2024 AMOS Conference

By: Cindy Schumacher

Celebrating its 25th anniversary on Maui, the annual Advanced Maui Optical and Space Surveillance Technologies Conference (AMOS) was held on September 17-20 at the Wailea Beach Resort-Marriott. Presented by Maui Economic Development Board (MEDB), AMOS is the premier technical conference in the nation devoted to Space Situational Awareness (SSA). It is renowned for bringing together leading experts, researchers, and practitioners from all space- related fields, representing many private-sector, government, and academic organizations, to foster dialogue and international collaboration. In addition to technical sessions, the AMOS Conference included keynote speakers, SSA policy forums, exhibit and poster sessions, and 14 short courses, besides feature presentations and networking events.

With space debris becoming a growing hazard to space vehicles, a group of space-faring nations have entertained some policy options to create an international SSA database. However, much discussion is still needed to regulate spaceflight to make it safe for all. Also, as more nations enter the fray, many experts believe that collisions in space are inevitable without international space traffic coordination. That prospect makes SSA data-sharing now, before accidents happen, more critical than ever.

“The continued growth in AMOS attendance, 1308 attendees and 25 participating countries this year, reflects a growing interest in space sustainability and space commerce initiatives as new actors, including national governments, private companies, non-governmental organizations, and universities, become involved in these activities,” said Leslie Wilkins, MEDB President and CEO.

Sandy Ryan, MEDB Conference Director, added, “Celebrating a quarter-century of this conference reflects continuing innovation, collaboration, and progress in the space domain. We are honored to be an active partner in this growth and look forward to the exchange of knowledge and ideas shaping the future of space.”

 

KEYNOTES AND POLICY FORUMS

Day 1:

Lt. Gen. Philip Garrant, commander of the Space Systems Command (SSC) presented the opening keynote. “Space Force is facing pressure to improve SSA, the ability to track and understand what is happening with satellites and other objects in space,” Garrant said. “The service is exploring nontraditional commercial options and international partnerships to fill critical gaps in space surveillance. A top priority is SSA in geosynchronous (GEO) orbit, a region of space critical to both civilian and military operations.

“We’re going to need contributions from across the space community and to minimize dependencies on traditional large-scale programs.

Sharing of data and information with our allied

partners is extremely important. As part of our international collaboration, SSC has partnered with Japan to launch two hosted payloads on Japan’s Quasi-Zenith Satellite System. This partnership, born from a 2020 Memorandum of Understanding between our two nations, will help the U.S. maintain persistent surveillance in GEO.”

Gen. Garrant’s remarks were followed by the first of three SSA Policy Forums over the course of the conference. Organized with Secure World Foundation, the SSA Policy Forum brought together the developers and implementers of SSA capabilities and the thought-leaders of SSA policy to discuss a landscape that is rapidly evolving.

 

 

Day 1 Forum: Sustainable Operations of Large Constellations: The Role of Orbital Carrying Capacity and Other Tools

Moderator Ian Christenson, Senior Director, Private Sector Programs, Secure World Foundation, was joined by Richard Linares, Associate Professor, Department of Aeronautics and Astronautics, Massachusetts Institute of Technology; Erik Babcock, Director of Starlink Guidance, Navigation, and Control, Space X; Andrew Muciaccia, Politecnico di Milano; Andrew Ratcliffe, Chief Engineer, United Kingdom Space Agency; and Audrey Schaffer, Slingshot Aerospace.

Given the increasing operational complexity in the space environment, including the deployment and operation of large satellite constellations, and the increasing variety of space actors, the panel discussed the community’s needs to improve global approaches to mitigating risks to safety and sustainability in that environment. Approaches combining policy, operational, and SSA services aspects are expected to have important benefits for business and service continuity, maintaining access to orbit for future users, and ensuring safety in a multi-user domain.

 

Day 2:

Dr. Hiroshi Yamakawa, President, Japan Aerospace Exploration Agency (JAXA), kicked off the second day with a keynote presentation. First joining JAXA in 2003, Yamakawa was engaged in mission design of numerous Earth-orbiting scientific satellite projects as well as in lunar and interplanetary missions. He was appointed as President of JAXA in 2018. He spoke about the Japanese Space Policy and JAXA’s role and activities related to sustainable use of outer space.

“JAXA promotes global discussions to establish international rules for space debris mitigation in cooperation with GoJ and related ministries. We continue to contribute to the Inter-Agency Space Debris Coordination Committee and other international assemblies such as UN/COPUOS, ISO. Also, along with JAXA’s standardization activities and the JAXA Public-Domain Analysis Tool for Collision Avoidance there are active space debris removal techniques by Astroscale-Japan.”

Day 2 Forum: SSA in the Asia-Pacific: Where We are, Where We Are Going

Moderator Victoria Samson, Chief Director, Space Security and Stability, Secure World Foundation, was joined by Melrose Brown, Director UNSW Canberra Space; Dan Ceperley, Founder and Chief Operating Officer, LeoLabs; Sittiporn Channumsin, Director of Space Technology Research Center, GISTDA; and Lexie Weikert, Manager Business Development, National Security, Astroscale.

