3

Assessment of Current Progress vis-à-vis Vision and Voyages and Guidance for the Rest of the Decade

This chapter assesses the degree to which the National Aeronautics and Space Administration’s (NASA’s) current planetary science program addresses the strategies, goals, and priorities outlined in Vision and Voyages and other relevant National Research Council (NRC) and National Academies of Sciences, Engineering, and Medicine reports, and assesses NASA’s progress toward realizing these strategies, goals, and priorities and effectiveness in maintaining programmatic balance.

This chapter recommends actions that could be taken to optimize the science value of the planetary science program, and provides guidance about implementation of the decadal survey’s recommended mission portfolio and decision rules for the remaining years of the current decadal survey.

In this assessment, the committee was instructed not to revisit or redefine the scientific priorities or mission recommendations from the decadal survey. However, the committee includes guidance on how to take into account emergent discoveries since the decadal survey in the context of current and forecasted resources available to it.

CADENCE AND BUDGET CONSIDERATIONS

The NASA Planetary Science Division (PSD) manages a portfolio consisting of missions, research and analysis (R&A), technology investments for future missions and analysis, infrastructure to support technology, laboratory work, fieldwork (part of R&A), ground-based telescopes, and management efforts. Vision and Voyages made specific recommendations on how best to balance that portfolio to maintain a vibrant research and development community, which in turn serves NASA. These recommendations were based on the budget given at the time, but also made clear how to respond to budget decreases as well as increases. Specifically, “If cuts to the program are necessary, the first approach should be descoping or delaying large strategic (flagship) missions. Changes to the New Frontiers or Discovery programs should be considered only if adjustments to large strategic missions cannot solve the problem. And high priority should be placed on preserving funding for research and analysis programs and for technology development.” Although Vision and Voyages did not explicitly state this, delaying large strategic missions may be counter to the purpose and detrimental unless it is applied before the mission enters formulation, because money expenditures increase dramatically once formulation starts. The impact of budget changes can actually in the aggregate not only affect the large strategic missions severely, but also disrupt the whole portfolio in a major way. Large strategic missions can have enormous impacts on the overall program, and must be initiated and managed with extreme prudence.

Decadal Findings: The PSD budget was assumed by the decadal survey in 2011 to include technology and R&A wedges as foundational activities, with commitments—existing programs and overhead—given to the survey committee by NASA. MAX-C (Mars Astrobiology Exploration-Cacher) was the highest-priority large strategic (flagship) mission and the Jupiter Europa Orbiter (JEO) was included in the assumed budget if the cost could be reduced and PSD budgets increased.

Assessment: The current view of the budget is shown in Figure 3.1, generated by this committee. The budget projection from 2013 to 2022 is roughly in line with what Vision and Voyages projected in 2011. This equates to $17.1 billion currently as projected versus $17.6 billion assumed during the decadal survey. While there is a slightly reduced budget relative to what the decadal survey assumed occurred during the first half of the decade, NASA initiated both Mars 2020 (reduced scope MAX-C) and Europa Clipper (reduced scope JEO). Although Mars 2020 is behind schedule relative to a descoped MAX-C as envisioned in Vision and Voyages, implementation of the “focused and rapid” architecture could result in Earth return of the samples on or ahead of the envisioned schedule when Vision and Voyages was written.

R&A PROGRAMS AND TECHNOLOGY INVESTMENT

Vision and Voyages recommended an increase to the R&A budget “as multiple small grants” to “increase the number of ideas funded for planetary research and analysis.” In particular, Vision and Voyages recommended that NASA increase the research and analysis budget for planetary science by 5 percent above the total finally approved FY 2011 expenditures in the first year of the coming decade, and increase the budget by 1.5 percent above the inflation level for each successive year of the decade.

In 2017 the National Academies produced the report Review of the Restructured Research and Analysis Programs of NASA’s Planetary Science Division (NASEM, 2017). That report did not address funding levels, only whether the new structure mapped all the research.

So that the committee could assess NASA’s response to the survey’s recommendations, Planetary Science Division Director Jim Green on two occasions presented to the committee on the levels of spending by the PSD

on R&A, technology, and infrastructure. These presentations were not granular enough to assess the Vision and Voyages recommendations, so the committee worked with analysts within the PSD to develop a more rigorous analysis. This analysis was conducted using keyword searches within funded contracts and grants.

The most detailed analysis year is for FY 2016, where the PSD has complete keyword assignment and program knowledge. The methodology and keyword definition was based on this year to fully illustrate the results of the keyword search and breakout process. Analysts chose multiple keywords for infrastructure and technology, both from a database and from talking with program managers, who may choose their own keywords. For any grant that has multiple keywords assigned, the amount awarded was apportioned equally among the keywords, so this analysis represents an overall aggregate rather than an accurate accounting within each grant. The funding by R&A, technology, and technology support and infrastructure, FY 2011-2016, is broken out in Table 3.1 based on data from NASA. Because programs have come and gone over the decade, some programs (such as Lunar Quest) that were phased out before FY 2016 contain only the bottom-line number rather than a fuller breakout, although even in these cases the split between technology, infrastructure, and R&A was done by keyword.¹

A similar keyword analysis was then used to reach the overall research spending across the R&A portfolios. (See Table 3.2.) The majority of activities in this category are competed grant activities, or “small” grants to the research community through calls like NASA Research Opportunities in Space and Earth Sciences (ROSES). This category also includes the NASA Astrobiology Institute (NAI) (but not the Solar System Exploration Research Virtual Institute [SSERVI]). NASA PSD facilities such as the Ames Vertical Gun Range (AVGR), Reflectance Lab (RELAB), the Glenn Extreme Environments Rig at Glenn Research Center, the Aeolian Facility at Ames, and support to the Lunar and Planetary Institute (LPI) are considered infrastructure and their funding is not counted in R&A in this report.² Similarly, other infrastructure investments like the Deep Space Network (DSN) and Planetary Data System (PDS) are not counted under R&A spending.

