Sample return missions are the most difficult tasks we ask robotic spacecraft to undertake in exploring our solar system, but we do so because of the high value returned samples have for the planetary science community. Thus far, we have only acquired samples from: the Moon, three asteroids, a comet’s tail, and the solar wind at the Earth-Sun Lagrange Points. The National Academy’s most recent decadal survey of planetary science in NASA — Origins, Worlds, Life (OWL) — emphasized the value of samples returned to Earth for analysis and called for NASA to prioritize samples returned from Mars, the Moon’ South Pole, a Jupiter-family comet, and Ceres. Currently available rockets and propulsion technology impose severe, and possibly insurmountable, limits to where we can send robot explorers and return samples within a reasonable timescale. Now, the advent of large new rockets offers the potential for very high C3 Earth escape trajectories. Parallel developments in Nuclear Propulsion yield much higher ISP than chemical propulsion and can operate far away from the Sun. Our novel trajectory and mission architecture analysis shows that, combining these technologies, sample return from all across the solar system starts to become feasible within the career lifetime of a planetary scientist.

This paper details a study evaluating the critical requirements for effective deployment and integration of Radioisotope Power Systems (RPS) in future space missions. It expands upon prior research by comparing various RPS technologies - including the MMRTG, Next Gen RTG, and two conceptual Stirling RPS variants - within the context of a lunar rover mission concept. The methodology is based on a three-pronged, parallel assessment, incorporating the critical interfaces and perspectives of the rover/spacecraft team, a NASA RPS Program development team, and a launch vehicle (LV) integration team. The study yields a comprehensive framework for assessing the feasibility of advanced or novel RPS implementation, complete with a detailed analysis of the resultant impacts on mission requirements and implementation across all three stakeholder perspectives.

Sample return missions are among the most difficult tasks for robotic spacecraft in exploring our solar system. However, the samples they return to Earth have significantly high value for the planetary science community. Thus far, we have only acquired samples from the Moon, three asteroids, a comet's tail, and the solar wind at the Earth-Sun Lagrange Points. The National Academy's most recent decadal survey of planetary science at NASA emphasized the value of samples returned to Earth for analysis and called for NASA to prioritize samples returned from Mars, the Moon's South Pole, a Jupiter-family comet, and Ceres. Currently available rockets and propulsion technology impose severe, and possibly insurmountable, limits to where we can send robot explorers and return samples within a reasonable timescale. Now, the advent of large new rockets offers the potential for very high C3 (characteristic energy) Earth escape trajectories. Parallel developments in Nuclear Propulsion yield much higher ISP than chemical propulsion and can operate far away from the Sun. Our novel trajectory modeling results and mission architecture analysis show that, by combining these technologies, sample return from across the solar system becomes feasible within the career lifetime of a planetary scientist.

Different mission architectures, propulsion system and launch vehicle technologies were investigated for Uranus Orbiter and Probe Flagship interplanetary trajectories. The cruise time was limited to 13.5 yr for a launch window of 2034 thru 2045. Broad search was conducted for four different architectures. Jupiter starts losing alignment in 2035-2036 depending upon the launch C-3. Architecture EEU provides frequent launch opportunities but demands high C-3, whereas trajectories with Venus flyby requires lower C-3 but less frequent launch opportunities with potential thermal concerns. Biprop staging and low thrust SEP system are considered in the trade study. The baseline launch vehicle is Falcon Heavy Expendable and SLS Block 1B, upper kick stage STAR48 and SpaceX Starship are in the trade study. For very fast trajectories, aerocapture technology and Starship were employed resulting in massive UOP core mass deliveries.

