6

Preparing for the Next Heliophysics Decadal Survey

Item six in the midterm assessment committee’s charge is to “Recommend any actions that should be undertaken to prepare for the next decadal survey—for example: enabling community-based discussions of (a) science goals, (b) potential mission science targets and related implementations, and (c) the state of programmatic balance; as well as identifying the information the survey is likely to need regarding the vitality of the field.” In responding to this charge, the committee drew on discussions at several town halls, internal deliberations, and the findings and recommendations in the 2015 report The Space Science Decadal Surveys Lessons Learned and Best Practices (NASEM, 2015), The committee was also attentive to recent changes in agency responsibilities for the science behind space weather, as well as emerging science and technology topics. Included in this chapter are three recommendations calling for action to (1) support advanced planning for the next decadal survey, (2) have a demographics/diversity survey prior to the next decadal survey, and (3) ensure the next decadal survey statement of task addresses the evolving needs for science-driven strategic plans. The committee also makes nine findings in conjunction with these recommendations and an additional finding—Finding 6.10—that lists several emerging topics of interest for the next decadal survey committee to consider.

6.1 PREPARATIONS BEFORE NEXT DECADAL SURVEY

The preparation for decadal surveys has evolved since the last heliophysics decadal survey, and lessons learned from the other science divisions decadal surveys could benefit heliophysics strategic planning. First, there have been funded NASA opportunities to define mission concepts for the Planetary Science Division (PSD) and Astrophysics Division (APD) that enable them to prepare well in advance for their next decadal surveys. For example, the PSD initially formed assessment/analysis groups (AG) in 2004 in different disciplines and science areas, including groupings such as Mars and Outer Planets, to involve the community in defining and prioritizing targeted science goals and formulating strategic plans before the next planetary decadal survey. These AGs function both as standing, inclusive science forums and as resources whose ongoing activities naturally lead to decadal survey and related “road mapping” and science definition team (SDT) inputs.

In another approach—one requiring significant agency investment—the APD charged its program analysis groups to solicit community input on a small number of compelling and executable strategic mission concepts. The latter resulted in four large strategic missions—HabEX (the Habitable Exoplanet Observatory), LUVOIR (the Large Ultraviolet/Optical/Infrared Surveyor), OST (Origins Space Telescope), and Lynx—being endorsed for further study by science and technology definition teams (STDTs). These STDTs were drawn from a large cross section of the community.

An attractive characteristic of these approaches is that they enable a broader range of institutions to participate in both science definition and mission concept development. The AG approach, in particular, involves relatively low direct cost because it takes advantage of all levels of participation, from those who choose to provide science input—based on their research funded by existing missions and other sponsored programs—to NASA centers and other enterprises with internal sources of support for such purposes. The playing field can also be leveled to some degree by providing programs to fund mission concept studies, such as those recently fielded by NASA’s PSD and APD. Such funded efforts are especially important to kick-start principal investigator (PI)-led missions, which are increasing within the NASA Heliophysics Division (HPD) now that Solar-Terrestrial Probes (STP) missions along with Explorers are executed in PI-mode.

Funded mission concept studies also enable non-NASA-center participation in strategic mission studies. Such practices allow NASA to draw from a larger pool of expertise and ideas and to develop and consider strategic mission concepts in a more complete and updated context, in advance of the decadal survey process. For example, rapid progress toward an AG-like heliophysics vehicle could be attached to the widely attended SHINE, GEM, CEDAR, and AAS/SPD (American Astronomical Society/Solar Physics Division) workshops that provide a regular opportunity and open forum where sponsoring agency personnel interact in a relatively informal setting. These are already well-established venues where researchers and (active and potential) mission/project architects and planners meet in an atmosphere that both fosters science debate, definition and prioritization and creates additional paths to mission and project ideas, involvement, and leadership. The matter of funded mission concept studies could be explored through heliophysics agencies’ internal inquiries regarding the benefits and costs of these types of programs relative to present practices.

Finally, the committee notes that the solicitation of white papers from the community has always been a key feature of decadal surveys. For example, prior to its first meetings, Astro2020, the latest decadal survey for astronomy and astrophysics, issued calls for white papers in two categories: “Science” and “Activities, Projects, and State-of-the-Profession Considerations.”¹ These white papers are informing the work of the steering committee and the 12 Astro2020 science and program panels.

