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Configuration and Projected Capabilities of the Common Habitat Medical Care Facility

The Common Habitat is a large, long-duration habitat being explored as part of a conceptual study (not an active NASA program) that uses an SLS core stage Liquid Oxygen (LOX) tank as its primary structure. It is intended for use on the Moon as part of a permanently occupied outpost, on Mars as part of an outpost that will be occupied for hundreds of days at a time, and in deep space as part of the Deep Space Exploration Vehicle where it will support crewed missions up to 1200 days in duration. A study of internal orientation and crew size resulted in a Common Habitat configuration sized for a crew of eight with a three-deck horizontal orientation. Additional work outside the scope of this paper is developing a vertical translation system, a crew mobility aids system based on wearable gecko-derived grippers, and a crew seating/restraint system. These systems are all assumed for use in conjunction with the Medical Care Facility, which is needed to maintain crew well-being during these missions, where distance from Earth precludes the possibility of evacuation to Earth. This paper describes recent improvements in the Common Habitat Medical Care Facility and associated benefits for crew survivability in long duration missions beyond Earth orbit. These improvements were made with the assistance of a NASA Pathways intern whose experience includes a tour of duty in Afghanistan as an Army combat medic with the 691st GHOST-T, attached to the 1st and 7th US Special Forces Groups as part of Operation Freedom’s Sentinel, where he helped provide far-forward surgical capabilities in austere combat environments. The initial baseline Medical Care Facility was developed working in conjunction with University of Houston Space Architecture graduate students. The facility was placed on the upper deck of the Common Habitat in a location that provided privacy, operational volume, and was close to the vertical translation pathway. The notional outfitting repurposed component CAD models from unrelated studies and notionally indicated a level of care roughly equivalent to that aboard the International Space Station. The CAD modeling provided notional stowage volumes, a deployable surface, some fixed equipment, an ultrasound, and a potentially reconfigurable treatment table. While this facility is clearly a competent arrangement, it was desired to leverage available expertise and upgrade the station given the vast distances from Earth to be experienced by the Common Habitat. Key driving requirements applied to the upgrade included to provide NASA’s Medical Level of Care V, offer enhanced telemedicine capabilities, provide patient physical accommodation, provide caregiver access to the patient from all sides, include sliding pocket doors for access to hygiene and to the Vertical Translation System, and to add any additional capability possible for the best achievable medical care. The first step in the facility upgrade was to quantify the current medical inventory on the International Space Station and ensure that sufficient stowage volume was present for this purpose. To that end, the ISS medical kits were reviewed, and eight full size mid deck lockers were placed in the facility. A number of additional devices were also added, based on the co-author’s combat medic experience. Also, two fixed shelves and one horizontal work surface were added to the Medical Care Facility, with the shelves providing storage space for the additional devices and the work surface providing a location for the caregiver to work or stage equipment. Four display monitors were added to the wall above the horizontal work surface, supporting data display, telemedicine, conferencing, or other needs. The existing treatment table was replaced with a mobile surgical stretcher-chair. Two additional doors were added to the Medical Care Facility. One leads directly to the hygiene compartment, allowing it to support medical operations in addition to providing galley/wardroom support. The other door leads directly into the Vertical Translation System. The wall adjacent to the subsystems bay was moved, adding additional volume to the Medical Care Facility. This improved caregiver access to the patient and allowed for a larger number of caregivers to be present. It also provided options for relocation of support equipment relative to the patient as needed. In the upgraded Medical Care Facility, the Surgical Stretcher-Chair and the Vertical Translation System can work together to provide incapacitated crew member transport from a site of injury on any deck of the Common Habitat to the Medical Care Facility. It can also support patient treatment in a variety of positions including a variety of sitting postures and a supine posture at a variety of pitch angles. The facility can also support caregiver office work for review of examination results, private consultation, inventory and maintenance, and a variety of other purposes. A forward activity will be to conduct evaluations of the Medical Care Facility with different medical scenarios. Additionally, ambient and task lighting selections remain as forward work. The eight middeck lockers can be augmented to use as portable equipment carts, similar to a manner in which maintenance facility stowage was used as portable carts during the NASA Desert Research and Technology Studies in the Constellation Program. Trash accommodation will also need forward work to assess, including provision for wet trash, dry trash, and biological waste. It will be important to assess a redesign of the surgical stretcher-chair. The commercial version used in the upgrade can only enable vertical translation in the seated configuration, requiring the patient to bend both hips and knees. A possible redesign of the chair will allow for vertical translation without requiring any bending at the hip or knees. Also, the commercial version is wheeled, making it mobile in gravity but unanchored in microgravity. Work will be needed to adapt the chair for gravity-independent performance. The hygiene compartment can be redesigned to serve both as a medical scrub facility and for galley hand washing. Pending sufficient volume, it may also be possible to place sanitation equipment in this location to clean medical tools. Finally, most space architectures have never allowed for more than one incapacitated crew member, but several scenarios could potentially injure two or more crew in the same incident. This facility could be assessed to determine its present ability to address two or more injured crew in parallel and determine the potential upper limit for number of treatable crew in a multi-crew injury scenario, or to treat polytrauma of a single patient.