NASA has a long history of using Radioisotope Power System (RPS) technologies to enable space missions. Today, NASA's RPS Program, working with the Department of Energy, deliver RPS to NASA missions to enable the exploration of cold, dark, dusty, and harsh environments. The RPS Program manages the investments made to develop RPS products to enable future missions. To better understand what technologies could most benefit current and future missions, the RPS Program conducts mission and systems studies. This study was undertaken to understand the impact of different RPS technologies on a lunar surface rover mission concept. The Endurance mission concept is one of the mission concept studies for the 2023-2032 Planetary Science and Astrobiology Decadal Survey. It would be an autonomous rover mission enabled by the RPS to traverse 2,000 km on the lunar surface collecting and delivering samples to the Artemis basecamp near the south pole. The baseline RPS used in the design concept for the four-year mission is the Next Gen RTG (NGRTG). To gain insight into the power requirements of a lunar rover mission concept, the RPS Program Office and the Jet Propulsion Laboratory's (JPL's) Team-X conducted a study comparing the impact of various RPS technology options using the Endurance rover concept as a baseline. The study generated parametric point-designs that analyzed one of two different thermal subsystem designs and, notably for the power system, one of four RPS products: MMRTG, NGRTG, plutonium oxide-based Stirling RPS, and an americium-based variant of Stirling RPS. From the RPS Program's perspective, the MMRTG is the current state-of-the-art, the NGRTG is a planned next generation product, and both Stirling RPS variants are potential future product offerings. The rover's thermal and mechanical design and configuration were altered to accommodate the RPS; other variables were kept constant throughout the study, facilitating the comparison of different point-designs. This paper provides a summary of the results of the Team-X study for the seven point-design that were evaluated. The metrics for evaluation were the estimated mass of the rover and the estimated mission duration; these metrics were selected to track the viability of rover delivery via a Commercial Lunar Payload Service (CLPS) lander, and in meeting the four-year mission duration requirement. Overall, the results showed that achieving mission closure for the Endurance rover mission is possible with any of the specified power systems and either of the heater architectures (depending on the power system implemented).

Motivation: The Origins, Worlds, and Life Decadal Survey recommends a Uranus Orbiter and Probe (UOP) mission as the next planetary flagship [1]. The current President's Budget Request for Fiscal Year 2025 does not support NASA-funded mission studies until 2027 [2], which will likely result in missing a potential Jupiter Gravity Assist (JGA). We thus need to find other trajectory options to Uranus, arriving ideally before Equinox in 2050 for unique observations. Additionally, other challenges drive the UOP design. We describe these challenges and a novel mission concept which mitigates them while achieving comparable science return to that in the Decadal Survey mission concept. Challenges: The UOP flagship faces numerous challenges. Losing the JGA means reducing flight system mass to maintain flight times to Uranus of 13.5 yrs with thermally-benign perihelia above 0.9 AU. Another challenge is power. Uranus will be 18-19 AU from the Sun, which makes Radioisotope Thermoelectric Generators (RTGs) the best power source option. Based on current best estimates, the inventory of RTGs is likely to be limited in this timeframe, driving a desire to reduce power demand and the number of RTGs required while maintaining flagship -worthy science and the earliest possible launch date that budget profiles will allow. Another challenge is ensuring launch date flexibility which allows CONOPS-similar backup launch opportunities. Perhaps the ultimate challenge is to meet these previously mentioned challenges using a credible low-cost and low-risk approach. Approach: Mass and power drivers were examined, informed by > 50 years of experience in developing space science missions at JPL. In this preliminary study, we assumed the same Decadal UOP study payload and probe mass [3]. Significant power and mass reductions were achieved by techniques such as eliminating reaction wheels and adopting new electrical power distribution architectures. While some technology evolution was required, we took a "no miracles" approach. We chose a trajectory that allows launch any year without a JGA and without going much below 1 AU (no Venus flybys), thus providing yearly launch and backup opportunities with virtually identical CONOPs and environments. Results: By using a combination of new design approaches, we were able to match the same payload and science as the Decadal UOP study with 42% less dry mass and a requirement of only two Next Gen Mod 1 RTGs. The mass reduction enabled a trajectory that matches the Decadal UOP's cruise duration while providing yearly launch opportunities. Our approach used a Falcon Heavy Expendable launch vehicle and a kick stage instead of a Falcon Heavy Expendable. The design was run through JPL's Team-X which demonstrated that all appropriate design and cost margins were achieved. Mission development and operations phase costs were comparable to the UOP Decadal study costs. This approach is potentially extensible to other future mission concepts. Conclusions: Based on this initial study, it appears that all challenges can be met with adequate margins while achieving comparable Decadal study science using this novel approach. Evolutionary technology was used that can achieve Technology Readiness Level (TRL) 6 by the end of Phase A.