While it is apparent that a certain baseline level of SSA is needed to ensure spaceflight safety, different operators and actors have different needs for it. The panel examined how countries and companies are determining what should be prioritized, and how they are developing their own SSA capabilities. The possibility of regional cooperation in sharing SSA data was discussed along with what challenges and possible roadblocks to doing so might arise.

Day 3:

Keynote speaker Pam Melroy, Deputy Administrator of NASA, announced that NASA had received, just the previous day, the required approvals from congressional appropriations committees for the reorganization required to create the Space Sustainability Division that will consolidate much of the work the agency is doing on orbital debris and related issues.

“We will access about $40 million across the agency to use towards tackling challenges in orbital debris research,” Melroy said. “The strategy calls for developing a framework for space sustainability as well as improved metrics and modeling to address serious uncertainties about debris models. I am calling on debris researchers to work on ways to reduce uncertainty in these models. This can lead to more consensus around projects that we can do together.”

 

Day 3 Forum: Space Weather and SSA: What’s Needed Next?

Krystal Azelton, Senior Director, Program Planning, Secure World Foundation moderated the panel that included: Marco Concha, Flight Dynamics Lead, Amazon Kuiper; Tzu-Wei Fang, Space Scientist, NOAA Space Weather Prediction Center; Piyush Mehta, Associate Professor, West Virginia University; and Matthew Shouppe, Senior Associate, Commercial Space Strategy, Booz Allen Hamilton.

Recent events such as the February 2022 loss of 38 Starlink satellites due to space weather highlight the important connection between space weather and orbital trajectory predictions. Historically, the limited operational low Earth orbit (LEO) population with an altitude distribution biased towards high LEO meant operations were less sensitive to the accuracy of space weather prediction. The proliferation of LEO and very LEO with large constellations makes space weather modeling and forecasting an acute challenge.

The panel examined space weather prediction capabilities, current practices for atmospheric density modeling, and the impact that these have on both the accuracy of SSA and conjunction warnings as well as the ability to share SSA data among various stakeholders. Further, it looked to U.S. and international plans to address these issues in light of changing SSA data and service models.

 

AAS PARTICIPATION AT AMOS

The American Astronautical Society’s archival publication Journal of the Astronautical Sciences (JAS) has long presented new results and state-of-the-art surveys in all areas of astrodynamics, navigation and guidance, and space-related sciences, so a natural overlap exists with the topics presented at the AMOS Conference. While all AMOS papers are posted on the conference website (amostech.com), AAS further serves the community by publishing annually a selection of peer-reviewed AMOS papers in a special edition of the JAS. In addition, the AAS Space Surveillance Committee sponsors best-paper awards at the AMOS Conference, selecting from papers nominated by the AMOS Conference technical session chairs. Awards are presented for both Best Paper and Best Student Paper. The 2024 results, like those of past years, show the high quality and cutting-edge nature of much of the work presented at AMOS.

 

AAS 2024 AMOS BEST PAPER AWARD

Dr. Sam Wishnek
BAE Systems
Senior Systems Engineer

Sam Wishnek received his Ph.D. degree in aerospace engineering at the University of Colorado at Boulder with a focus on information-optimal space domain awareness. He now works at BAE Systems, Space and Mission Systems, as an algorithm developer with a continued focus on topics relating to space domain awareness.

                                                           Abstract

Minimum Observation Methods of Initial Maneuver Determination

Maneuvering objects introduce significant additional challenges to the maintenance of object custody and space situational awareness. When an object with a known orbit undergoes an unknown maneuver, the maneuver introduces four new degrees of freedom. These are the time of the maneuver and the three elements of the delta-v vector. For an approximately instantaneous maneuver, the only remaining constraint is that the new and old orbits intersect at the point where the object maneuvered. With these constraints and two additional post-maneuver electro-optical observations, a unique time and delta-v vector can be found to describe the maneuver and post-maneuver orbit. Inspired by initial orbit determination algorithms, this research explains and assesses a new algorithm that uses this minimal amount of data to provide an initial maneuver estimate. Key metrics include the speed, accuracy, and stability of the solution under realistic dynamics and errors. Much of the existing work on maneuver estimation tends to focus on either comparing pre-maneuver and post-maneuver orbits or running a filter over data that encompasses the maneuver time. Both methods assume a relatively large amount of data to perform the estimation and determine a precise solution. An important difference between prior work and the proposed work is that the proposed work can estimate the maneuver with the bare minimum amount of data. Three electro-optical observations are required for initial orbit determination when there is no prior information, so the initial maneuver determination algorithm necessarily leverages the pre-maneuver state to determine the post-maneuver state. The new algorithm provides a new capability to perform this estimation with too little data for existing algorithms to estimate the maneuver or post-maneuver state. This approach is inspired by approaches taken by existing algorithms for initial orbit determination. The Gooding algorithm for angles-only initial orbit determination takes three angles-only observations of a space object, assumes range values for the first and third observation, and finds the orbit that fits the first and third position states. The first and third range values are iteratively corrected to minimize the error with the middle observation. The proposed maneuver determination approach uses a similar initial setup by applying trial range values to the latter angles-only observation and then replaces the other range guess with a trial value of the time or eccentric anomaly of the maneuver and then corrects based on the error between the predicted and observed first observation. The research covers the method of the algorithms and their relative performance in time and accuracy running inputs with realistic dynamics and errors. The accuracy of the solution under measurement error is an essential metric for demonstrating the real-life utility of the algorithms. Analysis of the algorithm includes a build-up to progressively more realistic scenarios. The full analysis shows acceptable performance with realistic initial state error, measurement error, high precision orbital dynamics, and finite maneuvers. This is despite the proposed algorithm using simple two-body dynamics and an assumption of instantaneous maneuvers to optimize the algorithm for speed. Additional results include performance metrics for various maneuver magnitudes, observation geometries, and relative times between observations.

