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1 Introduction The National Academies of Sciences, Engineering, and Medicine established the Committee on Astrobiology and Planetary Sciences (CAPS) in 2012 to serve two major roles. First, to support scientific progress in astrobiology and planetary science. Second, to assist the federal government in integrating and planning programs in these fields by providing advice on the implementation of decadal survey recommendations. One of the primary means by which CAPS addresses its twin roles is by monitoring the progress in implementation of the recommendations of the most recent planetary science decadal survey, Vision and Voyages for Planetary Science in the Decade 2013-2022 (hereafter V&V).1 Planetary science decadal surveys evaluate the state of the field, identify the most important scientific questions and themes, and prioritize missions and activities for the decade in question based on scientific merit, technical feasibility, and anticipated cost. The need for careful monitoring is underscored by the fact that some of the decadal surveyâs recommendations are triggered at specific programmatic decision points. This short report addresses one such decision point associated with NASAâs New Frontiers program. THE NEW FRONTIERS PROGRAM NASAâs Planetary Science Division (PSD) provides opportunities for individual investigators to propose, develop, build, launch, and operate small- and medium-class spacecraft missions for the study of solar system bodies. These so-called principal investigator (PI)-led missions fall under the aegis of the Discovery (â¤$500 million) and New Frontiers (â¤$1 billion) programs, respectively (note that launch vehicle and certain other costs do not presently count toward these cost caps). The ground rules for these two programs differ. Broadly speaking, PIs responding to an announcement of opportunity (AO) issued by the Discovery program may propose missions to any solar system body. Whereas, PIs responding to an opportunity in the New Frontiers program are restricted to a specific set of mission targetsâor mission themesâidentified in the most recent planetary science decadal survey. Once a specific New Frontiers target has been addressed by a mission, it is removed from the list of decadal surveyâapproved future- mission options.2 To date, three New Frontiers missions have been launched and are successfully operating. New Horizons has flown through the Pluto-Charon system and by a small Kuiper belt object (KBO) called Arrokoth and is currently outbound from the solar system. Juno is mapping the gravitational and magnetic fields of, and making numerous other measurements at, Jupiter. OSIRIS-REx is orbiting the near-Earth asteroid Bennu and will collect surface samples for return to Earth later in the 2020s. V&V recommended that two missions be implemented between 2013 and 2022 through NASAâs New Frontiers program and identified seven possible mission themes. For the New Frontiers 4 (NF4) competition, there were five (in unranked order): Comet Surface Sample Return, Lunar South Pole- Aitken Basin Sample Return, Saturn Probe, Trojan Tour and Rendezvous, and Venus In Situ Explorer. 1 National Research Council, Vision and Voyages for Planetary Science in the Decade 2013-2022, The National Academies Press, Washington, D.C., 2011, http://www.nap.edu/catalog/13117.html. 2 See Table ES.2 in V&V. PREPUBLICATION COPY â SUBJECT TO FURTHER EDITORIAL CORRECTION 1
For the New Frontiers 5 (NF5) competition, V&V recommended including the unselected mission themes from NF4 along with two additional themes: Io Observer and Lunar Geophysical Network (LGN). Prior to the release of the NF4 AO, in response to scientific advances, programmatic considerations, and congressional direction,3 NASA added a sixth mission theme, âOcean Worlds (Titan and/or Enceladus),â focused on the search for signs of extant life and characterizing the potential habitability of Titan and/or Enceladus (see Box 1.1). NASA does not prescribe how any missions or investigations responsive to a mission theme should actually be accomplished. However, NASA requires that any mission architecture achieve a preponderance of the science objectives listed.2 After a competitive down-select, a rotorcraft mission to the surface of Titan, Dragonfly, was selected and is currently in development. BOX 1.1 Scientific Objectives for the Ocean Worlds Mission The scientific objectives for the Ocean Worlds mission theme listed in the announcement for opportunity for the fourth New Frontiers mission are as follows:1 The Ocean Worlds mission theme is focused on the search for signs of extant life and/or characterizing the potential habitability of Titan and/or Enceladus. For Enceladus, the science objectives (listed without priority) of this mission theme are as follows: â¢ Assess the habitability of Enceladusâ ocean; and â¢ Search for signs of biosignatures and/or evidence of extant life. For Titan, the science objectives (listed without priority) of the Ocean Worlds mission theme are the following: â¢ Understand the organic and methanogenic cycle on Titan, especially as it relates to prebiotic chemistry; and â¢ Investigate the subsurface ocean and/or liquid reservoirs, particularly their evolution and possible interaction with the surface. 