Because R&A and technology efforts are spread across the PSD portfolios and funding lines, accurate spending numbers do not come from single program lines or Work Breakdown Structure (WBS) codes. The keyword search does a more accurate (although still not perfect) accounting. For example, some awards made through the PICASSO and MatISSE programs actually drew funding from the Icy Satellites Surface Technology portfolio. These awards were still considered competed R&A, but were paid out of a different Work Breakdown Structure. Another consideration is that research that is conducted as part of a competed mission—that is, by funded co-investigators on a mission team—is not included in this analysis; however, competed participating scientist programs are counted under R&A. Similarly, technology developed by individual missions is not counted in the technology total, but technology development funded by program offices in service of directed missions is counted (for example, the Mars Helicopter development).

The actual spending for R&A and technology as compared to the Vision and Voyages recommendations is shown in Table 3.3 and Figure 3.2.

R&A spending levels have risen 32 percent relative to FY 2011 spending levels, the year Vision and Voyages had budget information. This well exceeds the Vision and Voyages recommendation.

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¹ Neither the committee nor the reader has access to the NASA accounting system or the keywords they use. The committee asked NASA to do a breakout, and the method they chose was keyword analysis. Table 3.2 gives programs, not keywords. The committee does not have the list of keywords.

² In 2016 NASA’s PSD performed a review of large facilities, how they are working, and the extent to which they serve the science needs of the broader planetary community; see https://www.lpi.usra.edu/psd-facilities/documentations-presentations/2015-16-Planetary-Facilities-Review-Web-Release.pdf.

TABLE 3.1 Planetary Science Division (PSD) Spending on Research and Analysis (R&A), Technology, and Technology Support and Infrastructure, Fiscal Year (FY) 2011-2016 (millions of dollars)

^a 95 percent of this budget line item is being counted as infrastructure, while the remaining 5 percent is counted as technology (innovative process improvements).

TABLE 3.2 Technology Spending Broken Out by Funding Source (and Program for FY 2016) (millions of dollars)

PROGRAMMATIC BALANCE (AMONG MISSION CLASSES)

Decadal Findings: Vision and Voyages identified key themes in planetary science to guide the selection of missions in the planetary program:

• Building new worlds—understanding solar system beginnings;
• Planetary habitats—searching for the requirements for life; and
• Workings of solar systems—revealing planetary processes through time.

Advances in meeting these objectives were shown to require a mix of missions varying in scale, cost, and complexity. Vision and Voyages emphasized the importance of balancing the program not only in the area of mission size and cost, but also in terms of the selection of target bodies and scientific questions addressed. It stated, “NASA’s suite of planetary missions for the decade 2013-2022 should consist of a balanced mix of Discovery, New Frontiers, and large strategic (flagship) missions, enabling both a steady stream of new discoveries and the

TABLE 3.3 Spending for Research and Analysis (R&A) and Technology as Compared to Vision and Voyages for Planetary Science in the Decade 2013-2022 (millions of dollars)

^a From the Bureau of Labor Statistics.

NOTE: PSD, Planetary Science Division.

capability to address larger challenges like sample return missions and outer planet exploration” (NRC, 2011, p. 13). The recommended program was designed to achieve such a balance. Specific medium and large missions were identified and prioritized. Targets of special interest for small missions were identified in the report, but Vision and Voyages stated that NASA should continue the competitive Discovery program.

The Vision and Voyages committee was required to conduct an independent cost estimate of all large missions (both large strategic [flagships] and New Frontiers) in the report. The CATE process was specifically designed to address this issue by taking a realistic approach to cost estimation and the technical maturity of the proposed missions. Vision and Voyages also emphasized the importance of an appropriate balance among the many potential targets in the solar system. Achieving this balance was one of the key factors that went into the recommendations for medium and large missions. The decadal committee noted that there should be no entitlement in a publicly funded program of scientific exploration. It further noted that achieving balance must not be used as an excuse for avoiding difficult but necessary choices. The decadal committee’s recommendation implicitly assumed that Discovery missions would address important questions that do not require medium or large missions.

Four criteria were recommended in Vision and Voyages to evaluate the missions to be flown. The first and most important was science return per dollar. Science return was judged with respect to the key scientific questions, and costs were estimated using a CATE study. The second criterion was programmatic balance, striving to achieve an appropriate balance among mission targets across the solar system and an appropriate mix of small, medium, and large missions. The other two criteria were technological readiness and availability of trajectory opportunities within the 2013-2022 time period.

For the large strategic (flagship) mission category, all of the options under consideration proved to be of a higher cost than originally anticipated. The highest priority was a Mars rover mission (then called MAX-C, now called Mars 2020); a first step in the return of samples from Mars, but with a mission architecture that was derived from the Mars Science Laboratory (MSL)/Curiosity mission. This recommendation was contingent on reducing the cost to $2.5 billion FY 2015 (the original CATE estimate was $3.5 billion)—the current Mars 2020 budget is

~$2.5 billion. This mission was conceived to have significant scientific return in addition to being the first step in a campaign to return samples, but it also meant an implicit commitment beyond the time frame of the decadal survey.

The second priority mission (flagship) was a Europa orbiter mission (then called the Jupiter Europa Orbiter), but here too, the choice was contingent on the development of a mission design that was much reduced in cost from the original concept, which the CATE estimated at $4.7 billion, and new money had to be found. This mis-

sion, no longer an orbiter but a multiple-flyby mission, has now become the Europa Clipper, which achieves many but not all of the science goals identified for the Jupiter Europa Orbiter mission.

Vision and Voyages emphasized that the gas giants, Uranus and Neptune, are of great scientific interest but have received little attention in the NASA planetary program. The scientific importance of these bodies called for additional investigation such as could be achieved by a third large strategic (flagship)-class mission, a Uranus Orbiter and Probe. Thus a mission to an ice giant would be central to revealing planetary processes through time and understanding solar system beginnings.

