable improved understanding of nearshore and winter processes such as sea ice production, dense shelf water production, oceanic forcing of Antarctic ice shelves, water mass modification in polynyas, and ecosystem processes on sea ice and in coastal polynyas (Chapters 3, 4, 5; Table 6-1). This access to the coast across all seasons is also essential for deploying other capabilities such as ice stations (e.g., Ackley et al., 2020), and emerging autonomous platforms and drifting platforms capable of operation in ice-covered waters and within ice shelf cavities.

USAP access to East Antarctica (Box 6-1). Greater than 70 days endurance in the summer would allow access, for example, to the Totten Glacier in East Antarctica (Chapter 3), as its remoteness would entail significant transit (roughly 8–10 days one way from Hobart, Australia) and still accommodate a 50-day science cruise on site.

Following several prior community reports that called for greater than 80 days of endurance (Chapter 2), the endurance of the ARV is designed for midsummer optimal maximum of 90 days. This means that the ARV may be able to operate for 45–60 days for a midwinter cruise that requires significant icebreaking through areas of extensive ridging, thick snow cover, and greater ice pressure.¹

Helicopter Support

The ability for U.S. researchers to have access to two light-duty helicopters on USAP or partner vessels is Critical for access to near-shore areas for studies on sea level rise (Chapter 3; Table 6-1). Identifying and characterizing complex processes driving solid Earth–ice–ocean–atmosphere interactions requires tactical deployment of surface instrumentation, drilling equipment, and associated field camps in coastal areas. Many of the most compelling places to acquire data relevant to sea level rise research—such as fast-flowing glaciers, grounding zones, and ice shelves—are too dangerous or too remote to be accessed by fixed-wing aircraft such as Twin Otters (Figure 6-2). For example, the most rapidly retreating (and arguably the most important to study) section of Thwaites Glacier’s grounding line is heavily crevassed and impossible to land on using fixed-wing aircraft. As a result, the International Thwaites Glacier Collaboration (ITGC) has so far been limited to deploying surface camps on Thwaites’s less dynamic Eastern Ice Shelf, where an airplane could operate safely.² If ITGC had access to helicopters, it is possible that their hot water drilling efforts, for example, could have enabled robotic exploration of the most rapidly melting part of the Thwaites Glacier Tongue.

Access to USAP or partner vessels with helicopter support is also classified as Important for studies on global heat and carbon budgets and changing ecosystems (Chapters 4, 5; Table 6-1). Deployment of ice-tethered platforms via vessels with helicopter support is a common operation in the Arctic and has also been employed by several Antarctic programs (e.g., Krishfield et al., 2008). Helicopters have also enabled remote surveys of sea ice properties (e.g., Heil et al., 2009). Helicopters further support efficient deployment of buoy arrays and enable sampling on ice floes while freeing up the vessel to conduct other observations. For a complex buoy array, use of a helicopter can save many days of ship time and open access to some otherwise inaccessible areas of heavy ice. Additionally, vessels with helicopter support can aid in reconnaissance and possible access missions (e.g., facilitating heavy-lift operations for access drilling) for the exploration of ecosystems along grounding zones and coastal margins.

A vessel with full helicopter support (including a helideck and hangar to store and service two helicopters) was supported by previous community workshops and reports (ARVOC, 2006; NSF OPP Advisory Committee, 2019; UNOLS, 2011, 2012). Full helicopter support was eliminated from the Conceptual Design of the ARV in 2020 (Glosten, 2021). Key decision drivers for the removal of the helideck were the cost of construction and maintenance; the space required to accommodate the helideck, hanger, and supporting infrastructure; and concerns over the historical cost of supporting helicopter operations on the Nathaniel B. Palmer. Indeed, NSF has noted that the helideck on the Nathaniel B. Palmer has only been used three times in 30 years, although data on the number of projects that initially proposed helicopter work that were rejected or asked to descope the helicopter work due to costs were not available.³ NSF reports that full helicopter support could drive the ARV to be larger, increasing its displacement and operational costs⁴; however, the committee has not seen a documented technical analysis of the trade-offs. While the exact impacts are uncertain, increasing the size of the ARV could impact seakeeping, speed and fuel efficiency, and icebreaking, among other parameters.⁵ The current preliminary design of the ARV can host the landing and takeoff of a single helicopter—for example to transport scientists from the ARV to a partner vessel that supports helicopters or to enable transport with land-based helicopters. However,

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¹ Presentation to the committee by NSF, March 2023.

² Presentation to the committee by Keith Nicholls, British Antarctic Survey, March 2023.

³ Presentation to the committee by NSF, March 2023.

⁴ Presentation to the committee by NSF, May 2023.

⁵ Presentation to the committee by NSF, March 2023.

it does not provide full support for onboard helicopters without a partner vessel or base (ARV SASC, 2023). It should be stressed that, while access to USAP or partner vessels that support helicopters was judged as Critical for the sea level rise science driver, a potential lack of dedicated helicopter support on the ARV in no way invalidates the critical and important needs for a vessel with icebreaking and science capabilities as outlined in this report. Chapters 3–5 outline national science priorities that fully justify the needs for new science icebreaking capacity in their own right.

U.S. helicopter lease costs on cruises are currently sourced from the Antarctic sciences budget,⁶ rather than from the logistics budget, which is the practice in many other nations that provided input for this report. NSF estimates that the cost of supporting helicopter operations is approximately $2–3 million per deployment.⁷ Mobilization and demobilization costs (i.e., transporting the helicopters to and from the port[s] of departure and arrival) and the day rate for long expeditions (even if helicopters are only used part of the time) are the most significant cost drivers, along with jet fuel and extra safety gear.⁸ In contrast to NSF’s estimate, the committee found that the cost for a Canadian firm to operate two AS-350 helicopters on a 50-day cruise from Lyttelton, New Zealand, with the Korea Polar Research Institute (KOPRI) is currently close to USD 330,000⁹; but comparison of full-cost accounting budgets under various international funding models is beyond the scope of the committee’s task. Further exploration of cost-effective solutions and potential collaborations for helicopter-supported field work would benefit the science drivers in the report.

While helicopters can save many days of ship time and facilitate access to some difficult-to-access locations, this advantage can be partially offset by a vessel with PC3 icebreaking capabilities for sea ice and ocean studies. The ability to deploy small drifting platforms or expendable ocean profilers via uncrewed aerial systems (UASs) is an emergent capability that warrants investment in engineering. However, for most sensor modalities in or under ice this is not currently feasible, and it may never be practical for some high-value observations requiring complex logistics, such as ice-tethered profiler deployments on fast ice adjacent to ice shelves.

The use of heavy-lift UASs to support ice-based research (e.g., large-scale remote sensing surveys) may also be possible in the future, offering an alternative to crewed helicopters for some applications. This capability is currently best achieved with large, heavy-lift (gas-powered) UASs that can travel well beyond direct line-of-sight piloting. The primary limitation for this capability is regulatory. Enabling this capability on USAP vessels would be important in the absence of helicopter support. There are also several commercial companies developing autonomous aerial vehicles (AAVs) or electric vertical takeoff and landing (eVTOL) vehicles with passenger capabilities. Systems under development range from fully autonomous to piloted. Claimed capabilities include ranges of more than 100 km and capacities for up to four passengers (e.g., Joby Aviation). Significant challenges remain for operation in the Antarctic, including required long-ranges, remoteness, landing on uncertain terrain, and regulatory requirements. It is unclear whether future systems that meet the unique challenges of Antarctic operation could also be significantly smaller or cheaper, or have smaller support-personnel requirements than crewed light-duty helicopters. Additionally, it is unclear if they could be supported on the current design of the ARV. For example, current eVOTL aircraft designs (e.g., Joby Aviation, CityAirbus) are comparable in size to traditional light-duty helicopters with limited range. Smaller, unpiloted aircraft (e.g., Ehang) have very limited range. Greater range is possible with fueled AAVs. While it is difficult to predict what AAV capabilities may be possible in a decade or two, significant developments in battery technology (i.e., much greater ranges) and autonomy are needed before operation in remote areas is possible with platforms that are competitive in size, logistics, safety, and range with current traditional helicopters.

