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Polsgrove, Tara

Publications and source records attributed to Polsgrove, Tara.

At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2020

NASA’s Human Landing System: The Strategy for the 2024 Mission and Future Sustainability

In response to the 2018 White House Space Policy Directive- sustainable lunar exploration, and to the Vice President’s March 2019 direction to do so by 2024, NASA is working to establish humanity's presence on and around the Moon by: 1) sending payloads to its surface, 2) assembling the Gateway outpost in orbit and 3) demonstrating the first human lunar landings since 1972. NASA’s Artemis program is implementing a multi-faceted and coordinated agency-wide approach with a focus on the lunar South Pole. The Artemis missions will demonstrate new technologies, capabilities and business approaches needed for future exploration, including Mars. Assessing options to accelerate development of required systems, NASA is utilizing public-private engagements through the Human Exploration and Operations (HEO) Mission Directorate’s NextSTEP Broad Agency Announcements. The design, development and demonstration of the Human Landing System (HLS) is expected to be led by commercial partners. Utilizing efforts across mission directorates, the Artemis effort will benefit from programs from the Science Mission Directorate (SMD) and Space Technology Mission Directorate (STMD). SMD’s Commercial Lunar Payload Services (CLPS) initiative will procure commercial robotic lunar delivery services and the development of science instruments and technology demonstration payloads. The Space Technology Mission Directorate (STMD) portfolio of technology advancements relative to HLS include lunar lander components and technologies for pointing, navigation and tracking, fuel storage and transfer, autonomy and mobility, communications, propulsion and power. In addition to describing the objectives and requirements of the 2024 Artemis mission, this paper will present NASA’s approach to accessing the lunar surface with an affordable human-rated landing system, current status and the role o a sustainable lunar presence.

Chavers, Greg↗
NASA NTRS2018

The Moon as a Stepping Stone to Human Mars Missions

As we venture back to the Moon with a longer term goal of future Mars missions, lunar missions can provide an important testbed for technologies, systems and operations that directly feed forward to future Mars needs. Gateway missions can provide good in-space transportation feed forward to human Mars missions. Modest operations on the Moon such as the GER (Global Exploration Roadmap)-class missions, can provide key Mars human performance and surface mission capability development and risk reduction. A human return to the Moon can, if done correctly, serve as an excellent down payment to Mars.

Connolly, John F.↗
NASA NTRS2018

Payload Sensitivities for Human Mars Exploration Transportation Systems

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

Percy, Thomas K.↗
NASA NTRS2018

Human Mars Entry, Descent and Landing Architecture Study (EDLAS): Rigid Decelerators

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 NASA’s Space Technology Mission Directorate.

Polsgrove, Tara↗
NASA NTRS2017

Human Mars Mission Design - The Ultimate Systems Challenge

A human mission to Mars will occur at some time in the coming decades. When it does, it will be the end result of a complex network of interconnected design choices, systems analyses, technical optimizations, and non-technical compromises. This mission will extend the technologies, engineering design, and systems analyses to new limits, and may very well be the most complex undertaking in human history. It can be illustrated as a large menu, or as a large decision tree. Whatever the visualization tool, there are numerous design decisions required to assemble a human Mars mission, and many of these interconnect with one another. This paper examines these many decisions and further details a number of choices that are highly interwoven throughout the mission design. The large quantity of variables and their interconnectedness results in a highly complex systems challenge, and the paper illustrates how a change in one variable results in ripples (sometimes unintended) throughout many other facets of the design. The paper concludes with a discussion of some mission design variables that can be addressed first, and those that have already been addressed as a result of ongoing National Aeronautics and Space Administration (NASA) developments, or as a result of decisions outside the technical arena. It advocates the need for a 'reference design' that can be used as a point of comparison, and to illustrate the system-wide impacts as design variables change.

Connolly, John F.↗
NASA NTRS2017

Safe Haven Configurations for Deep Space Transit Habitats

Throughout the human space flight program there have been instances where systems failures resulting in smoke, fire, and pressure loss have occurred onboard space vehicles, putting crews at risk for loss of mission and loss of life. In most instances the missions have been in Low-Earth-Orbit (LEO) or Earth-Moon vicinity, with access to multiple volumes that could be used to quickly seal off the damaged module or access escape vehicles for return to Earth. For long duration missions beyond LEO, including Mars transit missions of about 1100 days, the mass penalty for multiple volumes and operating in an environment where a quick return will not be possible have been concerns. In 2016, a study was done to investigate a variety of dual pressure vessel configurations for habitats that could protect the crew from these hazards. It was found that with a modest increase in total mass it should be possible to provide significant protection for the crew. Several configurations were considered that either had a small safe haven to provide 30-days to recover, or a full duration safe haven using two equal size pressure vessel volumes. The 30-day safe haven was found to be the simplest, yielding the least total mass impact but still with some risk if recovery is not possible during that timeframe. The full duration safe haven was the most massive option but provided the most robust solution. This paper provides information on the various layouts developed during the study and provides a discussion of the findings for implementing a safe haven in future habitat designs.

