Mission Design Research Articles

Investigating effectiveness and compliance to DevOps policies and practices for managing productivity and quality variability

The Mission Design and Navigation Software (MDN) Group at the Jet Propulsion Laboratory (JPL) develops and continuously maintains software systems critical for NASA deep space missions. Due to limited resources and tight schedules, there is always the temptation to prioritize productivity over quality. However, such quality and productivity variations may be manageable during development, but they are too risky for operational use when there is a time-critical need for repair or enhancement and high reliability is essential.As a result, our process must be both highly productive and maintain high quality (e.g., reliability, maintainability, usability). Inspired by the “quality is free” paradigm, we have instituted six policies established from DevOps principles and practices specifically to address maintenance risk caused by high variability in quality and productivity concerns we encountered in the development phase from quality-productivity tradeoffs.CMMI level 3 requirements mandate that process improvements are monitored and adjusted to ensure that policies are adhered to, practices are performed, and that they are effective in producing the desired results. This article presents a process improvement investigation as to whether the DevOps practices, as currently implemented, are effective in achieving the expected effects and impacts for managing variability in quality and productivity. Additionally, we investigate practical methods to assure compliance to the six policies to determine if any adjustments to policy or practice are needed.For this investigation we focus on our flagship system MONTE. We have over 15 years of reliable and accurate quality and productivity data for MONTE, a critical system currently in continual operation and maintenance. Time series cross-correlation analyses were used to compare process productivity and quality characteristics before and after the implementation of DevOps. From this, we found strong evidence that:• There is a continual maintenance risk due to variability in productivity and quality.• The majority of the DevOps policies and practices are being complied with.• The policies and practices have been effective in managing this risk.

Concept and Feasibility Analysis of the Alba Cubesat Mission

AbstractAlbaSat is a 2-Unit CubeSat which is being developed by a student team at the University of Padova. The Alba project aims to design, build, test, launch, and operate the first student CubeSat of the University of Padova, featuring four different payloads. The first goal is to collect data regarding the debris environment in Low Earth Orbit, the second goal is the study of the satellite vibrations, the third one is about CubeSat attitude determination through laser ranging technology, and the fourth goal concerns satellite laser and quantum communication. The Alba CubeSat mission has been selected by the European Space Agency to join the Fly Your Satellite! Design Booster program in December 2022. This paper presents the feasibility study of the Alba CubeSat mission reproduced in the framework of the “Space Systems Laboratory” class of Master of Science in Aerospace Engineering at the University of Padova. In the beginning, a mission requirements definition was conducted. After that, the mission feasibility was considered, with preliminary requirements verification to assess the ability of the spacecraft to survive the space environment, including compliance with Debris Mitigation Guidelines, ground station visibility and minimum operative lifetime evaluation. The Alba mission sets a base for a better understanding of the space environment and its interaction with nanosatellites, and an improvement of the accuracy of debris models. Furthermore, this paper, describing the educational experience and the results achieved, will provide a useful example for future students’ studies on CubeSat mission design.

Chapter 10: Planetary Protection-History, Science, and the Future.

Planetary protection is a principle in the design of interplanetary missions that aims to prevent biological cross contamination between the target body and Earth. Planetary protection policies and procedures have worked to mitigate forward contamination (from Earth) and back contamination (to Earth) since the beginning of the space age. Today, planetary protection policy is guided by international agreements, nongovernmental advisory councils, and national space agencies. The landscape of planetary protection science and policy is changing rapidly, as new technologies, crewed missions to Mars and the Moon, and even orbital settlements are being developed. Space exploration, whether specifically targeted toward questions in astrobiology or not, must consider planetary protection concerns to minimize contamination that poses a risk to both astrobiological investigations as well as Earth's biosphere. In this chapter, we provide an introduction to and overview of the history, motivations, and implementation of planetary protection in the United States.