Common Habitat

Internal Architecture of the Common Habitat

The core stage liquid oxygen tank of the Space Launch System can be manufactured as a habitat instead of as a propellant tank, with a common design such that it is equally suitable for use in 0g, 1/6g, 3/8g, 1g, or variable artificial gravity. It is capable of sustaining a crew size of eight for missions up to 1200 days in duration. This Common Habitat can be the central element of a human spaceflight architecture that encompasses the Moon, Mars, and other destinations within the inner solar system. Within this archtiecture, the Common Habitat is specifically used as the core habitation element within a Lunar Base Camp, Mars Base Camp, and the Deep Space Exploration Vehicle. The Common Habitat internal architecture applies a design philosophy to separate crew functions according to deck. The lower deck is reserved for private functions. It includes eight private crew quarters and four waste and hygiene clusters – each with a private waste management compartment, private full body hygiene compartment, and private foyer/clothes changing area. The mid deck is primarily allocated to mission-related functions. It includes an exercise facility, fabrication / maintenance / repair facility, physical science laboratory (physics, geology, and remote sensing: astronomy, heliophysics, planetary science, and Earth science), and life science laboratory (biology and human research). The mid deck also has four external hatches, clocked one every 90 degrees, centered on the vehicle vertical centerline. Each hatch has a 60-inch tall by 40-inch wide opening with the mid deck floor 16 inches below the bottom lip of the hatch opening. The upper deck also includes some mission functions, but is primarily allocated to social functions. It includes a large galley, wardroom with projector and display screen, plant growth chambers, bulk stowage, command and control station, medical facility, hygiene compartment, and vehicle subsystems.

Habitability

Human Cargo Resupply Logistics at Mars Using 150kW SEP Tug Cyclers

The ultimate goal of the Evolvable Mars Campaign is to build up a sustainable outpost at Mars that would be continually staffed with rotating crews. During this stage of human Mars exploration, it would be necessary to provision the crews with equipment and supplies both before and during their missions. In this paper, we study the use of 150 kW reusable SEP tugs as a means to deliver elements both to orbit and to the surface. The SEP tugs would make use of technology currently being developed for the proposed Asteroid Robotic Redirect Mission (ARRM). They would also be used to deliver food and supplies to sustain the crews similar to resupply missions for the International Space Station. The SEP tugs envisioned would be staged at a quasi-stable Lunar Near Rectilinear Orbit (NRO). The tugs would then mate with cargo vessels and xenon propellant being delivered by an SLS launch vehicle and continue on to Mars orbit where the cargo is delivered and the SEP tug returns to NRO to repeat the process. It was found that it is more efficient to deliver surface cargo via direct launch and entry versus using the tug cycler. Thousands of optimized low-thrust trajectories were simulated in order to create “Bacon plots” (like porkchop plots, but for low thrust transfers) in order to map out potential trajectories for dates from 2039 to 2052. This study maps out the buildup of a surface outpost as well as the necessary orbital and surface resupply launches in order to maintain it. In the steady state, a cadence of 9 cargo launches is required every 4 years to sustain the human outpost.

