Earth observation (EO) satellites provide helpful imagery to a variety of applications ranging from weather monitoring to agricultural support. Disaster response imaging is an essential but difficult application for EO to support. Reconfigurable satellite constellations (ReCon) provide a flexible solution to the challenge of quickly providing imagery of unknown locations. ReCon leverages the natural shift of ground tracks due to the disparity between the Earth’s rotation and the period of an orbit to maneuver a constellation into repeating ground track (RGT) orbits. This maneuvering strategy relies on altitude changes to vary an orbit’s ascending node and mean anomaly, which both dictate the location of satellite’s ground track. Altitude changes require significantly less fuel than plane changes. Using ReCon allows for smaller constellations to provide high-performance imagery for disaster response for a lower cost. This work explores additional trades for consideration when developing ReCon designs. The following explores satellite image scheduling techniques to further the efficacy of an Earth observation constellation. The scheduler incorporates agile satellites to add imaging targets outside of the satellite’s nadir field of view. The ability for a satellite to slew to off-nadir targets is incredibly important when leveraging RGTs. Another design trade considered for ReCon is the propulsion system incorporated on the satellites. Performance and cost trades invoked when using electrical propulsion instead of chemical propulsion are presented within the ReCon framework. This work presents recommendations and future considerations to inform future designers. An investigation into the potential use of staged and responsive launch options further explores flexible options. Using alternative launch strategies allows a program to leverage dropping launch costs and adapt to uncertain imagery demand. The use of flexible options for EO satellite constellation design is vital in low Earth orbit as satellite technology improves, and space becomes a more crowded domain.

The papers contained in this Volume of Proceedings have been collected from an international Workshop entitled 'Mission Design and Implementation of Satellite Constellations' which was held in Toulouse, France, in November 1997. This Workshop represented the first international gathering of the specialists in this currently very active field of research activity. The initiative to organise a Workshop around this theme was conceived during the Congress of the International Astronautical Federation (IAF) in Beijing, China, in October 1996. On that occasion, the IAF explored concepts and possibilities for the conduct of small specialist Workshops and Symposia of current interest. Topical, interesting, and focused themes in the general field of space technology (both theories and applications) will be selected for these Symposia. They aim at offering a dedicated forum at international level for specialists and experts to exchange their views and experiences on recent and future developments within the selected theme. These specialist Workshops and Symposia supplement the comprehensive annual IAF Congresses which cover all aspects of space technology and draw a correspondingly diverse audience.

There are many time-sensitive mission applications for persistent satellite coverage, including dynamic and unpredictable events such as natural disasters, oil spills, extreme weather events, or geopolitical conflicts, which may progress rapidly and require frequently-updated information to co-ordinate the ground response. Reconfigurable satellite constellations can provide on-demand regional coverage by maneuvering orbits to focus passes over the area of interest. In contrast, traditional satellite constellations cannot maneuver to pass over specific ground locations, meaning that achieving persistent coverage spanning all possible locations of interest globally results in a requirement for thousands of satellites. This would present prohibitive costs for many applications, as well as contributing to worsening issues of space traffic management and congestion in Low Earth Orbit (LEO). Incorporating reconfigurability into constellation design allows for responsive maneuvering of satellites into repeating ground tracks (RGTs) over a location of interest, simultaneously reducing the required constellation size by improving the utilization of individual satellites and providing flexibility in the achievable ground coverage. Past work on reconfigurable constellations (ReCon) demonstrated average cost savings of 20-70% compared to iso-performance static constellations, although the complexity of the solution space for the design optimization process limited the maximum size of constellations that could be evaluated. In this thesis, a probabilistic performance metric is developed to compare constellation designs, adopting principles of reliability-based design optimization to quantify the confidence level that reconfigurable designs will outperform iso-cost static alternatives and by what margin of performance. The results show that 74.2% of reconfigurable designs outperform iso-cost static designs with a confidence level of 90% or higher, and with a margin of at least 10% improvement in the level of performance achieved. Computational intensity of the model presents the major constraint upon the size and complexity of simulation cases that may be modelled, so variance reduction techniques are applied to lower the standard error of mean performance in the output, allowing for a reduction in optimization size and runtime while maintaining the same level of error in the predicted results. Decision options for the operational phase of a reconfigurable constellation are presented and assessed to characterize how satellite operators must weigh mission priorities to evaluate trade-offs between propellant conservation and improved coverage of high-value targets.

This book is the highly anticipated sequel to the previous volume under the same title, dedicated to presenting a diverse range of timely and valuable contributions on the legal and policy related questions evoked by satellite constellations, including emerging mega-constellations. Given the proliferation of activities in the field of satellite constellations, and the critical roles they play in supporting and enabling communication, navigation, disaster monitoring, Earth observation, security and scientific activities, the insights of legal and policy experts from around the world have been gathered in this second volume to help expand the scientific literature in this precious field. Topics range from legal obstacles and opportunities facilitating small satellite enterprise for emerging space actors, international cooperation in the compatibility and interoperability of navigation systems, the designation of satellite constellations as critical space infrastructure, to an analysis of the paradigm shift which has occurred over the last decade to make the proliferation of small satellite constellations possible, and more.