Another possible alternative to ship-based helicopter support could be land-based combined fixed-wing and helicopter operations (the latter being necessary in those cases such as heavily crevassed ice shelves where fixed-wing landing is unfeasible). This type of operation has previously been supported by the USAP. For example, in 2012–2013, an expedition to Pine Island Glacier, adjacent to the Thwaites Glacier, involved the establishment

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⁶ Presentation to the committee by NSF, February 2023.

⁷ Presentation to the committee by NSF, May 2023.

⁸ Presentation to the committee by NSF, May 2023.

⁹ Presentation to the committee by Won Sang Lee, KOPRI, March 2023.

of a camp that included helicopter support. Helicopters were transported by ski-equipped LC-130s operated through McMurdo Station.¹⁰ Some of these operations have proved challenging in the past in regions that have poor weather and that are remote from bases. These challenges have led to significant impacts to science projects, with some teams with complex operations reporting month-long delays in departing McMurdo for remote camps (Hansen, 2009; Stewart, 2013).

Helicopter support on icebreakers has been prioritized by many international partners (Appendix B). For example, KOPRI’s Araon was initially designed to carry a single, heavy-lift Kamov Ka-32A, but has since adapted to carry either two light-utility AS-350 or Bell 206 helicopters. The Araon operates with a small hangar, thanks to the use of an extendable structure used to protect the aircraft during transit or in inclement weather (Figure 6-3). KOPRI relies on helicopter support on nearly all of their marine voyages; this regular usage has helped them develop practical strategies for efficient use of aircraft and balancing priorities on interdisciplinary expeditions. For example, KOPRI has used their helicopter capacity to tag Weddell seals on all sides of Thwaites Glacier, deploy surface-based GPS and weather stations, collect rock samples from nearby outcrops, install static radar sounders to measure basal melt rates, conduct airborne geophysical surveys, and acquire full-depth ocean profiles between icebergs within 10 km of Thwaites’s grounding line using expendable ocean sensors. KOPRI conducted this level of work in early 2022 during a season in which the icebreaker Araon was unable to gain access within 130 km of Thwaites Glacier.

Other partners that commonly use helicopters on vessel deployments include Australia, China, France, Germany, Japan, South Korea, Sweden, the International Association of Antarctica Tour Operators (IAATO), and the U.S. Coast Guard. The Swedish icebreaker Oden commonly uses helicopters but does not routinely operate in Antarctica. The United Kingdom is a common USAP partner and its new vessel, the Sir David Attenborough, is designed to support helicopters (see Appendix B). These partners offer opportunities for collaboration (see section on Collaboration and Partnerships), with partner nations taking advantage of the PC3 icebreaking capability of the ARV and the USAP taking advantage of partners’ helicopter support. However, there are also some potential disadvantages of relying exclusively on international partnerships for helicopter support. These include the added difficulty of facilitating and managing partnerships between scientists and the logistical organizations supporting the intended work, including the necessity to align science priorities between the national programs. The added cost of operating two ships for a single project is another disadvantage of relying on a two-ship model with international partnerships. Building and maintaining international partnerships through individual foreign collaborations can lead to inconsistency across programs and require that the principal investigator (PI) invest substantial time and remain much more flexible than when working solely through the USAP. So-called lead agency agreements¹¹ can facilitate international partnerships by allowing investigators represented by two national programs to submit linked proposals that, if funded, provide clear expectations and points of contact between the two programs. NSF’s Directorate for Geosciences has so far only established lead agency agreements with Germany, Ireland/Northern Ireland, Israel, Switzerland, Taiwan, and the United Kingdom (NSF, n.d.k); more are needed if international partnerships are expected to substitute for a lack of helicopter support on the ARV.

There may be creative solutions to addressing the design challenge that may stop short of the full helicopter support model chosen by other programs for recent ship designs (e.g., Australia, France, China, Norway, United Kingdom) but that could still enable two light-duty helicopters to operate on the ARV. While the committee cannot comment on the engineering design feasibility of these creative solutions, it is possible that discussions with partners about their vessel design may yield ideas that could be incorporated without delaying progression of the ARV through the Final Design Stage. For example, NSF could consider an approach in which the ARV helideck supports two light-duty helicopters without providing a hangar, analogous to the operation of the Swedish icebreaker Oden. Helicopters on the Oden utilize the sides of the helideck for takeoff, landing, and parking (Figure 6-4), which provides sufficient separation for safe operation of the second aircraft. The footprint of the Oden helideck would

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¹⁰ Written response from NSF to the committee, April 2023.

¹¹ Lead agency agreements “provide a framework for joint peer review of proposals by two funding agencies in different countries. One organization takes the lead in managing the review process with an agreed level of participation by the other, and both agencies accept the outcome of the review process and fund the costs of the successful applications in their respective countries” (UKRI, 2022, para. 3).

fit approximately within the space provided on the present design of the ARV aviation deck; however, the committee does not have the expertise to comment on the feasibility of adjustments to the side railings and Foremast Instrument Platform to enable safe approaches. Helicopter hangars are used primarily to protect aircraft from sea spray on transits to and from Antarctica or during stormy weather, and to provide a heated space for maintaining the aircraft. The rearward placement of the Oden’s helideck may partially mitigate the impact of sea spray on

transits and in stormy weather, a feature that the ARV would lack with the planned helideck placement on the bow; note, however, that the planned height of the ARV’s helideck is 16 feet higher than the level of the Oden’s helideck (51 ft vs. 35 ft). The committee is not appropriately constituted to comment on the engineering design of the ARV, but engagement with potential helicopter operators and others may assist in evaluating what is feasible.

It may be possible for USAP to consider a helideck-only approach thanks to its management of robust intercontinental aviation contracts. The USAP could leverage this unique position to reposition helicopters and their pilots and support staff to and from Antarctica to meet the ARV when needed, thus minimizing marine transits across the Southern Ocean with aircraft exposed to sea spray. The KOPRI represents an existing precedent for this operation. To guarantee uninterrupted helicopter support, KOPRI routinely uses C-130 aircraft to reposition two AS-350 helicopters between Christchurch and Jang Bogo Station in Terra Nova Bay (Figure 6-5). While McMurdo is a natural hub for this type of operation, nine other runways could currently support large, wheeled aircraft such as C-130s and C-17s, which both can carry two helicopters; a tenth optional runway could become available if the French Polar Institute refurbished its Piste du Lion runway facility near Dumont d’Urville Station (Figure 6-6). International agreements for runway access could be particularly compelling, considering the ARV’s long endurance; it is conceivable that within a 90-day cruise window, the ARV could conduct voyages with and without helicopter support if passengers and helicopters could be transported to and from the ARV from one of the participating runways.

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¹² A baltic room is a garage for equipment that leads out onto the back deck.

certain wind and wave conditions, such as in the marginal ice zone or in coastal polynyas in winter. A moonpool could allow CTD operations in practically all conditions but would require significant space to accommodate.

Inclusion of an interior midship moonpool on the ARV would come at the expense of laboratory space and/or berthing,¹³ and although considered potentially useful, did not receive widespread support at the February 2023 Community Workshop. Additionally, it is uncertain whether a moonpool of sufficient size on the aft deck could be accommodated (as has been retrofitted on the Nathaniel B. Palmer for drilling), as it may interfere with the positioning of the propulsion system.¹⁴ Concerns about deployment of CTD and UUV in difficult conditions without a moonpool appear to be mitigated in the current ARV design, which includes podded thrusters for better seakeeping, improved ability (relative to the Nathaniel B. Palmer) to maneuver in ice, better load handling on the CTD winch (including articulating arms for deployment), and active heave compensation. These capabilities suggest over-the-side operations will be possible in higher winds, sea state, and more challenging ice conditions than is currently possible on the Nathaniel B. Palmer¹⁵ (NSF, 2023d).

