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This presentation summarizes the case for using precision assembly of space structures for efficient and cost-effective construction of large systems such as iSAT primary mirror assembly and surface applications
The Space Science and Technology (S&T) Partnership Forum was established in 2015 to identify synergistic efforts and technologies across the government, with a focus on key pervasive and game-changing technologies across government space agencies in order to more efficiently and effectively manage S&T resources. As principal partners of the interagency S&T Partnership Forum, the U.S. Air Force (USAF), the National Aeronautics and Space Administration (NASA), and the National Reconnaissance Office (NRO) identified and prioritized several S&T collaboration topic areas. Autonomous and semi-autonomous in-space assembly (iSA) is the focus of the topic area that NASA, under the direction of the Office of Chief Technologist, is currently coordinating among the S&T principal partners and affiliate partners, such as the Defense Advanced Research Projects Agency (DARPA) and the U.S. Naval Research Laboratory (NRL). The S&T iSA facilitation and analysis team, led by NASA, collected data from the participating agencies on their current developments, activities, and needs in the area of in-space assembly. This paper provides an overview of the S&T iSA facilitation and analysis team’s efforts in establishing the value proposition and strategic framework for interagency collaboration in iSA within the partnership as a foundation to deliver value and achieve iSA topic objectives across government space agencies. Further, this paper describes the early products of these efforts in the definition of the iSA capabilities, design drivers, and stakeholder goals to facilitate dialogue within the partnership and the larger community.
“When is it advantageous to assemble telescopes in space rather than deploying them from launch vehicle fairings”? This question forms the crux of the objectives of a NASA study we have been conducting in collaboration with colleagues from different NASA centers, industry and academia. In this study, we have engaged a broad cross section of experts from the various fields of optics engineering, that is, telescope design and instrument design, structure and thermal engineering, robotics, launch system engineering, orbital mechanics, integration and testing, astrophysics, and NASA programmatics among others. Initial efforts began with a quick review of the current state of art of the component technologies that contribute towards an in-space assembled telescope. Then, leveraging the collective expertise of the diverse group of experts, we formulated a reference telescope design and attempted to develop a baseline approach to modularize the telescope into components amenable for robotic assembly. The group identified different trades associated with modularization and also developed a set of criteria to discern between the different options as revealed by the trades. Based on the modularization of the telescope, we will assess the impact of various launch vehicles, orbits for assembly and operation, robotic systems and operational approaches, and other related variables. From this, a concept to assemble the reference telescope in space from modular components will be developed. Based on this concept, and definition of the modules, we will develop a mission lifecycle plan for an assembled telescope over different phases of preliminary design, detailed design, assembly-test-and-integration, and in space operations. The mission lifecycle plan will be used to evaluate cost and risk implications of in-space assembly toward answering our fundamental question of the advantages, if any, of assembling a telescope in space as compared to self-deployment. In this paper, we summarize the objectives of the study, a review of the status of the underlying component technologies, a description of the methodology, including three different multi-day technical interchange meetings (TIMs), summary of findings from the TIMs and other related activities. In addition, a detailed description of the various factors that impact in-space assembly, their interplay and criteria for discerning among them, a preliminary description of the life cycle plan, including the test and integration plan, and initial observations on cost and risk implications will be included in the paper.
In-Space assembly (ISA) expands the opportunities for cost effective emplacement of systems in space. Currently, spacecraft are launched into space and deploy into their operational configuration through a carefully choreographed sequence of operations. The deployment operation dictates the arrangement of the primary systems on the spacecraft, limiting the ability to take full advantage of launch vehicles volume and mass capability. ISA enables vastly different spacecraft architectures and emplacement scenarios to be achieved, including optimal launch configurations ranging from single launch and assembly to on-orbit aggregation of multiple launches at different orbital locations and times. The spacecraft can be visited at different orbital locations and times to effect expansion and maintenance of an operational capability. To date, the primary application of ISA has been in large programs funded by government organizations, such as the International Space Station. Recently, Space Systems Loral (SSL) led a study funded by the Defense Advanced Research Projects Agency (DARPA), called Dragonfly, to investigate the commercial applicability and economic advantages of ISA. In the study, it was shown that ISA enables SSL to double the capability of a commercial satellite system by taking advantage of alternate packaging approaches for the reflectors. The study included an ultra-light-weight robotic system, derived from Mars manipulator designs, to complete assembly of portions of the antenna system using a tool derived from DARPA orbital express and National Aeronautics and Space Administration (NASA) automated structural assembly experience. The mechanical connector that enables robotic ISA takes advantage of decades of development by NASA from the 1970's to 1980's during the Space Station Freedom program, the precursor to the ISS. The mechanical connector was originally designed for rapid astronaut assembly while also providing a high quality structural connection with linear load deflection response. The paper will discuss the business case for ISA, the general approach taken to exploit on-orbit assembly in the GEO communication satellite market, and the concept of operations associated with the ISA approach, thus laying the foundation for ISA to become an accepted operational approach for commercial in-space operations.