Two further targets for large strategic (flagship)-class missions are discussed in Vision and Voyages: an Enceladus Orbiter and a Venus Climate mission, even though Vision and Voyages did not envision commencement of additional large strategic missions in this decade. The PSD responded to the suggestions in Vision and Voyages concerning a Venus mission by creating a science definition team jointly with the Russian Space Agency. This type of preliminary study is most appropriate in planning for the large missions of the next decade and encourages continued study of possible mission architectures.

Assessment: NASA’s current portfolio of missions is shown in Figure 3.3. Considerable progress has been made toward meeting the large mission goals of Vision and Voyages. The Mars 2020 rover represents the first step in the goal of Mars sample return, as described in Chapter 5. The Europa Clipper mission has been descoped from the mission concept envisaged at the time of Vision and Voyages, and funding has been allocated for this mission. A Uranus Orbiter and Probe mission has yet to be initiated; however, NASA has carried out a study on a mission to the ice giants, as described later in this chapter.

NASA announced two Discovery calls (June 2010 and November 2014; another is expected in ~February 2019) and one New Frontiers call (December 2016). Over that time period, NASA initiated one New Frontiers mission (The Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer [OSIRIS-REx]), and three Discovery missions (InSight, Lucy, and Psyche, although InSight was part of the previous decadal survey period), as well as selecting Comet Astrobiology Exploration Sample Return (CAESAR) and Dragonfly as New Frontiers finalists. (See Figures 3.4 and 3.5.)

DISCOVERY MISSIONS

Decadal Findings: Vision and Voyages concluded that there is much compelling science that can be addressed by small (Discovery class) missions, and recommended continuation of the Discovery program at its then-current level, adjusted for inflation, with a cost cap per mission that is also adjusted for inflation from the current value (i.e., to about $500 million in fiscal year [FY] 2015). The survey recommended a regular, predictable, and preferably rapid (≤24 month) cadence for release of Discovery announcements of opportunity (AOs) and for selection of missions. Vision and Voyages also recommended that NASA continue to allow proposals for Discovery missions to all planetary bodies, including Mars. It further recommended that future Discovery AOs allow proposals for space-based telescopes, and that planetary science from space-based telescopes be listed as one of the goals of the Discovery program. Finally, the decadal survey noted that Missions of Opportunity provide a chance for new entrants to join the field, for technologies to be validated, and for future PIs to gain experience, and welcomed the introduction of the highly flexible SALMON approach. It recommended that this be used wherever possible to facilitate Mission of Opportunity collaborations.

Assessment: Around the time of the Vision and Voyages report, an AO was released in June 2010 that resulted in the InSight selection in August 2012. The InSight launch was originally planned for March 2016, but delayed to May 2018. In late 2016 NASA indicated that this delay cost NASA ~$153 million, an overrun that impacted the overall program. The PSD released the next Discovery announcement of opportunity on November 5, 2014, 4 years after the last AO (2010) release. (See Figure 3.6.)

As recommended by the decadal survey, this AO allowed all solar system bodies, except Earth and the Sun, and did not restrict the type of complete mission to be proposed, although it did not list space-based telescopes as one of the goals of the Discovery program as recommended in Vision and Voyages. The AO cost cap was $450 million in FY 2015 dollars for phases A though D, not including the cost of the Expendable Launch Vehicle (ELV) or the value of any contributions. Phase E and F costs are no longer under the AO cost cap. This AO approach meets the recommendations of the decadal survey for the cost of future Discovery missions.

Two missions were selected from this 2014 AO for flight, Lucy and Psyche. Lucy will explore six Jupiter Trojan asteroids trapped by Jupiter’s gravity in two swarms that share the planet’s orbit, one leading and one trailing Jupiter. Lucy is scheduled to launch in October 2021, arrive at its first destination, a main belt asteroid, in 2025, and continue science investigations until 2033. The Psyche mission will explore a large metal asteroid, known as 16 Psyche. This asteroid is thought to be composed mostly of metallic iron and nickel, and could be an exposed core of an early planet that could have been as large as Mars, but that lost its rocky outer layers due to violent collisions billions of years ago. Psyche is targeted to launch in October 2023, arriving at its target in 2030. (See Figures 3.7 and 3.8.)

In addition to selecting the Lucy and Psyche missions for formulation, the agency will extend funding for the Near Earth Object Camera (NEOCam) project for an additional year. The NEOCam space telescope is designed to survey regions of space closest to Earth’s orbit, where potentially hazardous asteroids may be found.

Discovery AOs were released in 1994, 1996, 1998, 2000, 2004, 2006, 2010, and 2014, with the next AO planned for 2019. Twelve missions have been selected from these AOs to date. Since the first two missions were directed, 14 Discovery missions have been approved for an overall program average of 1 mission every 24 months—the recommended average in Vision and Voyages. While this is overall a good record, the recommendation in Vision and Voyages was created because the AO releases in the previous decade did not meet the targeted 24-month cadence, and in the present decade the rate will also not meet that recommended by the decadal survey. Because of the high investment required to prepare and review Discovery proposals, the rate of mission selection and launch may be considered as a proxy for the Discovery AO release, particularly in the 2014 round, where two missions (Lucy and Psyche) were selected, to enable a healthier Discovery portfolio. However, there will only be two selection rounds and three launches in this decade, including Psyche’s launch in 2023. The reduced pace of Discovery AOs in this decade was driven by the reductions to the PSD’s budget in the early part of this decade, coupled with the focus on initiating two large strategic (flagship)-class missions. Additional funding was added to the PSD budget in more recent years. Since the funding situation has improved, the planned release of the next AO in 2019 works toward restoring the Discovery rate of announcements and flight.

In order to minimize the stress on the community, NASA could stagger New Frontiers and Discovery AOs.