Several potential partners’ ships include a moonpool, including the Sir David Attenborough, the Agulhas II, the Nuyina, the Polarstern II (under construction), and a planned future Swedish icebreaker. However, partnerships could only reasonably compensate for the lack of a moonpool on USAP vessels in rare cases, like well-coordinated joint operations. The Nathaniel B. Palmer does have a small moonpool, but since it is accessed on the aft deck (making use difficult for significant operations since it takes potential van space) and is known to get clogged with ice, it has seen limited use. As other nations’ vessels are new or not yet built, it remains unproven how well their moonpools operate under various conditions—particularly in ice.

Zodiacs, Rigid Inflatable Boats, and Other Small Boats Associated with an Icebreaker

Rigid inflatable boats, zodiacs, and other small boats associated with larger vessels are Critical for studies on global heat and carbon budgets and changing ecosystems (Chapters 4, 5) and Important for studies on sea level rise (Chapter 3; Table 6-1). These small boats are often essential to the deployment and recovery of small AUVs. Access to small boats on the Nathaniel B. Palmer and Laurence M. Gould often requires descending a ladder over the side of the research vessel, which significantly limits the conditions in which small boat operations can be conducted. For example, the design of the Laurence M. Gould makes it difficult to get small boats and equipment safely off the side of the vessel, requiring a rope ladder climb that can be difficult in icy conditions, as well as a well-timed transition from the ladder to the inflatable that can be hazardous in choppy seas (Figure 6-7). Moreover, craning pallets over the side of the Laurence M. Gould into inflatable boats is challenging because of the lack of direct visibility between the crane operator and the boat being loaded with supplies. An improved system for craning equipment into inflatable boats is needed to support the science drivers outlined in this report.

The conceptual design of the ARV includes four high-quality small boats, including a large landing craft and multibeam survey boat (Glosten, 2021). The design currently allows for launching small boats and inflatable craft while at sea. The ability for some of these small boats to be launched in rough seas and to get through thicker, brash ice to land equipment and personnel on Antarctic shores is needed in order to support the science drivers. The ARV will need to be capable of launching and recovering small boats rapidly and safely to take advantage of small windows of good weather, particularly as the need for winter data increases alongside the attendant challenges of operating in difficult weather conditions.

Hull-Mounted Sensors

Hull-mounted sensors (e.g., shipboard sonar and sub-bottom profiler) are Critical for studies on sea level rise, global heat and carbon budgets, and changing ecosystems (Chapters 3–5; Table 6-1). Specifically, these sensors

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¹³ Presentation to the committee by NSF, May 2023.

¹⁴ Presentation to the committee by NSF, May 2023.

¹⁵ Presentation to the committee by NSF, May 2023.

would assist in improving mesopelagic biomass estimates (Chapter 5) and bathymetry, geology, and water mass structures of coastal and deep-sea regions around Antarctica (Chapters 3 and 4).

Acoustic waves are the most effective form of energy propagation in the ocean. Lower-frequency acoustic waves (below about 20 Hz) can propagate thousands of kilometers before their energy is absorbed by the water. The energy of higher-frequency acoustic waves (above 10 or 100 kHz) can attenuate faster, but their short wavelength enables high-resolution observations of ocean environments. These waves can also reflect from interfaces or be scattered by objects and rough surfaces in the water. With advanced signal-processing techniques, the reflected or scattered acoustic wave can be analyzed to image the underwater world. Broadband bioacoustics sonar systems (Lavery et al., 2007; Loranger et al., 2022) are critical instruments for imaging and estimating mesopelagic biomass, and Acoustic Doppler Current Profilers (ADCPs) are necessary for measuring ocean currents in different depths of water (Meijers and Klockers, 2010; Wilson et al., 1997). Wide-angle multibeam echosonar systems (Dorschel et al., 2022; NOAA, n.d.a) and sub-bottom acoustic profilers (Larter et al., 2021) are the most efficient and effective tools for mapping the seafloor and the shallow sub-bottom layering structure (Gales et al., 2014). These mapping tools are especially critical for conducting Antarctic coastal and glacial research in uncharted areas. In addition to seafloor survey, multibeam echosounders also have midwater imaging capabilities and backscattering strength measurements, enabling many other critical observations, including mapping of submerged iceberg or ice shelf fronts/faces, identification and characterization of different habitats for benthic ecosystems, localization and characterization of seeps or hydrothermal systems, and their associated midwater plumes. Besides environmental study, another important application of underwater acoustics is communication and navigation (Freitag et al., 2015; Paull et al., 2014), which is critical for operating UUVs, navigating moorings and profilers, and communicating with underwater instruments and operators.

The preliminary design of the ARV includes a number of science underway sensors, including deep- and shallow-water multibeam mapping, ADCPs from 38–300 kHz, sub-bottom profilers (3.5 kHz, chirp or parametric narrow-beam profiler), marine biology echosounder/sonars from 18 to 200 kHz, an ultrashort baseline transceiver, an acoustic release transponder (12 kHz), hydrophones, and a forward-looking camera and sonar (Antarctic Support Contractor, 2023). It is worth noting that recent development on acoustic and echosounder technology has enabled narrower beams, wider bandwidth, and larger swath coverages for high-resolution surveys and mapping. It is

Critical to include state-of-the-art echosounders to enable the best-possible environmental sensing and underwater communication capabilities.

Towed Sampling and Over-the-Side Instrumentation

Towed sampling and instrumentation (e.g., underway profiling CTD packages, nets for trawling, multichannel streamers and airgun arrays, controlled-source electromagnetics, towed magnetometers) are Critical for studies on global heat and carbon budgets and changing ecosystems (Chapters 4 and 5) and Important for studies on sea level rise (Chapter 3; Table 6-1).

This report identifies the need for interdisciplinary observations that target biogeochemical and ecosystem processes at temporal and spatial scales that reflect the underlying physical dynamics of the region. This need is particularly important for improving constraints in the carbon budget to capture processes related to air–sea exchange, vertical mixing, input of nutrients and micronutrients from glacier melt, and lateral transport and in situ biological processes in coastal zones. The most traditional method for sampling the water column in oceanography is to lower a rosette hosting a range of sensors while the ship is stationary. In coastal Southern Ocean regions, the presence of sea ice and icebergs can limit the availability of open water for deployment of the rosette or can damage sensors attached to it. In situations where the rosette can be deployed, the time between casts may be significant, creating challenges in separating spatial and temporal variability in observed properties.

The need for more frequent and closely spaced CTD casts is particularly acute in coastal regions where the scales of physical circulation tend to be smaller than in the open ocean. Boundary currents along the coast or along troughs in continental shelves may be 1–10 km in width and can vary on subdaily timescales. While autonomous vehicles such as ocean gliders can collect observations with high spatial and temporal resolution, they typically have slow speeds, which can lead to aliasing of rapidly evolving processes. Underway profiling CTD measurements are an essential capability for application, requiring rapid or continuous sampling. Approaches include continuously sampled hull-based water intake to packages or instrument platforms that are towed behind the ship. The latter may sample at uniform depths (e.g., surface arrays or net for capturing biology) or profile vertically through the water column as it is towed (e.g., Triaxus instrument). Towed ship surveys are the best way to collect snapshots of ocean properties and may also be used in combination with remote sensing data products to link surface and interior processes. As analytical technology evolves, making underway observations of both physical and biochemical properties will be possible. The ability to tow new in situ instrumentation needs to be considered, especially those designed for ice-filled seas.