Smitherman, David↗
NASA NTRS2017

Safe Haven Configurations for Deep Space Transit Habitats

Throughout the human space flight program there have been instances where smoke, fire, and pressure loss have occurred onboard space vehicles, putting crews at risk for loss of mission and loss of life. In every instance the mission has been in Low-Earth-Orbit (LEO) with access to multiple volumes that could be used to quickly seal off the damaged module or escape vehicles for a quick return to Earth. For long duration space missions beyond LEO, including Mars transit missions of about 1000 days, the mass penalty for multiple volumes has been a concern as has operating in an environment where a quick return will not be possible. In 2016 a study was done to investigate a variety of dual pressure vessel configurations for habitats that could protect the crew from these hazards. It was found that for a modest increase in total mass it should be possible to provide significant protection for the crew. Several configurations were developed that either had a small safe haven to provide 30-days to recover, or a full duration safe haven using two equal size pressure vessel volumes. The 30-day safe haven was found to be the simplest, yielding the least total mass impact but still with some risk if recovery is not possible during that timeframe. The full duration safe haven was the most massive option but provided the most robust solution. This paper provides information on the various layouts considered in the study and provides a discussion of the findings for implementing a safe haven in future habitat designs.

Smitherman, David↗
NASA NTRS2017

Methane Propulsion Elements for Mars

Human exploration beyond LEO relies on a suite of propulsive elements to: (1) Launch elements into space, (2) Transport crew and cargo to and from various destinations, (3) Provide access to the surface of Mars, (4) Launch crew from the surface of Mars. Oxygen/Methane propulsion systems meet the unique requirements of Mars surface access. A common Oxygen/Methane propulsion system is being considered to reduce development costs and support a wide range of primary & alternative applications.

Percy, Tom↗
NASA NTRS2017

Human Mars EDL Pathfinder Study: Assessment of Technology Development Gaps and Mitigations

This paper presents the results of a NASA initiated Agency-wide assessment to better characterize the risks and potential mitigation approaches associated with landing human class Entry, Descent, and Landing (EDL) systems on Mars. Due to the criticality and long-lead nature of advancing EDL techniques, it is necessary to determine an appropriate strategy to improve the capability to land large payloads. A key focus of this study was to understand the key EDL risks and with a focus on determining what "must" be tested at Mars. This process identified the various risks and potential risk mitigation strategies along with the key near term technology development efforts required and in what environment those technology demonstrations were best suited. The study identified key risks along with advantages to each entry technology. In addition, it was identified that provided the EDL concept of operations (con ops) minimized large scale transition events, there was no technology requirement for a Mars pre-cursor demonstration. Instead, NASA should take a direct path to a human-scale lander.

Lillard, Randolph↗
NASA NTRS2017

Impacts of Launch Vehicle Fairing Size on Human Exploration Architectures

Human missions to Mars, particularly to the Martian surface, are grand endeavors that place extensive demands on ground infrastructure, launch capabilities, and mission systems. The interplay of capabilities and limitations among these areas can have significant impacts on the costs and ability to conduct Mars missions and campaigns. From a mission and campaign perspective, decisions that affect element designs, including those based on launch vehicle and ground considerations, can create effects that ripple through all phases of the mission and have significant impact on the overall campaign. These effects result in impacts to element designs and performance, launch and surface manifesting, and mission operations. In current Evolvable Mars Campaign concepts, the NASA Space Launch System (SLS) is the primary launch vehicle for delivering crew and payloads to cis-lunar space. SLS is currently developing an 8.4m diameter cargo fairing, with a planned upgrade to a 10m diameter fairing in the future. Fairing diameter is a driving factor that impacts many aspects of system design, vehicle performance, and operational concepts. It creates a ripple effect that influences all aspects of a Mars mission, including: element designs, grounds operations, launch vehicle design, payload packaging on the lander, launch vehicle adapter design to meet structural launch requirements, control and thermal protection during entry and descent at Mars, landing stability, and surface operations. Analyses have been performed in each of these areas to assess and, where possible, quantify the impacts of fairing diameter selection on all aspects of a Mars mission. Several potential impacts of launch fairing diameter selection are identified in each of these areas, along with changes to system designs that result. Solutions for addressing these impacts generally result in increased systems mass and propellant needs, which can further exacerbate packaging and flight challenges. This paper presents the results of the analyses performed, the potential changes to mission architectures and campaigns that result, and the general trends that are more broadly applicable to any element design or mission planning for human exploration.

Jefferies, Sharon↗
NASA NTRS2016

Design and Development of a Methane Cryogenic Propulsion Stage for Human Mars Exploration

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 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 the required stages for returning crew from Mars. While this changes the risk posture of the architecture, it provides 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 3000 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.

Percy, Thomas K.↗