MEDIUM (NEW FRONTIERS) MISSIONS

Decadal Findings: At the time of the survey, two medium (New Frontiers) missions were under way (New Horizons to Pluto and beyond, and Juno to Jupiter) and a third had not yet been announced; OSIRIS-REx, an asteroid sample return mission, was subsequently chosen.

Vision and Voyages recommended medium-class mission decision rules to achieve an appropriate balance among small, medium, and large missions, and that NASA should select two New Frontiers missions in the decade 2013-2022. The decadal survey committee’s statement of task called for a list of specific mission objectives for these New Frontiers missions. On the basis of their science value and projected costs, the committee identified seven candidate New Frontiers missions for the decade 2013-2022, with no priority among them: Comet Surface Sample Return, Io Observer, Lunar Geophysical Network, Lunar South Pole-Aitken Basin Sample Return, Saturn Probe, Trojan Tour and Rendezvous, and Venus In Situ Explorer.

The decadal survey chose five candidates for the New Frontiers 4 opportunity with no relative priority: Comet Surface Sample Return, Lunar South Pole-Aitken Basin Sample Return, Saturn Probe, Trojan Tour and Rendezvous,

and Venus In Situ Explorer. The decadal survey also recommended that the list for the New Frontiers 5 selection be augmented by adding two more missions, Io Observer and Lunar Geophysical Network.

In addition, the survey proposed a modest but significant change to the cost cap for this class of mission by adjusting the cost cap to $1.0 billion FY 2015, excluding launch vehicle costs.

Assessment: The PSD released the New Frontiers 4 (NF4) announcement of opportunity on December 9, 2016. This AO called for proposals that address at least one out of any of the six mission themes listed here:

• Comet Surface Sample Return,
• Lunar South Pole-Aitken Basin Sample Return,
• Ocean Worlds (Titan and/or Enceladus),
• Saturn Probe,
• Trojan Tour and Rendezvous, and
• Venus In Situ Explorer.

This list differed from the survey by adding a new category, Ocean Worlds (Titan and/or Enceladus), that was not included in the survey’s original list. Prior to including the new category in the NF4 solicitation, the director of the PSD sought the advice of the National Academies Committee on Astrobiology and Planetary Science (CAPS). CAPS could not, at that time, make recommendations to NASA and did not endorse this addition to New Frontiers 4.³ No changes to the New Frontiers 4 solicitation were made as a result of prior National Academies reports.⁴

Proposals from this solicitation were reviewed by NASA, and in December 2017 NASA selected two missions to go into step 2 of the New Frontiers 4 competition. One selection, CAESAR, is designed to return a sample from the comet visited by Rosetta, 67P/Churyumov-Gerasimenko. The second selection, Dragonfly, proposes to explore Titan’s prebiotic chemistry and habitability with a drone-like rotorcraft. The down selection to one mission will occur in 2019. NASA also provided technology development funds for spacecraft contamination techniques for the Enceladus Life Signatures and Habitability (ELSAH) mission, as well as for the Venus Element and Mineralogy Camera from the Venus In situ Composition Investigations (VICI) mission proposal for further study.

The 2016 AO increased the cost cap to $850 million, not including the launch vehicle, contributions, and phases E and F—similar to the approach used for the 2014 Discovery mission AO. Comparing the survey’s recommended $1 billion versus this $850 million is difficult because the operations costs in phase E can vary widely depending on the length of the mission operations.

The survey recommended that two missions be selected in this decade. The next New Frontiers announcement of opportunity is now planned for 2023, so the PSD will not achieve the recommended rate proposed by the survey. As with the Discovery program, this was partially attributable to the budget cuts that were imposed on the PSD during the early part of the decade. The PSD has stated that its objective is to have two New Frontiers missions each decade, and the current budget forecast looks like this is achievable. Final selection for New Frontiers 4 is planned for July 2019.

The Vision and Voyages New Frontiers mission list included a Trojan tour and rendezvous mission as one of the options for New Frontiers mission proposals. In 2017 NASA selected a Discovery class mission, Lucy, to conduct a tour of the Trojan asteroids. Lucy will address some but not all of the objectives of the Trojan Tour and Rendezvous mission as described in Vision and Voyages. Its visible imaging, shortwave infrared (SWIR)

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³ However, the CAPS co-chair reported the principal messages he received from the CAPS membership to the Space Studies Board and stated that “Enceladus and Titan are significant elements of the decadal survey, and their inclusion is consistent with the overall scientific priorities discussed in the survey report.”

⁴ In 2007 the National Academies produced the report New Opportunities in Solar System Exploration: An Evaluation of the New Frontiers Announcement of Opportunity, which evaluated options prior to the release of NASA’s New Frontiers 3 announcement of opportunity. The decadal survey committee was aware of the National Academies report while writing Vision and Voyages. However, the recommendations of the 2007 report were not intended to apply to future New Frontiers opportunities. The only National Academies-recommended missions for New Frontiers 4 and 5 are the ones in the Vision and Voyages report. No changes to the New Frontiers 4 solicitation were made in response to National Academies reports.

spectroscopy, and thermal infrared imaging investigations address the geologic, spectral reflectance, and surface textural investigations for Trojan Tour and Rendezvous. The radio science and imaging experiments together will constrain density. Trojan Tour and Rendezvous would have used measurements of elemental abundances, of key major and minor elements including hydrogen, as a primary constraint on Trojan asteroid origins. The absence of such measurements from Lucy may leave key Trojan science questions—origin and volatile content—open to future investigation.