The science drivers identified in this report also support the need for other towed sampling and over-the-side instrumentation, including capabilities for deep-water (greater than 1,000 m) benthic sampling using benthic trawls (e.g., otter trawl, Blake trawl), benthic/epibenthic sleds and baited traps, and midwater pelagic collections with large trawl nets, such as the Isaacs-Kidd Midwater trawl and the rectangular midwater trawl (Chapter 5). Deep trawls will require large drums to hold sufficient wire. In addition, a large back deck with direct access to the aquarium room and wet labs is necessary for biological sampling and experimentation. The deployment of controlled-source electromagnetics (Chapter 3) and active-source seismic reflection and refraction instruments, such as multichannel streamers and airgun arrays (Chapter 3), is also necessary. Multichannel streamers and airgun arrays are currently listed as Science Mission requirements for the ARV (Future USAP, 2022).

Seafloor and Submarine Sampling

Seafloor and submarine samplers (e.g., coring, drilling, dredging, seafloor and borehole observatory) are Critical for studies on sea level rise, global heat and carbon budgets, and changing ecosystems (Chapters 3–5; Table 6-1). Seafloor and submarine sampling would enable better constraints on grounding zone instabilities that may occur during warm paleoenvironments (Chapter 3); changes in ocean circulation, temperatures, productivity, sea ice cover, carbon cycle, and gas exchange (Chapter 4); and sedimentation rates, paleobiology, or active geomicrobiology in Antarctic fjords and ecosystems (Chapter 5).

Specific tools needed for seafloor sampling include long (40–50 m recovery) piston coring, which requires a substantial side A-frame and appropriate winch and wire capabilities for heavy lifts. Other needs include

(1) seafloor lander drills that enable roughly 200 m subseafloor recovery, which require a robust stern A-frame capability of at least 30 metric tons for operation to 2,500 m depth (or 40 metric tons for operation to 4,000 m depth), and (2) sufficient ship deck space for specialized launch and recovery systems, conducting cable umbilicus with a portable winch, and van- or laboratory-based support. Various shorter sediment coring devices include gravity and multicoring systems and towed seafloor dredges that can sample volcanic and other rock outcrops, as well as undisturbed collections of sediment–water interfaces. Dynamic positioning is also a critical vessel capability for seafloor sampling, as is a mechanism to protect over-the-side equipment and its wires from chafing damage due to heavy sea ice. Camera systems mounted on sampling devices, ideally with real-time imagery or video feed for detailed site selection, are desirable for some applications in which conducting cable can be used.

The preliminary design of the ARV currently supports 40–50 m piston coring, and a stern A-frame with 9 m (30 ft) of vertical clearance and strength members up to 120,000 lbs (54 metric tons) break strength (Antarctic Support Contractor, 2023). If the larger seafloor sampling equipment that requires specialized staffing and support will see intermittent use on the ARV, it would be desirable to share this equipment with other vessels, such as the equipment within the University-National Oceanographic Laboratory System (UNOLS) fleet, with common management for cost-effective, global use.

At present, long sediment coring facilities exist on some potential partner vessels (e.g., the Kronprinz Haakon and the Araon). Academic lander-based drilling with penetration over 100 m currently exists in the MeBo facility at the University of Bremen in Germany¹⁶ and is utilized on several German ships, including the icebreaker Polarstern, as well as others in the global oceans. A similar seafloor drill was recently acquired by the Geological Survey of China. Some additional lander drilling systems are in use by the offshore geotechnical industry in several countries. A ship-mounted drilling system, Shaldrill, was used in the past on the Nathaniel B. Palmer via a small moonpool on the fantail (Scientific Drilling, 2006). Lack of a similar moonpool on the ARV would likely limit seafloor drilling options to those that can be deployed over the side.

At the time of this report’s publication, NSF has decided to not renew its cooperative agreement with Texas A&M University for operations of its flagship JOIDES Resolution drilling vessel (NSF, 2023a). This could eliminate, for a time, the ability for a U.S. vessel to obtain deep drill cores around Antarctica. NSF notes the possibility of a future drillship, but some gaps in capabilities are likely to occur, underscoring the need for long-coring and lander drilling that could be deployed from the ARV. The availability of these facilities on the ARV would open new areas for study that were inaccessible from JOIDES Resolution, which is not an icebreaker.

Live Organism Experiment Capabilities

It is Critical for studies on changing ecosystems (Chapter 5; Table 6-1) that vessels be capable of accommodating experiments with live organisms. This includes modular aquarium facilities large enough to accommodate a range of tank sizes and configurations and plumbed with running seawater. Some research will also require an optional workbench in the aquarium space. The facilities require controlled seawater systems (including control of temperature, pH, and dissolved oxygen) and should provide sufficient space for specialized equipment (e.g., respirometry chambers). For experiments on organisms occupying the mesopelagic or benthic environments, where ambient seawater temperature is warmer than at the surface, seawater supplied to the aquarium room or on-deck incubators can be warmed to mimic deeper ambient temperatures. In addition, the ability to chill incoming seawater would allow researchers to continue live experiments while the ARV transits north and could be useful in the future if researchers propose to transport live animals outside of the Antarctic, as has been done by the British Antarctic Survey (BAS) and Australian Antarctic Division. If the aquarium facilities on the ARV are located immediately adjacent to the back deck, live organisms can be quickly and efficiently transported from the deck to the aquarium. In addition, many live experiments are conducted in incubators, either outdoors on deck or inside in laboratories dedicated to live organism work. Outdoor incubation experiments require adequate deck space and running seawater. Indoor incubation experiments require incubators with adjustable internal temperatures and clean laboratory space that is free from prior use of fixatives (e.g., formaldehyde).

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¹⁶ Personal communication by Tim Freudenthal, March 2023.

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¹⁷ Some historical large and technically complex projects include the Global Ocean Ecosystems Dynamics (GLOBEC) project, the U.S. Joint Global Ocean Flux Study (JGOFS), the Multidisciplinary Drifting Observatory for the Study of Arctic Climate (MOSAiC), the Research on Ocean-Atmosphere Variability and Ecosystem Response in the Ross Sea project (ROAVERRS), and the Export Processes in the Ocean from Remote Sensing (EXPORTS) field campaign by the National Aeronautics and Space Administration (NASA).

(Glosten, 2021). While the greater berthing ability of the ARV will allow multiple science projects per cruise, additional berths may lead to difficulties in scheduling unless the science teams have compatible goals and are well coordinated. Harmonizing multiple science projects per cruise can be facilitated by significant precruise planning and information exchange across the different teams (including the PIs of each project), who should meet to discuss how their respective goals can be achieved within the cruise’s time constraints. More science projects per cruise will likely result in longer cruises, which may result in science teams spending many days at sea with only a few days of dedicated ship time for their respective projects. Some investigators may not participate in prolonged cruises because of teaching or administrative responsibilities associated with their respective academic appointments.

The designed berthing ability of the ARV is consistent with the capacity of science and technical personnel on many partner vessels. The berthing capacity of other nations’ Antarctic and polar research vessels ranges from about 117 passengers and 32 crew on the Australian research supply vessel Nuyina, to the Norwegian research vessel Kronprins Haakon, which can support about 40 scientists and technical personnel and about 15 crew. Other vessels’ berthing capacities include about 100 passengers/researchers and about 45 crew aboard the South African research and supply vessel Agulhas II; about 90 crew and scientists aboard the Chinese polar research vessel Xue Long 2; about 60 scientists, researchers, and support staff capacity on the British research ship Sir David Attenborough and Korean research vessel Araon; about 53 scientists onboard the German research vessel Polarstern; and 44 scientists aboard the Swedish icebreaker Oden (Appendix B).

TOOLS AND TECHNOLOGY

To adequately address the suite of science drivers outlined in this report, platforms that can extend the spatial and temporal reach of traditional vessel-based observations and capabilities are necessary. They also provide observations in areas and locations where vessel access will not be available (either because of limited capabilities or scheduling). Over the longer term, advances in many of these tools and technologies will provide cost-effective observational access beyond the reach of what can be supported solely through a single icebreaker.

To assist NSF in the consideration of trade-offs between capabilities given budgetary constraints for investments in tools and technologies, the committee classified them as Critical or Important for advancing the report’s three science priorities (Table 6-2). Justification for these classifications are expanded in the sections below, including references back to the science priorities in Chapters 3, 4, and 5.

