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Airborne Platforms to Advance NASA Earth System Science Priorities: Assessing the Future Need for a Large Aircraft (2021)

Chapter: 6 Recommendations for the Future Need of a Large Aircraft

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Suggested Citation:"6 Recommendations for the Future Need of a Large Aircraft." National Academies of Sciences, Engineering, and Medicine. 2021. Airborne Platforms to Advance NASA Earth System Science Priorities: Assessing the Future Need for a Large Aircraft. Washington, DC: The National Academies Press. doi: 10.17226/26079.
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6

Recommendations for the Future Need of a Large Aircraft

The NASA DC-8 has served as a critical and unique component of the integrated observing system for Earth system science for the past three decades. As the largest Earth system science research aircraft in the fleets of the U.S. government or other countries, it has provided a combination of capabilities found only in a large aircraft, including long duration, heavy lift, multiple ports, and cruising ability at all altitudes from Earth’s planetary boundary layer (PBL) up to about 12 km, that is unmatched by other aircraft. The DC-8 has served several vital roles: providing crucial observations for Earth system science during more than 140 campaigns, serving as a testbed for satellite instrument development and means for satellite instrument calibration, and promoting NASA’s mission through public outreach and workforce training and development. It has also been able to meet unanticipated evolving needs in different areas of Earth system science because of its unique combination of capabilities and its fundamental flexibility.

Several characteristics and combinations of characteristics of the DC-8 have driven and will continue to drive the need for a large aircraft. The ability to reach remote locations, such as Antarctica and the southern oceans, is one. Others are the need for multiple, simultaneous, co-located measurements in the atmosphere. The need derives from the temporal and spatial variability that exists over a wide range of scales for atmospheric processes and parameters. Only with multiple measurements co-located on the same moving platform can key atmospheric processes be adequately explored, diagnosed, and verified. This requirement can be met in some instances using multiple smaller aircraft if the needed instrument and operator payload can be accommodated. For some ecological change research, the requirements of simultaneity and co-location can be less stringent because the phenomena of interest typically change over hours or more; requirements for surface dynamics, sea-level rise, and water and energy cycles, where the change extends to days or longer, are also less stringent. Even in cases of more rapid changes (e.g., flooding, earthquake damage), the reference point for any change is a geographic location rather than a moving air parcel; hence, several smaller aircraft may be sufficient to measure the change, even flown hours to days apart. This distinction between the need for large and small aircraft generally tracks with the historical usage of the DC-8. The field of atmospheric chemistry has used the DC-8 most consistently, with extensive use also for remote sensing of the cryosphere and solid Earth when its unique capabilities were needed.

Looking to the future, airborne observations will remain essential to the integrated Earth system science research strategy by facilitating the understanding of Earth system

Suggested Citation:"6 Recommendations for the Future Need of a Large Aircraft." National Academies of Sciences, Engineering, and Medicine. 2021. Airborne Platforms to Advance NASA Earth System Science Priorities: Assessing the Future Need for a Large Aircraft. Washington, DC: The National Academies Press. doi: 10.17226/26079.
×

processes, connecting surface and satellite observations, and informing models. Within the U.S. airborne fleet that supports this research system, a large aircraft will remain particularly well suited to address NASA’s Earth system science needs as identified in the 2017 Earth Science and Applications from Space Decadal Survey (ESAS), to facilitate continued advancement in a number of disciplinary and interdisciplinary areas in NASA’s Earth system science portfolio, and to train future generations of scientists.

Recommendation 1: NASA should acquire, maintain, and operate a large aircraft as part of its aircraft fleet in order to address priority questions developed for the 2017 Earth Science and Applications from Space Decadal Survey and to support satellite calibration and validation, computer model testing, instrument development, and workforce training and development.

Across the priority science areas discussed in this report, most have identified ESAS questions that could be best addressed using a large aircraft that has the unique combination of long duration, heavy lift, multiple ports, and cruising ability at all altitudes from Earth’s PBL up to about 12 km. The committee found a large aircraft to be critical for increasingly interdisciplinary Earth system science research, atmospheric science research, innovative approaches for multi-instrument remote sensing, engaging and developing the next generation of Earth system scientists, and providing capacity to respond quickly to unexpected environmental events.