LARGE STRATEGIC (FLAGSHIP) MISSIONS

Europa Clipper

Decadal Findings: Vision and Voyages named a Europa orbiter mission as its second priority large strategic (flagship) mission, but deemed the $4.7 billion cost of the JEO mission concept that NASA had developed to be unaffordable given the expected budget profile. JEO was conceived as one component of the Europa Jupiter System Mission (EJSM). The other component was the European Space Agency’s (ESA’s) Jupiter Ganymede Orbiter (JGO); this spacecraft subsequently morphed into the Jupiter Icy Moons Explorer (JUICE) mission. The original JEO mission profile would have taken the spacecraft into the Jovian system for 30 months of measurements of the Jupiter atmosphere, rings, and environment, as well as the larger Galilean satellites, Io, Ganymede, and Callisto, before entering Europa orbit for approximately 9 months. Once in orbit the spacecraft would have carried out a number of detailed geophysical, geological, and particles and fields measurements. JEO would also have carried out synergistic measurements with the JGO spacecraft, expected to be carrying out its mission in the Jupiter system at the same time. The survey directed NASA to develop a mission design that was much reduced in cost from the original concept, and to find new money to fund the mission.

Assessment: In order to meet the first challenge of bringing the cost down, a new mission was developed in which the science return was scaled back such that the Jupiter system science was entirely eliminated, and the

mission trajectory modified such that the spacecraft no longer enters orbit about Europa. Instead it orbits Jupiter, and encounters Europa multiple times over a ~3-year period, making over 40 close flybys of the surface. The new trajectory enables global coverage of Europa to be built up over the course of the mission, and has the benefit of enabling the spacecraft to dip in and out of the Jovian magnetosphere, which slows the effects of radiation damage, thereby prolonging the lifetime of the spacecraft. This approach preserves much of the JEO Europa science proposed to the decadal—estimates from the project science office are 73 percent—but the major loss is to the geophysical science objectives; without being in orbit it is challenging to establish the interior structure of Europa. In addition, all the Jupiter system and other Galilean satellite science has been completely deleted from the mission concept (but Europa, Ganymede, and Callisto will be studied by JUICE, which has some U.S. participation). The proposed cost of this mission is ~$3.1 to $4 billion, including launch vehicle.⁵

The second challenge given to the Europa mission by Vision and Voyages was that new funding had to be secured, since the worst-case funding scenario analyzed could not accommodate a Mars sample return mission as well as a Europa large strategic (flagship) mission. This has also been accomplished; the Europa Clipper mission has received strong congressional support and moved into Phase A in June 2016. Preliminary design review (PDR) is planned for August 2018 and Confirmation Review is scheduled for October 2018, after which more firm cost estimates for the project will become available.⁶

Europa Lander

NASA is currently studying a Europa Lander, the primary goal of which would be to search for evidence of habitability and potential biosignatures, for which in situ surface measurements will be required. The lander would launch after the Europa Clipper, which is designed to determine whether Europa is a habitable world and should be helpful in identifying landing sites.

Decadal Findings: Vision and Voyages notes the importance of searching for contemporary habitats elsewhere in the solar system with the necessary conditions conducive to life, and noted that a lander would probably be required to fully characterize organics on the surface of Europa. Vision and Voyages states that in situ measurements could help determine whether the isotope ratios of carbon, hydrogen, oxygen, and nitrogen in volatiles on Europa’s surface are indicative of internal processing or resurfacing. Regarding the question of life, Vision and Voyages notes, “A key future investigation of the possibility of life on the outer planet satellites is to analyze organics from the interior of Europa. Such analysis requires either a lander in the far term or the discovery of active Enceladus-style venting, which would allow analysis from orbit with a mission started in the next decade” (NRC, 2011, p. 240).

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⁵GAO (2018, p. 49) also notes the following: “This estimate is preliminary, as the project is in formulation and there is uncertainty regarding the costs associated with the design options being explored. NASA uses these estimates for planning purposes.”

⁶GAO (2018, p. 24) also notes the following: “The Europa Clipper project implemented a process whereby cost growth threats would be offset by descoping instruments in whole or in part. For example, if an instrument exceeds its development cost by 20 percent, the project would propose a descope option to NASA that brings instrument cost below that threshold. NASA has not descoped any instruments to date.”

In 2016 the Jet Propulsion Laboratory (JPL) produced the “Europa Lander Study 2016” report, which underwent a Mission Concept Review in June 2017. Dr. Thomas Zurbuchen, NASA associate administrator for the Science Mission Directorate (SMD), then directed JPL to convene a team to explore additional architecture options for a potential Europa Lander. That team rescoped the science and mission design. The planetary midterm committee heard briefings about the lander during its study, and in June 2018 the committee contacted the head of NASA’s PSD and asked for the latest releasable information on the Europa lander study and any releasable cost estimate. In response, NASA provided a five-page summary of the Europa lander architecture representing the latest information, and indicated that there is no releasable cost estimate for the mission concept.⁷ The midterm committee, although it lacks an official cost estimate, believes the mission cost to be in the multiple billions of dollars range.

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⁷ “2018 Europa Lander Architecture Update,” May 17, 2018 (provided to the committee in early June 2018).

Ice Giants

Decadal Findings: Vision and Voyages outlined nine prioritized science objectives for an ice giant mission including an orbiter and atmospheric probe. In a mission concept study performed in support of the decadal survey, all of these objectives were addressed to some extent using a scientifically broadly based complement of small, high-heritage instruments based on successful, previously flown instrumentation.

Assessment: In 2015 NASA commissioned the Ice Giants Pre-Decadal Study Final Report (NASA, 2017) to take a fresh look at science priorities and concepts for missions to the Uranus or Neptune system. The study team developed 12 science objectives, of which 2 were identified as higher priority. Compared to Vision and Voyages,

• Internal convection was identified as a new, high-priority objective;
• Study of the large and small moons was subdivided into several objectives, placing greater emphasis on characterization of the structure, origin, and composition of smaller moons, mass transport between moons, and the origin and evolution of organic compounds on the moons; and
• Investigation of clouds as a function of depth was dropped.