Uncrewed Aerial Systems

UASs (drones) are Critical for studies on global heat and carbon budgets and changing ecosystems (Chapters 4 and 5) and Important for studies on sea level rise (Chapter 3; Table 6-2). Specifically, the use of UASs would enable population-trend monitoring of key species for which there is limited knowledge (Chapter 5). UAS capabilities are also rapidly replacing crewed aircraft for remote sea ice surveys, surveillance for ice navigation, and air–sea interactions (Chapters 3 and 4). Additionally, UASs are an emerging capability for buoy and float deployment for observations of changing ocean circulation and sea ice, and ice–ocean interaction processes (Chapter 4). For example, inexpensive air-drop systems are currently available for light-duty UASs that could be used to deploy, for example, expendable ocean profilers or small drifters. For larger payloads (e.g., Argo floats), systems such as the Bell Autonomous Pod Transport UASs can deliver a 70-pound payload at ranges of tens of miles (Bellflight, 2023) in a platform compact enough to be operated from a ship. To fully realize this potential, new buoy and sensor platform capabilities will need to be developed for uncrewed deployment in or on sea ice. Very long–range UASs have the potential to support large-scale electromagnetic surveys of ice thickness and other aerogeophysical remote sensing (e.g., ice-penetrating radar, gravity, magnetics, laser altimetry) that are presently possible or practical only with fixed-wing aircraft from coastal stations. Similarly, future developments in long-range, heavy-lift UASs and sensor platforms may permit the deployment of an array of miniaturized platforms (including ice buoys and profiling floats) that can, in some cases, provide alternatives to both icebreaker and helicopter support.

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¹⁸ Rows 3 and 4 in Table 6-2.

Gliders and ASVs will support spatial observations of rapid ocean processes (e.g., mesoscale circulation or ice-edge process studies; Chapter 4).

These vehicles are rapidly evolving technologies that promise to supplement, and in some cases supplant, in situ, stationary, or drifting platform observations. However, UUV capabilities will not be able to replace most vessel-supported observations or sampling, particularly for remote locations. Rather, they represent an enhancement to a vessel’s observational capability that can enable increased spatial and temporal reach and improved observations in previously difficult-to-access areas, such as at the ice shelf front, under ice shelves, or under thick sea ice. Glider operations under sea ice for days to weeks have been demonstrated in the Arctic (Lee et al., 2022), but at present, only a few glider operations under ice have been conducted in the Antarctic. For example, gliders have made sustained, year-round observations under the Dotson Ice Shelf with acoustic navigation aids (Rainville et al., 2019). Under–ice shelf observations have also been achieved with the U.K. National Oceanography Center Autosub and the Swedish Hugin AUVs. These types of vehicles are expensive, complicated, have relatively short sampling durations, and they require dedicated technicians. Improved capabilities for long-term autonomous observations at ice shelf front (Friedrichs et al., 2022; Miles et al., 2016b) and under ice shelves (e.g., Rainville et al., 2019) are emerging, but even long-range vehicles will still require ship-based access for deployment.

Sustained AUV observations under ice in remote areas will require new long-range and long-endurance vehicles with sophisticated navigation and environment-aware mission planning. Existing technology could achieve these requirements via an acoustic localization network similar to the HAFOS network¹⁹ that was previously maintained in the Weddell Sea for under-ice floats (Boebel et al., 2005). Sustained navigation under ice over very long ranges (several thousand kilometers) are also possible with advances in terrain-aided and environment-aware navigation, and with advances in hybrid vehicles (e.g., combining efficiencies of buoyancy- and thruster-driven operation), low-power sensors, and high-capacity battery technology. These advances may enable limited ice–ocean observations over very long ranges from shore, potentially alleviating the need for icebreaker support for deployment, recovery, or both. Improvements in reducing size, cost, and power requirements of navigation aids and power-recharging networks for AUVs may facilitate more widespread and sustained observations under ice in the decades to come.

ASVs hold promise for sustained observations in ice-free Antarctic waters. Saildrones and Wave Gliders can provide autonomous observations of air–sea fluxes but have seen limited use and will face limitations in the challenging conditions of the Southern Ocean. Emerging ASV designs (e.g., the 15 m Mayflower Autonomous Ship) may have capabilities and payload capacities that far exceed those of previous ASVs and may supplant some measurements and sampling that are currently supported by crewed vessels in open-water regions. However, these are likely to be limited to monitoring-type activities and unlikely to supplant crewed vessels for process or most biological studies for the foreseeable future.

Some international partners have facilities that support large UUVs for use by individual investigators (such as the U.K. Autosub), but the United States does not have a similar facility. The National Deep Submergence Facility (NDSF), which is overseen by UNOLS, does host ROVs for this purpose, but the current NDSF fleet is not typically used in the Antarctic. However, large, specialized, state-of-the-art, under-ice ROVs have been developed and are available in the United States (Bowen et al., 2014), and smaller UUVs (gliders, AUVs, ROVs) and ASVs are becoming widely available in the United States and elsewhere. Expansion of shared instrument and equipment pools to support cost-effective and equitable access to large ROVs and AUVs with under-ice capabilities would require significant investment. However, it would also require significant investment from NSF to support individual researchers purchasing these platforms. One approach might be for the USAP to partner with other Antarctic programs through the Scientific Committee on Antarctic Research (SCAR) or the Council of Managers of National Antarctic Programs (COMNAP) to develop, maintain, and position a shared pool of resources at vessel homeports. If investments in pooled resources are considered, it is important to weigh how emerging technologies might supersede existing capabilities as autonomous vehicle capabilities are rapidly evolving.

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¹⁹ The HAFOS, or the hybrid Antarctic float observation system, is a mooring network in the Atlantic sector of the Southern Ocean.

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²⁰ Rows 5 and 6 in Table 6-2.

²¹ CORKs (Circulation Obviation Retrofit Kits) are instruments that are long-term observatories to investigate subseafloor fluid circulation. These are often linked to a long-term data logger on the seafloor, accessible with a human-occupied or remotely operated vehicle (WHOI, 2000).

²² SOCCOM is the Southern Ocean Carbon and Climate Observations and Modeling project.

small AUVs, in addition to shallow on-shelf CTDs and water sampling along the western Antarctic Peninsula. For example, small coastal research vessels have been used to deploy gliders in the Arctic (Lee et al., 2012). These capabilities will enable observations of changes in ocean circulation, Circumpolar Deep Water, and ice–ocean interactions (Chapter 4) along the western Antarctic Peninsula, and further afield as UUV capabilities continue to evolve. Such observations are essential for understanding processes driving atmospheric warming on the Peninsula and drivers of sea ice and glacial ice loss in the Bellingshausen Sea (and, with the advent of long-range UUVs, potentially into the Amundsen Sea).

The USAP does not currently operate any coastal boats of this size. Small yachts (15–25 m length, 2–4 m draft) have been operating safely in Antarctic waters for decades and have supported many successful scientific expeditions funded by organizations other than the NSF (e.g., South Orkney Islands on Damien II [Poncet and Poncet, 1985], the Antarctic Peninsula on Damien II [Poncet and Poncet, 1987], the South Sandwich Islands on Golden Fleece [see Figure 6-8] [Lynch et al., 2016], Deception Island on Pelagic Australis [Naveen et al., 2012], Grandidier Channel to Marguerite Bay on Golden Fleece [Casanovas et al., 2015], the Danger Islands on Hans Hansson [Borowicz et al., 2018], the South Sandwich Islands on Pelagic Australis [Liu et al., 2021]). While small yachts can be chartered, there is a severe shortage of vessels whose crews have the kind of experience that would be required for supporting research. Medium-sized vessels (50–75 m length, 4–6 m draft) have also proven useful in the Antarctic and can carry larger science teams while providing the agility of smaller yachts. Some global- to regional-class UNOLS vessels may be appropriate if they are available for Antarctic work (e.g., Sikuliaq), but their needs elsewhere often limit their deployment to Southern high latitudes. Greenpeace has two vessels, the Arctic Sunrise and the Esperanza, that have supported Antarctic research over the last decade (e.g., Borowicz et

al., 2020; Strycker et al., 2021; Wethington et al., 2023), although these expeditions must be mutually beneficial and are thus appropriate for a limited set of research projects. Although IAATO currently supports some research on the Antarctic Peninsula, these vessels’ schedules are entirely dictated by passenger needs, and thus researchers have no control over timing. Moreover, some kinds of research are often discouraged within view of tour ship passengers (e.g., UAS work, blood sampling, tagging), which greatly constrains the types of projects that can be supported, even if a team is able to gain access to their targeted location.