Multiphase Autonomous Docking via Model-Based and Hierarchical Reinforcement Learning

With the rise of traffic around Earth’s orbit, spacecraft mission designs have placed an unprecedented demand on the capabilities of autonomous systems. In the early 2000s, the state-of-the-art autonomous spacecraft controllers were designed for static and uncluttered environments. A little over a decade later, the challenges facing spacecraft autonomy now include cluttered, dynamic environments with time-varying constraints, logical modes, fault tolerances, uncertain dynamics, and complex maneuvers. With this rise in complexity, many areas of research have been investigating more experimental control strategies, such as reinforcement learning (RL), as a potential solution to this problem. The research presented herein aims to expand on efforts to quantify the use of RL in autonomous rendezvous, proximity operations, and docking (ARPOD) environments, with consideration to the inherent drawbacks of the more common algorithms present in the field. We present hierarchical model-based RL as a solution to an autonomous docking problem. This algorithm can learn satellite parameters, extrapolate trajectory information, and learn uncertain dynamics via data collection. By using gradient-free model predictive control logic, the algorithm can handle nondifferentiable objectives and complex constraints. Lastly, the hierarchical structure demonstrates an ability to generate feasible trajectories in the presence of integrated third-party subcontrollers commonly found in spacecraft. This study highlights the ability of the hierarchical algorithm to combine and manipulate third-party subpolicies to achieve trajectories not previously trained on.

HPIC: The Habitable Worlds Observatory Preliminary Input Catalog

The Habitable Worlds Observatory Preliminary Input Catalog (HPIC) is a list of ∼13,000 nearby bright stars that will be potential targets for the Habitable Worlds Observatory (HWO) in its search for Earth-sized planets around Sun-like stars. We construct this target list using the TESS and Gaia DR3 catalogs and develop an automated pipeline to compile stellar measurements and derived astrophysical properties for all stars. We benchmark the stellar properties in the HPIC relative to those of the manually curated ExEP HWO Precursor Science Stars list and find that, for the 164 best targets for exo-Earth direct imaging, our stellar properties are consistent. We demonstrate the utility of the HPIC by using it as an input for yield calculations to predict the science output of various mission designs, including those with larger telescope diameters and those focused on other planet types besides Earth analogs, such as Jupiter-mass planets. The breadth and completeness of the HPIC is essential for accurate HWO mission trade studies, and it will be useful for other exoplanet studies and general astrophysics studying the population of bright nearby stars.

Improving casualty risk estimates for uncontrolled rocket body reentries

Approximately 70 % of launches in 2022 resulted in an uncontrolled rocket body reentry, creating an unnecessary casualty risk to people on the ground, at sea, and in aircraft. Rocket bodies have masses ranging from tens of kilograms to 20 tonnes. Using known rocket body masses and correlations between mass and casualty area, we present revised estimates for the expected risk, finding a 20–29 % probability of one or more casualties over the next decade.Some states use a 1-in-10,000 threshold for accepting an uncontrolled reentry casualty risk when approving a space activity. This threshold, which is not universally agreed upon, represents a risk acceptance by one country, but imposed on the world population. As the use of space expands, with a record 180 successful launches in 2022, states and other launch providers should adopt technologies and mission designs that ensure controlled reentries. Uncontrolled reentries, particularly of large rocket bodies, constitute an unsafe and unnecessary practice.

Surface Charging of Jupiter’s Moon Europa

Europa’s surface is exposed to a constant flow of plasma from its ionosphere and Jupiter’s magnetosphere. As these particles flow onto the surface, an electrostatic surface potential forms. We investigate the electrostatic charging of Europa’s surface using 3D particle-in-cell simulations. We find that surface potentials on Europa vary from −14 to −52 V. The predicted surface potentials vary as a function of location on Europa, illumination conditions, plasma environment, and surface properties. We reveal that the ionosphere has a significant “dampening effect,” limiting the formation of large negative surface potentials. Furthermore, we find that secondary emission is a key factor in determining the surface charge on Europa. We discuss how such potentials may be remotely detected by upcoming missions, such as Europa Clipper and JUICE. Our results may also be of use in the design of future missions to Europa’s surface, such as landers and other robotic explorers.

