Tradespace Investigation of a Telescope Architecture for Next-generation Space Astronomy and Exploration

Humanity’s endeavor to further its scientific understanding of the celestial heavens has led to the creation and evolution of increasingly powerful and complex space telescopes. Space telescopes provide a view of the solar system, galaxy, and universe unobstructed by Earth’s atmosphere and have profoundly changed the way people view space. In an effort to further advance space telescope capability and achieve the accompanying scientific understanding, the Massachusetts Institute of Technology (MIT), specifically, course 16.89 Space Systems Engineering, explored the tradespace of architectural enumerations encompassed within the design of an ultraviolet-optical-infrared (UVOIR) space telescope located at Sun-Earth Lagrangian Point Two (SE-L2). SE-L2 presents several advantages as an operating location for a UVOIR telescope such as a thermally stable environment and an orbit that allows the telescope to maintain a constant orientation with respect to all of the primary sources of heat and light. The main disadvantages associated with SE-L2 are caused by its relatively large distance from Earth, which marginalizes the effectiveness of real-time telerobotics because of latency and increases the cost of communications, launch, and servicing. Course 16.89 believes that, for this UVOIR application, the strengths of this operating location outweigh its weaknesses and therefore decided to explore the family of opportunities associated with SE-L2. This course used appropriate performance and system metrics to quantify the effectiveness of the aforementioned architectures and create a Pareto front of viable architectures. Evaluating the designs along the Pareto front allowed the course to characterize and group architectures and present these group-types to stakeholders for the selection of an optimal space telescope according to stakeholder requirements and resources. This course also developed sensitivity analysis, which allowed for a greater understanding of how architectural decisions affect the performance of the satellite. Segmentation, modularity, assembly, autonomy, and servicing were key aspects of this multidimensional analysis given the 16.8-meter class size and location of the telescope. Within the respective operating environment and for a spacecraft of similar characteristics, this model will allow stakeholders to predict the long-term operational effectiveness of different space telescope architectures and capture the synergistic effects of combining various architectural decisions into a spacecraft design. The following sections step through the aforesaid analysis and design efforts conducted in 16.89 beginning with Section III, which explicitly performs the stakeholder analysis and articulates the requirements of the mission. Section IV gives an overview of past designs and expands upon the architecture enumerations pertinent to this project, while Section V presents the methods and metrics by which those architectures will be evaluated and the system metrics which will be balanced and optimized in the creation of this space telescope. Section VI will present the model validation of this project and Section VII will discuss the results and analyses of the project. Finally, Section VIII will explore the future work opportunities of this project, while Section IX will present the conclusions and recommendations drawn from this project.MIT Department of Aeronautics and Astronautic

Reconfigurable thruster selection algorithms for aggregative spacecraft systems

Thesis: S.M., Massachusetts Institute of Technology, Department of Aeronautics and Astronautics, 2014.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Cataloged from student-submitted PDF version of thesis.Includes bibliographical references (pages 167-170).The vast majority of today's space systems launch to orbit as completely assembled spacecraft stowed within a single launch vehicle. However, there is demand for large space systems (e.g., large space telescopes, fuel depots, space habitats, and solar power stations) that are overly limited by the lifting capability and fairing size of one launch vehicle. By separating large space systems into modules on multiple launches, these restrictions can be lifted, given a method to assemble and recongure the modules once on orbit. Specific control challenges associated with this reconguration need to be overcome before on-orbit assembly can be proven to be cost and resource eective. Some of these challenges have been addressed through adaptive and robust controller design, however an area that has not been explored deeply enough is that of thruster selection algorithms. In spacecraft control, thruster selection algorithms determine which thrusters to re to produce a commanded force or torque on the system. Thus, these algorithms are critical for implementation of new controllers. To solve some of the control challenges associated with a system gaining additional thrusters, the goal of a recongurable thruster selection algorithm is to adapt to the new mass properties and thruster layout of the aggregated spacecraft, while optimizing for fuel consumption, precision, and agility. In this thesis, the proposed methodology is presented. A simulation for testing these algorithms is described, and results detailing the success of these recongurable thruster selection algorithms are discussed. In addition, results from preliminary testing of these algorithms using the MIT Synchronized Position Hold, Engage, Reorient, Experimental Satellites (SPHERES) facility in the three degree-of-freedom ground testbed are reported.by Christopher Michael Jewison.S.M

Guidance and control for multi-stage rendezvous and docking operations in the presence of uncertainty

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Aeronautics and Astronautics, 2017.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Cataloged from student-submitted PDF version of thesis.Includes bibliographical references (pages 251-267).Rendezvous and docking missions have been a mainstay of space exploration from the Apollo program through present day operations with the International Space Station. There remains a growing interest in several mission types that not only rely on rendezvous and docking, but also rely on maneuvering spacecraft once docked. For example, there is active interest in orbital debris removal, on-orbit assembly, on-orbit refueling, and on-orbit servicing and repair missions. As these missions become more and more popular, the number of rendezvous and docking class operations will increase dramatically. Current methods focus on performing rendezvous and docking to very well-known targets and in very well-known conditions. Inherent to these new mission types, however, is an increasing element of uncertainty to which new guidance and control architectures will need to be robust. As guidance and control techniques become more robust, a corresponding tradeoff in performance can typically be experienced. This thesis attempts to address the uncertainties in rendezvous and docking operations while maintaining a probabilistically optimal level of performance. There are two main focuses in the thesis: spacecraft trajectory optimization and reference-tracking controller selection. With respect to trajectory optimization, the goal is to nd probabilistically optimal trajectories given large uncertainties in mission critical parameters, such as knowledge of an obstacle's position, while knowing that the trajectory is able to be replanned onboard the spacecraft when higher precision information is obtained. This baseline optimal trajectory and subsequently replanned trajectories are then followed by an optimally determined set of reference-tracking controllers. These controllers are selected and scheduled throughout the phases of the mission based on the probabilistically expected performance in the presence of noise and uncertain parameters. This process is explored through its implementation on a generic problem setup for rendezvous, docking, and joint maneuvering. Results specfic to this problem and associated analysis motivate the use of probabilistic planning in future space missions. Specically, the thesis shows that fuel and tracking performance can be improved if multi-stage missions are planned continuously through phase transitions and without the use of waypoints. Furthermore, under the presence of large uncertainties, the techniques in this thesis produce better expected fuel and tracking performance than traditional trajectory planning and controller selection methods.by Christopher Michael Jewison.Ph. D

Definition and testing of an architectural tradespace for on-orbit assemblers and servicers

This paper proposes a set of eight architectures that fully span the design tradespace of on-orbit assembler and servicer satellites. A framework is presented that defines the tradespace for servicing and assembly architectures across the three axes of distributed vs. centralized functionality, proximity operation vs. fully captured operations, and integrated vs. external servicing/assembly satellites. A qualitative analysis of the architectural tradespace details the advantages and disadvantages of each of the core architectures. In addition, the paper discusses current and future hardware-in-the-loop testing of various architectures in a sequence of iterative and incremental tests in ground and microgravity environments as part of the Synchronized Position Hold Engage and Reorient Experimental Satellites (SPHERES) facility. New hardware is being sent to the International Space Station to provide quantitative validation of the previously qualitative trades within this space. The paper describes how the results from this testing and the planned test sequences for the remaining architectures will reduce risk for on-orbit assembly and servicing missionsAmerican Society for Engineering Education. National Defense Science and Engineering Graduate Fellowshi