Answering questions requiring observations of rapidly changing weather conditions with co-located in situ and remote sensing instrumentation is better accomplished with a large aircraft. For atmospheric chemistry, two smaller aircraft flying in formation with minimal separation cannot be considered an alternative when large, multiple instrumented payloads are required. Most airborne atmospheric chemistry research requires the capabilities of a large aircraft.

Without a large aircraft, the potential is diminished for innovative approaches to integrated and interdisciplinary research for ecosystem change—land and ocean; surface dynamics, geological hazards, and disasters; and sea level rise in a changing climate and coastal impacts. There is envisioned potential use of a large aircraft to address some key questions in these research areas, especially those that are interdisciplinary, require multisensor measurements, and occur in remote regions. Earth system science is becoming increasingly interdisciplinary, as explored in the ESAS integrating themes, and the committee found potential for a large aircraft to support the advancement of questions that will foster expanded and new investigation across fields. As questions and collaborations emerge, a large aircraft will provide important flexibility to accommodate new approaches and needs to collect novel combinations of measurements simultaneously.

Suggested Citation:"6 Recommendations for the Future Need of a Large Aircraft." National Academies of Sciences, Engineering, and Medicine. 2021. Airborne Platforms to Advance NASA Earth System Science Priorities: Assessing the Future Need for a Large Aircraft. Washington, DC: The National Academies Press. doi: 10.17226/26079.
×

For instrument development, some new instrument concepts for eventual space-based instruments will be able to take advantage of current state-of-the-art technologies and can be flown on smaller aircraft, but likely not all. Some will likely be large, heavy, more conservatively designed, and operated by people on board as well as requiring a large amount of power, thus requiring a large aircraft as a testbed, similar to Airborne Synthetic Aperture Radar when its technology was state of the art. A large aircraft is essential for testing some future measurement concepts, whether they be multisensor or new discoveries. Having a large aircraft available fosters such innovative thinking, just as it has done for comprehensive airborne studies of global atmospheric composition, such as the Atmospheric Tomography Mission. Also, there is a need for new instrument prototypes to be operated on the same airborne platform as the legacy instruments they are replacing so that their performance can be evaluated. A large platform is necessary to accomplish both of these needs.

The need for a large aircraft for calibration and testing of space-based observations for atmospheric sensing satellites will continue to grow. First, long-range, total-troposphere capability of a large aircraft is needed for vertical profiling underneath satellite overpasses and over surface-based calibration and validation facilities for a wide range of locations and weather. Second, only a large platform can enable the simultaneous measurements of atmospheric composition and state variables necessary to connect the more limited spaceborne observations to the chemical transport and climate models that are used to relate the observations to the atmospheric science problems being addressed. Third, the advances in spaceborne atmospheric observations for atmospheric composition, state, and spatial resolution will require airborne observations of even more atmospheric constituents and state variables that these new satellites will be able to retrieve.

Finally, a large aircraft is an effective facility for attracting, training, and developing a diverse workforce, as discussed further in Recommendation 5.

Recommendation 2: To meet NASA objectives, a new large aircraft must have characteristics that are comparable to or better than those of the DC-8 in terms of payload capacity, altitude and distance ranges, instrument sampling port versatility, instrument integration, and durability.

The DC-8’s unique combination of characteristics has made it especially valuable for Earth system science research, as discussed in Chapter 3. Addressing future Earth system science needs requires a large aircraft that matches or improves on the DC-8’s capabilities, as discussed in the individual sections of Chapter 4. Based on past experiences and a vision for future airborne research, the committee here provides a list of essential characteristics and desired minimum values of some characteristics that a new large aircraft should have. However, the characteristic values are not meant to be prescriptive but rather to be guidance for selecting a new large aircraft. As discussed in

Suggested Citation:"6 Recommendations for the Future Need of a Large Aircraft." National Academies of Sciences, Engineering, and Medicine. 2021. Airborne Platforms to Advance NASA Earth System Science Priorities: Assessing the Future Need for a Large Aircraft. Washington, DC: The National Academies Press. doi: 10.17226/26079.
×

Chapter 3, the committee recognizes that optimizing combined performance specifications of a new large aircraft involves performance trade-offs. However, the combination of these characteristics is essential.

