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Publications

Note: Bolded names indicate SSORL members.

Under Review

M. Fox, G. Baker, D. Williams Rogers, and H. Lee, "Observability, Estimation, and Performance of Space-Based Laser Debris Remediation Under Uncertainty," (Under Review).

Journal Articles

D. Williams Rogers, D. Won, D. Koh, K. Hong, and H. Lee, "Optimal Satellite Constellation Configurations Design: A Collection of Mixed Integer Linear Programs," Journal of Spacecraft and Rockets, (Accepted).
Full-Text Open Access Satellite Constellations Mission Design
S. Paul and H. Lee, "Hybrid Sensing for Near-Earth Space Domain Awareness: Leveraging Space-Based Assets for Augmenting Optical Ground Observations," The Journal of the Astronautical Sciences, vol. 73, no. 1, 2026, doi: 10.1007/s40295-025-00546-y.
Full-Text Abstract BibTeX Open Access Space Domain Awareness

Abstract: Because of recent advancements in space technologies, easier and more economical access to space, and an increase in commercial interests, the near-Earth space environment has witnessed an exploding number of objects being put into orbit. In particular, the low Earth orbit (LEO) region is at an increased risk of orbital collisions from large satellite constellation projects. Thus, monitoring LEO objects for space domain awareness and space traffic management has become increasingly imperative. In this paper, we use the concept of limited-CDF (cumulative distribution function) surface and mutual information for designing sensor tasking algorithms focusing on regular observation of known catalog LEO objects (follow-up). Observations are carried out using simulated ground-based optical telescope(s). The simulations are representative of realistic observation processes. We investigate how data from passive space-based sensors can be used to improve the follow-up performance of the telescope(s). A sensor-tasking framework is developed in which we conduct a comparative study to assess how different types of satellite constellation patterns such as Walker-Delta and Walker-Star affect the overall sensor tasking performance. Through several case studies, we (1) analyze the appropriate characteristics of the parameters to be optimized and their impact on the evolution of orbital state uncertainties, (2) compare different traditional and non-traditional algorithms for sensor tasking problem, (3) investigate the effect of measurements from different constellation configurations of passive space-based sensor, and (4) identify a suitable coordinate system for the limited-CDF surface construction.
```
@article{Pearl2025,
author = {Paul, {Smriti Nandan} and Lee, {Hang Woon}},
title = {Hybrid Sensing for Near-Earth Space Domain Awareness: Leveraging Space-Based Assets for Augmenting Optical Ground Observations},
journal = {The Journal of the Astronautical Sciences},
volume  = {73},
number  = {1},
year    = {2026},
doi     = {https://doi.org/10.1007/s40295-025-00546-y}
```
B. Pearl, J. Miller, and H. Lee, "Reconfigurable Earth Observation Satellite Scheduling Problem," Journal of Aerospace Information Systems, doi: 10.2514/1.I011659, (Article in Advance).
Full-Text Abstract BibTeX Open Access Earth Observations Mission Design

Abstract: Earth observation satellites (EOSs) play a pivotal role in capturing and analyzing planetary phenomena, ranging from natural disasters to societal development. The EOS scheduling problem (EOSSP), which optimizes the schedule of EOSs, is often solved with respect to nadir-directional EOS systems, thus restricting the observation time of targets and, consequently, the effectiveness of each EOS. This paper leverages state-of-the-art constellation reconfigurability to develop the reconfigurable EOS scheduling problem (REOSSP), wherein EOSs are assumed to be maneuverable, forming a more optimal constellation configuration at multiple opportunities during a schedule. This paper develops a novel mixed-integer linear programming formulation for the REOSSP to optimally solve the scheduling problem for given parameters. Additionally, since the REOSSP can be computationally expensive for large-scale problems, a rolling horizon procedure (RHP) solution method is developed. The performance of the REOSSP is benchmarked against the EOSSP, which serves as a baseline, through a set of random instances where problem characteristics are varied and a case study in which Hurricane Sandy is used to demonstrate realistic performance. These experiments demonstrate the value of constellation reconfigurability in its application to the EOSSP, yielding solutions that improve performance, while the RHP enhances computational runtime for large-scale REOSSP instances.
```
@article{Pearl2025,
author = {Pearl, Brycen D. and Miller, Joseph M. and Lee, {Hang Woon}},
title = {Reconfigurable Earth Observation Satellite Scheduling Problem},
journal = {Journal of Aerospace Information Systems},
volume = {0},
number = {0},
pages = {1-19},
year = {0},
doi = {10.2514/1.I011659}
}
```
A. Abdul-Hamid, B. Pearl, H. Lee, and H. Chen, "Space Logistics Analysis and Incentive Design for Commercialization of Orbital Debris Remediation," Journal of Spacecraft and Rockets, doi: 10.2514/1.A36465, (Article in Advance).
Full-Text Abstract BibTeX Space Logistics Orbital Debris Remediation

