Currently, the next planetary science decadal survey is planned to begin in late 2019. The plan is to have a statement of task from the National Aeronautics and Space Administration (NASA) by the end of that year, announce a chair by March 2020, and begin meetings by spring-summer 2020. The goal is to deliver the final report by spring 2022. NASA, the National Academies of Sciences, Engineering, and Medicine, and the planetary science community will all have to prepare for the next decadal survey, often in collaboration with each other. Some of this preparation, such as meetings of the various planetary analysis groups (AGs) is already under way.
The National Academies Committee on Astrobiology and Planetary Science (CAPS) has been designated by the NASA PSD “keeper of the decadal survey” and will be involved in shaping the statement of task prior to the start of the study.
There are many subjects that CAPS and NASA will have to consider as they prepare for the next decadal, including the following:
- Changes in civil space policy between now and the decadal survey, including such issues as the Lunar Orbital Platform-Gateway, the Commercial Lunar Payload Services request for proposals, and the development of commercial spaceflight capabilities.
- How to structure the decadal survey panels:
- By planetary body—for example, the past decadal survey’s panels “inner planets,” “Mars,” “gas giants,” “satellites,” and “primitive bodies” (comets, asteroids, and Kuiper belt objects); or
- By topical areas such as “the search for life,” “solar system formation,” and so on.
- How the community may respond to science that comes out after the decadal survey is released.
- New mission studies prior to (or even during) the decadal survey.
- The creation of new program lines, such as an Ocean Worlds program line.
- The emergence of small and cube satellites.
- How cost and schedule have affected implementation of the decadal survey.
- The role of planetary protection.
- The role of the virtual institutes.
When the last decadal survey started, NASA was pursuing the Constellation program to return humans to the Moon. By the time Vision and Voyages (NRC, 2011) was released, Constellation had been canceled and the human spaceflight program had been shifted toward the objective of sending humans to Mars, with a nearer-term goal of sending humans to an asteroid. Soon thereafter, the goals of the human spaceflight program were focused on the Asteroid Redirect Mission. By 2018 NASA was focusing on sending humans to the vicinity of the Moon and the possibility of using commercially developed landers to land on the lunar surface. These changes in the goals of the human spaceflight program—which is not guided by a decadal survey—serve to highlight the value of the decadal process in providing stability and clarity to the planetary science program.
In addition, there have been significant developments in nongovernment spaceflight such as the emergence of new launch providers and private initiatives to explore beyond low Earth orbit. Many of these new actors remain unproven, and their impact on the planetary science program is therefore hard to determine. The next decadal survey will have to consider how to plan for the consequences of commercial and human spaceflight on the ability to do planetary science, on the Moon and on Mars. This will raise difficult questions such as how to take advantage of newly emerging capabilities, as well as how to prioritize science versus the interests of other stakeholders. This is a long-term planning issue for planetary scientists, filled with both opportunities and disadvantages. Can science exploration and human activities coexist? This will raise questions such as how to take advantage of newly emerging capabilities, as well as how to prioritize science versus the interests of other stakeholders.
Vision and Voyages was released in March 2011 and covered the period of 2013-2022. Scientific discoveries and policy changes were occurring even before the implementation of the decadal survey. This experience demonstrates that, in the future, opportunities may present themselves that were not considered in the last decadal survey. These can take the form of new programmatic objectives (e.g., Europa lander), new technological capabilities (CubeSats and other SmallSats, new instrument capabilities), or scientific developments and discoveries (e.g., ocean worlds, exoplanet discoveries).
The challenge for those conducting the next decadal survey is to find methods of both taking advantage of new opportunities while not abandoning the carefully laid-out plans and strategies from the decadal.
The committee concluded that there is a middle ground in which NASA and the science community would give thoughtful consideration to potential deviations from the decadal plan. New opportunities should be considered, but will need to be consistent with the general philosophy and approach of the decadal survey. Appropriate input from the science community should be solicited and incorporated into the decision process, including on the scientific value of possible deviations as well as the priorities relative to the previously established directions.