Finding 6.1 Community analysis group workshops and funded mission concept development for defining critical science goals and related mission concepts as employed by NASA’s PSD and APD in preparation for their decadal surveys have been productive for broader and deeper definitions of strategic mission concepts based on key science objectives and any emerging technology important for future missions. This midterm assessment committee emphasizes that the science objectives and related measurement requirements are more important to define than specific missions/facilities.

The National Science Foundation’s (NSF’s) Mid-Scale Research Infrastructure (RI) program, which began in 2018, represents an important potential resource for heliophysics research that needs to be examined in the next decadal survey. There are two classes of Mid-Scale RI projects: those costing between $6 million and $20 million, and projects costing between $20 million and $70 million. Such projects can play a very

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¹ Science and APC white papers are described on the Astro2020 community input link at National Academies of Sciences, Engineering, and Medicine, Decadal Survey on Astronomy and Astrophysics (ASTRO2020), “Community Input,” http://sites.nationalacademies.org/DEPS/Astro2020/DEPS_192906.

important role in meeting NSF research goals. However, the Mid-Scale RI program competition is NSF-wide across all science areas and is thus highly competitive and over-subscribed (Box 6.1). As in the case involving mission concepts and definition, prioritization of heliophysics Mid-Scale RI projects by the heliospheric community and by the next heliophysics decadal survey could provide critical science goals and needed justification for reference Mid-Scale RI projects for the future NSF-wide Mid-Scale RI opportunities. The ideas for new Mid-Scale RI projects could have broad appeal to other disciplines and connect to other NSF divisions. This need could also be filled within the community engagement framework suggested above.

Finding 6.2 The NSF Mid-Scale RI opportunity is highly competitive; since proposals are competed across all NSF divisions, the selection rate is expected to be low. The NSF AGS (Atmospheric and Geospace Sciences) and AST (Astronomical Sciences) divisions could improve their chance of selection within the NSF-wide Mid-Scale RI program if they strategically planned and prioritized a few key RI concepts that have broad community support.

Recommendation 6.1: NASA and NSF should implement and fund advanced planning for the next solar and space physics decadal survey that involves the community strategically in the formulation of decadal goals and stretch goals (ambitious objectives that might extend past the next decade). NASA and NSF could request the Space Studies Board’s Committee on Solar and Space Physics (SSB-CSSP) to evaluate options for implementing this planning for the next decadal survey.

Some specific ideas for this advanced planning include the following:

• NASA-supported opportunities for the heliophysics community to host assessment group workshops in order to develop strategic science challenges and goals and to define high-priority measurements for the STP and LWS (Living With a Star) programs in advance of starting the next heliophysics decadal survey, and
• NSF-supported workshops to plan strategically the next decade science challenges and goals and to identify high-priority measurements for the Mid-Scale RI and other research infrastructure concepts with the heliophysics community.

While, anecdotally, more women and minority scientists are studying heliophysics, and more nations every year are becoming involved in heliophysics research and practical space weather applications, the impact on the heliophysics workforce in general, and its diversity in particular, is not well understood. An important part of understanding and supporting those changes begins with a demographics/diversity survey

of students and early-career scientists and engineers, followed by development of action plans to positively encourage continued growth of diversity for the science and engineering communities who support the science programs, missions, and facilities of NASA, NSF, and the National Oceanic and Atmospheric Administration (NOAA). To ensure that such efforts are successful, career survey specialists should be involved, such as the American Institute of Physics who conducted the early-career survey for the AAS.

Finding 6.3 The demographics and diversity of scientists and engineers in heliophysics may have evolved significantly since the 2013 heliophysics decadal survey. A new demographics/diversity survey would clarify those changes over the past few years, and results from such a survey could enlighten planning for improving diversity in the heliophysics community.

Some members of the previous decadal survey have commented that the demographics survey for the last decadal survey came too late in the process, and thus the information was not fully analyzed and incorporated into the last decadal survey report. Furthermore, as many space scientists work in multiple disciplines and across different NASA science divisions, a demographics survey of all space science communities would benefit all of the future decadal survey activities.

Finding 6.4. The demographics survey for the last decadal survey was completed late in the study, limiting its utility. It is important that an updated demographics survey be available in advance of the initiation of the next decadal survey.