Abstract: As orbital debris continues to become a higher priority for the space industry, there is a need to explore how partnerships between the public and private space sectors may aid in addressing this issue. This research develops a space logistics framework for planning orbital debris remediation missions, providing a quantitative basis for partnerships that are mutually beneficial between space operators and debris remediators. By integrating network-based space logistics and game theory, we illuminate the high-level costs of remediating orbital debris and the surplus that stands to be shared as a result. These findings indicate significant progress toward the continued development of a safe, sustainable, and profitable space economy.
```
@article{Abdu-Hamid2025,
author = {Abdul-Hamid, Asaad and Pearl, Brycen D. and Lee, {Hang Woon} and Chen, Hao},
title = {Space Logistics Analysis and Incentive Design for Commercialization of Orbital Debris Remediation},
journal = {Journal of Spacecraft and Rockets},
volume = {0},
number = {0},
pages = {1-13},
year = {0},
doi = {10.2514/1.A36465}
}
```
D. Williams Rogers, M. Fox, P. Stysley, and H. Lee, "Optimal Placement and Coordinated Scheduling of Distributed Space-Based Lasers for Orbital Debris Remediation," Advances in Space Research, vol. 76, no. 9, pp. 5265-5293, 2025, doi: 10.1016/j.asr.2025.07.093.
Full-Text Abstract BibTeX Orbital Debris Remediation Mission Design

Abstract: The significant expansion of the orbital debris population poses a serious threat to the safety and sustainability of space operations. This paper investigates orbital debris remediation through a constellation of collaborative space-based lasers, leveraging the principle of momentum transfer onto debris via laser ablation. A novel delta-v vector analysis framework quantifies the cumulative effects of multiple concurrent laser-to-debris (L2D) engagements by utilizing the vector composition of the imparted delta-v vectors. The paper formulates the Concurrent Location-Scheduling Optimization Problem (CLSP) to optimize the placement of laser platforms and the scheduling of L2D engagements, aiming to maximize debris remediation capacity. Given the computational intractability of the CLSP, a decomposition strategy is employed, yielding two sequential subproblems: (1) determining optimal laser platform locations via the Maximal Covering Location Problem, and (2) scheduling L2D engagements using a novel integer linear programming approach to maximize debris remediation capacity. Computational experiments evaluate the efficacy of the proposed framework across diverse mission scenarios, demonstrating critical constellation functions such as collaborative and controlled nudging, deorbiting, and just-in-time collision avoidance. A sensitivity analysis further explores the impact of varying the number and distribution of laser platforms on debris remediation capacity, offering insights into optimizing the performance of space-based laser constellations.
```
@article{WilliamsRogers2025,
author = {{Williams Rogers}, David O. and Fox, Matthew C. and Stysley, Paul R. and Lee, {Hang Woon}},
title = {Optimal placement and coordinated scheduling of distributed space-based lasers for orbital debris remediation},
journal = {Advances in Space Research},
volume = {76},
number = {9},
pages = {5265-5293},
year = {2025},
doi = {https://doi.org/10.1016/j.asr.2025.07.093}
}
```
E. Gkaravela, H. Lee, and H. Chen, "Distributed Space Resource Logistics Architecture Optimization under Economies of Scale," Journal of Spacecraft and Rockets, vol. 62, no. 5, pp. 1654-1666, 2025, doi: 10.2514/1.A36271.
Full-Text Abstract BibTeX Cislunar Space Logistics

