Small satellites are enabling multisatellite missions that were not otherwise possible because of their small size and modular nature [1]. Multiple small satellites can be flown instead of a much bigger and costlier conventional satellite for distributed sensing applications such as atmospheric sampling, distributed antennas [2], and synthetic apertures [3,4]. Missions with multiple small satellites can deliver a comparable or greater mission capability than a monolithic satellite, but with significantly enhanced flexibility (adaptability, scalability, evolvability, and maintainability) and robustness (reliability, survivability, and fault tolerance) [1,5]. Small satellites that weigh less than 10 kg can be broadly classified into nanosatellites (mass between 1 and 10 kg), picosatellites (mass between 0.1 and 1 kg), and femtosatellites (mass less than 100 g) [1,6].

Review of Formation Flying and Constellation Missions Using Nanosatellites

Comprehensive Survey and Assessment of Spacecraft Relative Motion Dynamics Models

Cooperative tracking plays a key role in space situation awareness for scenarios with a limited number of observations or poor performance of a single sensor or both. To use the information from multiple networked sensors, both centralized and decentralized fusion algorithms can be used. Compared with centralized fusion algorithms, decentralized fusion algorithms are more robust in terms of communication failure and computational burden. One popular distributed estimation approach is based on the average consensus that asymptotically converges to the estimate by multiple exchanges of neighborhood information. Consensus-based algorithms have become popular in recent years due to the fact that they do not require global knowledge of the network or routing protocols. The main contributions of this paper are 1) an effective space-based object (SBO) measurement model that considers the geometric relation of the Sun, the space object, the SBO sensor, and the Earth; 2) two consensus-based filters, the information-weighted consensus filter (ICF) and the Kalman consensus filter (KCF), are used to track space objects by using multiple SBO sensors; and 3) the cubature rule-embedded ICF (Cub-ICF) and KCF (Cub-KCF) are proposed to improve the accuracy of the ICF and KCF. Three scenarios that contain one or two space objects and four SBOs are used to test proposed algorithms. We also compare the consensus-based space object tracking algorithms with the centralized extended information filter (centralized EIF) and the centralized cubature information filter (centralized Cub-IF). The simulation results indicate that 1) cooperative space object tracking algorithms provide better results than algorithms using a single sensor, 2) the consensus-based tracking algorithms can achieve performance close to that of the centralized algorithms, and 3) the Cub-ICF and Cub-KCF outperform the conventional ICF and KCF for a challenging space object tracking case shown in the paper. The proposed Cub-ICF and Cub-KCF algorithms should facilitate the application of using consensus-based filters for cooperative space object tracking.

Cooperative space object tracking using space-based optical sensors via consensus-based filters

https://arc.aiaa.org/doi/pdf/10.2514/1.G002868

Survey on Guidance Navigation and Control Requirements for Spacecraft Formation-Flying Missions

CubeSats provide a cost effective means to perform scientific and technological studies in space. Due to their affordability, CubeSat technologies have been diversely studied and developed by educational institutions, companies and space organizations all over the world. The CubeSat technology that is surveyed in this paper is the propulsion system. A propulsion system is the primary mobility device of a spacecraft and helps with orbit modifications and attitude control. This paper provides an overview of micro-propulsion technologies that have been developed or are currently being developed for CubeSats. Some of the micro-propulsion technologies listed have also flown as secondary propulsion systems on larger spacecraft. Operating principles and key design considerations for each class of propulsion system are outlined. Finally, the performance factors of micro-propulsion systems have been summarized in terms of: first, a comparison of thrust and specific impulse for all propulsion systems; second, a comparison of power and specific impulse, as also thrust-to-power ratio and specific impulse for electric propulsion systems.

https://www.mdpi.com/2226-4310/4/4/58/pdf

An Overview of Cube-Satellite Propulsion Technologies and Trends

A computationally efficient algorithm is developed for onboard planning of n-impulse fuel-optimal maneuvers for establishment and reconfiguration of spacecraft formations. The method is valid in ci...

Formation Establishment and Reconfiguration Using Differential Elements in J2-Perturbed Orbits

Overview and GNC design of the CubeSat Proximity Operations Demonstration (CPOD) mission

The effects of third-body perturbations on satellite formations are investigated using differential orbital elements to describe the relative motion. Absolute and differential effects of the lunar perturbation on satellite formations are derived analytically based on the simplified model of the circular restricted three-body problem. This analytical description includes averaged long-term effects on the orbital elements, including the full transformation between the osculating elements and the lunar-averaged elements, which is absent from previous research. A simplified Earth-Moon system model is used, but the results are applicable to any formation reference orbit about the Earth. Simulations are performed to determine the effects of the lunar perturbation on example formations in upper MEO, highly eccentric orbits by using the formation design criteria of Phases I and II of the NASA Magnetospheric Multiscale mission. The changes in angular differential orbital elements (δ
 ω, δΩ, and δ
 M
 0) and in science return quality due to this perturbation are compared to changes due to J
 2. The method is then expanded to include the inclination of the Moon’s orbit and results are compared to simulation using the NASA General Mission Analysis Tool.

Third-Body Perturbation Effects on Satellite Formations

The Magnetospheric Multiscale Mission requires a formation of four satellites in a nearly regular tetrahedron throughout a region of interest defined near the apogee of a highly eccentric reference orbit. Previous papers have addressed the design of formations in orbits of high eccentricity to maximize a quality factor in a region of interest, including the use of differential mean orbital elements as design variables. In this paper, a robust optimization method is presented to improve formation performance in the presence of formation initialization errors. Several design methods are analyzed by applying differential semimajor axis errors, which have a strong effect on the long-term stability of spacecraft formations. It is shown that large formations can satisfy mission requirements for a longer time than smaller formations, when the same magnitude of errors are considered, and generally exhibit less variation in quality factors due to these errors. The robust optimization method is applied to these smaller formations and produces results that are much more stable when semimajor axis errors are included, at a cost of some performance in the nominal error-free case. The results are verified using the NASA General Mission Analysis Tool and are shown to be reasonably accurate, except in predicting very long-term behavior. A physical analysis of the geometry of several magnetospheric multiscale formation designs is provided, and eight distinct optimal tetrahedron orientations are identified (two configurations, in which the chief satellite can be placed at any of the four vertices).

Christopher W. T. Roscoe

Papers

Formation Establishment and Reconfiguration Using Differential Elements in J2-Perturbed Orbits

Overview and GNC design of the CubeSat Proximity Operations Demonstration (CPOD) mission

Third-Body Perturbation Effects on Satellite Formations

Optimal Formation Design for Magnetospheric Multiscale Mission Using Differential Orbital Elements

Satellite formation design in orbits of high eccentricity with performance constraints specified over a region of interest: MMS phase II ☆