Satellite Formation-Flying and Rendezvous

GNSS has come to play an increasingly important role in satellite formation-flying and rendezvous applications. In the last decades, the use of GNSS measurements has provided the primary technique for determining the relative position of cooperative co-orbiting satellites in low Earth orbit

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

Robotics and AI-Enabled On-Orbit Operations With Future Generation of Small Satellites

The low-cost and short-lead time of small satellites has led to their use in science-based missions, earth observation, and interplanetary missions. Today, they are also key instruments in orchestrating technological demonstrations for On-Orbit Operations (O 3 ) such as inspection and spacecraft servicing with planned roles in active debris removal and on-orbit assembly. This paper provides an overview of the robotics and autonomous systems (RASs) technologies that enable robotic O 3 on smallsat platforms. Major RAS topics such as sensing & perception, guidance, navigation & control (GN&C) microgravity mobility and mobile manipulation, and autonomy are discussed from the perspective of relevant past and planned missions

On Development of 100-Gram-Class Spacecraft for Swarm Applications

A novel space system architecture is proposed, which would enable 100-g-class spacecraft to be flown as swarms (100 s-1000 s) in low Earth orbit. Swarms of Silicon Wafer Integrated Femtosatellites (SWIFT) present a paradigm-shifting approach to distributed spacecraft development, missions, and applications. Potential applications of SWIFT swarms include sparse aperture arrays and distributed sensor networks. New swarm array configurations are introduced and shown to achieve the effective sparse aperture driven from optical performance metrics. A system cost analysis based on this comparison justifies deploying a large number of femtosatellites for sparse aperture applications. Moreover, this paper discusses promising guidance, control, and navigation methods for swarms of femtosatellites equipped with modest sensing and control capabilities

System Design of the Miniaturized Distributed Occulter/Telescope (mDOT) Science Mission

The miniaturized Distributed Occulter Telescope (mDOT) will provide unprecedented detection and direct measurements of brightness of extrasolar dust disks at short visible to ultraviolet wavelengths. The baseline mission will observe over 15 targets using a starshade for high-contrast imaging, blocking the target star with a specially shaped free-flying occulter to allow nearby objects to be detected. mDOT operates on a much smaller scale than flagship NASA missions, with an autonomous formation of two small satellites in sun-synchronous low Earth orbit. An occulter-smallsat (246kg, 192W) carries a precisely manufactured 3m-diameter starshade and a telescope-cubesat (6U, 12kg, 40W) carries a 10cm-diameter telescope. The satellites are launched combined as a secondary payload for a total mission lifetime of 1.1 years. After launch, the occulter-smallsat ejects the telescope-cubesat and maneuvers to establish the desired relative orbit, leaving the spacecraft at slightly different longitudes of ascending node. Relative eccentricity and inclination vector separation provides the baseline for scientific observations at the equator (500 km) and a minimum safe distance perpendicular to the flight direction at all times (\u3e1km). The starshade suppresses the light of the target star by 10-7 or more. During a science pass, high-ISP green propellant thrusters on the occulter-smallsat maintain the formation, while differential GNSS is used for cm-accurate relative navigation. Earth’s oblateness perturbations are used to precess the orbits and acquire the science targets over the mission lifetime at minimal propellant cost. The mission addresses key NASA science objectives and provide the unique opportunity to mature starshade techniques for future exoplanet missions

Summary of NASA Advanced Telescope and Observatory Capability Roadmap

The NASA Advanced Telescope and Observatory (ATO) Capability Roadmap addresses technologies necessary for NASA to enable future space telescopes and observatories operating in all electromagnetic bands, from x-rays to millimeter waves, and including gravity-waves. It lists capability priorities derived from current and developing Space Missions Directorate (SMD) strategic roadmaps. Technology topics include optics; wavefront sensing and control and interferometry; distributed and advanced spacecraft systems; cryogenic and thermal control systems; large precision structure for observatories; and the infrastructure essential to future space telescopes and observatories