A detailed trade space analysis of the proposed Uranus Orbiter and Probe mission informs options related to decisions on science, cost, and risk, including design choices of science tour phases, probe and orbiter payload mass, orbiter spacecraft mass, mission duration, and frequency of launch opportunities. The science tour phases flow from baseline and threshold objectives for different scientific disciplines: atmospheres, rings and small satellites, large moons, magnetospheres, and interiors. A broad search of both interplanetary cruise trajectories and Uranian tours produce a trade space of launch opportunities, flight times, and DeltaV that set bounds on spacecraft dry and wet mass. The mission concept employs current technology, such as a Falcon Heavy launch vehicle and a chemical propulsion system. Gravity assists from Venus and/or Earth enable launches throughout the 2030s, when Jupiter is unavailable. The low-risk and low-cost approach would deliver a probe to Uranus and completes a tour of its rings, moons, and magnetosphere within 19 years. A mission duration of 21 years enables multiple close approaches to Uranus that complete the set of objectives called for in the Planetary Science and Astrobiology Decadal Survey.

There has been an increase in interest in missions that drive significantly longer distances per day than what has currently been performed. For example, Endurance-A proposes driving several kilometers a day in order to reach its target traverse of 2000 km in 4 years. Additionally, some of these proposed missions, including Endurance-A and rovers for Permanently Shadowed Regions (PSRs) of the moon, require autonomous driving and absolute localization in darkness. Endurance-A proposes to drive 1200 km of its total traverse at night. The lack of natural light available during these missions limits what can be used as visual landmarks and the range at which landmarks can be observed. In order for planetary rovers to traverse long-ranges, onboard absolute localization is critical to the rover's ability to maintain its planned trajectory and avoid known hazardous regions. Currently, the localization performed onboard rovers is relative to the rover's frame of reference and is performed through the integration of wheel and visual odometry and inertial measurements. To accomplish absolute localization, a "ground-in-the-loop" (GITL) operation is performed wherein a human operator matches local maps or images from onboard with orbital images and maps. This GITL operation places a limit on the distance that can be driven in a day to a few hundred meters, which is the distance that the rover can maintain acceptable localization error via relative methods. Previous work has shown that using craters as landmarks is a promising approach for performing absolute localization on the moon during the day. In this work we present a method of absolute localization that utilizes craters as landmarks and matches detected crater edges on the surface with known craters in orbital maps. We focus on a localization method based on a perception system which has an external illuminator and a stereo camera. While other methods based on lidar exist, lidar is not currently planned for deployment on the current proposed nighttime and PSR missions. In this paper, we evaluate (1) both monocular and stereo based surface crater edge detection techniques, (2) methods of scoring the crater edge matches for optimal localization, and (3) localization performance on simulated Lunar surface imagery at night. We demonstrate that this technique shows promise for maintaining absolute localization error of less than 10 m required for most planetary rover missions.