Recommendation 6.2: NASA Heliophysics Division should conduct a demographics/diversity survey before the next heliophysics decadal survey to understand how the community’s demographics have evolved and to assess whether progress has occurred in enhancing diversity in the community (see also this report’s Recommendation 5.1). Thereafter, to benefit all of the space science disciplines within NASA’s Science Mission Directorate (SMD) and to inform decadal survey planning across SMD, NASA, at the SMD-level, should conduct this demographics/diversity survey on a 5-year cadence with clear identification of science areas relevant for each science division. It is important that career survey specialists, such as the American Institute of Physics, are involved in a new survey.

6.2 CONSIDERATIONS FOR NEXT DECADAL SURVEY PROCESS

With an underlying goal to give additional focus to the decadal survey and to actively address the evolving strategic needs of the heliophysics community, the midterm assessment committee identified several topics that agency sponsors could include in the next survey’s task statement for the next decadal survey.

Distinguish Between NASA’s STP and LWS Programs

NASA’s STP program has traditionally supported missions to explore fundamental physical processes important for heliophysics, while their LWS program missions have focused on the variability of the Sun and in Earth’s environment and those aspects of heliophysics science that can have societal impacts. Both STP and LWS programs have supported the studies of interactions between the different heliophysics components. The 2013 heliophysics decadal survey made recommendations that future STP missions should all be PI-led (and lower-cost) strategic missions while the larger (and more-expensive) strategic missions should be in the LWS program.

Separation of strategic missions into the STP and LWS programs by their cost, instead of by their science focus, is not an effective long-term scenario to maintain two distinct programs, nor for planning a regular cadence for strategic missions that comparably advance the different heliophysics subdisciplines. Lessons learned from implementing the PI-led IMAP (Interstellar Mapping and Acceleration Probe) mission under STP and from implementing the Parker Solar Probe and planning the Geospace Dynamics Constellation-like mission under LWS will provide valuable guidance in defining future NASA strategic missions. Furthermore, elucidation of the overarching and unique science goals for the distinct STP and LWS programs are important as guidance for the next decadal survey studies.

Finding 6.5 The next decadal survey committee may want to consider how to best distinguish the NASA Heliophysics LWS and STP strategic mission lines, both in terms of critical science goals and implementation strategies. Without distinct goals for these two programs, there is a risk to limit effective planning for larger strategic missions.

Realistic Agency Budget Plans

Soon after the 2013 heliophysics decadal survey was released, the NASA HPD budget plan had significant decreases resulting in a flat budget instead of a rising budget with an assumed inflation rate. Consequently, the planning for the NASA Heliophysics Roadmap in 2014 was challenged by how to implement the recommendations in the 2013 decadal survey, and thus there was a slow start for NASA implementing any of the 2013 decadal survey recommendations.

Finding 6.6 To mitigate the risk of decadal survey recommendations being regarded as difficult or not possible to implement in the next decade period, each agency needs to ensure that the budget 10-year plan is as accurate, up-to-date, and complete as possible throughout the course of the survey’s work. It can benefit strategic planning if future budget scenarios included a nominal (baseline) budget and optimal (best-case) budget. The two-budget approach can allow for defining clear decision rules for reprioritizing under each scenario.

Keep Decision Rules for Large Programs/Missions

Cost growth of large programs/missions beyond the Phase C/D cost cap threatens to disrupt the progress of the overall heliophysics program and should not be accepted without careful consideration. The 2013 decadal survey (its Chapter 6) recommended specific trigger points that NASA should implement to maintain the program balance through the decade. The decadal survey went on to emphasize that these trigger points should initiate a review by NASA, in which the expected outcome would be actions by NASA to preserve the large program in question and also maintain balanced progress through the decade. These decision rules put programs on notice that they are to remain within their budgets and, at the same time, do not overly constrain NASA’s ability to execute the most cost effective and scientifically rewarding overall program possible within the budget constraints.

Finding 6.7 The next decadal survey could benefit by having decision rules for large programs/missions as was done in the 2013 heliophysics decadal survey.