Instrument payload weight of 13,600 kg (30,000 lb) or more. Current comprehensive payloads on the DC-8 to meet research goals already sometimes exceed the weight capacity, and, even with decreasing instrument weights, payloads to meet the goals of some science areas with growing suites of instrumentation and increasingly interdisciplinary research in the future are likely to require similar or greater weight capacities.

Flight duration of on the order of 12 hours, depending on payload, altitude, and weather conditions. Such an extended duration is required to reach and survey remote regions, such as Antarctica, or to observe processes, such as large-scale weather patterns, that evolve on the timescale of a day.

Range of 10,000 km (5,400 nmi) or larger. This range allows researchers to reach and survey remote regions or to observe phenomena developing on a 1,000-km scale.

Altitude ceiling of at least 12.5 km (41,000 ft). This range is required to sample the upper troposphere and the lower stratosphere at least in the northern mid-latitudes and polar regions, to provide in situ vertical profiles to test satellite column measurements of atmospheric composition, or to allow remote sensing surface observations over larger swaths. (Note: a ceiling of 15 km [49,000 ft] to reach the upper troposphere and the transition layer into lower stratosphere in the tropics would be even better but not at the expense of payload weight and volume and in-flight seating for researchers.)

Extensive vertical profiling capability, with the ability to cruise at altitudes from the PBL to the altitude ceiling. This capability is essential for performing observations, including those on level flight legs, of important atmospheric composition and weather at all levels of the troposphere, especially in the PBL, or for enabling remote sensing of Earth’s surface with different resolutions and area coverage.

Precision autopiloting. This precise flying is needed to measure minute changes in surfaces and their properties by repeated observations over days to weeks, or to provide in situ observations useful for satellite testing.

In-flight seating for about 42 or more researchers in addition to crew. Going well into the future, there will be a need to accommodate the investigators operating the many instruments that are essential in current payloads and will likely be important for potential increasingly interdisciplinary payloads in the future. Having seating capacity also aids workforce recruitment, training, and development goals.

In-flight satellite communication links to operations on the ground. These communication links are necessary to optimize flight observation strategies by providing two-way information exchange between the aircraft and science operations centers on

Suggested Citation:"6 Recommendations for the Future Need of a Large Aircraft." National Academies of Sciences, Engineering, and Medicine. 2021. Airborne Platforms to Advance NASA Earth System Science Priorities: Assessing the Future Need for a Large Aircraft. Washington, DC: The National Academies Press. doi: 10.17226/26079.
×

the ground and to enable broader participation in mission flights by observers on the ground.

Instrument payload integration and operation flexibility such as multiple diverse sample and access ports along the fuselage sides as well as the top and the bottom, external inlet mounting, multiple underwing pylons that sample unperturbed flow, a cargo bay, and ample power availability of about 80 kVA. This flexibility is required to accommodate current suites of multiple mission-critical instruments, both remote sensing and in situ, with their diverse aircraft location and sampling needs, and to allow for future instruments and their optimal sampling strategies.

Durability, allowing for minimal maintenance downtime, for operations in adverse weather conditions, and for flying series of frequent and sometimes back-to-back flights. Durability is essential to minimize the cancellation of scheduled time-sensitive missions due to unscheduled maintenance; to enable observations in regions with challenging weather conditions, such as flights from high-latitude airports; to sample the many processes and events that occur over several days; to do surveys over large regions efficiently; and to observe infrequent events that occur with little warning during a mission.

This list covers many of the important characteristics that a new large aircraft should have, as identified by the committee, but it is not exhaustive. The new large aircraft should match or improve upon the DC-8 for those characteristics deemed important for accomplishing future Earth system science research goals including those that may not be on this list.

Recommendation 3: NASA should continue operating a diverse array of airborne platforms in addition to a large aircraft, as part of the broader government, university, and commercial fleet, in order to meet the evolving airborne needs for advancing Earth system science research.

A new large aircraft is a necessary member of the NASA fleet but is only one key contributor to the diverse array of airborne platforms that is needed to address the variety of Earth system science objectives as prioritized in ESAS. Aircraft with diverse specifications of payload, range, altitude, onboard pilot, and operational flexibility form a complementary fleet that can meet a wide range of mission objectives. As airborne research evolves and gaps in airborne capability are identified, such as a storm-penetrating aircraft for atmospheric convection research, the composition of the entire fleet will likely evolve to meet those needs when feasible.