The Width of Magnetic Ejecta Measured near 1 au: Lessons from STEREO-A Measurements in 2021–2022

Coronal mass ejections (CMEs) are large-scale eruptions with a typical radial size at 1 au of 0.21 au but their angular width in interplanetary space is still mostly unknown, especially for the magnetic ejecta (ME) part of the CME. We take advantage of STEREO-A angular separation of 20°–60° from the Sun–Earth line from 2020 October to 2022 August, and perform a two-part study to constrain the angular width of MEs in the ecliptic plane: (a) we study all CMEs that are observed remotely to propagate between the Sun–STEREO-A and the Sun–Earth lines and determine how many impact one or both spacecraft in situ, and (b) we investigate all in situ measurements at STEREO-A or at L1 of CMEs during the same time period to quantify how many are measured by the two spacecraft. A key finding is that out of 21 CMEs propagating within 30° of either spacecraft only four impacted both spacecraft and none provided clean magnetic cloud-like signatures at both spacecraft. Combining the two approaches, we conclude that the typical angular width of an ME at 1 au is ∼20°–30°, or 2–3 times less than often assumed and consistent with a 2:1 elliptical cross section of an ellipsoidal ME. We discuss the consequences of this finding for future multi-spacecraft mission designs and for the coherence of CMEs.

Non-linear dynamics of a test particle near the Lagrange points L4 and L5 (Earth-Moon and Sun-Earth case)

The two-bodies problem can be fully solved, and was solved by Kepler (1609) and Newton (1687). The general three-body problem is often given as an example of a mathematical problem that ‘can’t be solved’. So, there is no general analytical solution. This problem can be significant and a special case of this problem is the Circular Restricted Three-Body Problem (CRTBP), which can be applied to the Earth-Moon system with a spacecraft, the Sun-Earth system with an asteroid, etc. In this paper, let’s focus on the motion of a test particle near the triangular Lagrange points L4 and L5 in the Earth-Moon and the Sun-Earth systems. Studying the movement of an object around these points is especially important for space mission design. To generate a trajectory around these points, the non-linear equations of motion for the circular restricted three-body problem were numerically integrated into MATLAB® 2023 software and the results are presented in the plane (x, y) and the phase plane (x, vx) and (y, vy). By numerical orbit integration, it is possible to investigate what happens when the displacement is relatively large or short from the Lagrange points. Then the small astronomical body may vibrate around these points. The results in this paper are shown in the rotating and inertia axes. Various initial positions near the Lagrange points and velocities are used to produce various paths the test particle can take. The same examples of numerical studies of trajectories associated with Lagrange points are shown in the inertial and the rotating coordinates system and are discussed. From the results of the numerical tests performed in MATLAB® 2023, it is possible to saw that there are different types of periodic, quasi-periodic, and chaotic orbits

B-Plane Resonant Flybys: Theory Extension to Elliptical Orbits and Dynamic Programming Application

A convenient formalism for the design of resonant flyby trajectories is the B-plane, where postencounter orbits with target resonance conditions or semimajor axes can be analytically mapped. This framework has been developed by many authors starting from the classical Öpik’s theory for close encounters, but it still relies on the approximation of circular orbits of the flyby bodies. In this work, the theory is analytically extended to account for elliptical planetary orbits. The classical and the extended formulations are tested and compared on two mission design applications, showing nonnegligible differences when the flyby body has a marked eccentricity. Further validation using a full three-body model confirmed the greater accuracy of the extended formulation. The second part of the paper proposes an efficient dynamic programming approach to the design of unperturbed resonant flybys. This problem has traditionally been addressed within broader optimization frameworks involving generic multiple gravity assists. However, focusing only on the resonant sequence allows the problem to feature a convenient structure for the implementation of dynamic programming. The developed algorithm is tested by reproducing the design of Solar Orbiter’s resonant phase with Venus, used in the actual mission to gradually raise the ecliptic inclination and reduce the distance at perihelion.

Rapid generation of time-optimal rendezvous trajectory based on convex optimisation and DNN

Abstract The minimum flight time of spacecraft rendezvous is one of the fundamental indexes for mission design. This paper proposes a rapid trajectory planning method based on convex optimisation and deep neural network (DNN). The time-optimal trajectory planning problem is reconstructed into a double-layer optimisation framework, with the inner being a convex optimisation problem and the outer being a root-finding problem. The thrust properties corresponding to time-optimal control are analysed theoretically. A DNN-based rapid planning method (DNN-RPM) is put forward to improve computational efficiency, in which the trained DNN provides a high-quality initial guess for Newton’s method. The DNN-RPM is extended to search for the optimal entering angle of natural-motion circumnavigation orbit injection problem and the minimum reconfiguration time of spacecraft swarm. Numerical simulations show that the proposed method can improve the computational efficiency while ensuring the calculation accuracy.