This white paper addresses the following priority question identified by NASA's Small Bodies Assessment Group: Do sustainable habitable environments exist on any of the small bodies?This question is motivated by the results of the Dawn and New Horizons missions at Ceres and the Pluto system during the past decade.These missions revealed a class of objects that could potentially be habitable in the past and at present given the occurrence of internal oceans." Sustainability " is key here as these bodies are presumably heat-starved in the absence of recent tidal heating.The mechanisms that contributed to the preservation of liquid inside dwarf planets and their recent, and potentially ongoing activity, remain to be fully comprehended.Future investigations should confirm conditions for present-day habitability (e.g., liquid abundance and environmental conditions) and identify mechanisms that drive endogenic activity.This is particularly critical as abundant organic matter has been found at these objects.It is likely that many other bodies beyond Pluto's orbit are water-and organic-rich and geologically active.In order to pursue the exploration of small bodies of astrobiological value, recommendations for the next decade are ( in no priority order ): * To dedicate telescope time (including Vera C. Rubin Observatory and JWST) for the detailed surface characterization of dwarf planets and other large TNOs, * To pursue theoretical, experimental, and analog research addressing small body habitability, * To deploy a sample return mission to dwarf planet Ceres under the New Frontiers program, * To deploy a Pluto Orbiter as a part of the Flagship program, * To deploy a flyby mission to a dwarf planet or a large TNO in the Kuiper belt (possibly within the New Frontiers program and/or combined with other missions).Specific technology developments and investments required to achieve these endeavors are addressed in separate white papers but include in particular: * Experimental research on organics, brines, and super/hypervolatiles * Development of instrumentation suitable for astrobiology affordable under the resource allocations of competitive mission solicitations * Spacecraft technologies (consistent with OPAG's Recommendations) -Maturation of radioisotope electric propulsion and development of fission reactors -Continuation/augmentation of radioisotope production for radioisotope power systems -Investment in telecommunication technologies -Maturation of on-board data processing and autonomous operation technologies We also recommend that the decadal survey consider the critical role of team dynamics, equity, diversity, inclusion, and accessibility in planetary science.

We present a concept study for a distinctive robotic spacecraft mission that combines both the exploration of a never-before-visited class of planetary bodies and cutting-edge astrophysical investigations. The planetary targets are a class of objects called Centaurs that have relatively recently escaped from the Kuiper Belt and currently orbit closer to the Sun among the giant planets. We developed a trajectory that would visit several Centaurs, including the second largest known Centaur, 2060 Chiron, which displays enigmatic coma activity at large heliocentric distances and orbiting ring or dust structures. This concept takes advantage of the cruise times between planetary encounters to conduct nearly continuous astrophysical observations at wavelengths that are not accessible by ground-based facilities. Additionally, ride-along cubesats included aboard can be deployed at different points in the mission to perform various experiments or observations. This mission concept achieves its objectives with solar power (MegaFlex arrays), no new technology development, and within the approximate budget of a NASA New Frontiers class mission. The mission design accomplishes its objectives using solar electric propulsion and the recently developed NASA Evolutionary Xenon Thruster (NEXT) ion engines.

A performance analysis for aerocapture at Uranus and Neptune is presented and considers entry corridor width, peak deceleration, peak heat rate, total heat load, and the effect of postcapture orbit on the design parameters. Aerocapture mass benefit vs chemical capture is also quantified. Design relationships are found that can be used in flight system sizing for future studies involving aerocapture. Results are obtained for interplanetary trajectories for launch years from 2025 to 2036, including both chemical capture and high arrival V-infinity. The results show that based on the current assumption for errors and uncertainties aerocapture at Uranus and Neptune requires a mid-lift-to-drag ratio between 0.6 and 0.8. Technology recommendations are made for aerocapture missions to Uranus and Neptune.

Co-Authors: Gonçalo Afonso Samuel Albert Hisham Ali Antonella Alunni James Arnold Gilles Bailet Patricia Beauchamp Alan Cassell Jim Cutts Rohan Deshmukh Robert Dillman Sarah D’Souza Soumyo Dutta Charles Edwards Donald Ellerby John Elliott Giusy Falcone Alberto Fedele Jay Feldman Anthony Freeman Roberto Gardi Athul Girija Jeffrey Hill Tiago Hormigo Shayna Hume Christopher Jelloian Vandana Jha Breanna Johnson Craig Kluever Jean-Pierre Lebreton Marcus Lobbia Ping Lu Ye Lu Rafael Lugo Daniel Matz Robert Moses Michelle Munk Adam Nelessen Isil Sakraker Özmen Miguel Pérez-Ayúcar Richard Powell Zachary Putnam Jeremy Rea Sachin Alexander Reddy Thomas Reimer Sarag Saikia Kunio Sayanagi Stephan Schuster Jennifer Scully David Skulsky Ronald Sostaric Christophe Sotin Ben Tackett Ethiraj Venkatapathy Paul Wercinski Michael Wilder Michael Wright Cindy Young

