Many facets of studies in planetary science are dependent on analyzing large volumes of in-situ and spacecraft data. Our understanding of the lunar evolution and its connection to deeper interior layers has been dramatically improved by the so-called deep space exploration missions, including NASA’s lunar reconnaissance orbiter narrow-angle camera, China’s Moon and Mar exploration program, and Chang’e series lunar relay satellite program, in coordination with Earth-based supporting observations. From Apollo 17 lunar surface operations (1972), there are many related operations including China’s lunar and deep space exploration (Chang’e-1 2007; Chang’e-2 2010; Chang’e-3 2013; Chang’e-4 2018; Chang’e-5 2020). On the 50th anniversary of the final Apollo mission to the Moon, this topic will bring together theory, numerical models, and observations capable of advancing our understanding of lunar evolution.

In spring 2011 the National Academies of Sciences, Engineering, and Medicine produced a report outlining the next decade in planetary sciences. That report, titled Vision and Voyages for Planetary Science in the Decade 2013-2022, and popularly referred to as the "decadal survey," has provided high-level prioritization and guidance for NASA's Planetary Science Division. Other considerations, such as budget realities, congressional language in authorization and appropriations bills, administration requirements, and cross-division and cross-directorate requirements (notably in retiring risk or providing needed information for the human program) are also necessary inputs to how NASA develops its planetary science program. In 2016 NASA asked the National Academies to undertake a study assessing NASA's progress at meeting the objectives of the decadal survey. After the study was underway, Congress passed the National Aeronautics and Space Administration Transition Authorization Act of 2017 which called for NASA to engage the National Academies in a review of NASA's Mars Exploration Program. NASA and the Academies agreed to incorporate that review into the midterm study. That study has produced this report, which serves as a midterm assessment and provides guidance on achieving the goals in the remaining years covered by the decadal survey as well as preparing for the next decadal survey, currently scheduled to begin in 2020.

On December 11, 2017, President Donald Trump signed Space Policy Directive-1 (SPD-1). The new directive replaced original text in the National Space Policy of the United States of America and instructed the Administrator of the National Aeronautics and Space Administration (NASA) to "lead the return of humans to the Moon for long-term exploration and utilization, followed by human missions to Mars and other destinations". In response to and in support of the vision expressed in SPD-1, the first report reviewed decadal and other community-guided lunar science priorities as context for NASA's current lunar plans and then presented and evaluated the actions being taken by NASA's Planetary Science Division (PSD) to support lunar science. At the request of NASA PSD, this second report explores plans for commercial partnerships, lunar infrastructure development, and related aspects of NASA's lunar science and exploration initiative.

This study discusses the publicly available studies of future flagship- and New Frontiers-class missions NASA initiated since the completion of Vision and Voyages. The report considers the priority areas as defined in Vision and Voyages where publicly available mission studies have not been undertaken; appropriate mechanisms by which mission-study gaps might be filled in the near- to mid-term future; and other activities that might be undertaken in the near- to mid-term future to optimize and/or expedite the work of the next planetary science decadal survey committee.

The Committee on Astrobiology and Planetary Sciences of the National Academies of Sciences, Engineering, and Medicine is tasked with 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. 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 survey's recommendations are triggered at specific programmatic decision points. Options for the Fifth New Frontiers Announcement of Opportunity addresses one such decision point. For each of the following four New Frontiers targets: Ocean Worlds, Trojan Tour and Rendezvous, Io Observer and Lunar Geophysical, this report summarizes changes in scientific understanding or external factors since the release of Vision and Voyages or its midterm review and considers whether those changes have 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.

Lunar and Planetary Surface Conditions considers the inferential knowledge concerning the surfaces of the Moon and the planetary companions in the Solar System. The information presented in this four-chapter book is based on remote observations and measurements from the vantage point of Earth and on the results obtained from accelerated space program of the United States and U.S.S.R. Chapter 1 presents the prevalent hypotheses on the origin and age of the Solar System, followed by a brief description of the methods and feasibility of information acquisition concerning lunar and planetary data, either from fixed terrestrial observatories or from instrumented or manned space probes. Chapter 2 reviews all conditions pertaining to the surface aspects of the closest celestial neighbor, the Moon. Sections in this chapter deal sequentially with the atmosphere, temperature conditions, subsurface stratification, field intensities (gravitational, electric, and magnetic), and lastly with the biological conditions existing on the lunar surface. This chapter also provides information on the density of the lunar atmosphere under quiescent or high-flux transient conditions, on the topography of the lunar surface, and on the probable proportion of crater-covered areas in the highlands and on the Maria. Chapter 3 is a detailed treatment of the surface conditions on the terrestrial planets, comprising Mercury, Venus, and Mars, while Chapter 4 deals with similar information relating to the so-called Jovian planets (Jupiter, Saturn, Uranus, Neptune) and Pluto. This book will prove useful to lunar and planetary mission planners, both those concerned with the purely scientific aspects of surfaces and immediate subsurfaces, and those involved in the development of roving exploration vehicles.