ALBERT

Description: NASA is currently working on the Evolvabe Mars Campaign (EMC) study to outline transportation and mission options for human exploration of Mars. One of the key aspects of the EMC is leveraging current and planned near-term technology investments to build an affordable and evolvable approach to Mars exploration. This leveraging of investments includes the use of high-power Solar Electric Propulsion (SEP) systems, evolved from those currently under development in support of the Asteroid Redirect Mission (ARM), to deliver payloads to Mars. The EMC is considering several transportation options that combine solar electric and chemical propulsion technologies to deliver crew and cargo to Mars. In one primary architecture option, the SEP propulsion system is used to pre-deploy mission elements to Mars while a high-thrust chemical propulsion system is used to send crew on faster ballistic transfers between Earth and Mars. This high-thrust chemical system uses liquid oxygen - liquid methane main propulsion and reaction control systems integrated into the Methane Cryogenic Propulsion Stage (MCPS). Over the past year, there have been several studies completed to provide critical design and development information related to the MCPS. This paper is intended to provide a summary of these efforts. A summary of the current point of departure design for the MCPS is provided as well as an overview of the mission architecture and concept of operations that the MCPS is intended to support. To leverage the capabilities of solar electric propulsion to the greatest extent possible, the EMC architecture pre-deploys to Mars orbit the stages required for returning crew from Mars. While this changes the risk posture of the architecture, it can provide some mass savings by using higher-efficiency systems for interplanetary transfer. However, this does introduce significantly longer flight times to Mars which, in turn, increases the overall lifetime of the stages to as long as 2500 days. This unique aspect to the concept of operations introduces several challenges, specifically related to propellant storage and engine reliability. These challenges and some potential solutions are discussed. Specific focus is provided on two key technology areas; propulsion and cryogenic fluid management. In the area of propulsion development, the development of an integrated methane propulsion system that combines both main propulsion and reaction control is discussed. This includes an overview of potential development paths, areas where development for Mars applications are complementary to development efforts underway in other parts of the aerospace industry, and commonality between the MCPS methane propulsion applications and other Mars elements, including the Mars lander systems. This commonality is a key affordability aspect of the Evolvable Mars Campaign. A similar discussion is provided for cryogenic fluid management technologies including a discussion of how using cryo propulsion in the Mars transportation application not only provides performance benefits but also leverages decades of technology development investments made by NASA and its aerospace contractor community.

Description: A study was performed in conjunction with the In Space Technology Investment Area of NASA's Marshall Space Flight Center to investigate potential applications of solar sails to Mars missions. While solar sails have been proposed as possible candidates for several missions, including Geostorm and a Polar Observer mission, Mars has often been overlooked as a potential destination. It was found that solar sails may have potential in Mars observation missions with smaller payloads. Sail aerocapture maneuvers also show an improvement in payload delivery capability. This study has shown that solar sail spacecraft rival chemical interplanetary probes to Mars and may have applications in future Mars exploration.

Description: No abstract available

Description: Describes concept of the Fission Fragment Rocket Engine (FFRE).

Description: Fusion-based nuclear propulsion has the potential to enable fast interplanetary transportation. Due to the great distances between the planets of our solar system and the harmful radiation environment of interplanetary space, high specific impulse (Isp) propulsion in vehicles with high payload mass fractions must be developed to provide practical and safe vehicles for human spaceflight missions. Magneto-Inertial Fusion (MIF) is an approach which has been shown to potentially lead to a low cost, small fusion reactor/engine assembly (1). The Z-Pinch dense plasma focus method is an MIF concept in which a column of gas is compressed to thermonuclear conditions by an estimated axial current of approximately 100 MA. Recent advancements in experiments and the theoretical understanding of this concept suggest favorable scaling of fusion power output yield as I(sup 4) (2). The magnetic field resulting from the large current compresses the plasma to fusion conditions, and this is repeated over short timescales (10(exp -6) sec). This plasma formation is widely used in the field of Nuclear Weapons Effects (NWE) testing in the defense industry, as well as in fusion energy research. There is a wealth of literature characterizing Z-Pinch physics and existing models (3-5). In order to be useful in engineering analysis, a simplified Z-Pinch fusion thermodynamic model was developed to determine the quantity of plasma, plasma temperature, rate of expansion, energy production, etc. to calculate the parameters that characterize a propulsion system. The amount of nuclear fuel per pulse, mixture ratio of the D-T and nozzle liner propellant, and assumptions about the efficiency of the engine, enabled the sizing of the propulsion system and resulted in an estimate of the thrust and Isp of a Z-Pinch fusion propulsion system for the concept vehicle. MIF requires a magnetic nozzle to contain and direct the nuclear pulses, as well as a robust structure and radiation shielding. The structure, configuration, and materials of the nozzle must meet many severe requirements. The configuration would focus, in a conical manner, the Deuterium-Tritium (D-T) fuel and Lithium-6/7 liner fluid to meet at a specific point that acts as a cathode so the Li-6 can serve as a current return path to complete the circuit. In addition to serving as a current return path, the Li liner also serves as a radiation shield. The advantage to this configuration is the reaction between neutrons and Li-6 results in the production of additional Tritium, thus adding further fuel to the fusion reaction and boosting the energy output. To understand the applicability of Z-Pinch propulsion to interplanetary travel, it is necessary to design a concept vehicle that uses it. The propulsion system significantly impacts the design of the electrical, thermal control, avionics, radiation shielding, and structural subsystems of a vehicle. The design reference mission is the transport of crew and cargo to Mars and back, with the intention that the vehicle be reused for other missions. Several aspects of this vehicle are based on a previous crewed fusion vehicle study called Human Outer Planet Exploration (HOPE), which employed a Magnetized Target Fusion (MTF) propulsion concept. Analysis of this propulsion system concludes that a 40-fold increase of Isp over chemical propulsion is predicted. This along with a greater than 30% predicted payload mass fraction certainly warrants further development of enabling technologies. The vehicle is designed for multiple interplanetary missions and conceivably may be suited for an automated one-way interstellar voyage.