Developing New Technology for Long Term Stretch Goals

Discussion of stretch goals (longer-term vision than a decade) could well identify science questions and related future observations that could fall outside the next decadal period. In areas where technology is the limiting factor in making progress, the next decadal survey committee could identify technology developments important for the next decade. One example of that scenario in the previous heliophysics decadal survey is the need to develop solar sail propulsion technology to support an Interstellar Probe mission to the outer limits of the heliosphere and for a Solar Polar Imager mission to fly over the solar poles (e.g., 2013 decadal survey sections 10.5.2.8 and B.4.2.1). NASA Marshall Space Flight Center has developed solar sails with industry partners during the last few years, and they were recently selected for a technology demonstration of their solar sails for the 2018 IMAP rideshare opportunity. Furthermore, the Johns Hopkins University Applied Physics Laboratory has recently crafted a mission concept for the Interstellar Probe. The other selection for Phase A study for this IMAP technology demonstration rideshare is a NASA Goddard Space Flight Center small satellite with optical communication to significantly increase deep space data rates.

The solar sail and optical communication are just two examples of enabling technology that could be considered for future missions in the next decade. Another example (mentioned in both the inaugural and most recent decadal survey) would be the practical implementation of a large constellation concept for magnetospheric studies. Similarly, a sequence of satellites to address long-term science goals, such as understanding the 11-year solar activity cycle, may be important for some stretch goals that cannot be implemented with the historical planning of stand-alone, single-satellite missions.

Finding 6.8 For next decadal survey discussions about stretch-goal science objectives and related missions, it will be important to identify what technologies are required for those stretch-goal missions and to consider actions that could develop such technology in the next decade.

NOAA Engagement in Next Decadal Survey

For a variety of reasons, the 2013 heliophysics decadal survey was unable to provide actionable plans to integrate NOAA plans for space weather research and applications with the strategic plans for NASA and NSF.² The National Space Weather Action Plan (NSWAP) has been recently updated in 2019 and details many aspects of integrated plans and coordination across many agencies. As discussed in the NSWAP, NOAA is the key civil agency for space weather operations. Thus it is imperative that the next decadal survey engage with NOAA in developing its space weather plans.

Finding 6.9 It is critically important for future planning of space weather applications to have NOAA better integrated into the space weather–related strategic plans for the next decade.

Recommendation 6.3: NASA, NSF, and NOAA, the anticipated principal sponsors of the next solar and space physics decadal survey, should work together to develop an integrated statement of task that reflects the research and application needs for each agency and across the federal government. To address the evolving needs for science-driven strategic plans, the agency sponsors should ensure the following items are included as tasks for the next decadal survey committee:

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² It should be noted that NOAA did not participate formally in the development of the task statement for the survey. In contrast to the inaugural 2003 decadal survey in solar and space physics, the budget process in place at the initiation of the most recent decadal did not permit NOAA to be a financial sponsors.

• Definition of distinct science goals and implementation strategies for NASA’s Solar Terrestrial Probe and Living With a Star programs,
• Evaluation of strategic plans with nominal (baseline) budget and optimal (best-case) budget,
• Inclusion of decision rules for guiding implementation of recommendations, and
• Identification of enabling technology needed in the coming decade to support longer-term stretch goals.

6.3 EMERGING TOPICS OF INTEREST FOR THE NEXT DECADAL SURVEY

There are many aspects of identifying and prioritizing science goals and related observations and modeling efforts for developing a decadal survey with the scientific community. One aspect is learning from the previous decadal surveys and identifying any missing or new topics of interest for the next decadal survey. From this midterm assessment, several key topics arose in the committee discussions that have not been discussed much in the previous chapters. These topics of interest for future strategic studies are briefly discussed below and then summarized in Finding 6.10.

In response to the decadal survey, NASA brought the Explorers program back to the level where it was a decade ago. NASA issued an AO (Announcement of Opportunity) for Small Explorer (SMEX) missions in 2016 and an AO for Medium-Class Explorer (MIDEX) missions in 2019. Thus, NASA has achieved the decadal survey-requested 2- to 3-year cadence for the Explorers program opportunities. For the 2016 SMEX AO, NASA selected five missions for Phase A study and down-selected in July 2019 to two missions for flight development. The NASA HPD director stated that selecting multiple missions under the same Explorers AO was in response to comments from the community, who conveyed that preparing and reviewing mission proposals is an expensive and time-consuming process. By the time of the next decadal survey, the effectiveness and consequences, both good and bad, of selecting multiple missions from fewer AOs may be evident. The next decadal survey committee could consider a trade study on the effectiveness and consequences of selecting more missions per AO versus higher cadence for the SMEX/MIDEX AOs.