1 NASA, âAnnouncement of Opportunity: New Frontiers 4,â NASA Solicitation NNH16ZDA011O, December 9, 2016, Closed/Past Solicitation in https://nspires.nasaprs.com/external/. PSD plans to begin the task of drafting the AO for NF5 in the latter part of 2020 and is planning to release it to the community in its final form in the fall of 2022. This date is sufficiently late in the decadal cycle that NASA asked CAPS to evaluate any changes in scientific understanding and external factors,4 such as programmatic developments and/or technological advances, that would warrant a reconsideration of four of the identified New Frontiers mission themesâOcean Worlds, Trojan Tour and Rendezvous, Io Observer, and Lunar Geophysical Network.5 Examples of programmatic developments include NASAâs selection of the Lucy multiple-Trojan-flyby mission in the small-mission-class 3 House Report 114-130 accompanying Commerce, Justice, Science, and Related Agencies Appropriations Bill, 2016, p. 59, https://congress.gov/114/crpt/hrpt130/CRPT-114hrpt130.pdf. 4 The next decadal survey in astrobiology and planetary science was formally initiated in March 2020 and is scheduled to release its report by the end of March 2022. As such, the findings and recommendations of the new decadal survey will be unable to impact the drafting of the announcement of opportunity for the fifth New Frontiers mission or community preparation for responding to it in any meaningful way. 5 NOTE: The committee was not asked to address other mission themes. PREPUBLICATION COPY â SUBJECT TO FURTHER EDITORIAL CORRECTION 2
Discovery program, the selection of Dragonfly as noted above, the selection in February 2020 of Io Volcano Observer (IVO) for a Discovery phase A concept study,6 and the renewed emphasis on lunar exploration within both NASAâs Science Mission Directorate (SMD), Space Technology Mission Directorate (STMD), and the Human Exploration and Operations Mission Directorate (HEOMD). Examples of technological advancements include developments in power and propulsion and the results of ongoing investments in instrument maturation, radiation hardening, communication, and other technologies. CAPS evaluates each of the questions posed in the statement of task below for Ocean Worlds (Titan and/or Enceladus), Trojan Tour and Rendezvous, Io Observer, and LGN. The phasing of the various missions discussed in this report relative to the completion of the next planetary science and astrobiology decadal survey and the release of the AO for NF5 is outlined in Table 1.1. STATEMENT OF TASK Against the backdrop described above, PSD Director Lori Glaze requested that CAPS address the following task: In keeping with its charge to monitor the âimplementation of the decadal surveyâs recommended scientific and technical activities,â and, specifically, to draft short reports addressing topics relating to the âscientific impact of a change in the â¦. programmatic sequencing of one or more of the survey-recommended activitiesâ¦..and the scientific impact of a course of action at a decision point described in the survey report,â the Committee on Astrobiology and Planetary Sciences will draft a short report that will answer the two questions below for the following four New Frontiers targets: Ocean Worlds, Trojan Tour and Rendezvous, Io Observer and Lunar Geophysical Network: 1. Has scientific understanding or external factors such as programmatic developments or technological advances, significantly changed since the release of the planetary science decadal survey or its midterm review? 2. Has scientific understanding or external factors, such as programmatic developments or technological advances, been sufficiently substantial to warrant reconsideration of the four targets for inclusion in the New Frontiers 5 announcement of opportunity, scheduled for release in early 2022? CAPS began to address this task by holding a committee-wide conference call on March 10, 2020. Detailed presentations, discussions, and deliberations were held during a virtual meeting on March 31 to April 2. Presentations heard by the committee included those on the relevant science goals for the exploration of Enceladus, Titan, Trojan asteroids, Io, and the Moon, together with details concerning the plans for Dragonfly, Lucy, and IVO.7 Committee discussions continued through the first half of April. The reportâs conclusions were finalized during a committee-wide conference call on April 21, and the complete report was sent to seven external reviewers on May 1. The report was revised in response to reviewer comments during June and delivered to NASA in late-June. Details concerning the organization and principal conclusions of this study can be found in Box 1.2. 