Concept for a Distributed, Modular, In-space Robotically Assembled, RF Communication Payload in GEO

In this paper, we discuss a concept for a Radio Frequency (RF) Ka band communications payload that is robotically assembled and serviced in space using a servicing vehicle such as the Robotic Servicing of Geosynchronous Satellites (RSGS) vehicle being developed by the Defense Advance Research Projects Agency (DARPA). Our work focuses on how to modularize a representative Ka band communications payload into discrete modules that are hosted on a persistent platform. In our concept, each module consists of a primary aperture and the associated RF and electronics required to serve a particular coverage area or type. These modules are notionally packaged in a form factor capable of launching as a secondary payload via an EELV Secondary Payload Adapter (ESPA) ring or a Payload Orbital Delivery System (PODS) module. The overall payload consists of an earth coverage module, regional coverage modules, high gain regional coverage modules, and a host interface unit (HIU). We discuss the notional capabilities and requirements of each module. We present two different architecture concepts corresponding to two different persistent platform concepts. In one concept, the persistent platform is made up of small, independent spacecraft that are connected together with structural members with communication channels. The payload modules are hosted on the individual spacecraft. In the second approach, the platform consists of a large central spacecraft with a structural truss that has power, communication and thermal loops. The payload modules are hosted on the truss through standard interfaces. We present aspects of the mission concept on how the payload may be modularized, launched (as secondary launch elements), acquired by the RSGS vehicle in space and assembled on to the persistent platform. We discuss the robotics aspects of assembly and servicing of the payload modules. A key aspect of this concept is the serviceability of the payload. Central to the modular and discrete payload design is an intent to refurbish the payload incrementally as technology evolves or the components fail. Existing geosynchronous communication satellites are designed and built as monolithic spacecraft which makes any servicing beyond refueling fairly complicated. This makes it hard to take advantage of the post launch evolution in technology, particularly in the electronics elements. Our concept is aimed at modularizing the payload such that the modules, particularly the electronics elements, can be easily serviced using the RSGS vehicle. Our concept attempts to take advantage of the long service life of high reliability system components in the core satellite bus while allowing rapid expansion and upgrading of the communications payload through the addition and replacement of individual payload modules

Concept for a Distributed, Modular, In-space Robotically Assembled, RF Communication Payload in GEO

In this paper, we discuss a concept for a Radio Frequency (RF) Ka band communications payload that is robotically assembled and serviced in space using a servicing vehicle such as the Robotic Servicing of Geosynchronous Satellites (RSGS) vehicle being developed by the Defense Advance Research Projects Agency (DARPA). Our work focuses on how to modularize a representative Ka band communications payload into discrete modules that are hosted on a persistent platform. In our concept, each module consists of a primary aperture and the associated RF and electronics required to serve a particular coverage area or type. These modules are notionally packaged in a form factor capable of launching as a secondary payload via an EELV Secondary Payload Adapter (ESPA) ring or a Payload Orbital Delivery System (PODS) module. The overall payload consists of an earth coverage module, regional coverage modules, high gain regional coverage modules, and a host interface unit (HIU). We discuss the notional capabilities and requirements of each module. We present two different architecture concepts corresponding to two different persistent platform concepts. In one concept, the persistent platform is made up of small, independent spacecraft that are connected together with structural members with communication channels. The payload modules are hosted on the individual spacecraft. In the second approach, the platform consists of a large central spacecraft with a structural truss that has power, communication and thermal loops. The payload modules are hosted on the truss through standard interfaces. We present aspects of the mission concept on how the payload may be modularized, launched (as secondary launch elements), acquired by the RSGS vehicle in space and assembled on to the persistent platform. We discuss the robotics aspects of assembly and servicing of the payload modules. A key aspect of this concept is the serviceability of the payload. Central to the modular and discrete payload design is an intent to refurbish the payload incrementally as technology evolves or the components fail. Existing geosynchronous communication satellites are designed and built as monolithic spacecraft which makes any servicing beyond refueling fairly complicated. This makes it hard to take advantage of the post launch evolution in technology, particularly in the electronics elements. Our concept is aimed at modularizing the payload such that the modules, particularly the electronics elements, can be easily serviced using the RSGS vehicle. Our concept attempts to take advantage of the long service life of high reliability system components in the core satellite bus while allowing rapid expansion and upgrading of the communications payload through the addition and replacement of individual payload modules

Human Space Flight and Future Major Space Astrophysics Missions: Servicing and Assembly