A large aircraft like the current DC-8 is an essential component of such a diverse fleet for much of atmospheric chemistry, composition, and weather research, as well as future interdisciplinary research. Smaller airborne platforms enable critical measurements to

Suggested Citation:"6 Recommendations for the Future Need of a Large Aircraft." National Academies of Sciences, Engineering, and Medicine. 2021. Airborne Platforms to Advance NASA Earth System Science Priorities: Assessing the Future Need for a Large Aircraft. Washington, DC: The National Academies Press. doi: 10.17226/26079.
×

answer ESAS questions in all six of the science areas in this report, and they address interdisciplinary research needs. As instrumentation continues its evolution toward being smaller, lighter, and more energy efficient, remote sensing of Earth’s surface has gravitated to smaller platforms. A smaller platform can be chosen with characteristics that optimize the measurements of a single or a few instruments, whether it is to fly slowly at low altitude to increase remote sensing resolution or at high altitude to increase spatial coverage. Other characteristics, such as pointing stability and accuracy in repeat overpasses, can also be achieved with smaller aircraft. However, all of these different measurement requirements can only be met by access to a fleet of aircraft that have diverse characteristics and capabilities.

In addition to piloted aircraft, a diverse array of small uncrewed airborne systems (UAS) are already being deployed routinely for a variety of Earth system science studies, including observations of the water and energy cycles, ecological system changes, Arctic ice, and volcanic fuming. Although current flight restrictions limit UAS use, particularly over land, their use is likely to expand as UAS and instrument technologies advance on several fronts: more sophisticated adaptive and automated flight control; greater UAS payload capacity; smaller, lighter, more power efficient, and more automated instrumentation; and a growing diversity of designs to meet specific needs. However, even in swarms, their capability will complement, not replace, piloted aircraft.

Finally, large helium-filled balloons will likely remain the only way to sample the middle stratosphere in situ for the near future and thus continue to be an important NASA capability for Earth system science research. In addition, steerable large helium-filled balloons may become useful for niche surface and atmospheric observations once the technology is further developed and the balloon payload capacity better matches instrument size, weight, and power needed for Earth system science research. However, while there are some promising developments in high-altitude, long-duration UAS and in steerable balloons, these technologies may not advance quickly enough to contribute significantly to Earth system science research within the next decade.

Often NASA contributes its platforms to collaborative efforts that include airborne platforms from other U.S. agencies, other countries, universities, and private organizations. The cross-organization collaborative efforts will become even more essential as Earth system science questions become more interdisciplinary and more complex. NASA’s unique large aircraft capability will play an essential and enabling role in many of these complex, interdisciplinary efforts.

Recommendation 4: NASA should continue to solicit large aircraft requests that span the breadth of NASA Earth system science, especially encouraging those for interdisciplinary science across the interfaces of Earth system components with integrated multi-instrument payloads and novel strategies for remote sensing and in situ observations.

Suggested Citation:"6 Recommendations for the Future Need of a Large Aircraft." National Academies of Sciences, Engineering, and Medicine. 2021. Airborne Platforms to Advance NASA Earth System Science Priorities: Assessing the Future Need for a Large Aircraft. Washington, DC: The National Academies Press. doi: 10.17226/26079.
×

High-impact weather, climate, and geophysical extreme events are usually the results of complex interactions of various processes either within or among different components of the Earth system and they have large impacts on society, as highlighted by the ESAS integrating themes. The inherent complexity of the Earth system, emerging questions resulting from a foundation of disciplinary knowledge, and rapid Earth system changes being observed today are highlighting the need for growth in interdisciplinary research to meet societal needs. The committee found that primary ESAS questions in all science areas link to those in other areas, indicating that the need for a large aircraft to carry multi-instrument payloads and air-deployable devices including UAS is likely to grow.

