Fault tolerant design and autonomous spacecraft


System fault protection design for the Cassini spacecraft


Formal Specification and Verification of Autonomous Robotic Systems: A Survey

M. Luckcuck
M. Farrell
L. A. Dennis
C. Dixon
M. Fisher


SPIDER - A simple emergent system architecture for autonomous spacecraft fault protection

AIAA Space 2001 Conference and Exposition


Satellite and satellite subsystems reliability: Statistical data analysis and modeling

Reliability Engineering and System Safety


Beyond reliability, multi-state failure analysis of satellite subsystems: A statistical approach


Single versus mixture Weibull distributions for nonparametric satellite reliability


Assurance of model-based fault diagnosis


Statistical reliability analysis of satellites by mass category: Does spacecraft size matter?


Statistical analysis and modelling of small satellite reliability


Spacecraft attitude control subsystem: Reliability, multi-state analyses, and comparative failure behavior


A hybrid procedural/deductive executive for autonomous spacecraft

B. Pell
D. E. Bernard
S. A. Chien
E. Gat
N. Muscettola et al.

Second International Conference on Autonomous Agents


Railroads and American Economic Growth: Essays in Econometric History


Spacecraft early design validation using formal methods


A Robust Fault Protection Strategy for a COTS-Based Spacecraft


Spacecraft autonomy flight experience: The DS1 Remote Agent Experiment

Space Technology Conference and Exposition


On-board planning for New Millennium Deep Space One autonomy

N. Muscettola
P. P. Nayak
B. Pell
B. C. Williams


On-board fault management for autonomous spacecraft


Autonomy for Space Robots: Past, Present, and Future


Applications and Challenges of Artificial Intelligence in Space Missions


Improving Spacecraft Health Monitoring with Automatic Anomaly Detection Techniques


Smart anomaly detection in sensor systems: A multi-perspective review


The Precautionary Principle (with Application to the Genetic Modification of Organisms)

N. N. Taleb
R. Read
R. Douady
J. Norman
Y. Bar-Yam


Understanding long-term orbital debris population dynamics


Regression Models and Life-Tables

Journal of the Royal Statistical Society: Series B


Cox's Regression Model for Counting Processes: A Large Sample Study


Modeling Survival Data: Extending the Cox Model


Time-Dependent Covariates in the Cox Proportional-Hazards Regression Model


Competing Risk Regression Models for Epidemiologic Data


Frailty Models in Survival Analysis


On-board, Autonomous, Hybrid Spacecraft Subsystem Fault and Anomaly Detection, Diagnosis, and Recovery

R. Stottler
S. Ramachandran
C. Belardi
R. Mandayam


Autonomous, Hybrid Space System Fault and Anomaly Detection, Diagnosis, Root Cause Determination, and Recovery

R. Stottler
S. Ramachandran
C. Healy
A. Singhal


R. Stottler
A. Singhal
C. Healy
S. Ramachandran
K. Quinn
J. Palmieri
S. Logan


Time-to-Event Data (Survival Analysis) based Modelling of Maneuver Occurrence of Non-Cooperative Satellites


Agent-based approaches for distributed space systems and mission management: Methodologies, current practices and challenges

M. R. Jabbarpour
Q. B. Vo
G. El-Dalahmeh
H. Tahir
R. Kowalczyk
T. Bessell
J. Barr


Autonomy and operational concept for self-removal of spacecraft: Status detection, removal triggering and passivation

A. Wander
K. Konstantinidis
R. Förstner
P. Voigt


Lessons from the Dawn mission to Ceres and Vesta


Femtosatellite mission architectures and mission assurance strategies

C. Teale
J. Beeley
G. Baillet
C. R. McInnes


Social Savings


Antifragile: Things That Gain from Disorder (review)


Cliometrica after 10 years: definition and principles of cliometric research


The Consequences of Financial Innovation: A Counterfactual Research Agenda

Abstract: Financial innovation has been both praised as the engine of growth of society and castigated for being the source of the weakness of the economy. In this paper, we review the literature on financial innovation and highlight the similarities and differences between financial innovation and other forms of innovation. We also propose a research agenda to systematically address the social welfare implications of financial innovation. To complement existing empirical and theoretical methods, we propose that scholars examine case studies of systemic (widely adopted) innovations, explicitly considering counterfactual histories had the innovations never been invented or adopted.


The Impact of Cliometrics on Economics and History

Abstract: La cliométrie a transformé l’histoire économique en passant d’une approche essentiellement narrative à une approche mathématique, suscitant par là même beaucoup d’appréhensions et de débats quant à l’équilibre approprié entre l’économie et l’histoire. Le point culminant de cette transformation s’est produit en 1993 lorsque les pionniers de la cliométrie Robert Fogel et Douglass North ont reçu le prix Nobel de science économique. La cliométrie a réalisé un équilibre délicat entre économie et histoire. Elle n’est ni trop « étroitement » économique, c’est-à-dire qu’elle ne se contente pas de mesurer les phénomènes sans les expliquer, ni trop historique (elle ne rejette pas les contacts avec les économistes). En fusionnant l’histoire économique avec les techniques modernes, les cliométriciens n’ont pas mis fin à l’histoire économique, mais ils lui ont donné une autre dimension.