Post, Kevin

Down-Selection of Four Common Habitat Variants

The Common Habitat is a large habitat that uses the Space Launch System core stage liquid oxygen tank as its primary structure. It has a gravity-independent internal architecture, such that identical units can be used on the lunar surface, Mars surface, and in microgravity. In developing the habitat, two key architectural questions emerged. Should the internal layout use a vertical or horizontal orientation of the tank? Should the crew size be four or eight? This led to the design of four variants: a four-crew horizontal, four-crew vertical, eight-crew horizontal, and eight-crew vertical. The primary consideration applied for down-selection was the crew experience living and working in the habitat, inclusive of crew productivity, well-being, and survivability. Based on this consideration, a series of seven assessments was performed to compare the four variants. A stowage assessment developed a standard logistics module and then considered the amounts of water to be stored in each variant. It then estimated how much stowage could be carried onboard each Common Habitat and how many logistics modules are required by each variant for a given mission duration. A functional analysis identified and compared the living and working functions across the four habitat, ranking them relative to each other. A crew time assessment first estimated the total crew time, building a weekly crew timeline for both four and eight-person crews. It then allocated time to activities linked to living and working functions, comparing how much time was available for each function in each variant. A science productivity assessment developed a relative metric using crew time, science stowage, and assumed rates of experiment consumables use to analytically compare the four variants. It also comparatively ranked the habitats with respect to a number of subjective parameters and a workstation acceptability rating. A maintenance capacity assessment identified and compared eleven generic maintenance capabilities across the four variants and also ranked the variants for their predicted ability to complete twelve fabrication, maintenance, and repair scenarios. A contingency responsiveness analysis examined twelve serious in-flight contingencies. For each scenario, the number of crew needed to respond was predicted and acceptability of various aspects of contingency response was evaluated, comparing the four variants against each other. Finally, in a habitability assessment, 120 habitability characteristics reflecting 13 major categories were evaluated for each habitat. These results were compared to identify the most acceptable habitat in each category. Ultimately, the data was shown to favor the horizontal orientation over the vertical and an eight-person crew over four. Implications of selecting this variant are discussed, including specific architectural challenges that result from the use of the full SLS liquid oxygen tank.

Habitability

Down-Selection of Four Common Habitat Variants

The Common Habitat is a large habitat developed as an alternative architecture study, not part of the current NASA baseline, that uses the SLS core stage liquid oxygen tank as its primary structure. It has a gravity-independent internal architecture, such that identical units can be used on the lunar surface, Mars surface, and in microgravity. In developing the habitat, two key architectural questions emerged. Should the internal layout use a vertical or horizontal orientation of the tank? Should the crew size be four or eight? This led to the design of four variants: a four-crew horizontal, four-crew vertical, eight-crew horizontal, and eight-crew vertical. The four-crew variants use a shortened version of the tank while the eight-crew variants use the entire tank. The primary consideration applied for down-selection is the crew experience living and working in the habitat, inclusive of crew productivity, well-being, and survivability. Based on this consideration, a series of seven assessments were performed to compare the variants. This analysis was performed as an unfunded, volunteer activity leveraging civil servants across multiple field centers, most with expertise working in various Artemis teams. Additionally, the evaluation was limited to the use of CAD models, images, and spreadsheet data, with no resources available for mockups or Virtual Reality. A logistics analysis developed a standard logistics module and then estimated how much stowage could be carried onboard each Common Habitat and how many logistics modules are required by each variant for a given mission duration. It also considered the amounts of water to be stored in each variant. A functional analysis identified and compared the living and working functions across the habitats, ranking them relative to each other. A crew time assessment first estimated the total crew time, building a weekly crew timeline for both four and eight-person crews. It then allocated time to activities linked to living and working functions, comparing how much time was available for each function in each variant. A science productivity assessment developed a relative metric using crew time, science stowage, and assumed rates of experiment consumables use to analytically compare the four variants. It also comparatively ranked the habitats with respect to a number of subjective parameters and a workstation acceptability rating. A maintenance capacity assessment identified and compared eleven generic maintenance capabilities across the variants and also ranked them for their predicted ability to complete twelve fabrication, maintenance, and repair scenarios. A contingency responsiveness analysis examined twelve serious in-flight contingencies. For each scenario, the number of crew needed to respond were predicted and acceptability of various aspects of contingency response were evaluated, comparing the variants against each other. Finally, in a habitability assessment, 120 habitability characteristics reflecting 13 major categories were evaluated for each habitat. These results were compared to identify the most acceptable habitat in each category. Ultimately, the data favored the horizontal orientation over the vertical and an eight-person crew over four. Implications of selecting this variant are discussed, including specific architectural challenges that result from the use of the full tank.