The Heliosphere System Observatory (HSO) is an ensemble of operating strategic and Explorers-class missions for the NASA HPD, and the combination of these missions has proven valuable for system-level and cross-disciplinary advances in understanding heliophysics. The concept for the HSO can easily be expanded to encompass the NSF ground-based facilities that support heliophysics research. The small-satellite missions (with mass less than 100 kg) were used more for technology demonstration than for science when the previous decadal survey study was executed. The recent rapid growth of technology that supports CubeSats has now enabled a new generation of small-satellite missions doing science research, such as the Miniature X-ray Solar Spectrometer CubeSat that flew successfully in 2016-2017 as the first science CubeSat for the NASA HPD. With 18 NASA Heliophysics CubeSat missions, with 6 already launched and another 12 being launched in the next few years, the HSO can further be expanded to include this small-satellite class of missions. Furthermore, the reliability of the CubeSat technology has progressed to the point that CubeSat missions could be considered for extended missions as part of the senior review process. The concept of the HSO could be expanded beyond NASA’s strategic and Explorers-class missions to include NSF’s ground-based facilities and the upcoming fleet of heliophysics small-satellite science missions to further enhance the scientific exploration involving multiple disciplines and for advancing the understanding of fundamental processes throughout the heliosphere.

HSO is currently a constellation of 18 spacecraft that make a wide range of measurements throughout the heliosphere. The HSO has only three missions now in their prime mission phase: Parker Solar Probe, GOLD (Global-scale Observations of the Limb and Disk), and SET-1 (Space Environment Testbeds). The rest are in extended mission, and several are well beyond their originally intended lifetime. This aging fleet

with mostly extended-mission satellites continues to make system-science advances. For example, measurements of the solar wind at 1 AU from the 22-year old Advanced Composition Explorer spacecraft enable long-term studies of the 11-year activity cycle, and continued measurements from the 42-year old Voyager spacecraft reveal new results about the structures of the local interstellar medium beyond the heliosphere.

While individual missions in the HSO have stand-alone science objectives, the community increasingly relies on the HSO for system-level science. Therefore, one of the elements of the decadal survey plan could be how to maintain and augment the HSO for such system-level science endeavors. In particular, there could be modifications to the overall strategic plan should one or more elements of the HSO no longer be available. Additionally, NASA research proposal evaluations could consider how the research proposed can enhance the HSO at a system-level and support cross-disciplinary research. HSO is a critical asset for addressing key solar and space physics science objectives, one that must be sustained and further developed. Coordination between NSF and NASA is needed to ensure that ground- and space-based assets are integrated into a balanced heliospheric systems observatory.

The 2013 decadal survey recognized the importance of space weather research for the nation. Since that decadal survey, NASA’s role in space weather has continued to be essential, as evidenced in the 2015 NSWAP and ongoing activities of the Space Weather Operations, Research, and Mitigation Working Group. In decadal survey recommendation A2.5, the decadal survey called for distinct funding lines for basic space physics research and for space weather applications, additionally recommending that forecasting that should be developed and maintained, including at NASA. Funding lines for space weather science are currently being formulated within NASA and NSF. For example, NASA is starting up their Space Weather Science and Applications (SWxSA) program. As pointed out by the Office of Inspector General audit of NASA’s Heliophysics Portfolio (OIG, 2019), NASA HPD has 19 of its assigned NSWAP tasks still to complete due in part to space weather physics/modeling complexity, unrealistic deadlines in the NSWAP, and lack of other agency partners’ action. This topic is also discussed in this report’s Chapter 4. Further evaluation of enhancing the science of space weather within NASA and NSF is expected to improve the integrated approach for space weather research and applications as specified in the NSWAP (NSTC, 2015; 2019).

As related to one of the DRIVE Integrate recommendations, there has been some progress during this decade to improve multi-agency coordination for space- and ground-based observations. Considering the new plans from the National Space Weather Strategy and Action Plan (NSWSAP) about expanding space weather research, NASA, NSF, and the next decadal survey committee could consider ways to maximize scientific returns through improved coordination of space weather research with satellite and ground-based facility observations of multiple agencies and also with international collaborations. For example, and as discussed in this report’s Chapter 3, NASA could invest in ground-based measurements that support its missions, and NSF ground-based facilities could better support NASA suborbital campaigns and international missions, such as Solar Orbiter. One concept from this midterm assessment committee is that the NASA HSO could be more fully exploited if it was extended to include coordination with NSF observatories. The next decadal survey committee could identify enhanced approaches and new opportunities to improve the multi-agency and international coordination of heliophysics research and space weather applications.