6 The selection of missions in the Discover and New Frontiers programs proceeds via a two-step process. The initial (or Step-1) selection of a small number of proposed candidates for additional study, followed by the final (or Step-2) selection of the candidate selected for implementation and flight. 7 For more information about IVO see, for example, https://ivo.lpl.arizona.edu. PREPUBLICATION COPY â SUBJECT TO FURTHER EDITORIAL CORRECTION 3
TABLE 1.1 The Phasing of the Various Discovery, New Frontiers, and Lunar (via the Commercial Lunar Payload Services (CLPS) Program) Missions Discussed in This Report Relative to the Timeline for the Selection of the Fifth New Frontiers Mission and the Release of the Scheduled Planetary Science and Astrobiology Decadal Survey Lucy Dragonfly IVO CLPS New Frontiers 2020 In development In development In competition Potential New Frontiers 5 with three other (NF5) proposers mission concepts formulating their mission concepts 2021 Launch (October) Earliest possible CLPS-1 NF5 Announcement of selection date (September) Opportunity (AO) (April) CLPS-2 released in draft form (October) (~October) 2022 Earth flyby (October) CLPS-3 Decadal survey released (December) with advice on New Frontiers 6 and beyond (~March) NF5 AO released in final form (~October) 2023 CLPS-4 (Early in NF5 Step-1 down select year) (~May) VIPER (TBD) 2024 Earth flyby (December) NF5 Step-2 down select (~August) 2025 Flyby of main belt In development asteroid Donaldjohanson (April) 2026 Launch (April) Earliest launch date (November) 2027 Flybys of L4 Trojans Venus flyby Mars flyby (April) Eurybates and its small (April) satellite (August) and Polymele (September) 2028 Flybys of L4 Trojans Earth flyby Leucus (April) and (May) Orus (November) 2029 Earth flyby Earliest launch of NF5 (January) (depends on the mission selected) 2030 Earth flyby (December) 2031 Earth flyby Jupiter arrival (September) (December) 2032 2033 Flyby of L5 Trojan binary Patroclus- Menoetius (March). End of primary mission. 2034 Titan arrival (December) 2035 End of primary mission 2036 2037 End of primary mission NOTE: All dates mentioned, including those associated with the announcement of opportunity (AO) for NF5, are based on current best estimates and are subject to change. The dates shown for the Io Volcano Observer assume that it is selected and launches at earliest of its two possible launch opportunities. PREPUBLICATION COPY â SUBJECT TO FURTHER EDITORIAL CORRECTION 4
BOX 1.2 Organization and Principal Conclusions of this Report The organization and principal conclusions of this report are as follows: Chapter 1âContains introductory details concerning spacecraft missions discussed in this report (i.e., Dragonfly, Lucy, and Io Volcano Observer, and future endeavors responsive to the New Frontiers programâs Ocean Worlds, Trojan Tour and Rendezvous, Io Observer, and Lunar Geophysical Network (LGN) mission themes), and the statement of task for this study. Chapter 2âAddresses the first question in the committeeâs statement of task by discussing whether or not the scientific, technical, and programmatic context for spacecraft missions addressing the Ocean Worlds, Trojan Tour and Rendezvous, Io Observer, and the LGN mission themes have changed since the release of the Vision and Voyages planetary science decadal survey in 2011. Chapter 3âAddresses the second question in the committeeâs statement of task by discussing whether or not any of the contextual changes for the four mission themes identified in Chapter 2 are sufficient to cause NASA to reconsider the inclusion of any and all of them in the announcement of opportunity for the fifth New Frontiers (NF5) mission. Chapter 4âSummarizes the committeeâs key conclusions relating to the various spacecraft missions discussed in the report as follows: â¢ Ocean Worlds (Enceladus) and LGN remain compelling mission themes, without any developments suggesting that NASA reconsider their inclusion in NF5; â¢ The selection of Io Volcano Observer for flight in Discovery 15/16 would represent a programmatic development suggesting that, in that event, NASA reconsider the inclusion of Io Observer for NF5; â¢ The development of the Lucy mission suggests that NASA reconsider the inclusion of Trojan Tour and Rendezvous in NF5; â¢ The development of the Dragonfly mission suggests that NASA reconsider the inclusion of Ocean Worlds (Titan) in NF5, for reasons of programmatic balance. PREPUBLICATION COPY â SUBJECT TO FURTHER EDITORIAL CORRECTION 5