Abstract: This paper proposes an optimization framework for distributed resource logistics system design to support future multimission space exploration. The performance and impact of distributed in-situ resource utilization (ISRU) systems in facilitating space transportation are analyzed. The proposed framework considers technology trade studies, deployment strategy, facility location evaluation, and resource logistics after production for distributed ISRU systems. We develop piecewise linear sizing and cost estimation models based on economies of scale that can be easily integrated into network-based mission planning formulations. A case study on a multimission cislunar logistics campaign is conducted to demonstrate the value of the proposed method and evaluate key tradeoffs to compare the performance of distributed ISRU systems with traditional concentrated ISRU. Finally, a comprehensive sensitivity analysis is performed to assess the proposed system under varying conditions, comparing concentrated and distributed ISRU systems.
```
@article{Gkaravela2024,
author = {Gkaravela, Evangelia and Lee, {Hang Woon} and Chen, Hao},
title = {Distributed Space Resource Logistics Architecture Optimization Under Economies of Scale},
journal = {Journal of Spacecraft and Rockets},
volume = {62},
number = {6},
pages = {1654-1666},
year = {2025},
doi = {10.2514/1.A36271}
}
```
B. Pearl, L. Gold, and H. Lee, "Benchmarking Agility and Reconfigurability in Satellite Systems for Tropical Cyclone Monitoring," Journal of Spacecraft and Rockets, vol. 62, no. 4, pp. 1138-1151, 2025, doi: 10.2514/1.A36177.
Full-Text Abstract BibTeX Earth Observations Mission Design

Abstract: Tropical cyclones (TCs) are highly dynamic natural disasters that travel vast distances and occupy a large spatial scale, leading to loss of life, economic strife, and destruction of infrastructure. The severe impact of TCs makes them crucial to monitor such that the collected data contribute to forecasting their trajectory and severity, as well as the provision of information to relief agencies. Among the various methods used to monitor TCs, Earth observation satellites are the most flexible, allowing for frequent observations with a wide variety of instruments. Traditionally, satellite scheduling algorithms assume nadir-directional observations, a limitation that can be alleviated by incorporating satellite agility and constellation reconfigurability—two state-of-the-art concepts of operations (CONOPS) that extend the amount of time TCs can be observed from orbit. This paper conducts a systematic comparative analysis between both CONOPS to present the performance of each relative to baseline nadir-directional observations in monitoring TCs. A dataset of 100 historical TCs is used to provide a benchmark concerning real-world data through maximizing the number of quality observations. The results of the comparative analysis indicate that constellation reconfigurability allowing plane-change maneuvers outperforms satellite agility in the majority of TCs analyzed.
```
@article{Pearl2023,
  author  = {Pearl, Brycen D. and Gold, Logan P. and Lee, {Hang Woon}},
  title   = {Benchmarking Agility and Reconfigurability in Satellite Systems for Tropical Cyclone Monitoring},
  journal = {Journal of Spacecraft and Rockets},
  volume  = {60},
  number  = {6},
  pages   = {1811-1824},
  year    = {2023},
  doi     = {10.2514/1.A36177}
}
```
T. H. Clareson, M. Fox, D. Amato, and H. Lee, "Embedded State Estimation for Optimization of Cislunar Space Domain Awareness Constellation Design," Journal of Spacecraft and Rockets, vol. 62, no. 3, pp. 898-914, 2025, doi: 10.2514/1.A36102.
Full-Text Abstract BibTeX Cislunar Space Domain Awareness Mission Design

Abstract: The traffic in cislunar space is expected to increase over the coming years, leading to a higher likelihood of conjunction events among active satellites, orbital debris, and noncooperative satellites. This increase necessitates enhanced space domain awareness (SDA) capabilities that include state estimation for targets of interest. Both Earth surface-based and space-based observation platforms in geosynchronous orbit or below face challenges such as range, exclusion, and occlusion that hinder observation. Motivated by the need to place space-based observers in the cislunar space regime to overcome these challenges, this paper proposes a cislunar SDA constellation design and analysis framework that integrates state estimation into an optimization problem for determining the placement of observers for optimal state estimation performance on a set of targets. The proposed multiobserver placement optimization problem samples from a range of possible target orbits. Upon convergence, the optimized constellation is validated against a broader set of targets to assess its effectiveness. Two comparative analyses are presented to evaluate the effects of changes in the sensor tasking procedure and sensor fidelity on the optimized constellation, comparing these to a single observer baseline case. The results demonstrate that the optimized constellations can provide accurate state estimation for various orbit families.
```
@article{Clareson2025,
  author  = {Clareson, Thomas H. and Fox, Matthew C. and Amato, Dominic K. and Lee, {Hang Woon}},
  title   = {Embedded State Estimation for Optimization of Cislunar Space Domain Awareness Constellation Design},
  journal = {Journal of Spacecraft and Rockets},
  volume  = {62},
  number  = {3},
  pages   = {898-914},
  year    = {2025},
  doi     = {10.2514/1.A36102}
}
```
H. Lee, D. Williams Rogers, B. Pearl, H. Chen, and K. Ho, "Deterministic Multistage Constellation Reconfiguration Using Integer Programming and Sequential Decision-Making Methods," Journal of Spacecraft and Rockets, vol. 62, no. 1, pp. 206-222, 2025, doi: 10.2514/1.A35990.
Full-Text Abstract BibTeX Earth Observations In-space Mobility Mission Operations