It is important to note that a small coastal vessel provides both unique capabilities and a mechanism for continuing a significant amount of the summer work typical for the western Antarctic Peninsula region once the Laurence M. Gould is retired. As such, this small coastal vessel would provide a cost-effective alternative to the use of the ARV or other much larger ships with icebreaking or endurance capabilities that are not required in the relatively ice-free Antarctic Peninsula. It is worth noting that personnel could be transported to the airstrip on King George Island via a commercial airline, which would allow the coastal vessel to remain in the Antarctic Peninsula, reducing the time spent transiting across the Drake Passage.

Remote Sensing Observations

Addressing the science priorities identified in this report will require the ability to scale findings and projections to the entire Antarctic, which is possible only with the support of satellite- and airborne-based remote sensing data. Each chapter in this report identifies several priority research questions for which these tools are Critical components (Table 6-2), including the study of ice shelf thinning and breakup processes (Chapter 3), sea ice variability (Chapter 4), variability in ocean–atmosphere–ice interactions (Chapter 4), pathways for ocean water transport over the continental shelf (Chapter 4), the impacts of global climate change on Antarctic and Southern Ocean ecosystems (Chapter 5), biotic adaptations (Chapter 5), and new species migration into the Antarctic (Chapter 5).

Over the last 4 years, two-thirds of all papers involving Antarctica in Science and Nature, regardless of the funding agency, used remote sensing imagery or imagery products (Lynch, 2023a). This underscores its critical role in high-impact Antarctic science. Satellite-based remote sensing research in Antarctica is currently supported through collaborations with other agencies (e.g., NASA) and through partnerships with commercial entities (e.g., Maxar), and is coordinated through the NSF-funded Polar Geospatial Center at the University of Minnesota (Lynch, 2023b). Although cloud cover in the Antarctic presents some difficulties for visible and infrared imagery, passive optical sensors²³ currently allow for up to 31 cm resolution imagery, and the depth (number of repeated images) and areal coverage of commercial imagery available to NSF-funded researchers is unmatched globally. In addition, passive microwave satellites have provided near-continuous observations of the Southern Ocean since 1979 (Pope et al., 2014), coverage that is valuable in quantifying Antarctic change—including aquatic and terrestrial biology and ecology, sea ice extent, and other properties—over time. The ability to task and obtain sub-meter commercial satellite imagery for the Antarctic is essential for examining scientific, logistical, and geospatial challenges; it is necessary to maintain the current licensing structure that allows access to commercial imagery for Antarctic research.

Several federal missions and sensors benefit NSF and the USAP. Passive remote sensing systems—such as NASA and the U.S. Geological Survey’s Landsat and NASA’s MODIS (Moderate Resolution Imaging Spectroradiometer) Terra and Aqua—provide important temporal observations of environmental conditions at local to regional scales in Antarctica. NASA’s ICESat-2 (Ice, Cloud and Land Elevation Satellite) provides highly precise altimetry measurements that can be used to estimate sea ice thickness, the changing height of the ice surface (e.g., melting glaciers and thinning of ice shelves), and variability in sea surface height (related to ocean circulation). NASA’s Gravity Recovery and Climate Experiment (GRACE) and GRACE FO (Follow-On) missions provide detailed data on ice mass change. Other platforms—such as the European Space Agency’s CryoSat-2, the Soil Moisture and Ocean Salinity (SMOS) mission, the planned CRISTAL (Copernicus Polar Ice and Snow Topography Altimeter) mission, and NASA’s Soil Moisture Active Passive (SMAP) mission—can

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²³ Passive sensors detect reflected or emitted radiation.

provide complementary data for glacial and sea ice thickness (CryoSat-2 and CRISTAL), and thin sea ice thickness (SMOS and SMAP). Sustained satellite altimeter observations and synthetic aperture radar (SAR), including multisensor capabilities, are required for ice characterization and drift. NISAR, a collaboration between NASA and the Indian Space Research Organization that will be launched in 2024, will be the first U.S. cocontributed SAR satellite platform since 1978, and the first SAR configured for optimal coverage of the Southern Ocean given its left-looking configuration. NISAR will provide, for the first time, high spatial and temporal resolution ice drift data over most of the entire Southern Ocean with a temporal resolution of 3 days (NASA, n.d.b). While commercial and federally funded satellite programs are currently meeting research needs for optical imagery, additional capabilities in the realm of active sensors²⁴ are required. Future NASA missions that could provide wind speeds over open ocean and air–sea fluxes are needed to extend in situ observations to the pan-Antarctic and to monitor climate change and variability in the Southern Ocean.

In situ validation data are needed to leverage global satellite-based observations to broaden temporal and spatial scales for the study of long-term change and its drivers. To date, relatively few shipboard in situ validation campaigns have been conducted in the Southern Ocean (in contrast to the Arctic), and when they have occurred, they have often relied on international partners (e.g., the Winter Weddell Gyre expedition aboard the Polarstern [Comiso et al., 1989], the Australian ARISE [Antarctic Remote Ice Sensing Experiment] expedition [Massom et al., 2006]). To best leverage the science enabled by future USAP icebreakers and emerging complementary technologies, barriers to interagency field work and essential satellite sensor validation work must be reduced.

Airborne remote sensing enables the acquisition of regional datasets via instruments that cannot be used from orbit (e.g., ice-penetrating radar sounders operating at high or very high frequencies). Airborne remote sensing also provides far higher resolution (e.g., gravity and magnetic field surveys) than satellite remote sensing and enables calibration and validation of orbital datasets (e.g., laser altimetry and ocean color). For example, repeated airborne radar surveys can be used for estimating geothermal heat flux, englacial temperature, and basal melt rates, as well as identifying subglacial hydrology (Chapter 3). While recent advances in UASs and sensor technology permit many short-range (around 10 km) remote sensing surveys with small UASs that can readily be deployed from ships, larger systems (e.g., deep-penetrating ice radars) and range requirements (e.g., ice shelf surveys) will require future developments. In the near term, airborne remote sensing will require land-based crewed aircraft support.

Fixed-Wing Aircraft and Helicopters

Fixed-wing aircraft and helicopters are not only utilized for remote sensing measurements, but also for deploying instruments and people, making the combination Critical for studies on sea level rise (Chapter 3) and Important for studies of global heat and carbon budgets and changing ecosystems (Chapters 4 and 5; Table 6-1). For example, airborne platforms are essential for repeat deployments of oceanographic profilers in areas that marine platforms struggle to access, and for deployment of autonomous land-based and ocean-bottom stations. While fixed-wing aircraft can be used to deploy expendable oceanographic sensors (e.g., Fenty et al., 2016; Yang et al., 2020) and profilers (e.g., Porter et al., 2019) along ice shelf fronts in some cases, helicopters are needed to deploy such sensors in ice shelf rifts or broken terrain (Nakayama et al., 2023; Straneo et al., 2011). Another option, in some cases, could be the use of a float-equipped fixed-wing aircraft (i.e., seaplane).