The heliophysics focus on “Living With a Star,” taken literally, should embrace the rapidly expanding knowledge (and need for heliophysics knowledge) within the areas of exoplanetary and planetary research. Planetary science research seeks to understand the role space weather and solar activity over time have played in planetary evolution and habitability, as in the case of the investigations related to Mars climate change (e.g., Jakosky et al., 2018), Venus climate change (Kumar et al., 1984), and the role of an intrinsic planetary magnetic field. Exoplanet research also relies on heliophysics for interpreting what is remotely sensed, ranging from distinctions between starspots and planets (e.g., Rackham et al., 2018), to planetary transits showing indications of stellar wind erosion of atmospheres (e.g., Spake et al., 2018; Bourrier et

al., 2018), to hydrogen walls suggesting the presence of astrospheres and stellar winds (e.g., Wood et al., 2014), and to speculating on causes and consequences of observed superflares (e.g., Howard et al., 2018; Nostu et al., 2019).

In the meantime, the topic of our own star’s long-term history, which is critical to understanding our own habitable zone planets, has made little progress since the post-Apollo era of lunar sample analysis other than through limited studies of Sun-like stars. Cross-fertilization is essential to the progress of what has become one of the major strategic themes of NASA science; exoplanets research is likely to dominate its visibility to the public in the imminent era of the James Webb Space Telescope and the search for evidence of extra-Earth and extra-solar system life. The NExSS (Nexus for Exoplanet System Science) Program, functioning as a virtual institute within NASA’s SMD, incorporates some of these valuable interdisciplinary interactions but only as an organization of research projects previously selected and funded within the separate division core programs. A NASA SMD cross-divisional research and analysis program in which heliophysics could play a central role, where work now only touched upon in the context of NExSS, could become a targeted and long-standing competed element managed by NASA HPD.

NSF solar, heliospheric, and space weather (SHSW) science is currently distributed between two directorates (Mathematical and Physical Sciences and Geosciences) and in two divisions (AST and AGS). This is not optimum. Not only does it hamper strategic planning, requiring responsiveness to two decadal surveys, it complicates coordination between NSF and other agencies such as NASA. Moreover, important elements of the scientific portfolio—e.g., the outer heliosphere—fall between the cracks. The idea of consolidating SHSW science into a single NSF division under one directorate was explored some years ago. Reconsideration of plans to consolidate all elements relevant to solar, heliospheric, and space weather physics under a single division within NSF is timely and necessary given the changing landscape in which new NSF assets like DKIST (Daniel K. Inouye Solar Telescope) and the Expanded Owens Valley Solar Array are coming online, additional SHSW assets are under consideration for development, the NSWSAP is a significant national priority, and continuing integration and optimization of the HSO is a key community objective. Ground-based solar, heliospheric, and space weather science could be better supported within a new, consolidated division under a single directorate at NSF.

NSF funding for Management, Operations and Data Analysis continues to be a challenge for new and currently operating NSF ground-based research facilities. Creative solutions may exist involving inter- and intra-agency collaborations, technological innovations, and partnerships with the commercial sector. For example, multi-purpose facilities can have cost benefits through sharing of logistics, power systems, telemetry, data handling, and data centers by multiple programs (e.g., heliophysics and Earth sciences). For such an approach, data and meta-data standards and guidelines are important to establish. NSF with the involvement of the heliophysics community could explore these and other creative solutions for improving the operations of their ground-based observatories before the next decadal survey.

The quality assurance expectations for NASA small missions with costs less than $150 million have recently been redefined for the new tailored Class D option (Lightfoot, 2014; Zurbuchen, 2017). This transition to tailored Class D appears to be evolving slowly within NASA centers and thus may be an on-going topic to be evaluated for the next heliophysics decadal survey. Recent history shows that the Interface Region Imaging Spectrograph SMEX ($150 million cost cap) was developed as a Class D mission, and the Ionospheric Connection Explorer ($200 million cost cap) as a Class C mission, and the near future SMEX ($150 million cost cap) and MIDEX ($250 million cost cap) missions are planned to be developed as Class D and Class C missions, respectively. Considering the cost of inflation over a decade and limited cost-cap values for NASA Explorers missions, the midterm assessment committee envisions the possibility for reduction of Explorers mission class requirements to enable high-impact exploratory missions at lower cost and with reasonably acceptable risks. Instead of cost as the driver for determining mission classifi-