The core recommended payload complement meeting a $2 billion cost cap was nearly the same mass as with the Vision and Voyages ice giants mission study (50 versus 55 kg), but was reduced to only two remote instruments (a Doppler imager for seismological measurements of interior structure and a camera), and a magnetometer, plus a probe with a mass spectrometer and an atmospheric structure instrument. The 2017 recommended payload did not include a nephelometer that was part of the Vision and Voyages strawman. A Doppler imager for investigation of giant planet structure, which accounts for half the payload mass, has not been flown previously on any spacecraft. The notional instruments were significantly more massive than assumed in the previous study, possibly due to assumed additional radiation shielding appropriate to a Jovian environment.

The mission concept described in the 2017 Ice Giants report is ambitious in investigating the interior structure of an ice giant using a Doppler imager, analogous to undertaking helioseismological investigations of the Sun. This approach at any giant planet, including ice giants, is currently unproven theoretically or experimentally. Indeed, the study itself states: “There are several significant risks associated with a Doppler imager-type instrument, however, which must be assessed before selecting it for any actual ice-giant flight opportunity. The one easily addressed is the TRL level (currently 6), which—while a common level for a proposal—is the lowest for any instrument considered for the main spacecraft. More problematic is that while oscillations have likely been detected on Jupiter (Gaulme et al., 2011) and Saturn (Hedman and Nicholson, 2013), we do not know if the oscillation amplitudes on Uranus or Neptune will be detectable, and their excitation mechanism is not well-enough understood to even make an accurate prediction from what we see on the gas giants” (NASA, 2017, 3-43–3-44).

In order to accommodate this large instrument, the proposed payload is reduced in scientific scope. Loss of several instruments from the Vision and Voyages strawman payload compromises some of the principal objectives for an Ice Giant mission. Without data from plasma spectrometers, studies of the structure and dynamics of the magnetosphere and effects of solar wind on the magnetosphere will be incomplete, and characterization of the internal field may be degraded. Without a UV imaging spectrograph, a visible/near-IR imaging spectrometer, and a thermal IR radiometer, important investigations of the composition and regolith structure at both large and

small satellites will be incomplete, and compositional information on the ice giant atmosphere away from the probe site will not be obtained. In the event that the Doppler imager does not perform successfully, a large part of the Vision and Voyages science objectives would be degraded or lost. The reduction of the magnetospheric objectives of an ice giant large strategic (flagship) mission appears premature. The magnetospheres of these planets represent numerous unique physical situations that will enable a broader and more general understanding of planetary magnetospheric physics. The magnetic field of both Uranus and Neptune may be crucially important in understanding their internal structure.

CONTINUING MISSIONS

Decadal Findings: Before suggesting new missions, Vision and Voyages encouraged NASA to “continue missions currently in flight, subject to . . . senior review,” and to “ensure a level of funding that is adequate for successful operation, analysis of data, and publication of the results of these missions, and for extended missions that afford rich new science return” (NRC, 2011, p. 12). Figure 3.3 indicates that NASA’s planetary program is supporting a large portfolio of missions of varying scales and at different stages of operation, and is exploring a diverse set of target bodies, as proposed in Vision and Voyages. Collectively, the operating missions are well distributed among size and scale of mission cost.

Assessment: The PSD has held senior reviews to ensure that mission extensions are justified by important science objectives and that the costs are appropriate. For example, funding of Cassini’s extended mission enabled investigators to acquire extensive information on Enceladus and Titan and their oceans, providing new insight into planetary evolution, dynamics, and habitat. The extended mission characterized seasonal effects in Saturn’s atmosphere and magnetosphere and established more fully the internal mass distribution and the high-order internal magnetic field components, both central to understanding the deep interior of the planet.

The 2016 National Academies study Extending Science: NASA’s Space Science Mission Extensions and the Senior Review Process (NASEM, 2016) pointed out the importance of continuing extended missions. It also recommended transitioning from a 2-year cadence to a 3-year cadence for senior reviews, which NASA is now adopting. The committee agrees with the recommendations in that report and with NASA’s continuance of extended missions and adoption of a 3-year cadence for senior reviews. (See Figure 3.10.)

Need for Large Strategic (Flagship) Program Cost/Risk Review Process

In the 2008 Space Act, Congress mandated a “lifecycle cost and technical readiness” review of proposed NASA projects. Such reviews have become an important part of the decadal survey process. The CATE process is used by decadal surveys to provide an independent, standardized process to produce a figure-of-merit for technical and cost risk that aids in science prioritization. CATE is used to forecast the potential cost of the final system as built, which may undergo multiple iterations and may be very different than what was initially conceived.

Concepts conceived during decadal surveys are typically in preliminary stages of development—pre-phase A (in NASA project-lifecycle terms)—and are estimated to be of a certain complexity and associated cost. Downstream of the decadal survey, as the project is formulated, complexity grows as the development team understands more about the undertaking, new requirements may be introduced, and new instrumentation may be added. The rate at which a needed technology matures may be slower than had been expected. Cost and schedule growth follow such developments. When a project moves into implementation (phases C and D), it typically encounters new technical challenges—for example, during integration and testing—that the project team must work to overcome.

The Preliminary Design Review is the major milestone in development where NASA’s independent cost estimation process engages. Key Decision Point-C (after PDR) is when NASA conducts an independent cost estimate of the mission. This is usually the point at which the agency commits to further development of the mission, or reevaluates the mission. A major cost increase for a single large strategic (flagship) mission can have a dramatic effect on the overall program.

The committee was aware of the experience of the NASA astrophysics program, where cost overruns of large strategic missions have threatened the balance of that program. The astrophysics decadal survey midterm review report New Worlds, New Horizons—Midterm Assessment, published in 2016, included a recommendation for an independent review of the Wide Field Infrared Survey Telescope (WFIRST) program prior to KDP-B, a review that NASA subsequently performed. The planetary community can learn from this experience.

An independent review consists of an independent group of experts that looks at the scope and resources from a different perspective than a standard review board would. To be of value, this review should be conducted ahead of SRR/MDR, and after instruments are selected, to properly assess the system-level impacts induced by selection of instruments and system level complexity, among other things.