Results are reported from a new lunar base study with a concise architectural program: build and operate a human-tended base that produces enough oxygen and hydrogen from lunar polar ice In-Situ Resource Utilization (ISRU) for four flights per year of a reusable lander shuttling between the Lunar Gateway and the base. The study examines for the modern era issues first developed and reconciled by the Robotic Lunar Surface Operations (RLSO) study published in 1990 and resurrected at the 69th IAC in Bremen. The new study updates key assumptions for 1) resources - lunar polar ice instead of ilmenite; 2) solar power - polar lighting conditions instead of the 28-day equatorial lunation cycle; 3) transportation - use of multiple flight systems now in development and planning; 4) base site planning - a range of options near, straddling, and inside permanently shadowed regions; 5) ISRU scenarios - for harvesting ice and for constructing radiation shielding from regolith. As did the original study, RLSO2 combines US experts in mission design, space architecture, robotic surface operations, autonomy, ISRU, operations analysis, and human space mission and lunar surface experience. Unlike the original study, the new study uses contemporary tools: CAD engineering of purpose-design base elements, and integrated performance captured in a numerical operations model. This allows rapid iteration to converge system sizing, and builds a legacy analysis tool that can assess the performance benefits and impacts of any proposed system element in the context of the overall base. The paper presents an overview of the ground rules, assumptions, methodology, operations model, element designs, base site plan, and quantitative findings. These findings include the performance of various regolith and ice resource utilization schemes as a function of base location and lunar surface parameters. The paper closes with short lists of the highest priority experiments and demonstrations needed on the lunar surface to retire key planning unknowns.

The highest priority science goals for Ice Giant missions are: 1) Interior structure of the Planet, and 2) Bulk composition that includes isotopes and noble gases. The interaction between the planetary interior and the atmosphere requires sustained global measurements. Noble gas and Isotope measurements require in situ measurement. Drag modulated aerocapture utilizing ADEPT offers more mass delivered to the Ice Giants than with propulsive orbit insertion. The Galileo Probe entered at a ‘hot’ spot which created interpretation challenges. Juno is providing valuable orbital measurements, but without in situ measurements the story is incomplete. Planetary scientists interested in Ice Giant missions should perform mission design studies with these new Entry System technologies to assess the feasibility within the context of the international collaboration framework. A mission architecture that includes probe(s) along with an orbiting spacecraft can deploy the probes at the desired location while taking simultaneous measurements from orbit to provide invaluable data that can correlate both global and local measurements. Entry System Technologies currently being developed by NASA are poised to enable missions that position the Orbiter & Probes through drag modulated aerocapture (ADEPT), and HEEET enables the Probes to survive the extreme environments encountered for entry into the atmospheric interior.

The ice giant planets, Uranus and Neptune, represent an important and relatively unexplored class of planet. Most of our detailed information about them comes from fleeting looks by the Voyager 2 spacecraft in the 1980s. Voyager, and ground-based work since then, found that these planets, their satellites, rings, and magnetospheres, challenge our understanding of the formation and evolution of planetary systems. We also now know that Uranus-Neptune size planets are common around other stars. These are some of the reasons ice giant exploration was a high priority in NASA's most recent Planetary Science Decadal Survey. In preparation for the next Decadal Survey, NASA, with ESA participation, conducted a broad study of possible ice giant missions in the 2024–2037 timeframe. This paper summarizes the key results of the study, and addresses questions that have been raised by the science community and in a recent NASA review. Foremost amongst these are questions about the science objectives, the science payload, and the importance of an atmospheric probe. The conclusions of the NASA/ESA study remain valid. In particular, it is a high priority to send an orbiter and atmospheric probe to at least one of the ice giants, with instrumentation to study all components of an ice giant system. Uranus and Neptune are found to be equally compelling as science targets. The two planets are not equivalent, however, and each system has things to teach us the other cannot. An additional mission study is needed to refine plans for future exploration of these worlds.