Abstract: This paper addresses the problem of reconfiguring Earth observation satellite constellation systems through multiple stages. The Multistage Constellation Reconfiguration Problem (MCRP) aims to maximize the total observation rewards obtained by covering a set of targets of interest through the active manipulation of the orbits and relative phasing of constituent satellites. This paper considers deterministic problem settings in which the targets of interest are known a priori. We propose a novel integer linear programming formulation for MCRP, capable of obtaining provably optimal solutions. To overcome computational intractability due to the combinatorial explosion in solving large-scale instances, we introduce two computationally efficient sequential decision-making methods based on the principles of a myopic policy and a rolling horizon procedure. The computational experiments demonstrate that the devised sequential decision-making approaches yield high-quality solutions with improved computational efficiency over the baseline MCRP. Finally, a case study using Hurricane Harvey data showcases the advantages of multistage constellation reconfiguration over single-stage and no-reconfiguration scenarios.
```
@article{Lee2025,
  author  = {Lee, {Hang Woon} and Williams Rogers, David O. and Pearl, Brycen D. and Chen, Hao and Ho, Koki},
  title   = {Deterministic Multistage Constellation Reconfiguration Using Integer Programming and Sequential Decision-Making Methods},
  journal = {Journal of Spacecraft and Rockets},
  volume  = {62},
  number  = {1},
  pages   = {206-222},
  year    = {2025},
  doi     = {10.2514/1.A35990}
}
```
M. Patel, Y. Shimane, H. Lee, and K. Ho, "Cislunar Satellite Constellation Design Via Integer Linear Programming," The Journal of the Astronautical Sciences, vol. 71, no. 26, 2024, doi: 10.1007/s40295-024-00445-8.
Abstract BibTeX Cislunar Mission Design Satellite Constellations

Abstract: Cislunar space domain awareness is of increasing interest to the international community as Earth-Moon traffic is projected to increase, which raises the problem of placing space-based sensors optimally in a constellation to satisfy the space domain awareness demand in cislunar space. This demand profile can vary over space and time, making the design optimization problem challenging. This paper tackles the problem of satellite constellation design for spatio-temporally varying coverage demand by leveraging an integer linear programming formulation. The developed optimization formulation assumes the circular restricted 3-body dynamics and attempts to minimize the number of satellites required for the requested demand profile.
```
@article{Patel2024,
  author  = {Patel, Malav and Shimane, Yuri and Lee, {Hang Woon} and Ho, Koki},
  title   = {Cislunar Satellite Constellation Design via Integer Linear Programming},
  journal = {The Journal of the Astronautical Sciences},
  volume  = {71},
  number  = {3},
  pages   = {26},
  year    = {2024},
  doi     = {10.1007/s40295-024-00445-8}
}
```
H. Lee and K. Ho, "Regional Constellation Reconfiguration Problem: Integer Linear Programming Formulation and Lagrangian Heuristic Method," Journal of Spacecraft and Rockets, vol. 60, no. 6, pp. 1828-1845, 2023, doi: 10.2514/1.A35685.
Full-Text Abstract BibTeX Earth Observations In-space Mobility Mission Operations