Decentralized Control of Electromagnetic ChipSat Swarm Formations

Small satellite formation missions offer new options for space exploration and scientific experiments. Groups of satellites flying within short relative distances allow various important applications, such as spatially distributed instruments for atmospheric sampling or remote sensing systems. The ability to independently control the relative motion of each satellite is crucial to establish a swarm formation, using a large number of satellites moving along bounded relative trajectories. This type of mission poses several constraints on mass, size, and energy consumption; therefore, an autonomous and selfsufficient approach is necessary to assure relative motion control. A novel concept of miniaturized satellites, referred to as ChipSats, consists of a single printed circuit board which can be equipped with different sets of microelectronic components including power and communication systems, a variety of sensors, and a microcontroller. This study considers a swarm of ChipSats equipped with magnetorquers, operating at extremely short relative distances, and using the electromagnetic interaction force for relative motion and attitude control, assuming the absolute position and relative state of each unit is known. Despite the limitations imposed by using magnetorquers as the sole actuators onboard, the dipole interaction between drifting satellites can be used to achieve bounded relative trajectories, and to establish and maintain a compact swarm. Following a decentralized approach, the ChipSats are periodically linked in interchangeable pairs in order to apply the Lyapunov-based control algorithm and prevent relative drift between all satellites in the swarm. The magnetic dipole moments are used for angular velocity damping when orbit control is not required, and a repulsive collision avoidance electromagnetic control force is applied when two ChipSats are within dangerously close proximity to each other. The performance assessment is conducted through Monte Carlo simulations using MATLAB, by analyzing operational parameters and the effect of initial conditions after deployment.Formações de pequenos satélites oferecem novas opções para exploração espacial e experiências científicas. Grupos de satélites, operando a curtas distâncias relativas, possibilitam importantes aplicações tais como instrumentação espacialmente distribuída para amostragem atmosférica ou sistemas de sensoriamento remoto. A capacidade de controlar de forma independente o movimento de cada satélite é crucial para establecer uma formação em enxame, utilizando um grande número de satélites movendo-se ao longo de trajetórias relativas limitadas. Este tipo de missão impõe várias restrições ao nível do consumo de energia, da massa e do tamanho dos satélites, consequentemente, é necessária uma abordagem autónoma e auto-sustentável para assegurar o controlo das trajetórias relativas. Um novo conceito de satélite miniatura, denominado ChipSat, consiste de uma única placa de circuito impresso que pode ser equipada com diferentes conjuntos de componentes microelectrónicos. Este estudo considera um enxame de ChipSats equipados com magnetorquers, operando a distâncias relativas extremamente reduzidas, e usando a força de interação eletromagnética para controlo do movimento relativo e orientação dos satélites, assumindo que a posição absoluta e relativa de cada unidade é conhecida. Apesar das limitações impostas por usar os magnetorquers como únicos atuadores a bordo, a interação magnética dipolar pode ser usada para limitar trajetórias relativas e establecer um enxame compacto. Seguindo uma abordagem descentralizada, os ChipSats são periodicamente ligados em pares intermutáveis de modo a aplicar o algoritmo de control baseado no teorema de Lyapunov, impedindo o aumento da distância relativa entre todos os satélites no enxame. O momento magnético dipolar é usado para amortecimento da velocidade angular quando o control orbital não é necessário, e uma força eletromagnética repulsiva é usada para controlo de colisão quando dois ChipSats estão perigosamente próximos. A análise de performance é feita através de simulações Monte Carlo no MATLAB, estudando os parâmetros operacionais e o efeito das condições iniciais após o lançamento

Experimental Demonstration of Technologies for Autonomous On-Orbit Robotic Assembly

The Modular Reconfigurable High Energy (MRHE) program aimed to develop technologies for the automated assembly and deployment of large-scale space structures and aggregate spacecraft. Part of the project involved creation of a terrestrial robotic testbed for validation and demonstration of these technologies and for the support of future development activities. This testbed was completed in 2005, and was thereafter used to demonstrate automated rendezvous, docking, and self-assembly tasks between a group of three modular robotic spacecraft emulators. This paper discusses the rationale for the MRHE project, describes the testbed capabilities, and presents the MRHE assembly demonstration sequence

System Analysis Applied to Autonomy: Application to Human-Rated Lunar/Mars Landers

System analysis is an essential technical discipline for the modern design of spacecraft and their associated missions. Specifically, system analysis is a powerful aid in identifying and prioritizing the required technologies needed for mission and/or vehicle development efforts. Maturation of intelligent systems technologies, and their incorporation into spacecraft systems, are dictating the development of new analysis tools, and incorporation of such tools into existing system analysis methodologies, in order to fully capture the trade-offs of autonomy on vehicle and mission success. A "system analysis of autonomy" methodology will be outlined and applied to a set of notional human-rated lunar/Mars lander missions toward answering these questions: 1. what is the optimum level of vehicle autonomy and intelligence required? and 2. what are the specific attributes of an autonomous system implementation essential for a given surface lander mission/application in order to maximize mission success? Future human-rated lunar/Mars landers, though nominally under the control of their crew, will, nonetheless, be highly automated systems. These automated systems will range from mission/flight control functions, to vehicle health monitoring and prognostication, to life-support and other "housekeeping" functions. The optimum degree of autonomy afforded to these spacecraft systems/functions has profound implications from an exploration system architecture standpoint