cation, Hartman and Bordi (2016), for example, propose a four-part classification scheme based on the measurement difficulty, flexibility of requirements, design lifetime, and budget “rigidity” (the ability to make additional funding available at various stages of development). Heliophysics SALMON (Stand Alone Missions of Opportunities Notice), SMEX, and MIDEX missions could benefit greatly from such a classification scheme. These missions often use existing measurement capabilities, have very flexible requirements (e.g., no launch date constraints), are typically designed for a relatively short prime mission of 2 years or less, and often carry ample cost reserves well beyond the needs for missions with no technology development. Re-defining the classification based on these four criteria would reduce the classification of all types of missions and eliminate the issue of cost inflation going forward into the next decade. The next decadal survey may want to distinguish and clarify for the future Explorers and SALMON missions a consistent implementation plan for Tailored Class D, Class D, and Class C projects. The next survey may also want to consider the arguments that cost should not be the driver for mission classification.

As discussed more in this report’s Chapter 5, there is a growing concern that research topics have evolved to be more complex and more cross-disciplinary but that the typical research grant funding level has had only modest growth. Anecdotally, there appear to be more scientists, especially early-career scientists, who are leaving heliophysics research due to funding concerns for low-selection rates, low-level funding, and because of the long delays between proposal submission and availability of funding. Established in response to a recommendation from the inaugural decadal survey in heliophysics, the NSF Faculty Development in Space Science (FDSS) program was intended to establish a greater university base for the community; however, its outcomes have yet to be formally assessed. In response, NASA, NSF, and the next decadal survey committee could identify viable, different structural solutions to better support the heliophysics research grant programs, with particular emphasis on early-career scientists and soft-money scientists (i.e., those who are not professors or government employees). In addition, an assessment of the outcomes of the FDSS program could be conducted.

As also discussed in this report’s Chapter 3, the next decadal survey needs to consider how emergent technology and new data analysis techniques could help transform heliophysics in the next decade. A partial list of emergent analysis tools and techniques include data mining, statistics, machine learning, data visualization, high-performance computing (e.g., parallel computing), cloud computing, and collecting, curating, and cleaning high-volume, high-variety, and high-velocity data (Geiger et al., 2018). It is important that funding agencies encourage and sponsor the solar and space physics community to develop a modern data infrastructure and workflow.

These emerging topics for the next decadal survey are summarized in Finding 6.10. They are not in priority order nor an exhaustive list of topics for the next decadal survey.

Finding 6.10 The next heliophysics decadal survey committee could consider the following important topics:

• Trade study on SMEX/MIDEX AO cadence versus number of missions selected per AO;
• Expansion of the HSO concept to include NSF’s ground-based facilities and many upcoming small-satellite science missions;
• Identifying critical measurements in the current NASA and NSF facilities for future system-science plans and how to continue such observational capabilities;
• Better integrated approach for including the science of space weather within NASA and NSF to improve space weather predictability;
• Engaging NOAA in developing space weather research and applications for the next decadal survey;

• Improving the multi-agency and international coordination of heliophysics research and space weather applications;
• NASA cross-divisional opportunities for exoplanetary-planetary, astrospheric-heliospheric, solar-stellar, and atmosphere-Earth science research and development of a prioritized strategy for implementing such cross-disciplinary research;
• Consolidation of ground-based solar, heliospheric, and space weather science could be better supported within a new division under a single directorate at NSF;
• NSF improving and broadening its structure for heliophysics research (e.g., outer heliosphere and planetary science elements are currently missing);
• NSF improving the cost effectiveness of the operations of their many ground-based observatories, such as by sharing data analysis tools and data centers;
• Evaluating the mission class requirements for NASA’s Explorer program;
• Identifying viable structural solutions to better support the heliophysics research grant programs, with particular emphasis on early-career scientists and soft-money scientists (those who are not professors or government employees); and
• Better inclusion of emerging computer, data, and cloud technology and practices.

Heliophysics is a relatively new science area that has grown significantly during the space era and will continue to evolve as more space technology is deployed, as humans explore beyond the protection of Earth’s environment, and as we strive to better understand the habitability of exoplanets. This current decadal interval has seen significant progress for heliophysics studies, and there is much anticipation for further progress as we fully realize the decadal survey goals for heliophysics research and space weather applications.

6.4 REFERENCES

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