This book details key trends involving the recent formation of scores of companies that build and launch small satellites or provide key components for small satellite constellations. The applications and usage are quite diverse and include student experiments, serious scientific experimentation, and totally new types of commercial constellations, particularly in telecommunications and remote sensing. The explosive growth in the design, manufacturing, and launch of small satellites is one of the most dynamic aspects in the area of space exploration and exploitation today. New commercial space companies such as Planet Labs, Sky Box, OneWeb, and LeoSat are now building and launching thousands of small satellites and cubesats into orbit. Small companies and big aerospace companies alike are getting into this exciting and interesting new business. This is a practical guide that provides advice to students, researchers, LEO satellite companies, and regulators wrestling with some of the new challenges that small satellites present as more and more companies and countries around the world enter the new small satellite arena.

In recent years, the Earth Observation (EO) industry has experienced rapid growth and development, but the tools to analyze EO constellations and space systems are lagging behind the curve. In particular, as costs continue to decrease to the point where constellations are treated like commodities, it is critical to look past cost and towards value creation when designing future EO constellations. In particular, there is an increasing need for value driven tradespace methods that can assist in the development of future EO space systems. Although there exist a few value driven approaches towards EO constellation design, they tend to be non-general and rely on detailed information such as expert knowledge or detailed probability distributions. Due to these limitations and the growing need for value driven trade methods, this thesis presents a new quantitative approach, using a novel Value Function, that can be applied generally to EO constellation trade studies. This thesis hypothesizes that the value generated by an EO constellation can be generalized in that the quantity and quality of data drives value to various stakeholders. By focusing on this simple hypothesis, this thesis will derive the Value Function to highlight these key attributes. The Value Function can be applied to a EO constellation, and using this new metric, various constellations can be compared against one another in a standardized way. To help show this, three case studies are used. The first case study, Case Study A, looks at two existing EO constellations: Landsat 8 and RapidEye. Their tradespaces are re-examined, and it is shown that the designs that are currently in operation are not optimal. There exists a single satellite Landsat-like architecture that generates 19.44% more value as compared to the current Landsat satellite in orbit. There also exists a five satellite RapidEye-like constellation that generates 35.76% more value as compared to the existing RapidEye constellation. The second case study, Case Study B, examines the make versus buy decision. In particular, it provides a hypothetical case study to determine if the Governor of California should purchase satellite imagery directly from Planet Labs, or if the state should fund a new constellation. This case study that shows the importance of understanding both costs and benefits when making important and high-investment decisions. For example, this thesis will discover an architecture that has 2 satellites, where each satellite is similar to a Planet Flock 2p CubeSat, and an orbital geometry that emphasizes California as compared to global coverage. The value ratio of this architecture is 5.01, and it is always greater than the cost ratio. This implies that it is in the state's best interest to build the constellation as opposed to purchasing imagery directly. Other architectures will be shown that do not lead to this same conclusion. The third case study, Case Study C, examines a proposed Synthetic Aperture Radar small satellite constellation, MicroX-SAR, by exploring a small set of potential architectures. These architectures are compared quantitatively using the Value Framework presented in this thesis, and it is shown that proposed constellations that are Sunsynchronous and at altitudes of 600 km generate the most value for a global region of interest. This information can be used when designing the mission parameters, such as orbital geometry, that will be important for constellation implementation. Overall, this thesis contributes a new model to evaluate EO constellations that relies on value driven methods as opposed to commonly used cost based metrics.

Continuously increasing demand for Earth observation in atmospheric research, disaster monitoring, and intelligence, surveillance and reconnaissance (ISR) has been met by responsive architectures such as unmanned aerial systems (UAS) or artificial satellites. Space-based architectures can provide non-dominated design solutions on the utility-cost curve compared to alternate architectures through the use of two approaches: (1) reducing satellite manufacturing and launch costs and (2) introducing reconfigurability to the satellite constellations. Reconfigurable constellations (ReCons) enable fast responses to access targets of interest while providing global monitoring capability from space. The wide-area coverage and fast responses provided ReCon can complement high-resolution imagery provided by UAS. A newly proposed ReCon framework improves the model fidelity of previous approaches by utilizing Satellite Tool Kit (STK) simulations and Earth observation mission databases. This thesis investigates the design and optimization of ReCon in low Earth orbits. A multidisciplinary simulation model is developed, to which optimization techniques are applied for both single-objective and multi-objective problems. In addition to the optimized baseline ReCon design, its variants are also considered as case studies. Future work will potentially co-optimize ReCon and UAS-like systems.