The USAP has substantial fixed-wing capacity for the acquisition of aerogeophysical data (e.g., Behrendt et al., 1994; Holt, 2001; Tinto et al., 2019). A long-standing contract with the Air National Guard provides exclusive global access to export-controlled, ski-equipped LC-130 aircraft, which have been used to establish remote field camps for smaller aircraft for conducting surveys (e.g., Holt et al., 2006). Aging aircraft and budgetary constraints have impacted projects over the last decade by decreasing total flight hours (NASEM, 2021b). This is in addition to delays in scientific projects due to poor weather and other logistical constraints, with some teams reporting month-long delays in departing McMurdo for remote camps (Hansen, 2009; Stewart, 2013). NSF is presently increasing its traverse capacity to at least partially compensate for the reduction in aviation support, most notably with the development of the South Pole Traverse, which so far has emphasized fuel delivery.

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²⁴ Active sensors send out a pulse of energy and detect the changes in the return signal (e.g., laser altimetry, lidar, radar).

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²⁵ The Philberth probe is a “surface-controlled, nonrecoverable instrumented vehicle that can penetrate polar ice sheets down to 3600 m by melting. It can be used to measure temperature, stress, ice movement, and seismic, acoustic and dielectric properties. It can also be used for other investigations with remote instrumentation” (Aamot, 1967).

²⁶ https://anibos.com/data

data transmission system were incorporated into the tags (e.g., Iridium or Starlink Swarm) as data are currently recovered using the Advanced Research and Global Observation Satellite (ARGOS) system, which has limited bandwidth and large spatial location uncertainty. Tags would also benefit from the development of smaller sensors and improved power sources.

Autonomous Land-Based and Ocean-Bottom Stations

Autonomous land-based and ocean-bottom stations for geophysical and climate monitoring will be Critical components of studies on sea level rise (Chapter 3; Table 6-2). Specifically, these stations may include land-based and ocean-bottom seismometers, land-based global navigation satellite systems, and automatic weather stations. These stations will enable research on the surface mass balance of ice sheets, the evolution and role of mélange in buttressing, glacial isostatic adjustment, and sub-ice geology. These stations may be deployed from vessels or by air. Future improvements in this instrumentation may include reduced power usage for more reliable and sustainable observations; real-time data transfer through satellite systems; and more compact designs to warrant an easier deployment that requires less logistic support.

Seawater Aquarium Facilities at Palmer and McMurdo Stations

Experimental research on the effects of multiple stressors (e.g., increased temperature, hypoxia, ocean acidification) on Antarctic organisms is a Critical component for studies on changing ecosystems (Chapter 5; Table 6-2). These experiments are complicated and require sufficient replication to be statistically sound. Depending on the size of the organisms under investigation, experimental units may need to be quite large. For example, in an experiment investigating the individual and additive effects of increased seawater temperatures (at even just two temperatures, current and near-future predicted) and ocean acidification (also at just two levels, current and near-future predicted) on Antarctic krill physiology, there would need to be four different treatment combinations. Each of these would need to be replicated at least three times, bringing the total number of experimental units to 12. If the experiment lasts for 3 months and 10 krill are removed from each tank every 2 weeks to measure one variable,

then the experimental units would need to be at least 200 liters. Twelve 200-liter tanks take up considerable space and would need to each be outfitted with plumbing connected to the seawater intake system. Further, for an experiment in which temperature is raised and pH is reduced, the facility would need to have multiple holding tanks with heating and gas bubbling systems to create the desired experimental conditions. In order for each replicated unit to be truly independent from the others, each unit would need its own seawater source, separate from the others. This is not normally feasible, but improved facilities would allow researchers to conduct replicated, more statistically sound multifactorial experiments. These sorts of experiments can only be conducted in the field in Antarctica. Palmer and McMurdo stations would be ideal locations to do such experiments as USAP vessels do not have sufficient space.

Access to Sea Ice and Ocean from McMurdo Station

There is a Critical need to improve the infrastructure that allows researchers at McMurdo Station to access the sea ice and ocean safely for studies on changing ecosystems (Chapter 5; Table 6-1). Many of the existing structures and vehicles at McMurdo Station are more than 20 years old; existing heated structures have been unusable because of changing sea ice conditions; and ice bridges used for crossing sea ice cracks are inadequate for moving the existing shelters. The light vehicles (snow machines and PistenBully snow groomers) at McMurdo Station are also at the end of their lifespan and need frequent repair. As a result, recently, much of the science carried out on the sea ice has been compromised or delayed. More importantly, these limitations have reduced the safety of sea ice operations. Some infrastructure at McMurdo Station is already being updated under a long-range investment program called the Antarctic Infrastructure Modernization for Science project (Future USAP, 2023a).

Additionally, there is no capability to operate small boats out of McMurdo Station, as there is at Palmer Station. This has significantly limited the ability of researchers to deploy UUVs and to carry out open-ocean research, except when a research vessel is present. This limitation will become increasingly problematic as the sea ice conditions deteriorate further, limiting research into McMurdo Sound. There may be an opportunity to consider developing a small boat program at McMurdo similar to that currently operating out of Palmer Station.

APPROACHES

Support of Discovery-Based and Opportunistic Science

While hypothesis-driven and use-inspired science are the gold standards by which NSF-funded scientists typically operate, discovery-driven science is an essential part of Antarctic and Southern Ocean research, given that so little is known about the continent and its ocean. Additionally, given the rapidly changing physical environment of the Antarctic, opportunities for new discoveries may arise suddenly and unexpectedly. Thus, the inclusion of discovery-driven science in scientific programs and the flexibility to change plans if sudden environmental events or sampling opportunities present themselves (e.g., the collapse of the Larsen B ice shelf in 2002) will enable impactful discoveries. Responding to rapidly changing environmental conditions may require the ability to partner with another vessel (e.g., through UNOLS, U.S. Coast Guard, international partners) at short notice. In such an event, prior agreements with prospective partners would be beneficial to aid rapid deployment. Workshops and international meetings, such as SCAR, can help identify shared research priorities that could facilitate rapid mobilization of international efforts. In addition, having a shared annual to interannual international plan to know what platforms (e.g., ships, aircraft) will be sampling a given region could help investigators coordinate opportunities (e.g., the South Ocean Observing System’s Due South portal²⁷).

Collaboration and Partnerships

There are a number of U.S. agencies that work in the Southern Ocean and Antarctica, including NSF, the National Oceanic and Atmospheric Administration (NOAA), NASA, and the U.S. Coast Guard, among others.

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²⁷ See https://www.soos.aq/activities/duesouth.

Targeted inter- and intra-agency open competitions for interdisciplinary topics (e.g., planetary science, air–sea exchange, sea level rise, long-term Earth observations, validating satellite observations) will maximize the resources and expertise of the Southern Ocean and Antarctic science community.

There are numerous intra-agency collaboration opportunities for OPP, including partnerships with the Directorate for Engineering and the divisions of Ocean Sciences, Earth Sciences, and Atmospheric and Geospace Sciences to advance scientific and technological innovation. NSF divisions and directorates have also collaborated on relevant cross-disciplinary initiatives, such as “Engineering Technologies to Advance Underwater Sciences” and “Ocean Technology and Interdisciplinary Coordination.” In addition, the new Directorate for Technology, Innovation and Partnerships (TIP) at NSF advances use-inspired research through investments that accelerate the development of key technologies and research that address pressing societal and economic challenges. There are a number of use-inspired research priorities in the Southern Ocean and Antarctic that require technological advancements to address pressing societal challenges, such as research related to sea level rise (Chapter 3), global heat and carbon budgets (Chapter 4), and ecosystem services (Chapter 5). These areas provide a natural opportunity for collaboration with TIP.