In addition, it is possible to imagine benefits of using multiple remote sensing surface measurements from a single large aircraft for research in ecosystem change, coastal impacts, surface dynamics, and geological hazards and disasters. Currently, airborne remote sensing of Earth’s surface is accomplished using aircraft smaller than the DC-8 for several reasons: with the miniaturization of remote sensing instruments, a large payload is not needed; incompatible observing requirements for some combinations of remote sensing instruments on a large aircraft have made a combined payload undesireable; the DC-8’s large operating costs exceed available budgets; large, multi-investigator projects in some science areas, such as ecosystems, have not needed the DC-8 during the past 15 years; and the perception that the DC-8 would not be available impeded requests. Scientists will invest time in thinking of innovative strategies involving many measurements from a large aircraft only if they perceive it to be available to them.

By proactively seeking proposals involving innovative approaches for using a large aircraft to accomplish interdisciplinary research and surface remote sensing research, in addition to new disciplinary research, NASA will increase the impact that a large airborne aircraft can have on achieving its Earth system science research goals.

Recommendation 5: NASA is encouraged to build on the training and outreach opportunities it has established using the DC-8 and use a future large aircraft to expand its efforts to attract, develop, and train the next-generation workforce, with particular emphasis on diversity, equity, and inclusion, to foster capacity to conduct international Earth system science research, and to inform the public.

A large aircraft is an important facility for attracting, training, and developing a diverse workforce because it provides the space to accommodate many passengers beyond the core scientists and crew needed to carry out the mission.

Attracting young people starts with making them aware of and excited about Earth system science and research opportunities. Taking reporters on research flights and holding public open houses with tours of the aircraft during missions help to generate public knowledge and interest and to get some young children interested in science,

Suggested Citation:"6 Recommendations for the Future Need of a Large Aircraft." National Academies of Sciences, Engineering, and Medicine. 2021. Airborne Platforms to Advance NASA Earth System Science Priorities: Assessing the Future Need for a Large Aircraft. Washington, DC: The National Academies Press. doi: 10.17226/26079.
×

technology, engineering, and mathematics (STEM). For undergraduates already studying STEM, programs such as the Student Airborne Research Program or the High Altitude Student Platform engage them in NASA airborne science, encouraging them to pursue careers in Earth system science.

Training graduate students and postdocs on airborne field missions provides them with in-depth knowledge about aspects of Earth system science and associated technical skills, along with other career lessons and benefits. Graduate students and postdocs work closely with each other and more senior scientists as integral members of a team, thus gaining experience and recognition. Missions using large aircraft are particularly effective in this training by exposing early career scientists to the process of in-flight decision making and including them in the onboard discussions of real-time observations from multiple instruments that provide the scientific basis for in-flight decisions.

Creating a more diverse workforce starts with attracting members of underrepresented groups to STEM in K-12 and undergraduate programs and then training and retaining them as they launch their careers. Retention in STEM requires creating equity, inclusion, and a true sense of belonging. While several methods are being implemented by NASA and other organizations to accomplish these goals, some of these methods apply specifically to airborne fieldwork. These methods include training field program participants to adhere to an inclusive code of conduct, enabling participation in fieldwork that is balanced with demands at home, and adjusting approaches to addressing diversity, equity, and inclusion based on information gained from tracking outcomes and creating accountability to meet diversity goals.

Recommendation 6: NASA is encouraged to continue building on its use of the large aircraft capacity to enable scientists with next-generation measurement concepts, especially early career scientists, to become active participants in Earth system science research, even beyond airborne science research.

Future advancement of NASA airborne Earth system science research depends on new measurement strategies, new instrumentation, and a continual emergence of early career scientists to make measurements and eventually take over field study leadership roles currently held by more senior scientists. A way to ensure the continuity of new talent and their measurement ideas is to continue to provide opportunities for early career scientists to participate in NASA airborne science. Large aircraft have been an effective mechanism in NASA airborne science for fostering this mentoring because there is often enough capacity to include some unproven new instruments and inexperienced early career scientists while also having the suite of more proven instruments and scientists to accomplish the airborne field study Earth system science goals. As these early career scientists gain more experience in airborne science, including them in the writing of airborne field study proposals and giving them

Suggested Citation:"6 Recommendations for the Future Need of a Large Aircraft." National Academies of Sciences, Engineering, and Medicine. 2021. Airborne Platforms to Advance NASA Earth System Science Priorities: Assessing the Future Need for a Large Aircraft. Washington, DC: The National Academies Press. doi: 10.17226/26079.
×

opportunities to plan flights and serve as flight mission scientists provides the mentorship they need to emerge as leaders in future Earth system science research, including NASA airborne science research. Acquiring a large airborne platform as the DC-8 is retired is an essential part of these efforts.