A Method for Evaluating Global Navigation Satellite System Position Accuracy in Small Unmanned Aircraft Systems

Highlights A novel UAS-based GNSS testing system was developed to assess both horizontal and vertical accuracy components. Recommendations are provided for further standard development related to UAS GNSS testing protocols. Future research can utilize this framework to enhance understanding of UAS GNSS accuracy. Abstract. Current standards for Global Navigation Satellite Systems (GNSS) testing are primarily designed for assessing horizontal positioning accuracy in ground-based applications. However, there is a notable absence of guidelines specifically addressing vertical accuracy assessment and applications that extend beyond ground-based scenarios, including those involving small unmanned aircraft systems (UAS). This effort aimed to develop a UAS-based GNSS testing system, tailored for the evaluation of GNSS receiver performance in dynamic low-altitude scenarios. The main objectives included (1) designing a GNSS testing system for UAS applications and (2) validating the system through field testing. The system development consisted of GNSS receiver configuration, data acquisition system design, processing procedures, and UAS payload and base station component design. The UAS payload featured multiple GNSS receivers operating in different modes, and data were collected using a custom Python script on a Raspberry Pi computer. For in-field validation, dynamic flight testing with vertical profiles was conducted. A robotic tracking total station (TTS) was used as the reference instrument for measuring the location of the UAS payload. The findings underscore the system's capabilities, primarily emphasizing its functionality rather than conducting an extensive assessment of the individual GNSS receiver performance. The UAS-based testing system that was developed was capable of satisfying most of the criteria for existing GNSS test standards. The insights derived from this process offer recommendations for standardizing UAS-based GNSS testing methods, with a particular focus on mission design, battery management, data processing, and environmental adaptability. Keywords: Dynamic Error, Global Navigation Satellite Systems (GNSS), Positioning Accuracy, Tracking Total Station (TTS), Unmanned Aircraft Systems (UAS).

A Rendezvous Mission to the Second Earth Trojan Asteroid 2020 XL5 with Low-Thrust Multi-Gravity Assist Techniques

As the second of Earth’s Trojan asteroids, 2020 XL5 is worthy of rendezvous and even sample return missions in many aspects. In this paper, a rendezvous mission to Earth’s second Trojan asteroid 2020 XL5 is proposed. However, due to its high inclination and large eccentricity, direct impulsive transfer requires large amounts of fuel consumption. To address this challenge, we explore the benefits of electric propulsion and multi-gravity assist techniques for interplanetary missions. These two techniques are integrated in this mission design. The design of a low-thrust gravity-assist (LTGA) trajectory in multi-body dynamics is thoroughly investigated, which is a complex process. A comprehensive framework including three steps is presented here for optimization of LTGA trajectories in multi-body dynamics. The rendezvous mission to 2020 XL5 is designed with this three-step approach. The most effective transfer sequence among the outcomes involves Earth–Venus–Earth–Venus-2020 XL5. Numerical results indicate that the combination of electric propulsion and multi-gravity assists can greatly reduce the fuel consumption, with fuel consumption of 9.03%, making it a highly favorable choice for this rendezvous mission.

Bioverse: The Habitable Zone Inner Edge Discontinuity as an Imprint of Runaway Greenhouse Climates on Exoplanet Demographics

Long-term magma ocean phases on rocky exoplanets orbiting closer to their star than the runaway greenhouse threshold—the inner edge of the classical habitable zone—may offer insights into the physical and chemical processes that distinguish potentially habitable worlds from others. The thermal stratification of runaway planets is expected to significantly inflate their atmospheres, potentially providing observational access to the runaway greenhouse transition in the form of a habitable zone inner edge discontinuity in radius–density space. Here, we use Bioverse, a statistical framework combining contextual information from the overall planet population with a survey simulator, to assess the ability of ground- and space-based telescopes to test this hypothesis. We find that the demographic imprint of the runaway greenhouse transition is likely detectable with high-precision transit photometry for sample sizes ≳100 planets if at least ∼10% of those orbiting closer than the habitable zone inner edge harbor runaway climates. Our survey simulations suggest that, in the near future, ESA’s PLATO mission will be the most promising survey to probe the habitable zone inner edge discontinuity. We determine the survey strategies that maximize the diagnostic power of the obtained data and identify as key mission design drivers: (1) a follow-up campaign of planetary mass measurements and (2) the fraction of low-mass stars in the target sample. Observational constraints on the runaway greenhouse transition will provide crucial insights into the distribution of atmospheric volatiles among rocky exoplanets, which may help to identify the nearest potentially habitable worlds.