CAPS underwent a change in its charter starting in 2017 that enabled it to write letter reports—without recommendations—provided that the subject matter was consistent with issues raised in the decadal survey. This has been an important development for the community. The first CAPS report, Getting Ready for the Next Planetary Science Decadal Survey (NASEM, 2017a), was produced in 2017. Its next report, reviewing the Planetary Science Division’s (PSD’s) plans for the lunar and exploration initiative and determining if NASA’s plans are consistent with Vision and Voyages and other National Academies reports, was in process as this report went to review. Consulting CAPS can serve as an effective method to evaluate the consistency of NASA and other plans with the decadal survey. (See Figure 6.1.)
Getting Ready for the Next Planetary Science Decadal Survey reviewed studies of possible future large strategic (flagship)-class and New Frontiers-class missions that have been completed in the years since Vision and Voyages. The report also identified a list of priority areas that are candidates for large- or medium-class mission studies. Several of the concepts address new, high-priority science findings since Vision and Voyages. To maintain programmatic balance between different classes of missions, these new concepts—summarized below—warrant study to determine their science value per dollar and technical and cost feasibility as New Frontiers-class missions:
- Additional Venus concepts beyond Venera-D. High-priority new science that could be addressed include tessera composition and whether an ocean persisted late into Venus’s history.
- A Lunar Geophysical Network was recommended by Vision and Voyages for inclusion in New Frontiers 5. The concept can be revisited to consider incorporation of new approaches from InSight.
- A Lunar Polar Volatiles Mission to determine the nature of volatiles trapped in permanently shadowed polar regions remains a high science priority. Although the concept presents technical challenges, a reexamination of innovative technical approaches to such a mission is warranted.
- A medium-class Mars Rover would be much smaller than the Mars Science Laboratory (MSL) or Mars 2020. The rover would conduct in situ studies of deposits formed in habitable environments not sampled by Mars 2020, complementing and providing context for the more detailed results possible from Mars Sample Return. (See Figure 6.2.)
- A Mars Volatiles Orbiter would be a descoped version of the Next Mars Orbiter concept studies by NEX SAG, which addressed high-priority new Mars science involving recurrent slope lineae (RSL), shallow excess ground ice, and modern dynamical processes including volatile cycling.
- A Ceres Lander would conduct in situ investigations of Ceres’s composition, geology, and geophysics to determine whether it records a past ocean or extant liquid water environment. (See Figure 6.3.)
- An Io Observer was recommended by Vision and Voyages for inclusion in New Frontiers 5. The concept can be revisited to consider how best to address new results and incorporate innovative technical approaches.
- A Kuiper-Belt Mission beyond New Horizons would take the next steps in exploration of the Kuiper belt. Possible mission concepts include a New Horizons-like flyby of a different large Kuiper belt objects (KBOs) than Pluto and at least one smaller KBO, to assess KBO diversity; or a detailed rendezvous study of the Pluto system or Triton to study one or more KBOs in depth.
- A Dedicated Telescope for Solar System Science would conduct detailed studies of dynamical processes on numerous solar system objects that are now precluded by demands for observing time in large telescopes and at wavelengths inaccessible from the ground. Objectives would include Io volcanism, Titan weather, active processes at Europa and Enceladus, and characterization of outer planet satellites and KBOs.
The next decadal survey will develop a new list of New Frontiers mission candidates that will likely include many of the missions previously included in prior decadal surveys. The addition of two to three of these new concepts to the New Frontiers list by the next decadal survey could replenish the list of candidate missions after selection of New Frontiers 4; identify new directions for large missions; and provide intermediate-term new, high-priority Mars science before the long-term objective of Mars Sample Return is completed.
Finding: Even though the actual implementation of a large strategic (flagship) or New Frontiers mission may differ substantially from a mission concept, a concept study has value for the decadal survey. It enables science objectives to be defined, the overall mission scope (i.e., whether it is a large strategic (flagship)-class or a New Frontiers-class mission) to be determined, and the community to begin preparing for the next funding opportunities.