Abstract: A group of satellites, with either homogeneous or heterogeneous orbital characteristics and/or hardware specifications, can undertake a reconfiguration process due to variations in operations pertaining to Earth observation missions. This paper investigates the problem of optimizing a satellite constellation reconfiguration process against two competing mission objectives: 1) the maximization of the total coverage reward, and 2) the minimization of the total cost of the transfer. The decision variables for the reconfiguration process include the design of the new configuration and the assignment of satellites from one configuration to another. We present a novel biobjective integer linear programming formulation that combines constellation design and transfer problems. The formulation lends itself to the use of generic mixed-integer linear programming (MILP) methods such as the branch-and-bound algorithm for the computation of provably optimal solutions; however, these approaches become computationally prohibitive even for moderately sized instances. In response to this challenge, this paper proposes a Lagrangian relaxation-based heuristic method that leverages the assignment problem structure embedded in the problem. The results from the computational experiments attest to the near-optimality of the Lagrangian heuristic solutions and a significant improvement in the computational runtime as compared to a commercial MILP solver.
```
@article{Lee2023,
  author  = {Lee, {Hang Woon} and Ho, Koki},
  title   = {Regional Constellation Reconfiguration Problem: Integer Linear Programming Formulation and Lagrangian Heuristic Method},
  journal = {Journal of Spacecraft and Rockets},
  volume  = {60},
  number  = {6},
  pages   = {1828-1845},
  year    = {2023},
  doi     = {10.2514/1.A35685}
}
```
H. Lee, S. Shimizu, S. Yoshikawa, and K. Ho, "Satellite Constellation Pattern Optimization for Complex Regional Coverage," Journal of Spacecraft and Rockets, vol. 57, no. 6, pp. 1309-1327, 2020, doi: 10.2514/1.A34657.
Full-Text Abstract BibTeX Satellite Constellations Mission Design

Abstract: The use of regional-coverage satellite constellations is on the rise, urging the need for an optimal constellation design method for complex regional coverage. Traditional constellations are often designed for continuous global coverage, and the few existing regional constellation design methods lead to suboptimal solutions for periodically time-varying or spatially varying regional-coverage requirements. This paper introduces a new general approach to design an optimal constellation pattern that satisfies such complex regional-coverage requirements. To this end, the circular convolution nature of the repeating ground-track orbit and common ground-track constellation is formalized. This formulation enables a scalable constellation pattern analysis for multiple target areas and with multiple subconstellations. The formalized circular convolution relationship is first used to derive a baseline constellation pattern design method with the conventional assumption of symmetry. Next, a novel method based on binary integer linear programming is developed, which aims to optimally design a constellation pattern with the minimum number of satellites. This binary integer linear programming method is shown to achieve optimal constellation patterns for general problem settings that the baseline method cannot achieve. Five illustrative examples are analyzed to demonstrate the value of the proposed new approach.
```
@article{Lee2020,
  author  = {Lee, {Hang Woon} and Shimizu, Seiichi and Yoshikawa, Shoji and Ho, Koki},
  title   = {Satellite Constellation Pattern Optimization for Complex Regional Coverage},
  journal = {Journal of Spacecraft and Rockets},
  volume  = {57},
  number  = {6},
  pages   = {1309-1327},
  year    = {2020},
  doi     = {10.2514/1.A34657}
}
```
H. Chen, H. Lee, and K. Ho, "Space Transportation System and Mission Planning for Regular Interplanetary Missions," Journal of Spacecraft and Rockets, vol. 56, no. 1, pp. 12-20, 2019, doi: 10.2514/1.A34168.
Abstract BibTeX Space Logistics Mission Operations

Abstract: This paper develops a computationally efficient and scalable mission planning optimization method for regular space transportation missions, defined as a set of repeating and periodic interplanetary transportation missions over a long time horizon after one or a few setup missions. As more long-term manned missions to Mars are being conceptualized, the need for a sustainable interplanetary transportation system has become increasingly prominent. However, planning regular transportation missions with existing space mission planning optimization formulations has a limitation in computational scalability in the time dimension. The proposed partially periodic time-expanded network can address this limitation of the past studies; it is shown to be computationally scalable and capable of generating solutions that are practically preferred. Properties of the proposed partially periodic time-expanded network are analyzed, and a case study reveals that the total initial mass in the low Earth orbit of regular missions approaches to the theoretical lower bound as the number of transportation missions increases.
```
@article{Chen2019,
  author  = {Chen, Hao and Lee, {Hang Woon} and Ho, Koki},
  title   = {Space Transportation System and Mission Planning for Regular Interplanetary Missions},
  journal = {Journal of Spacecraft and Rockets},
  volume  = {56},
  number  = {1},
  pages   = {12-20},
  year    = {2019},
  doi     = {10.2514/1.A34168}
}
```
H. Lee, P. Jakob, K. Ho, S. Shimizu, and S. Yoshikawa, "Optimization of Satellite Constellation Deployment Strategy Considering Uncertain Areas of Interest," Acta Astronautica, vol. 153, pp. 213-228, 2018, doi: 10.1016/j.actaastro.2018.03.054.
Abstract BibTeX Satellite Constellations Mission Design