GNOS-II on Fengyun-3 Satellite Series: Exploration of Multi-GNSS Reflection Signals for Operational Applications

The Global Navigation Satellite System Occultation Sounder II (GNOS-II) payload onboard the Chinese Fengyun-3E (FY-3E) satellite is the world’s first operational spaceborne mission that can utilize reflected signals from multiple navigation systems for Earth remote sensing. The satellite was launched into an 836-km early-morning polar orbit on 5 July 2021. Different GNSS signals show different characteristics in the observations and thus require different calibration methods. With an average data latency of less than 3 h, many near real-time applications are possible. This article first introduces the FY-3E/GNOS-II mission and instrument design, then describes the extensive calibration methods for the multi-GNSS measurements, and finally presents application results in the remote sensing of ocean surface winds, land soil moisture and sea ice extent. Especially, the ocean surface wind product has been used in operational applications such as assimilation in the numerical weather prediction model and monitoring of tropical cyclones. Currently, GNOS-II has been carried by FY-3E, FY-3F (launched in August 2023) and FY-3G (launched in April 2023). It will be also carried by future follow-on FY series and a more complete multi-GNSS reflectometry constellation will be established.

Development of a sensitivity analysis tool for the trajectory of multistage launch vehicles

The primary objective of this work is to create a highly accurate sensitivity analysis tool for multi-stage launch vehicle trajectories. This tool is designed to assess the impact of various parameters on the trajectory and performance of multi-stage launch vehicles. To achieve this, we have developed high-fidelity simulation software that considers all translational and angular movements by modelling the six-degrees-of-freedom (6DOF) equations of motion. The validation of this software is based on experimental data. An essential aspect of this work is the utilization of the developed sensitivity analysis tool to determine how different parameters affect the trajectory of multi-stage launch vehicles. Through the sensitivity analysis conducted using the developed tool, it is possible to identify which parameters are of critical importance during the design phase. We apply a generic mission profile for the Minotaur-I launcher to obtain parametric dependencies of the flight path. Through a comprehensive parametric study, we evaluate a range of critical parameters, including gross lift-off weight, a specific impulse of each stage, pitch-over manoeuvre initial time and angle, and ignition impulse of each stage. These parameters significantly influence the trajectory, performance, and reliability of the launch vehicle for mission design and success. The results of the sensitivity analysis underscore that even minor variations in these parameters can result in substantial deviations from the nominal insertion altitude. The acceptability of errors in specific impulse changes varies across stages, with maximum changes of 6.07%, and the fourth stage showing less sensitivity at 0.13%. However, it's important to note that variations in the parameters of the first stage tend to be challenging to rectify once they occur, with maximum changes in specific impulses reaching 75.57%. Another noteworthy discovery is that the acceptability of changes in pitch-over manoeuvre initiation times depends on the rate of change; they can be deemed either acceptable or unacceptable based on this factor, with changes ranging between 17.90% and 98.38%.

Slow intrusion experiments into granular media under microgravity

This study presents the design and implementation of a low-speed intrusion experiment under microgravity, with a strong motivation to support the pre-research of the Chinese asteroid exploration mission. In the experiment apparatus, we reconstructed an effective gravity of 10-2 g in a free-falling capsule in the drop tower. The simulant of regolith particles is processed using natural basalt and sorted using layered screens. The irregular shapes of the particles are retained to mimic the realistic regolith. A detailed description of the experimental system components and the full-cycle procedure is first presented, which gives 3.6 s of microgravity time for each trial. Repeatable controlled experiments are performed to characterize the dynamical responses of the simulant particles under centimeter-per second intrusion. The results reveal diverse responses that depend on different variables, and the mechanism of different responses is discussed based on theories of granular mechanics. This experimental study is expected to improve our understanding of the contact mechanics of regolith material, which will facilitate the operation design of future asteroid missions.