The interagency Space Science and Technology (S&T) Partnership Forum was established in 2015 with participation from the United States Air Force, the National Aeronautics and Space Administration, and the National Reconnaissance Office. Seeking to leverage synergies and influence agency portfolios with a focus on key pervasive and game-changing technologies, the S&T Partnership Forum successfully identified and prioritized several collaboration topic areas with high potential for future cross-agency work. The S&T Partnership Forum determines the forum strategy, goals, and objectives, as well as the strategies and objectives specific to each collaboration topic area. In November 2018, the Partnership held a public open forum that focused on the topic area of in-space assembly (iSA). This open forum was coordinated to facilitate government and commercial dialogue, collect data, and perform data analysis to identify potential cross-agency collaboration between government and commercial participants for in-space assembly and promising technologies. This paper discusses the analysis performed on the commercially provided data in relation to previously identified government needs, observations on the correlation between technologies and capabilities between government and commercial industry, and recommendations for future government collaborations with commercial industry for iSA.
Many future human space exploration missions will probably require large vehicles that must be assembled on orbit. Thus, a device that can move, position, and assemble large and massive spacecraft components on orbit becomes essential for these missions. A concept is described for such a device: a space crane concept that uses erectable truss hardware to achieve high-stiffness and low-mass booms and uses articulating truss joints that can be assembled on orbit. The hardware has been tested and shown to have linear load-deflection response and to be structurally predictable. The hardware also permits the crane to be reconfigured into different geometries to satisfy future assembly requirements. A number of articulating and rotary joint concepts have been sized and analyzed, and the results are discussed. Two strategies were proposed to suppress motion-induced vibration: placing viscous dampers in selected truss struts and preshaping motion commands. Preliminary analyses indicate that these techniques have the potential to greatly enhance structural damping.
A space crane concept is presented which is based on erectable truss hardware to achieve high stiffness and low mass booms and articulating-truss joints which can be assembled on orbit. The hardware is characterized by linear load-deflection response and is structurally predictable. The crane can be reconfigured into different geometries to meet future assembly requirements. Articulating-truss joint concepts with significantly different geometries are analyzed and found to have similar static and dynamic performance, which indicates that criteria other than structural and kinematic performance can be used to select a joint. Passive damping and an open-loop preshaped command input technique greatly enhance the structural damping in the space crane and may preclude the need for an active vibrations suppression system.
This paper presents a modular, reconfigurable robotic manipulator for autonomous in-space assembly. On-orbit and planetary surface assembly is a challenging domain that encompasses various technological thrusts to support human exploration, science, and technology demonstration missions. The system architecture presented here addresses the need for robotic assembly of structures in locations that prohibit constant human oversight and/or teleoperation. This system is capable of scheduling, reconfiguring itself, and executing structural assembly tasks with the ability to assess construction and correct errors during the assembly as needed. An example concept of operations is presented. Details of the mechanical and electrical design of the robotic modules as well as the dynamic modeling approach, control algorithms, and sensing and perception systems are also provided.
Large space structure assembly analysis techniques are defined and simulation activities are described. The simulations included are: an extravehicular activity assembly simulation; a fabricated beam assembly series using a beam generating machine end caps, and cross beam brackets; deployment of a deployable truss, using the neutral buoyancy remote manipulator system with crewman assistance; and a series aboard the KC-135 zero g aircraft.
Early system-level life cycle assessments facilitate cost effective optimization of system architectures to enable implementation of both modularity and in-space assembly, two key Exploration Systems Research & Technology (ESR&T) Strategic Challenges. Experiences with the International Space Station (ISS) demonstrate that the absence of this rigorous analysis can result in increased cost and operational risk. An effort is underway, called Analysis of In-Space Assembly of Modular Systems, to produce an innovative analytical methodology, including an evolved analysis toolset and proven processes in a collaborative engineering environment, to support the design and evaluation of proposed concepts. The unique aspect of this work is that it will produce the toolset, techniques and initial products to analyze and compare the detailed, life cycle costs and performance of different implementations of modularity for in-space assembly. A multi-Center team consisting of experienced personnel from the Langley Research Center, Johnson Space Center, Kennedy Space Center, and the Goddard Space Flight Center has been formed to bring their resources and experience to this development. At the end of this 30-month effort, the toolset will be ready to support the Exploration Program with an integrated assessment strategy that embodies all life-cycle aspects of the mission from design and manufacturing through operations to enable early and timely selection of an optimum solution among many competing alternatives. Already there are many different designs for crewed missions to the Moon that present competing views of modularity requiring some in-space assembly. The purpose of this paper is to highlight the approach for scoring competing designs.