Abstract: This paper presents an integrated framework to design a flexible multi-stage telecommunication satellite configuration deployment strategy considering the uncertainties in the evolution of the areas of interest over time. The constructed stochastic demand model considers multiple possible scenarios for the evolution of the areas of interest with probabilities based on the market share growth in each area. The optimization aims to find each stage's design with minimum expected lifecycle cost considering all possible scenarios. Each stage of the constellation, assumed to be Flower constellation with circular orbits, provides a regional coverage of the current area of interest as well as additional coverage for the potential future areas of interest. The proposed multi-stage satellite constellation enables the constellation designer to react flexibly and efficiently to the uncertain future expansion of the areas of interest. A case study reveals a reduction in the expected lifecycle cost for an optimized system compared with the all-in-single-stage system and global coverage constellation.
```
@article{Lee2018,
  author  = {Lee, {Hang Woon} and Jakob, Pauline C. and Ho, Koki and Shimizu, Seiichi and Yoshikawa, Shoji},
  title   = {Optimization of satellite constellation deployment strategy considering uncertain areas of interest},
  journal = {Acta Astronautica},
  volume  = {153},
  pages   = {213-228},
  year    = {2018},
  doi     = {10.1016/j.actaastro.2018.03.054}
}
```

Conference Papers

J. Warner and H. Lee, "A Reinforcement Learning Framework for Station Keeping with Solar Sails," AIAA ASCEND, Washington, DC, May 2026, (Accepted).
D. Won, D. Williams Rogers, D. Koh, and H. Lee, "Quality-Aware Constellation Optimization for Space Domain Awareness: Case Studies on Resident Space Object Detection and Tracking from GEO and LEO-Hosted Payloads," AIAA ASCEND, Washington, DC, May 2026, (Accepted).
D. Williams Rogers and H. Lee, "Enhancing Orbital Debris Remediation with Reconfigurable Space-Based Laser Constellations," 2026 IEEE Aerospace Conference, Big Sky, MT, Mar. 2026, (Accepted).
S. Zemerick, M. Suder, D. Amato, D. Martinelli, and H. Lee, "Advancing the SmallSat Digital Twin for Active Debris Removal Simulations," 2026 AIAA SciTech, Orlando, FL, Jan. 2026.
G. Baker and H. Lee, "Reinforcement Learning-Based Task Planning of Space-Based Lasers for Orbital Debris Remediation," 2025 AAS/AIAA Astrodynamics Specialist Conference, Boston, MA, Aug. 2025.
B. Pearl, J. Warner, and H. Lee, "Autonomous Space-Based Wildfire Monitoring: Dynamic Scheduling of Maneuverable Satellites with CNN-Based Detection," 2025 AAS/AIAA Astrodynamics Specialist Conference, Boston, MA, Aug. 2025.
D. Amato and H. Lee, "Optimizing Placement and Reconfiguration of Space-Based Observers for Cislunar Space Domain Awareness Considering Scheduling Constraints," 2025 AAS/AIAA Astrodynamics Specialist Conference, Boston, MA, Aug. 2025.
D. Williams Rogers and H. Lee, "Concurrent Optimization of Space-Based Laser Sizing, Location, and Scheduling for Orbital Debris Remediation," 2025 AAS/AIAA Astrodynamics Specialist Conference, Boston, MA, Aug. 2025.
D. Williams Rogers, D. Won, D. Koh, K. Hong, and H. Lee, "Optimal Satellite Network Topology Design with Time-Dependent Traffic Demands," 2025 IEEE Aerospace Conference, Big Sky, MT, Mar. 2025.
B. Pearl and H. Lee, "Stochastic Multi-stage Satellite Constellation Reconfiguration for Tracking Uncertain Targets," 2025 IEEE Aerospace Conference, Big Sky, MT, Mar. 2025.
B. Pearl, J. Miller, and H. Lee, "Developing the Reconfigurable Earth Observation Satellite Scheduling Problem," 2025 AIAA SciTech, Orlando, FL, Jan. 2025.
D. Williams Rogers, M. Fox, and H. Lee, "Minimum Cost Cislunar Delay-Tolerant Network Design Using Integer Linear Programming," 2025 AIAA SciTech, Orlando, FL, Jan. 2025.
M. Fox, G. Baker, D. Williams Rogers, and H. Lee, "Space-Based Lasers for Orbital Debris Remediation: Observability, State Estimation, and Deorbiting Performance Analysis," 2025 AIAA SciTech, Orlando, FL, Jan. 2025.