CORTO: The Celestial Object Rendering TOol at DART Lab

The Celestial Object Rendering TOol (CORTO) offers a powerful solution for generating synthetic images of celestial bodies, catering to the needs of space mission design, algorithm development, and validation. Through rendering, noise modeling, hardware-in-the-loop testing, and post-processing functionalities, CORTO creates realistic scenarios. It offers a versatile and comprehensive solution for generating synthetic images of celestial bodies, aiding the development and validation of image processing and navigation algorithms for space missions. This work illustrates its functionalities in detail for the first time. The importance of a robust validation pipeline to test the tool’s accuracy against real mission images using metrics like normalized cross-correlation and structural similarity is also illustrated. CORTO is a valuable asset for advancing space exploration and navigation algorithm development and has already proven effective in various projects, including CubeSat design, lunar missions, and deep learning applications. While the tool currently covers a range of celestial body simulations, mainly focused on minor bodies and the Moon, future enhancements could broaden its capabilities to encompass additional planetary phenomena and environments.

Maximizing Societal Benefit Across Multiple Hyperspectral Earth Observation Missions: A User Needs Approach

AbstractImaging spectroscopy is a powerful tool used to support diverse Earth science and applications objectives, ranging from understanding and mitigating widespread impacts of climate change to management of water at farm‐scale. Community studies, such as those deployed by NASA's Surface Biology and Geology and ESA's Copernicus Hyperspectral Imaging Mission for the Environment, have offered new and tangible insights into user needs that are then incorporated into overall mission planning and design. These technologies and tools will be key to develop and consolidate downstream services for users and resource management, given the current pressures on the environment posed by climate change and population growth. This process has highlighted the degree to which planned mission capabilities are responsive to community needs. In this study, we analyze user requirements belonging to the Italian Copernicus User Forum and to the user pool of NASA's Surface Biology and Geology community for the synergic use of hyperspectral imaging technology, providing a reference for the development of earth observation services and the consolidation of existing ones. In addition, potential cross‐mission coordination is analyzed to highlight key benefits—(a) addressing shared community needs around products requiring more frequent temporal revisit and (b) shared resources and community expertise around algorithm development. This paper discusses the critical role of early engagement with users to establish a community of practice ready to work with high spatial resolution imaging spectroscopy data sets. The main outcome is a guide for the synergetic use of hyperspectral mission and data together with the identification of the main gaps between user needs and satellite capabilities influencing the development of key national and trans‐national downstream services.

Snapshot GNSS receivers for low-effort, high-gain space situational awareness

This paper proposes a novel concept of using highly efficient Snapshot Global Navigation Satellite Systems (GNSS) receivers to provide precise position fixes of single or multiple satellites in Low-Earth Orbit (LEO) to improve upper atmospheric modeling and thus contribute to superior space situational awareness (SSA). While tracking of LEO satellites and the use of onboard GNSS receivers for drag measurements and upper atmosphere modeling are well-established techniques, the expected advent of snapshot GNSS receivers for spaceborne scientific applications will allow massive improvements on the GNSS sensor’s Size, Weight, Power and Cost (SWaP-C). With chip-size dimensions of 4x4 mm2, a mass of less than 5 gr, an average power level below 0.1 mW, snapshot receiver technology is expected to provide position fixes in space with an accuracy of ∼19 m (3D r.m.s.), which will surpass the accuracy of Two-Line Elements (TLE) provided by the US Joint Space Operations Center (JSpOC) by at least two orders of magnitude. Equally important to their SWaP-C benefits, Snapshot GNSS receivers will allow mission and spacecraft designers to trade onboard-processing requirements versus payload downlink requirements, leading to either minimum onboard processing or a minimum amount of downlinked data. In this research, we establish the concept and architectural overview of using snapshot GNSS receivers for SSA, including the role of using them in a Distributed Space System (DSS), and detail their characterization and performance in terms of the required GNSS hardware and the impact of these payload on the power budget, the link budget and the OnBoard Data Handling (OBDH) budget of a satellite. It will be shown that these receivers lend themselves especially to their use on femto-, pico- and nano-satellites, although integrated snapshot modules may be flown as auxiliary payloads on micro- or mini-satellites as well. While this work focuses on the implications of the use of snapshot GNSS receivers on spacecraft design for the use of upper atmosphere modeling and SSA, their use may open up other science applications which avoid the need for expensive high-grade GNSS receivers.