Because large strategic (flagship) missions have the potential to disrupt the rest of the planetary science program if they overrun, the committee believes that they deserve extra attention regarding cost and schedule. An important point for this to happen in mission development is before Key Decision Point-C.

THE PSD INFRASTRUCTURE

Vision and Voyages called out multiple kinds of supporting investments, including laboratories and facilities, Earth-based telescopes, balloons and sounding rockets, the Deep Space Network, high-performance computing, sample curation, and data archiving. The committee assessed NASA performance in several, but not all, of these areas. In particular, data archiving and interoperability has come to the fore given the federal government’s initiative to make federally funded research results available to the public. Because NASA policy is evolving rapidly to meet the new guidelines, this committee was not able to assess current performance in this area.

Space and Earth-Based Telescopes

Decadal Findings: Vision and Voyages pointed out the importance of Earth-based telescopic facilities, particularly in chapters covering giant planets and primitive bodies, but also in other areas, highlighting the cross-cutting importance of these facilities. These assets include ground-based optical and radar telescopes (including the Infrared Telescope Facility, the Keck Observatory, Goldstone, Arecibo, and the Very Long Baseline Array), balloon- and rocket-borne telescopes, and space-based telescopes (Hubble Space Telescope, the Chandra X-ray Observatory, the Stratospheric Observatory for Infrared Astronomy, WISE, and others), all of which make important and often unique contributions to planetary science. Hubble observations remain a high priority for planetary research through the mission’s remaining lifetime, particularly because there is no ultraviolet-optical high-resolution alternative from the ground. Vision and Voyages stated: “The committee’s overall assessment is that NSF grants and support for field activities are an important source of support for planetary science in the United States and should continue” (NRC, 2011, p 28).

Assessment: Since Vision and Voyages was released, significant discoveries have been made using ground-based facilities, representing progress toward Vision and Voyages goals, including the possible discovery of and continued study of/search for Europa plume activity; the study of auroral activity on Saturn (in coordination with Cassini) using the unique ultraviolet (UV) capabilities of the Hubble Space Telescope (HST); use of HST to successfully find target choices for New Horizons following the Pluto encounter; HST observations of 2014 MU69 occultations to characterize the New Horizons target; and unique HST observations of Ceres in the UV in support of the Dawn mission. With the heightened emphasis on planetary defense, radar observations have been crucial for refining orbits of near-Earth asteroids in order to assess future impact probabilities and to plan and execute missions to these bodies. Arecibo, with its higher sensitivity but limited sky pointing range, and Goldstone, with fully steerable capability, are complementary and essential components of radar observations of near-Earth asteroids.

The Deep Space Network

Decadal Findings: Vision and Voyages recognized the DSN as a critical component of the solar system exploration program. The report specifically recommended that NASA expand the DSN capabilities to comfortably meet the navigation and communications requirements of all the recommended missions, and that all three stations should maintain high-power uplink capability in the X- and Ka-band, and downlink capability in the S-, Ka-, and X-bands. Ka-band provides significantly greater downlink capability; S-band is specifically needed for communications through the Venus atmosphere to the surface; while X-band is needed to communicate through Titan’s atmosphere and for spacecraft emergencies.

Assessment: Progress has been made toward the Vision and Voyages recommendations. Two new 34-meter antennas with X- and Ka-band capability have been commissioned in Canberra, Australia, with two more under construction in Madrid. Developments to support higher data rates include Ka-band antenna arraying and high data rate capability, Delay Tolerant Networking, and common platform implementation. The DSN is also working to create international protocols to facilitate use of international antennas.

The recommendation for Ka-band uplink and downlink at all stations has not yet been met. Ka-band downlink is available at all 3 stations, but Ka-band uplink is available only at Goldstone. The plan is to incorporate Ka-uplink at all stations in the next few years, but this is not yet a committed capability that missions in development can count on as it is not listed in the Space Communications and Navigation (SCAN) catalog.

The projected needs from planetary missions for DSN capabilities have only increased since Vision and Voyages was written. The DSN currently supports over 35 missions and maintains 99 percent reliability. The plethora of spacecraft at Mars offers a particular challenge. There are eight missions currently operating at Mars, with at least three NASA or ESA missions and possibly several more international missions planned to arrive in the 2020-2021 time period. Other demands include outer solar system missions that require 70-meter or equivalent antenna coverage, and high data rate instruments in the inner solar system. Thus, maintaining adequate resources for maintenance and expansion of the DSN is necessary to fully implement Vision and Voyages recommendations and keep pace with new, evolving demands. (See Figure 3.11.)

Sample Curation and Laboratory Facilities

Sample return missions from other planetary bodies and astromaterial sample collections here on Earth (e.g., Antarctic meteorites, cosmic dust) have been a vital part of NASA’s science vision since nearly its inception. Sample studies continue to provide fundamental insight into how our solar system and its constituent bodies formed and evolved over the past 4.5 billion years. New generations of scientists and instrumentation are poised to address many ever-evolving scientific questions with returned samples. Careful curation is vital to the long-term viability of any sample return mission: Curatorial efforts must begin at mission conception. Vision and Voyages states: “Sample curation facilities are critical components of any sample return mission, and must be designed specifically for the types of returned materials and handling requirements. Early planning and adequate funding

are needed so that an adequate facility is available once samples are returned and deemed ready for curation and distribution” (NRC, 2011, p. 23). Vision and Voyages recommended that “every sample return mission flown by NASA should explicitly include in the estimate of its cost to the agency the full costs required for appropriate initial sample curation,” and put forward the establishment of a single advisory group to provide input on all aspects of extraterrestrial sample curation (NRC, 2011, p. 23). Last, Vision and Voyages advised that “well before planetary missions return samples, NASA should establish a well-coordinated and integrated program for development of the next generation of laboratory instruments” (NRC, 2011, p. 23).