Some concepts for candidate future "flagship" space observatories approach the payload limits of the largest launch vehicles planned for the next few decades, specifically in the available volume in the vehicle fairing. This indicates that an alternative to autonomous self-deployment similar to that of the James Webb Space Telescope will eventually be required. Moreover, even before this size limit is reached, there will be significant motivation to service, repair, and upgrade in-space missions of all sizes, whether to extend the life of expensive facilities or to replace outworn or obsolete onboard systems as was demonstrated so effectively by the Hubble Space Telescope program. In parallel with these challenges to future major space astronomy missions, the capabilities of in-space robotic systems and the goals for human space flight in the 2020s and 2030s offer opportunities for achieving the most exciting science goals of the early 21st Century. In this paper, we summarize the history of concepts for human operations beyond the immediate vicinity of the Earth, the importance of very large apertures for scientific discovery, and current capabilities and future developments in robot- and astronaut-enabled servicing and assembly

In Space Assembled Telescope (ISAT) Study Preliminary Findings

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

Architecture for in-space robotic assembly of a modular space telescope

An architecture and conceptual design for a robotically assembled, modular space telescope (RAMST) that enables extremely large space telescopes to be conceived is presented. The distinguishing features of the RAMST architecture compared with prior concepts include the use of a modular deployable structure, a general-purpose robot, and advanced metrology, with the option of formation flying. To demonstrate the feasibility of the robotic assembly concept, we present a reference design using the RAMST architecture for a formation flying 100-m telescope that is assembled in Earth orbit and operated at the Sun–Earth Lagrange Point 2

A Robotically-Assembled 100-Meter Space Telescope

The future of astronomy may rely on extremely large space telescopes in order to image Earth-sized exoplanets or study the first stars. These telescopes will not be possible without a radical shift in design methods and concepts that are not limited by the size of a single payload fairing. In-Space Telescope Assembly Robotics (ISTAR) is one solution. The ISTAR project has developed a concept for an optical space telescope with a collecting area of nearly 8000 square meters, launched in pieces from the ground, and assembled by highly dexterous robots in space. The concept has been demonstrated to meet optical requirements and failure criteria. This paper focuses on the design and feasibility analysis of the telescope structure, as it has to be stiff and precise enough to maintain optical tolerances while also being amenable to robotic operations. The overall optical scheme of the telescope is first presented, which includes four main elements: a spherical primary mirror roughly hexagonal in shape spanning 100 meters flat to flat; an eyepiece containing all subsequent mirrors and detectors; a metrology system; and a sun shade. The conceived structure that connects and supports these components is then detailed, beginning with the concept of operations and assembly process and ending with the results of a comprehensive structural analysis. Particular attention is given to the truss structure that supports the primary mirror segments, called the backplane. The backplane design uses both robotic assembly and deployable structures to reduce assembly time, featuring expanding truss modules grouped with pre-assembled clusters of mirror segments that are connected together in space. The truss geometry of the structure was chosen from a vast design space, which was first narrowed using “back-of-the-envelope” analytical methods, to satisfy vibrational stiffness and mass criteria. Higher fidelity simulations using finite element analysis and matrix methods were then used to demonstrate that the structure meets optical and failure strength requirements while subjected to loads typically encountered in the space environment. This paper includes many of the decisions and trades made throughout the activity, providing a reference for the design of large modular space structures and laying the groundwork for future flight missions of this nature

Architecture for in-space robotic assembly of a modular space telescope

An architecture and conceptual design for a robotically assembled, modular space telescope (RAMST) that enables extremely large space telescopes to be conceived is presented. The distinguishing features of the RAMST architecture compared with prior concepts include the use of a modular deployable structure, a general-purpose robot, and advanced metrology, with the option of formation flying. To demonstrate the feasibility of the robotic assembly concept, we present a reference design using the RAMST architecture for a formation flying 100-m telescope that is assembled in Earth orbit and operated at the Sun–Earth Lagrange Point 2

Substructured multibody molecular dynamics.

We have enhanced our parallel molecular dynamics (MD) simulation software LAMMPS (Large-scale Atomic/Molecular Massively Parallel Simulator, lammps.sandia.gov) to include many new features for accelerated simulation including articulated rigid body dynamics via coupling to the Rensselaer Polytechnic Institute code POEMS (Parallelizable Open-source Efficient Multibody Software). We use new features of the LAMMPS software package to investigate rhodopsin photoisomerization, and water model surface tension and capillary waves at the vapor-liquid interface. Finally, we motivate the recipes of MD for practitioners and researchers in numerical analysis and computational mechanics