M. Fox, E. Boggs, and H. Lee, "Microgravity Linear Acceleration Effects on Lagrange Point Orbit Stability During Propellant Settling," 2025 AIAA SciTech, Orlando, FL, Jan. 2025.
L. Cottrill, A. Tiscareno, L. Park, J. Bardaji, A. Abdul-Hamid, H. Lee, and H. Chen, "Cost and Benefit Analysis of Removing Small Debris Using Space-Based and Ground-Based Laser Systems," 2025 AIAA SciTech, Orlando, FL, Jan. 2025.
A. Abdul-Hamid, B. Pearl, H. Lee, and H. Chen, "Developing Commercialization Framework for Space Debris Removal," 2025 AIAA SciTech, Orlando, FL, Jan. 2025.
T. Gosavi, D. Amato, J. Swecker, H. Lee, "Optimizing the Placement and Low-Thrust Maneuvers of Multi-Purpose Orbiters around Venus," 2024 AAS/AIAA Astrodynamics Specialist Conference, Broomfield, CO, Aug. 2024.
S. Paul and H. Lee, "Sensor Tasking for Low Earth Orbit Objects: Leveraging Space Sensor Data for Ground-Based Optical Observations," 2024 AIAA SciTech, Orlando, FL, Jan. 2024.
D. Williams Rogers, S. Kim, M. Lee, Y. Kim, and H. Lee, "Designing Optimal Satellite Constellation Patterns with Facility Location Problem Models and Mixed Integer Linear Programming," 2023 AIAA ASCEND, Las Vegas, NV, Oct. 2023.
T. H. Clareson, M. Fox, D. Amato, and H. Lee, "Optimization Framework for Space-based Multi-Sensor Systems in Cislunar Space Domain Awareness," 2023 AAS/AIAA Astrodynamics Specialist Conference, Big Sky, MT, Aug. 2023.
B. Pearl, L. Gold, and H. Lee, "Comparing the Effectiveness of Agility and Reconfigurability in Earth Observation Satellite Systems for Disaster Response," 2023 AAS/AIAA Astrodynamics Specialist Conference, Big Sky, MT, Aug. 2023.
M. Patel, Y. Shimane, H. Lee, and K. Ho, "Cislunar Satellite Constellation Design Via Integer Linear Programming," 2023 AAS/AIAA Astrodynamics Specialist Conference, Big Sky, MT, Aug. 2023.
H. Lee and Z. Liu, "A Novel Formulation for the Multi-Stage Satellite Constellation Reconfiguration Problem: Initial Results," 2023 AAS/AIAA Space Flight Mechanics Meeting, Austin, TX, Jan. 2023.
H. Lee, H. Chen, and K. Ho, "Maximizing Observation Throughput via Multi-Stage Satellite Constellation Reconfiguration," 2022 AAS/AIAA Astrodynamics Specialist Conference, Charlotte, NC, Aug. 2022.
P. Clifton, H. Lee, A. Honda, S. Yoshikawa, and K. Ho, "Optimization Framework for Minimal Conjunction Satellite Constellation Design and Post Mission Disposal Trajectories," 2022 IEEE Aerospace Conference, Mar. 2022.
H. Chen and H. Lee, "Distributed In-Situ Resource Utilization System Optimization for Multi-Mission Space Exploration," 2021 AIAA ASCEND, Nov. 2021.
H. Lee and K. Ho, "A Lagrangian Relaxation-Based Heuristic Approach to Regional Constellation Reconfiguration Problem," 2021 AAS/AIAA Astrodynamics Specialist Conference, Aug. 2021.
H. Lee and K. Ho, "Binary Integer Linear Programming Formulation for Optimal Satellite Constellation Reconfiguration," 2020 AAS/AIAA Astrodynamics Specialist Conference, Aug. 2020. John V. Breakwell Student Award
H. Lee and K. Ho, "Regional constellations as alternative business strategy: Overcoming startups’ challenges in the space-based communications industry," 2020 AAS John Glenn Memorial Symposium, Virtual, July 2020.
The Molly K. Macauley Award
H. Lee, K. Ho, S. Shimizu, and S. Yoshikawa, "A Semi-Analytical Approach to Satellite Constellation Design for Regional Coverage," 2018 AAS/AIAA Astrodynamics Specialist Conference, Snowbird, UT, Aug. 2018.
H. Chen, H. Lee, and K. Ho, "Space Transportation System and Infrastructure Design for Regular Interplanetary Cargo Missions," 2017 AIAA SPACE Conference and Exposition, Orlando, FL, Sep. 2017.
H. Lee, P. Jakob, K. Ho, S. Shimizu, and S. Yoshikawa, "Optimization of Satellite Constellation Deployment Strategy Considering Uncertain Areas of Interest," 9th International Workshop on Satellite Constellations and Formation Flying, Boulder, CO, Jun. 2017.
The Graduate College Conference Travel Award
M. Prinkey, D. Miller, P. Bauer, K. Cahoy, E. Wise, C. Pong, R. Kingsbury, A. Marinan, H. Lee, and E. Main, "CubeSat Attitude Control Testbed Design: Merritt 4-Coil per axis Helmholtz Cage and Spherical Air Bearing," AIAA Guidance, Navigation, and Control Conference, Boston, MA, Aug. 2013.