Suggested Citation:"6 Recommendations for the Future Need of a Large Aircraft." National Academies of Sciences, Engineering, and Medicine. 2021. Airborne Platforms to Advance NASA Earth System Science Priorities: Assessing the Future Need for a Large Aircraft. Washington, DC: The National Academies Press. doi: 10.17226/26079.
×

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Suggested Citation:"6 Recommendations for the Future Need of a Large Aircraft." National Academies of Sciences, Engineering, and Medicine. 2021. Airborne Platforms to Advance NASA Earth System Science Priorities: Assessing the Future Need for a Large Aircraft. Washington, DC: The National Academies Press. doi: 10.17226/26079.
×
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Suggested Citation:"6 Recommendations for the Future Need of a Large Aircraft." National Academies of Sciences, Engineering, and Medicine. 2021. Airborne Platforms to Advance NASA Earth System Science Priorities: Assessing the Future Need for a Large Aircraft. Washington, DC: The National Academies Press. doi: 10.17226/26079.
×
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Suggested Citation:"6 Recommendations for the Future Need of a Large Aircraft." National Academies of Sciences, Engineering, and Medicine. 2021. Airborne Platforms to Advance NASA Earth System Science Priorities: Assessing the Future Need for a Large Aircraft. Washington, DC: The National Academies Press. doi: 10.17226/26079.
×
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Suggested Citation:"6 Recommendations for the Future Need of a Large Aircraft." National Academies of Sciences, Engineering, and Medicine. 2021. Airborne Platforms to Advance NASA Earth System Science Priorities: Assessing the Future Need for a Large Aircraft. Washington, DC: The National Academies Press. doi: 10.17226/26079.
×
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Suggested Citation:"6 Recommendations for the Future Need of a Large Aircraft." National Academies of Sciences, Engineering, and Medicine. 2021. Airborne Platforms to Advance NASA Earth System Science Priorities: Assessing the Future Need for a Large Aircraft. Washington, DC: The National Academies Press. doi: 10.17226/26079.
×
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Suggested Citation:"6 Recommendations for the Future Need of a Large Aircraft." National Academies of Sciences, Engineering, and Medicine. 2021. Airborne Platforms to Advance NASA Earth System Science Priorities: Assessing the Future Need for a Large Aircraft. Washington, DC: The National Academies Press. doi: 10.17226/26079.
×
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Suggested Citation:"6 Recommendations for the Future Need of a Large Aircraft." National Academies of Sciences, Engineering, and Medicine. 2021. Airborne Platforms to Advance NASA Earth System Science Priorities: Assessing the Future Need for a Large Aircraft. Washington, DC: The National Academies Press. doi: 10.17226/26079.
×
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Suggested Citation:"6 Recommendations for the Future Need of a Large Aircraft." National Academies of Sciences, Engineering, and Medicine. 2021. Airborne Platforms to Advance NASA Earth System Science Priorities: Assessing the Future Need for a Large Aircraft. Washington, DC: The National Academies Press. doi: 10.17226/26079.
×
Page 144
Suggested Citation:"6 Recommendations for the Future Need of a Large Aircraft." National Academies of Sciences, Engineering, and Medicine. 2021. Airborne Platforms to Advance NASA Earth System Science Priorities: Assessing the Future Need for a Large Aircraft. Washington, DC: The National Academies Press. doi: 10.17226/26079.
×
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Suggested Citation:"6 Recommendations for the Future Need of a Large Aircraft." National Academies of Sciences, Engineering, and Medicine. 2021. Airborne Platforms to Advance NASA Earth System Science Priorities: Assessing the Future Need for a Large Aircraft. Washington, DC: The National Academies Press. doi: 10.17226/26079.
×
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The National Aeronautics and Space Administration (NASA) and other U.S. science research agencies operate a fleet of research aircraft and other airborne platforms that offer diverse capabilities. To inform NASA's future investments in airborne platforms, this study examines whether a large aircraft that would replace the current NASA DC-8 is needed to address Earth system science questions, and the role of other airborne platforms for achieving future Earth system science research goals.

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