Interagency collaborations are supported by a number of standing agreements. As described in Appendix B, the U.S. Coast Guard (USCG) currently operates the Polar Star for the annual breakout of McMurdo. In 2017, the USCG estimated that the service life of the Polar Star was expected to end in 2023, based on “deteriorating conditions and parts obsolescence.” The USCG began a service-life extension program in fiscal year 2021 to extend the service life of the Polar Star until at least 2029 or 2030 (GAO, 2023). The USCG is currently designing three new heavy icebreakers, the first of which is expected to be operational by 2028 (GAO, 2023). However, the ability to conduct science operations on these platforms will be constrained due to limited berths for scientists, the limited science capabilities commonly hosted by these vessels, and priorities of search and rescue, defense and security readiness, environmental protection, and marine mobility that may not always align with U.S. researcher needs (NASEM, 2017a). NOAA also has a significant presence in the Southern Ocean and Antarctica. It operates the Antarctic Ecosystem Research Division, which constitutes the U.S. contribution to CCAMLR, as well as the Global Monitoring Laboratory, which conducts ocean and atmospheric observations on two ships in the Drake Passage, and works with the National Center for Atmospheric Research to use aircraft to measure greenhouse gases.²⁸ As for global observations, NOAA supports satellite observations through the Joint Polar Satellite System and the planned Near Earth Orbit Network collaboration with NASA.²⁹ Finally, NASA has several operating aircraft and satellite missions that are relevant to Antarctica (see Remote Sensing Observations above). All of these agencies provide natural opportunities for collaboration.

Nongovernmental Organizations

Several nongovernmental organizations are executing field research and observations in the Antarctic and Southern Ocean and may be key partners for collaboration. UNOLS operates several global-class vessels that may be useful for USAP partnerships, including the ice-capable Sikuliaq (PC5). The committee considered the utility of the three regional class research vessels (RCRVs) currently in formulation, for support of the future USAP. These RCRVs are ABS [American Bureau of Shipping] Ice Class C-0, with 21-day endurance (OSU, n.d.), which may limit their utility to the relatively ice-free waters of the Antarctic Peninsula region. However, it may be difficult for the USAP to regularly partner with these new global- and regional-class vessels given their need in their areas of service. Nevertheless, the utilization of these global- or regional-class vessels in the Antarctic would provide an important platform for which to advance the use-inspired research highlighted in this report. The Sikuliaq, specifically, would provide research continuity once the Laurence M. Gould is retired, as they have many similar capabilities (80 m vs 76 m length; 5.8 m vs. 5.5 m draft; PC5 vs. ABS A1 rating; 24 vs. 26 scientist berths, respectively). However, while the Laurence M. Gould provides 75 days endurance, the Sikuliaq only supports 45 days.

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²⁸ Presentation to the committee by Sarah Kapnick, NOAA, March 2023.

²⁹ Presentation to the committee by Timothy Walsh, NASA, March 2023.

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³⁰ Presentation to the committee by Lisa Kelly, IAATO, March 2023.

³¹ Vessels in the DNV [Net Norske Veritas] IC ice class can maintain a minimum speed of 5 knots through 0.6 m (2 ft) of ice (MAN Energy Solutions, n.d.).

³² Presentation to the committee by Leonard Pace, Schmidt Ocean Institute, March 2023.

³³ Written response from NSF to the committee, March 2023.

review, and final selection of proposals was made with the goal of developing an integrated program that focused on understanding climate-driven biophysical coupling. Workshops were held prior to the field campaign to work out logistics and further refine the integrated research plan. An integrated program is currently needed, as it would ensure that multiple projects could be coordinated to make the most of the new research vessel, which is currently designed to have berths for about 55 science and technical personnel.

Understanding the effects of climate change on Antarctic ecosystems will also require integrated programs to collect key data over time (Chapter 5). One example of this is the Palmer Long-Term Ecological Research (LTER) study area, which has already provided significant insight into how climate change is impacting the ecosystem processes of the Antarctic Peninsula (Ducklow et al., 2022). The Ross Sea is the southernmost sea in Antarctica (Smith et al., 2014) and long-term monitoring in this region would provide an important counterpoint to the Palmer LTER, located in the lower latitudes of Antarctica, which are transitioning from an Antarctic to sub-Antarctic maritime habitat (Ducklow et al., 2013).

CONCLUSIONS AND RECOMMENDATIONS

The Southern Ocean and nearshore Antarctic are remote regions that have a significant impact on the global environment and society. This report identifies several interdisciplinary scientific drivers—sea level rise, global heat and carbon budgets, and changing ecosystems—that should be prioritized. However, these topics only scratch the surface of the diversity of fundamental, use-inspired, and discovery-driven research that occurs in the Southern Ocean and nearshore Antarctic. These investments will be significant, but if planned well they will make future research in the Antarctic region more impactful and cost-effective.

Conclusion 6-1: Southern Ocean and nearshore Antarctic research provides critical quantitative and predictive data about societally and economically relevant issues, such as rising sea level, the global carbon cycle, and ecosystem services. These science drivers, and the need to develop a robust workforce, justify major investments in the U.S. Antarctic Program, including investments in its infrastructure (e.g., vessels, aircraft, satellites, stations, tools), science mission, and partnerships.

U.S. Antarctic Program Vessels

At the time of this writing, both USAP research vessels—the Nathaniel B. Palmer and the Laurence M. Gould—are approaching or have exceeded their roughly 30-year design service life. Without near-term investments in USAP vessels, the United States will be less capable than other nations of undertaking research important to national security, such as research on sea level rise. A U.S.-owned and -operated icebreaker dedicated to science is critical to advance this report’s science drivers and U.S. interests in the region.

Conclusion 6-2: The near-term prioritization of the design and construction of the Antarctic Research Vessel will support U.S. national interests in use-inspired research, including studies that will advance resilience and adaptation to global climate change and rising sea levels. This critical research would otherwise be compromised by a gap in vessel support for the Antarctic and Southern Ocean region.

Unlike the Laurence M. Gould, which is partially utilized as a logistics vessel for resupply of Palmer Station, the Antarctic Research Vessel (ARV) will be focused solely on science support and will serve a diverse research community that operates in a variety of Southern Ocean and nearshore Antarctic environments. Therefore, the ARV needs a wide range of capabilities to accommodate the requirements of research. The need for wintertime access to nearshore regions is a needed capability that cuts across the three science drivers identified in this report, and thus is a critical performance parameter for the ARV.

Guard, the Office of Naval Research, and NASA. These inter- and intra-agency partners share many of OPP’s research interests, and important scientific advances depend on linking satellite remote observations with in situ field work and state-of-the-art numerical simulations. Thus, closer engagement between these partners and OPP will help to advance knowledge.

Conclusion 6-5: Targeted inter- and intra-agency open competitions on interdisciplinary topics (e.g., planetary science, air–sea exchange, sea level rise, long-term Earth observations, validation of satellite observations) will maximize the resources and expertise of the Southern Ocean and Antarctic science community.

Where possible, the United States should prioritize investments in its own infrastructure. However, partnerships with commercial organizations, nongovernmental organizations (e.g., UNOLS), and international organizations (e.g., National Antarctic Programs) are essential for advancing research questions and addressing logistical and resource constraints. Lead agency agreements, similar to those developed for the International Thwaites Glacier Collaboration, are effective for large, interdisciplinary programs and can address gaps that are inevitable in any single organization. Calls for proposals for programs with established lead agency agreements will improve access to opportunities for early-career and other researchers who may not have existing relationships with potential partners. The codevelopment of project plans by NSF and the partner agencies will also optimize outcomes and support these new partnerships.

Recommendation 6-8: The National Science Foundation should strengthen existing and identify new strategic opportunities for lead agency agreements with countries that can help support the science priorities identified in this report. This is particularly important for those nations with year-round stations and vessel capabilities that are complementary to those of the United States.

Partnerships can also alleviate concerns around the equitable access to advanced technologies due to their expense and limited availability. Resource pools, including mid-to-large ROVs and drones with dedicated technical support, that are accessible upon submission of a successful proposal may enhance the equitable allocation of resources.

Recommendation 6-9: The National Science Foundation should explore the creation and expansion of shared instrument and equipment pools to support cost-effective and equitable access.

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