 

AAS 2024 AMOS BEST STUDENT PAPER

Mr. Ethan Foss
Stanford University
Ph.D. Student

Ethan Foss received his Bachelor of Science degree in Mechanical Engineering at the University of California, San Diego in 2023. Following this, he pursued a Master of Science program in Controls and Mechatronics at UCSD under Professor Aaron J. Rosengren and completed his thesis on stochastic optimal control for station-keeping guidance of cislunar spacecraft in June of 2024. He will be starting his Ph.D. program in the fall of 2024 at Stanford University. Ethan’s research interests involve the integration of cutting-edge trajectory optimization and stochastic optimal control algorithms with advanced spacecraft missions.

Abstract

Reachability Analysis of Low-Thrust Cislunar Spacecraft Using State Transition Tensors

As presence in cislunar space expands, new methods for characterizing the capabilities of low-thrust spacecraft in the regions beyond geosynchronous orbit (GEO) are becoming more important. Spacecraft reachability analysis, which refers to the determination of the set of states that a spacecraft can travel to or come from using its propulsion system over a given amount of time, is a key aspect to unlocking a better awareness of spacecraft trajectories in this new dynamical topography. Reachability analysis offers multi-faceted utility to the space situational awareness community for tracking, detection, maneuver reconstruction, and evaluation of collision probabilities. However, the computation of reachable sets is a particularly difficult problem in astrodynamics and few methods exist to accurately and rapidly compute reachable sets for low-thrust spacecraft. Furthermore, computing reachable sets in the beyond GEO (XGEO) regime presents unique challenges due to the highly sensitive and chaotic dynamics environment. Several existing techniques for reachable set computation have been proposed for spacecraft applications. These include, but are not limited to, direct solutions to the Hamilton-Jacobi-Isaacs (HJI) PDE, solving direct minimum-time optimal control problems for a grid of terminal points, and indirect-method-based optimization of trajectories. Solutions using the HJI PDE can be prohibitively expensive and difficult to compute and can only be determined for systems with low dimensionality (5 or less). Likewise, the direct method, minimum-time, optimal-control technique is also computationally expensive. Lastly, the indirect-method technique, which has seen the most success for rapid reachable set computation, still has its limitations. The method does not perform well in sensitive dynamical regimes, such as near multiple gravitational bodies. It also does not provide mathematical guarantees for computation of non-convex regions of the reachable set and relies on the propagation of a large number of trajectories to accurately outline the contour of the reachable set. In this work, we propose leveraging state transition tensors and set-based computing to directly propagate the reachable sets of spacecraft in cislunar space. Set-based reachability analysis, which uses set representations like polytopes, zonotopes, Taylor models, and polynomial zonotopes, is a popular method for performing reachability analysis among the cyberphysical systems community. However, such a technique for reachability analysis has not been demonstrated for cislunar space situational awareness. Moreover, typical implementations of set-based reachability computing use inaccurate means of discretization. By leveraging state transition tensors, which have become popular for many astrodynamics applications like uncertainty propagation and optimal control, higher accuracy non-convex approximations of reachable sets can be obtained. We will show how the proposed method performs in comparison to a selection of previously-proposed methods for reachability set computation for families of distant retrograde orbits (DROs) in the circular, restricted, three-body problem (CR3BP). We then show how the method can be easily extended for higher-fidelity reachability set computation using ephemeris models of a cislunar spacecraft in a near-rectilinear halo orbit (NRHO).

SAVE THE DATE

The 26^th AMOS Conference will be held on September 16-19, 2025 at the Wailea Beach Resort – Marriott, on Maui.

 

AUTHOR : Cindy Schumacher 

Cindy Schumacher is a journalist from Maui, Hawaii. She currently writes the Focus Maui Nui articles in the Maui News for Maui Economic Development Board and is a contributing writer for the Lahaina News, and the Maui Pulse newspaper. She has written numerous articles on topics related to astronautics and space science for AAS Space Times, and has covered national and international conferences, including the annual AMOS Conference.

 

 

 

 

 

 

PHOTO CREDITS: Cindy Schumacher