Invited Technical Talks / Seminars

D. Williams Rogers, M. Fox, and H. Lee, "Rapid Response Debris Removal Using Reconfigurable Space-Based Laser Networks," Annual Technical Seminar, NASA Goddard Space Flight Center, Greenbelt, MD, July 2025.
D. Williams Rogers and H. Lee "A Mathematical Optimization-Based Satellite Constellation Design and Operational Framework," Korea Advanced Institute of Science and Technology, Daejeon, South Korea, June 2025.
D. Williams Rogers and H. Lee "A Mathematical Optimization-Based Satellite Constellation Design and Operational Framework," Korea Advanced Institute of Science and Technology, TelePIX, Seoul, South Korea, June 2025.
A. Abdul-Hamid, B. Pearl, H. Lee, and H. Chen, "Space Logistics Analysis and Incentive Design for Commercialization of Orbital Debris Remediation," Space Sustainability Workshop, NASA Headquarters, Washington, D.C., Dec. 2024.
H. Lee, "Optimizing Satellite Constellation Patterns for Complex Coverage," Heterogeneous Satellite constellation based ISR Research Center (HSRC) Workshop, Virtual (Workshop held in Jeongseon, South Korea), Nov. 2024.
H. Lee, "Recent Progress in Space Systems Operations Research," Sejong University, Seoul, South Korea, July 2024.
H. Lee, "A Mathematical Optimization-Based Satellite Constellation Design and Operational Framework," New Frontiers in Constellation Design for Microsatellite Missions, Daejeon, South Korea, July 2024.
D. Williams Rogers, M. Fox, and H. Lee, "Rapid Response Debris Removal Using Reconfigurable Space-Based Laser Networks," Annual Technical Seminar, NASA Goddard Space Flight Center, Greenbelt, MD, June 2024.
H. Lee, "Recent Progress in Space Systems Operations Research," Center for KINETIC Plasma Physics, West Virginia University, Morgantown, WV, Nov. 2022.
H. Lee, "Regional constellations as alternative business strategy: Overcoming startups’ challenges in the space-based communications industry," AAS John Glenn Memorial Symposium, Virtual, July 2020.
The Molly K. Macauley Award

Student Theses

T. H. Clareson, "Embedded State Estimation for Optimization of Cislunar Space Domain Awareness Constellation Design," M.S. Thesis, West Virginia University, 2024.

Magazine Articles

O. Gunasekara, H. Lee, K. Ho, "Commercial human spaceflight leads year of firsts," Aerospace America, Vol. 58, No. 11, pp. 68, Dec. 2020.
H. Lee and K. Ho, "Supplying the space station, preparing to put humans back on the moon," Aerospace America, Vo. 57, No. 11, pp. 63, Dec. 2019.