Nearly half a century ago, two papers postulated the likelihood of lunar lava tube caves using mathematical models. Today, armed with an array of orbiting and fly-by satellites and survey instrumentation, we have now acquired cave data across our solar system-including the identification of potential cave entrances on the Moon, Mars, and at least nine other planetary bodies. These discoveries gave rise to the study of planetary caves. To help advance this field, we leveraged the expertise of an interdisciplinary group to identify a strategy to explore caves beyond Earth. Focusing primarily on astrobiology, the cave environment, geology, robotics, instrumentation, and human exploration, our goal was to produce a framework to guide this subdiscipline through at least the next decade. To do this, we first assembled a list of 198 science and engineering questions. Then, through a series of social surveys, 114 scientists and engineers winnowed down the list to the top 53 highest priority questions. This exercise resulted in identifying emerging and crucial research areas that require robust development to ultimately support a robotic mission to a planetary cave-principally the Moon and/or Mars. With the necessary financial investment and institutional support, the research and technological development required to achieve these necessary advancements over the next decade are attainable. Subsequently, we will be positioned to robotically examine lunar caves and search for evidence of life within Martian caves; in turn, this will set the stage for human exploration and potential habitation of both the lunar and Martian subsurface. Collectively, these features represent a new frontier in planetary exploration. Pits, vents, fissures, and caves provide access to near surface geology and liquid oceans without the need for drilling or digging (Stamenković et al., 2019 ). On Mars, these features may provide access to preserved volatiles including water ice (Schörghofer, 2021 ; Williams et al., 2010 ), brines (D. M. Burt & Knauth, 2003 ), and organic matter (Richardson et al., 2013 ). More broadly, planetary SAPs may ultimately provide data on volatile delivery and climatic oscillations. Here, we discuss the state of knowledge pertaining to each question, as well as provide scientific and technical guidance for researchers addressing these issues in the future. 3.1. Astrobiology Q1: Do caves on Mars represent habitable systems for microbial life that once dwelled on the Martian surface? (#6; 85.4%) Q2: What lines of evidence are required to conclusively prove life exists/existed in planetary caves? Specifically, how may we design missions to reduce the likelihood of false negatives? (#7; 84.2%) Q3: Are speleothems in planetary caves potential archives for past microbial life? If so, how would we confidently identify these biosignatures? For the case of Mars, if microbial life arose and prospered on the surface, it may have later used caves as refugia (Q1) as the planet became increasingly drier and colder (Schulze‐Makuch & Irwin, 2018 ). Caves on Earth, because they are protected from surface processes (such as extreme temperature fluctuations and UV radiation) and have stable physicochemical conditions, harbor a vast diversity of microorganisms able to interact with minerals and exploit different metabolic pathways (e.g., Boston et al., 2001 ; Miller et al., 2020 ). Additionally, deep zones of some Mauna Loa caves support perennial ice (Schörghofer et al., 2018 ). Thus, knowing where to sample within a given planetary cave will require a robust understanding of environmental zones within terrestrial analog caves, as well as how to accurately model and transfer those environmental conditions to another planetary body. Moreover, an appropriate instrument payload (i.e., temperature, (#27; 79.3%) Q12: For a given Martian cave, what is the diurnal and seasonal temperature and relative humidity variations of the cave interior? Importantly, what sections of a given cave are most variable and what sections are most stable? (#38; 76.8%) Q13: How far does cosmic radiation attenuate beyond the cave entrance? In other words, how deep within the cave must either a rover or human traverse to reach an area insulated from surface radiation? (#42; 75.6%) Q14: What are the prevalent gases within lunar and Martian caves? How might their presence affect the search for life (specifically, on Mars)? Analogs provide a test bed for both technology demonstrations and validation of cave climate models (Léveillé & Datta, 2010 ). In addition to natural caves, human‐made caves (such as tunnels and mines) would provide a more controlled environment. Importantly, model caves could be constructed inside temperature and pressure‐controlled chambers (e.g., the Ames Planetary Aeolian Laboratory for simulating windborne processes), which could be used for both cave climate model validation, as well as to simulate predicted cave conditions on other planetary bodies. The decay of naturally occurring radioisotopes may dominate the dose within deep caves, while the buildup of radon gas will be affected by cave climate and external forcing by fluctuations in surface conditions (e.g., temperature, relative humidity, and barometric pressure; Šebela & Turk, 2011 ). Cave geometry also determines how surface conditions will influence the cave environment (de Freitas & Littlejohn, 1987 ; Tuttle & Stevenson, 1978 ; Williams & McKay, 2015 ; Williams et al., 2017 ). Key properties influencing solar system‐wide cave formation include temperature, pressure, gravity field, and if there is a liquid cycle, the properties of that liquid (e.g., water vs. supercritical CO 2 vs. methane; Malaska & Hodyss, 2014 ; Malaska et al., 2011 ). Host rock (or ice) properties will also influence cave formation processes; these include the strength (of various moduli) and deformation characteristics of substrate materials at local environmental conditions.