Human missions to Mars present several major challenges that must be overcome, including delivering multiple large mass and volume elements, keeping the crew safe and productive, meeting cost constraints, and ensuring a sustainable campaign. Traditional methods for executing human Mars missions minimize or eliminate in-space assembly, which provides a narrow range of options for addressing these challenges and limits the types of missions that can be performed. This paper discusses recent work to evaluate how the inclusion of in-space assembly in space mission architectural concepts could provide novel solutions to address these challenges by increasing operational flexibility, robustness, risk reduction, crew health and safety, and sustainability. A hierarchical framework is presented to characterize assembly strategies, assembly tasks, and the required capabilities to assemble mission systems in space. The framework is used to identify general mission system design considerations and assembly system characteristics by assembly strategy. These general approaches are then applied to identify potential in-space assembly applications to address each challenge. Through this process, several focus areas were identified where applications of in-space assembly could affect multiple challenges. Each focus area was developed to identify functions, potential assembly solutions and operations, key architectural trades, and potential considerations and implications of implementation. This paper helps to identify key areas to investigate were potentially significant gains in addressing the challenges with human missions to Mars may be realized, and creates a foundation on which to further develop and analyze in-space assembly concepts and assembly-based architectures.
In-space assembly (ISA), the ability to build structures in space, has the potential to enable or support a wide range of advanced mission capabilities. Many different individual assembly technologies would be needed in different combinations to serve many mission concepts. The many-to-many relationship between mission needs and technologies makes it difficult to determine exactly which specific technologies should receive priority for development and demonstration. Furthermore, because enabling technologies are still immature, no realistic, near-term design reference mission has been described that would form the basis for flowing down requirements for such development and demonstration. This broad applicability without a single, well-articulated mission makes it difficult to advance the technology all the way to flight readiness. This paper reports on a study that prioritized individual technologies across a broad field of possible missions to determine priority for future technology investment.
Viewgraphs describing the in-space assembly and construction technology project of the infrastructure operations area of the operation technology program are presented. Th objective of the project is to develop and demonstrate an in-space assembly and construction capability for large and/or massive spacecraft. The in-space assembly and construction technology program will support the need to build, in orbit, the full range of spacecraft required for the missions to and from planet Earth, including: earth-orbiting platforms, lunar transfer vehicles, and Mars transfer vehicles.
Review of Assemblers low TRL architecture for in-space assemble tasks.
The TriTruss is a novel and innovative structural module developed by researchers at the NASA Langley Research Center to construct modular structures which can be assembled on-orbit for future persistent missions, including in-space assembled telescopes and platforms for science and communications. The TriTruss offers unique modular structural features including compact packaging for launch, the possibility of staged packaging, simple robotic deployment and assembly, and design versatility for specific space mission applications. This paper presents the modeling and analysis procedure for the TriTruss modular structure and the predicted frequency response of an In-Space Assembled Telescope’s (iSAT) primary reflector.
The various U. S. government agencies that are pursuing in-space assembly technology have a common need to demonstrate technological capabilities on a space-based platform. Several of the agencies, and different mission developers within an agency, have independently begun planning such demonstrations. This paper reports on a study of how well the different planned platforms could support demonstrations of the agencies’ joint needs. The study first prioritized a comprehensive list of the needs for in-space assembly capabilities across the agencies against jointly agreed evaluation criteria. Each planned demonstration platform was characterized to a first order. The capability needs were qualitatively assessed against four figures of merit including their joint priority, and the platforms were assessed against five criteria to produce a quantitative weighting factor of reach capability need and each platform. A Quality Function Deployment (QFD) matrix was used to deploy the weighted capability needs against the weighted platforms capabilities. This first-order assessment showed that the platforms reflect a great deal of redundant capability without a strong reason to prefer one over the others. These results were largely insensitive to the details of the assumptions.
The Space Science and Technology Partnership Forum was established in 2015 to identify synergistic efforts and technologies across the government. In-Space Assembly (iSA) is the focus of the topic area that NASA is currently coordinating with other government agencies. This paper focuses on the data collection process, the data analysis of that information, and preliminary insights gleaned from the data. The goal of the analysis is to understand the linkages within the collected data, identifying synergies and gaps, and provide visualization of the current state of iSA needs and capability development across the government. Capability roadmaps, Venn diagrams, bubble charts, and scorecards (an overview of each individual iSA capability) are used to visualize the results of this analysis, which reveals areas of possible inter-agency collaboration, investment gaps in capabilities relative to the need, and capabilities that warrant engagement across multiple agencies to eliminate potential inefficiencies.