Habitability

Fast track lunar NTR systems assessment for the First Lunar Outpost and its evolvability to Mars

The objectives of the 'fast track' lunar Nuclear Thermal Rocket (NTR) analysis are to quantify necessary engine/stage characteristics to perform NASA's 'First Lunar Outpost' scenario and to assess the potential for evolution to Mars mission applications. By developing NTR/stage technologies for use in NASA's 'First Lunar Outpost' scenario, NASA will make a major down payment on the key components needed for the follow-on Mars Space Transportation System. A faster, cheaper approach to overall lunar/Mars exploration is expected.

Borowski, Stanley K.

Options for Offloading a 90-Ton Common Habitat from its Lander on the Surface of Mars

The Common Habitat is a large, long-duration habitat being explored as part of a conceptual study (not an active NASA program) that uses an SLS core stage liquid oxygen (LOX) tank as its primary structure. Measuring 8.4 meters in diameter and 15.6 meters in length, it is manufactured as a habitat and launched as such into space. It is intended for use on the Moon as part of a permanently occupied outpost, on Mars as part of an outpost that will be occupied for hundreds of days at a time, and in deep space as part of the Deep Space Exploration Vehicle where it will support crewed missions up to 1200 days in duration. A study of internal orientation and crew size resulted in a Common Habitat configuration sized for a crew of eight with a three-deck horizontal orientation. There are obvious challenges associated with the delivery of such a large habitat, which may mass as much as 90-tons when initially deployed. The Mars destination in particular imposes extreme challenges due to Martian gravity. This paper identifies initial options for the offloading of a 90-ton Common Habitat from a lander spacecraft on the surface of Mars. On Mars, the Common Habitat is part of a surface outpost where a Habitation Zone includes the Common Habitat docked to a two-chamber airlock node, up to two logistics modules, and up to two pressurized rovers. It is connected by underground conduit to a radiator farm and communications tower assembly. These elements and other surface infrastructure, including robotic systems for surface preparation, are landed prior to the Common Habitat. In the baseline Common Habitat Architecture, the Common Habitat is delivered on the third heavy cargo flight. The Habitation Zone configuration dictates that the Common Habitat needs to be offloaded from the lander. All of the docked elements require direct access to the surface and the Common Habitat must actually be placed in a trench to lower its docking ports to be level with those of the mated elements. Additionally, the habitat must be emplaced in a horizontal configuration, while for any conceivable Earth launch system it must be launched in a vertical configuration. It is true that the Common Habitat must be offloaded from its lander on both the Moon and Mars and a common offloading system must therefore work in both destinations. Mars, however, is considered the driving case for offloading in most, but not all, aspects. A four-day internal study in 2021 recommended that a modified Starship be used to land the Common Habitat on Mars and considered multiple approaches to offload the Common Habitat from the payload section and lower it to the surface. The topic was presented at a public hackathon organized by the Johnson Space Center’s Emerge Employee Resource Group. One team took on the challenge and proposed a concept in some ways similar to the previously considered jib crane. Despite the excellent innovation in the team’s work, a number of study refinements are necessary to truly establish feasibility. These and other future work needed to mature the concept are discussed in this work.

Lander Offloading

Mars extant-life campaign using an approach based on Earth-analog habitats

The Mars Robotic Outpost group at JPL has identified sixteen potential momentous discoveries that if found on Mars would alter planning for the future Mars exploration program. This paper details one possible approach to the discovery of and response to the 'momentous discovery'' of extant life on Mars. The approach detailed in this paper, the Mars Extant-Life (MEL) campaign, is a comprehensive and flexible program to find living organisms on Mars by studying Earth-analog habitats of extremophile communities.

orbital surveys

The diverse roles of unmanned precursors in supporting manned missions to Mars

The diverse roles of robotic precursors are examined in the context of recent NASA studies on a long-term program to establish a human outpost on Mars. The scenario in which these precursors must function and the requirements they must satisfy are discussed, and a tentative set of missions is developed which satisfy this scenario and the set of requirements. The missions and an example of vehicle implementation are described, and how these missions assist in technology demonstrations and building an appropriate infrastructure is addressed. The experience to be gained in the areas of mission operations and management as a result of executing the missions is considered.

Craig, Mark K.