Recommendation: NASA should sponsor 8 to 10 mission concept studies based on the list produced by the Committee on Astrobiology and Planetary Sciences, prioritized with input from the assessment and analysis groups, prior to the next decadal survey. Mission concept studies for large strategic (flagship)class missions should include options as described in the 2017 report Powering Science: NASA’s Large Strategic Science Missions (NASEM, 2017b).
1 At the time this report was being written, NASA was beginning a Ceres mission study.
Since the release of Vision and Voyages, the topic of Ocean Worlds has grown in importance/popularity/significance, owing to advances at Enceladus and Titan by the Cassini mission, along with Hubble Space Telescope (HST) observations of possible plume activity at Europa. (See Chapter 2.) The 2016 Congressional Commerce, Justice, Science, and Related Agencies Appropriations Bill directed NASA to create an Ocean Worlds Exploration Program, using a mix of programs already funded within NASA. The direction for this program was to seek out and discover extant life in habitable worlds in the solar system “using a mix of Discovery, New Frontiers and large strategic (flagship)-class missions consistent with the recommendations of current and future Planetary decadal surveys.”
Community-based efforts (e.g., the Outer Planets Assessment Group [OPAG]’s Roadmaps to Ocean Worlds group) are under way to define the goals and objectives and potential mission strategies and technologies needs of an Ocean Worlds Program. Results of these efforts will be fed into the next decadal survey. One possibility could be the creation of a new Ocean Worlds program line. The experience of the Mars Exploration Program could provide useful guidance.
The PSD has developed its own effort to enable small satellite concepts and continues to work with the Space Technology Mission Directorate (STMD) to leverage its efforts as well. Technology and subsystem developments within NASA centers and industry are moving toward increasingly more capable small platforms—SmallSats (<500 kg) and CubeSats that have potential for deployment as secondary or “rideshare” payloads on launches beyond low Earth orbit.
As discussed in Chapter 4, NASA has taken meaningful steps to begin to understand the potential for this scale of platform to address specific, limited, but useful planetary science objectives in the form of the Small Innovative Missions for Planetary Exploration program. The PSD has invested $6 million over 1 year on 19 awards for concept studies for Planetary Science Deep Space SmallSats (PSDS3) to scope the science capability and cost of small secondary missions. The awarded studies include concepts focused on Venus, the Moon, small bodies, Mars, and icy bodies and outer planets.
Finding: Aside from requirements derived from the competitively selected SIMPLEx and PSDS3 mission concepts, there is not a clear pathway for prioritizing development of the key CubeSat and SmallSat technologies and planetary deployment and operational architectures that would enable operations beyond the Earth-Moon environment. These include, but are not limited to, destination delivery approaches, propulsion, telecommunications, and deployable elements to provide power generation or instrument aperture.
Recommendation: In preparation for the next decadal survey, NASA should consider priorities and pathways for advancing the state of the art of CubeSats and SmallSat technology, and how science-driven planetary small mission concepts that leverage emerging capabilities are identified and possibly implemented for flight.
The committee notes that by the time of the next decadal survey, NASA will have some experience with planetary science SmallSats such as the MARCO spacecraft that were launched along with InSight to Mars. (See Figures 6.4 and 6.5.)
The objective of the cost and technical evaluation (CATE) process is to perform a cost and technical risk analysis for a set of concepts that may have a broad range of maturity, and to ensure that the analysis is consistent, fair, and informed by historical data. Typically, concepts evaluated via the CATE process are early in their
life cycles, and therefore are likely to undergo significant subsequent design changes. Historically, such changes have resulted in cost growth. Therefore, a robust process is required that fairly treats a concept of low maturity relative to one that has undergone several iterations and review. CATEs take into account several components of risk assessment. Because the CATE is best suited to the comparative evaluation of a family of pre-phase A concepts, it was the methodology used in the planetary decadal survey and is best suited to the early phase analysis of strategic missions.
The CATE process was successfully used in the Vision and Voyages decadal survey. The decadal survey’s top two large strategic (flagship) missions, the Mars Astrobiology Explorer-Cacher (MAX-C) and the Jupiter Europa Orbiter (JEO), had independent cost estimates prepared using the CATE process, and the resulting estimates showed that both missions were too expensive as proposed. As a result the decadal survey recommended that both missions be rescoped. NASA revised the missions to fit within these boundaries, and now both are approved and in development.