Description: This slide presentation reviews a project that aims to develop a conceptual design for a Z-pinch thruster, that could be applied to develop advanced thruster designs which promise high thrust/high specific impulse propulsion. Overviews shows the concept of the design, which use annular nozzles with deuterium-tritium (D-T) fuel and a Lithium mixture as a cathode, Charts show the engine performance as a function of linear mass, nozzle performance (i.e., plasma segment trajectories), and mission analysis for possible Mars and Jupiter missions using this concept for propulsion. Slides show views of the concepts for the vehicle configuration, thrust coil configuration, the power management system, the structural analysis of the magnetic nozzle, the thermal management system, and the avionics suite,

Description: NASA is continuing to investigate mission and transportation system alternatives to support human exploration of Mars. Several publications over the last few years have outlined, in detail, the baseline reference architectures under consideration. These alternatives include SEP-Chemical Hybrid Propulsion Systems, oxygen/methane propulsion stages, and nuclear thermal propulsion systems. Studies to date have focused on identifying mission architectures that leverage these different transportation options to best support a Mars mission within the context of overarching guidelines and constraints. The focus on identifying "closed" reference mission architectures for these transportation options is a key first step in comparing alternatives and supporting the development of technology investment strategies. Architecture closure implies that the architecture identified provides a viable solution which meets all constraints and closely aligns with guidelines. If a viable architecture cannot be identified for a given transportation option, there is no need to continue investigating that option. However, at this early stage of architecture development, metrics of comparison should look beyond how these architectures perform relative to the baseline reference mission. Architectural robustness, or an insensitivity to requirements drift, should also be considered in any comparison of architectures. At this early stage of design, mission requirements have the potential to change as more definition is provided and more analyses are completed. Particularly in relation to the mass of transported elements, including Mars landers and crew habitat, it is recognized that as designs for these elements mature there exists the potential for mass growth. Selection of an architecture alternative carries with it programmatic risks and relative sensitivity to mass growth can provide insight into a particular architecture option's risk of being unable to complete its mission without significant redesign as more element definition is provided. This paper outlines the current understanding of the sensitivity

Description: Astronauts on a mission to Mars will require several vehicles working together to get to Mars orbit, descend to the surface of Mars, support them while theyre there, and return them to Earth. The Mars Ascent Vehicle (MAV) transports the crew off the surface of Mars to a waiting Earth return vehicle in Mars orbit and is a particularly influential part of the mission architecture because it sets performance requirements for the lander and in-space transportation vehicles. With this in mind, efforts have been made to minimize the MAV mass, and its impact on the other vehicles. A minimal mass MAV design using methane and in situ generated oxygen propellants was presented in 2015. Since that time, refinements have been made in most subsystems to incorporate findings from ongoing research into key technologies, improved understanding of environments and further analysis of design options. This paper presents an overview of the current MAV reference design used in NASAs human Mars mission studies, and includes a description of the operations, configuration, subsystem design, and a vehicle mass summary.

Description: Develop two evolutionary rigid vehicle concepts to deliver human-scale payloads (20 metric tons) to the surface of Mars: Capsule; Lifting body, mid-range lift-to-drag ratio (Mid L/D). Determine vehicle configurations for various mission flight phases. Determine vehicle performance: Integrated system mass; Ability to meet landing constraints; Payload packaging and surface access. Provide technology investment recommendations to NASAs Space Technology Mission Directorate.