Since the cancellation of the Constellation Program, NASA officially has been focused on Mars as the next step for human exploration. Yet many in the space community believe that returning humans to the moon is more logical. Often-cited reasons for this include: (1) should Nature prove to be favorable, the moon could be the basis for expanding the space economy through Off-Earth Mining (OEM) and other commercial endeavors; (2) the moon is scientifically interesting and could serve as a platform for scientific facilities; and (3) useful experience could be gained there for the human journey to Mars. With this in mind, JPL's A-Team (Architecture Team) was tasked with developing conceptual lunar surface architectures that could simultaneously provide “living on another world” proving ground experience, but would also be affordable and offer truly significant commercial and international partnering opportunities. The task also required that the resulting architectures must eventually lead to and flow seamlessly into planning for human missions to Mars in the 2030s/2040s, if “things go well.” This aspect has been critically missing in other lunar architecture proposals. For continued NASA investment in any future human exploration architecture, affordability is a political imperative. This translates into managing the magnitude of the public investment by NASA in lunar infrastructure while doing those things that governments can do to stimulate new economic opportunities there. The menu of such potential strategic investments include: (1) engaging in science and exploration (e.g., Lewis and Clark); (2) reducing economic risks and resolving some technical uncertainties to create tipping points and real options for space entrepreneurs; (3) performing R&D/DDT&E and first buys of basic systems/services; (4) building public (lunar) infrastructure (e.g., roads, navigation aids, basic communications, logistics nodes, operational knowledge/de-confliction); and (5) acting as an anchor tenant. While incorporating these strategic elements into the architecture development as a way to encourage private sector development of the space economy and international partner contributions, the A-Team also recognized that both off-ramps and on-ramps (and periodic decision points) were needed to ensure that public goals for human space exploration were being met. Key questions might include: (1) are private investors coming on board; and (2) are we ready to go to Mars? In this paper, we present and describe the A-Team's lunar architecture that meets the requirements set out above using a high-level system-of-systems architectural view, which we call a “dance card.” We then process the information in the dance card into an affordability view, commonly called a “sand chart.” The method and model used for this is described in some detail, along with the sources of data. Lastly, we discuss the extensive commercial opportunities, which include in situ resource utilization (ISRU), cargo logistics, tourism, utilities for lunar activities, and construction, as well as the international partner contribution opportunities embodied within the architecture. We also review the viability of these commercial opportunities based on previous research.

The extreme environmental challenges of deep space exploration force unique solutions to small satellite design in order to enable their use as scientifically viable spacecraft. The challenges of implementing small satellites within limited resources can be daunting when faced with radiation effects on delicate electronics that require shielding or unique adaptations for protection, or mass, power" and volume limitations due to constraints placed by the carrier spacecraft, or even Planetary Protection compliant design techniques that drive assembly and testing. This paper will explore two concept studies where the environmental constraints and/or planetary protection mitigations drove the design of the Flight System. The paper will describe the key technical drivers on the Sylph mission concept to explore a plume at Europa as a secondary free-flyer as a part of the planned Europa Mission. Sylph is a radiation-hardened smallsat concept that would utilize terrain relative navigation to fly at low altitudes through a plume, if found, and relay the mass spectra data back through the flyby spacecraft during its 24-h mission. The second topic to be discussed will be the mission design constraints of the Near Earth Asteroid (NEA) Scout concept. NEAScout is a 6U cubesat that would utilize an 86 sq. m solar sail as propulsion to execute a" flyby with a near-Earth asteroid and help retire Strategic Knowledge Gaps for future human exploration. NEAScout would cruise for 24 months to reach and characterize one Near-Earth asteroid that is representative of Human Exploration targets and telemeter that data directly back to Earth at the end of its roughly 2.5 year mission.