The 2017 National Academies report Powering Science—NASA’s Large Strategic Science Missions (NASEM, 2017a), included recommendations on how to adjust the CATE process to provide for a range of cost and science
levels for large strategic (i.e., flagship) missions. These recommendations were heavily based on the experience with the MAX-C and JEO concepts in Vision and Voyages, as well as NASA’s efforts to follow the descoping options in the decadal survey. The committee believes that this can be a useful lesson for the next decadal survey. (See Figure 6.6.)
A National Academies study was under way at the time of this report to recommend improvements to the planetary protection policy process. The international consensus planetary protection policy maintained by COSPAR is designed to promote rather than impede the exploration of the solar system. These policies are motivated by the twin rationales of preserving extraterrestrial environments for future scientific studies and the protection of Earth’s biosphere from the unlikely, but not irrefutable, hazards posed by the introduction of alien organisms.
The implementation of planetary protection policies can complicate and add expense to the design and construction of spacecraft and their instruments and, in certain cases, impose operational restrictions on their intended use. In order to be effective, planetary protection regulations have to be formulated using the most up-to-date understanding of the relevant scientific and engineering issues, and these policies must be reviewed and updated regularly. The next decadal survey will have the results of the upcoming National Academies study on planetary protection and NASA’s response to it.
Vision and Voyages devoted relatively little attention to the two NASA virtual institutes: the NASA Astrobiology Institute (NAI) and the Solar System Exploration Research Virtual Institute (SSERVI, formerly the NASA Lunar Science Institute). The committee determined that the breakdown of NAI investment as a percentage of overall research and analysis (R&A) spending (from keyword analysis) is:
- FY 2011: 10 percent
- FY 2012: 12 percent
- FY 2013: 10 percent
- FY 2014: 8 percent
- FY 2015: 8 percent
- FY 2016: 9 percent
This demonstrates that the NAI alone represents a significant proportion of planetary R&A spending.
The National Academies last conducted a review of the NAI in 2008 (Assessment of the NASA Astrobiology Institute, NRC, 2008), prior to the start of the decadal survey. The National Academies has not conducted a review of SSERVI. An independent review of the role and performance of both NAI and SSERVI prior to the next decadal survey could be of value to that study.
Recommendation: A formal assessment by NASA of how well the program structure and funding of the virtual institutes are aligned with the Planetary Science Division’s science goals should be conducted on a regular basis, appropriately phased to the cycle of decadal surveys and midterm reviews.
Such a review could include (but not be limited to) an assessment of administration costs, the effectiveness of the institute in terms of publications, the difficulty of individual principal investigators to get into the institutes (where many are funded as teams), and issues of diversity among institute teams.
In addition, the committee notes that there have been substantial developments in communications and computer technology, such as the emergence of “cloud computing.” These are impacting many areas of science, including planetary science. The committee concluded that the next decadal survey should devote specific attention to them.
Recommendation: The next decadal survey committee should assess NASA’s ability to respond to new needs for data archiving and interoperability from spacecraft, laboratories, and publications.
There are likely to be many further science discoveries in the years before and during the next decadal survey. For example, the New Horizons spacecraft will fly past a KBO on January 1, 2019 (see Figure 6.7). These new discoveries will shape the decadal survey, but both the community and NASA have much to do to prepare.
NASEM (National Academies of Sciences, Engineering, and Medicine). 2017a. Report Series: Committee on Astrobiology and Planetary Science: Getting Ready for the Next Planetary Science Decadal Survey. The National Academies Press, Washington, DC.
NASEM. 2017b. Powering Science: NASA’s Large Strategic Science Missions. The National Academies Press, Washington, DC.
NRC (National Research Council). 2008. Assessment of the NASA Astrobiology Institute. The National Academies Press. Washington, DC.
NRC. 2011. Vision and Voyages for Planetary Science in the Decade 2013-2022. The National Academies Press. Washington, DC.