Education and Outreach

Vision and Voyages highlighted the importance of effective outreach by the planetary community, noting that planetary exploration is among the “most exciting and accessible” science activities funded by NASA or any government agency. Vision and Voyages further stated that the NASA planetary program has a special responsibility to reach out to the public. Vision and Voyages stressed the value in the near instant availability of images from planetary missions and the global access to planetary data, noting that “interested members of the public can be informed of discoveries and mission events as they happen through social media” (NRC, 2011, p. 289). Vision and Voyages recommended that “efforts to integrate effective outreach should be directly embedded within each planetary mission” (NRC, 2011, p. 289), and strongly endorsed NASA’s informal guideline that a minimum of 1 percent of the cost of each mission be set aside from the project budget for education and public outreach activities.

Since the publication of Vision and Voyages, major changes have been made to the way NASA’s SMD carries out its education and outreach activities in an effort to eliminate duplication of efforts and increase efficiency. Informed by National Academy of Sciences and stakeholder recommendations, in 2016 the SMD restructured its program of STEM Science Activation to fund activities that are “closely aligned with learners’ needs.” These consist of 27 multiyear cooperative agreements that leverage “SMD’s Astrophysics, Earth, Heliophysics and Planetary content and experts into the learning environment through leveraging community-based partners.” These are activities that “occur primarily in out-of-school settings and for learners of all ages.”

Partnerships

Understanding our solar system requires a multidisciplinary approach to leverage investment. Progress over the last few decades and more recently suggests benefits to NASA of developing partnerships within and outside SMD and external to NASA.

Science Mission Directorate Partnerships

Within NASA’s Science Mission Directorate, there are numerous options for partnering to enhance the planetary science program. The Planetary Science Division and Heliophysics Science Division can partner to further the understanding of how magnetospheres and planets and their satellites work as a system. The Planetary and Astrophysics Science Divisions can partner to further the comparison of exoplanetary systems and our solar system, the search for life within our solar system, and the investigation astronomically in searching for extra-solar systems capable of containing life. They can also partner to facilitate the understanding of how solar systems form. Planetary, Heliophysics, Astrophysics, and Earth Science Divisions can all work together to understand rocky planet evolution and habitability.

Such partnerships have taken many forms in the past, including hosting instruments from other divisions on planetary spacecraft, joint research funding, and other collaborations. For example, although Kepler was a Discovery mission funded by the Planetary Science Division, it has been operated by the Astrophysics Science Division.

Non-SMD NASA Partnerships

It is also possible for the PSD to cooperate with other parts of NASA outside the Science Mission Directorate, and this has been advantageous for the planetary science program. For example, the Lunar Reconnaissance Orbiter was primarily funded by the Human Exploration Operations Mission Directorate (HEOMD) at NASA, but included a substantial suite of planetary science missions and is now operated by the PSD. STMD and HEOMD have also funded heat shield instrumentation on the MSL Curiosity and the Mars 2020 missions, and are sponsoring the MOXIE in situ resource utilization experiment on Mars 2020.

International Partnerships

NASA has engaged in international partnerships on large strategic (flagship) missions and smaller PI-led missions with the Japan Aerospace Exploration Agency, ESA, Russia, and India. The PSD has sought to develop long-reaching strategies and joint missions not possible within any single country. The committee notes that missions under study by potential partners are not substitutes for actually meeting the science goals established in the decadal survey. For example, although Russia and NASA have jointly studied the Venera-D Venus mission, where NASA would potentially contribute instruments, there is no indication that Russia is fully funding this mission.

Commercial Partnerships

Perhaps the most exciting new development in the larger space field is the emergence of new commercial space actors with interest in operations beyond low Earth orbit. SpaceX has indicated an interest in Mars exploration, and other companies have been formed to engage in asteroid mining or sending spacecraft to the Moon. These plans are at very early stages of formulation and are uncertain. (As an example, the committee sought a briefing by SpaceX on its plan to launch two Red Dragon spacecraft to Mars, but the project was canceled soon after the committee began its work.) Despite the uncertainty, this newly emerging sector holds great promise for providing new opportunities for NASA.⁸

National Science Foundation (NSF)

Vision and Voyages assessed the contribution to planetary science research made by ground-based astronomical facilities and laboratory facilities and investigations under the auspices of the National Science Foundation (NSF). Reviewing the progress of NSF toward meeting these recommendations was beyond the scope of this committee; however, the committee reiterates the importance of the Vision and Voyages recommendations, including the following:

• The committee supports the National Observatories’ ongoing efforts to provide public access to its system of observational facilities, and believes that there is a synergy between ground-based observations and in situ planetary measurements for which the National Observatories could play a key role, perhaps through coordinated observing campaigns on mission targets. The committee notes that there are certain key elements of concern for planetary science, such as actions by NSF to divest itself from older observatories that are used also by NASA.
• The ground-based observational facilities supported wholly or in part by NSF are essential to planetary astronomical observations, both in support of active space missions and in studies independent of (or as follow-up to) such missions. Their continued support is critical to the advancement of planetary science. The committee also believes that expansion of NSF funding for the support of planetary science in existing laboratories, and the establishment of new laboratories as needs develop could be beneficial to the overall planetary science community.

REFERENCES

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⁸ SpaceX has indicated ambitious plans for future human exploration of Mars. See Musk (2017, 2018).

NASEM (National Academies of Sciences, Engineering, and Medicine). 2016. Extending Science: NASA’s Space Science Mission Extensions and the Senior Review Process. The National Academies Press. Washington, DC.

NASEM. 2017. Review of the Restructured Research and Analysis Programs of NASA’s Planetary Science Division. The National Academies Press. Washington, DC.

NRC (National Research Council). 2011. Vision and Voyages for Planetary Science in the Decade 2013-2022. The National Academies Press. Washington, DC.