Agriculture on Mars: Soils for Plant Growth

Robotic rovers and landers have enabled the mineralogical, chemical, and physical characterization of loose, unconsolidated materials on the surface of Mars. Planetary scientists refer to the regolith material as "soil." NASA is currently planning to send humans to Mars in the mid 2030s. Early missions may rely on the use of onsite resources to enable exploration and self-sufficient outposts on Mars. The martian "soil" and surface environment contain all essential plant growth elements. The study of martian surface materials and how they might react as agricultural soils opens a new frontier for researchers in the soil science community. Other potential applications for surface "soils" include (i) sources for extraction of essential plant-growth nutrients, (ii) sources of O2, H2, CO2, and H2O, (iii) substrates for microbial populations in the degradation of wastes, and (iv) shielding materials surrounding outpost structures to protect humans, plants, and microorganisms from radiation. There are many challenges that will have to be addressed by soil scientists prior to human exploration over the next two decades.

Ming, D. W.

Manned Mars Explorer project: Guidelines for a manned mission to the vicinity of Mars using Phobos as a staging outpost; schematic vehicle designs considering chemical and nuclear electric propulsion

The Manned Mars Explorer (MME) project responds to the fundamental problems of sending human beings to Mars in a mission scenario and schematic vehicle designs. The mission scenario targets an opposition class Venus inbound swingby for its trajectory with concentration on Phobos and/or Deimos as a staging base for initial and future Mars vicinity operations. Optional vehicles are presented as a comparison using nuclear electric power/propulsion technology. A Manned Planetary Vehicle and Crew Command Vehicle are used to accomplish the targeted mission. The Manned Planetary Vehicle utilizes the mature technology of chemical propulsion combined with an advanced aerobrake, tether and pressurized environment system. The Crew Command Vehicle is the workhorse of the mission performing many different functions including a manned Mars landing, and Phobos rendezvous.

Nolan, Sean

Long duration mission support operations concepts

It is suggested that the system operations will be one of the most expensive parts of the Mars mission, and that, in order to reduce their cost, they should be considered during the conceptual phase of the Space Exploration Initiative (SEI) program. System operations of Space Station Freedom, Lunar outpost, and Mars Rover Sample Return are examined in order to develop a similar concept for the manned Mars mission. Factors that have to be taken into account include: (1) psychological stresses caused by long periods of isolation; (2) the effects of boredom; (3) the necessity of onboard training to maintain a high level of crew skills; and (4) the 40-min time delays between issuing and receiving a command, which make real-time flight control inoperative and require long-term decisions to be made by the ground support.

Eggleston, T. W.

Common Habitat Base Camp for Moon and Mars Surface Operations

The Common Habitat uses the SLS Core Stage Liquid Oxygen tank as the primary structure (similar to Skylab) and has an internal architecture compatible with microgravity, lunar gravity, and Mars gravity, such that identical versions of the same design can be used in all three environments. Applying the large dimensions and eight-person crew size of the Common Habitat to a surface architecture leads to a unique base camp configuration. A notional such base camp is described in this analysis. The base camp includes four distributed zones – habitation, landing, power, and resource production. The base camp is deployed and assembled in three phases: site preparation, element staging, and habitat delivery, each of which are briefly discussed. Crew arrival and departure is discussed, including variations caused by orbital mechanics-induced differences between the Moon and Mars base camps. Trash and logistics operations are described. Finally, crew operations within the base camp are described.

Lunar Outpost

Fast Track Lunar NTR Systems Assessment for NASA's First Lunar Outpost and Its Evolvability to Mars

Integrated systems and missions studies are presented for an evolutionary lunar-to-Mars space transportation system (STS) based on nuclear thermal rocket (NTR) technology. A 'standardized' set of engine and stage components are identified and used in a 'building block' fashion to configure a variety of piloted and cargo, lunar and Mars vehicles. The reference NTR characteristics include a thrust of 50 thousand pounds force (klbf), specific impulse (I(sub sp)) of 900 seconds, and an engine thrust-to-weight ratio of 4. 3. For the National Aeronautics and Space Administrations (NASA) First Lunar Outpost (FLO) mission, and expendable NTR stage powered by two such engines can deliver approximately 96 metric tonnes (t) to trans-lunar injection (TLI) conditions for an initial mass in low Earth orbit (IMLEO) of approximately 198 t compared to 250 t for a cryogenic chemical system. The stage liquid hydrogen (LH2) tank has a diameter, length, and capacity of 10 m, 14.5 m and 66 t, respectively. By extending the stage length and LH2 capacity to approximately 20 m and 96 t, a single launch Mars cargo vehicle could deliver to an elliptical Mars parking orbit a 63 t Mars excursion vehicle (MEV) with a 45 t surface payload. Three 50 klbf engines and the two standardized LH2 tanks developed for the lunar and Mars cargo vehicles are used to configure the vehicles supporting piloted Mars missions as early as 2010. The 'modular' NTR vehicle approach forms the basis for an efficient STS able to handle the needs of a wide spectrum of lunar and Mars missions.

Borowski, Stanley K.

Outpost Assembly Using the ATHLETE Mobility System

A planetary surface outpost will likely consist of elements delivered on multiple manifests, that will need to be assembled from a scattering of landings. Using the All-Terrain Hex-Limbed Extra-Terrestrial Explorer (ATHLETE) limbed robotic mobility system, the outpost site can be prepared in advance through leveling, paving, and in-situ structures. ATHLETE will be able to carry pressurized and non-pressurized payloads overland from the lander descent stage to the outpost location, and perform precision docking and assembly of components. In addition, spent descent stages can be carried to assembly locations to form elevated decks for external work platforms above the planet surface. This paper discusses several concepts that have been studied for possible inclusion in the NASA Evolvable Mars Campaign human exploration mission scenarios.

Mars outpost

Exploration Studies Technical Report - Volume 3: Special Reports, Studies, and Indepth Systems Assessments

The NASA Office of Exploration has been tasked with defining and recommending alternatives for an early 1990's national decision on a focused program of human exploration of the solar system. The Mission Analysis and System Engineering (MASE) group, which is managed by the Exploration Studies Office at the Johnson Space Center, is responsible for coordinating the technical studies necessary for accomplishing such a task. This technical report describes the process that has been developed in a case study approach. The four case studies that were developed in FY88 include: 1. Human expedition to Phobos 2. Human expeditions to Mars 3. Lunar observatory 4. Lunar outpost to early Mars evolution The final outcome of this effort is a set of programmatic and technical conclusions and recommendations for the following year's work. Volume III is a collection of trade study results, indepth systems assessments, and workshop reports which describe aspects of FY 1988 analyses in more depth.

Interplanetary flight

Exploration Studies Technical Report - Volume 1: Technical Summary

The Office of Exploration (OEXP) at NASA Headquarters has been tasked with defining and recommending alternatives for an early 1990's national decision on a focused program of human exploration of the solar system. The Mission Analysis and System Engineering (MASE) group, which is managed by the Exploration Studies Office at the Lyndon B. Johnson Space Center, is responsible for coordinating the technical studies necessary for accomplishing such a task. This technical report, produced by the MASE, describes the process that has been developed in a case study approach. The four case studies developed in FY88 include: 1. Human Expedition to Phobos 2. Human Expedition to Mars 3. Lunar Observatory 4. Lunar Outpost to Early Mars Evolution The final outcome of this effort is a set of programmatic and technical conclusions and recommendations for the following year's work.

Lunar Mining & Oxygen Production

Exploration Studies Technical Report - Volume 2: Studies Approach and Results

The NASA Office of Exploration has been tasked with defining and recommending alternatives for an early 1990's national decision on a focused program of human exploration of the solar system. The Mission Analysis and System Engineering (MASE) group, which is managed by the Exploration Studies Office at the Johnson Space Center, is responsible for coordinating the technical studies necessary for accomplishing such a task. This technical report describes the process that has been developed in a case study approach. The four case studies that were developed in FY88 include: 1. Human expedition to Phobos 2. Human expeditions to Mars 3. Lunar observatory 4. Lunar outpost to early Mars evolution The final outcome of this effort is a set of programmatic and technical conclusions and recommendations for the following year's work. Volume 2 describes the case study process, the technical results of each of the case studies, and opportunities for additional study. Included in the discussion of each case study is a description of the mission key features and profile. Mission definition and manifesting are detailed, followed by a description of the mission architecture and infrastructure. Systems concepts for the required orbital nodes, transportation systems, and planetary surface systems are discussed. Prerequisite implementation plans resulting from the synthesized case studies are described and in-depth assessments are presented.

Interplanetary flight