Counterfactual Thinking as a Scientific Method

Social Science Open Access Repository (GESIS – Leibniz Institute for the Social Sciences)

Abstract: 'Seiner angeblichen Nutzlosigkeit zum Trotz begegnen wir in unserem Alltagsleben unzähligen Beispielen kontrafaktischen Denkens. In den letzten zwanzig Jahren ist dieses Phänomen von Psychologen eingehend analysiert worden. Es konnte gezeigt werden, dass kontrafaktische Gedanken über vergangene (und daher unveränderbare) Ereignisse oder Situationen für den Denkenden durchaus nützlich sein kann. Dieser Beitrag fasst die Effekte kontrafaktischen Denkens in Alltagssituationen zusammen und versucht daraufhin, diese in einen akademischen Kontext zu übertragen. Können counterfactuals in der Wissenschaft ähnliche analytische Qualitäten entfalten wie im Alltagsleben? Und falls ja, welche Beispiele gibt es dafür? Nach einer kurzen Betrachtung der psychologischen Aspekte kontrafaktischen Denkens, diskutiert der Text daher dessen Nutzen aus wissenschaftlicher Sicht bevor er sich der kontrafaktische


Cliometrics: A Market Account of a Scientific Community (1957-2006)

Abstract: Este artículo tiene como objetivo evaluar las principales contribuciones de la cliometría en la integración global y disciplinaria de las ciencias sociales. A través de una analogía de un pseudo-mercado del conocimiento son analizadas las presiones y respuestas que los cliometristas han enfrentado en tanto una empresa cuyo objetivo es proveer respuestas a ciertas preguntas que la sociedad formula. Basado en una valoración general de los productos cliométricos se encuentra que esta comunidad científica norteamericana revolucionó la práctica de la historia económica y ganó terreno frente a la competencia representada por la historia tradicional. Posteriormente, los cliometristas difundieron sus innovaciones internacionalmente, pero atravesaron divisiones internas que en última instancia han enriquecido sus prácticas y llamado a cooperar con otras comunidades científicas. Palabras clave: cl


Handbook of Cliometrics


The Evolution of Economic History since 1950: From Cliometrics to Cliodynamics

Abstract: This paper analyzes the evolution of economic history in the last 65 years. It argues that economic history has followed a path that goes from the strictly use of standard economics applied to economic past (i.e. cliometrics), to a general formal reflection of social history based on more flexible tools (i.e. cliodynamics). While cliometrics was a paradigm based on neoclassical theory and econometric methods, cliodynamics is a research agenda founded in non-neoclassical theoretical frameworks and quantitative methods not based on statistical inference. In that sense, the paper supports the idea that economic history has maintained its relevance in economics literature, despite the decay of particular traditions in the field.


Microeconomic Origins of Macroeconomic Tail Risks

Daron Acemoğlu
Asuman Ozdaglar
Alireza Tahbaz-Salehi

Abstract: Using a multisector general equilibrium model, we show that the interplay of idiosyncratic microeconomic shocks and sectoral heterogeneity results in systematic departures in the likelihood of large economic downturns relative to what is implied by the normal distribution. Such departures can emerge even though GDP fluctuations are approximately normally distributed away from the tails, highlighting the different nature of large economic downturns from regular business-cycle fluctuations. We further demonstrate the special role of input-output linkages in generating tail comovements, whereby large recessions involve not only significant GDP contractions, but also large simultaneous declines across a wide range of industries. (JEL D57, E16, E23, E32)


Tail risk of contagious diseases


Extreme value theory and Value-at-Risk: Relative performance in emerging markets


Tail Risk and Asset Prices


On the statistical properties and tail risk of violent conflicts

Physica A Statistical Mechanics and its Applications


Beyond the Precautionary Principle

Abstract: The precautionary principle has been highly influential in legal systems all over the world. In its strongest and most distinctive forms, the principle imposes a burden of proof on those who create potential risks, and it requires regulation of activities even if it cannot be shown that those activities are likely to produce significant harms. Taken in this strong form, the precautionary principle should be rejected, not because it leads in bad directions, but because it leads in no directions at all. The principle is literally paralyzing— forbidding inaction, stringent regulation, and everything in between. The reason is that in the relevant cases, every step, including inaction, creates a risk to health, the environment, or both. This point raises a further puzzle. Why is the precautionary principle widely seen to offer real guidance? The answer lies in identifiable cognitive mechanism


Beyond the Precautionary Principle


Cancer, COVID-19 and the precautionary principle: prioritizing treatment during a global pandemic

Timothy P. Hanna
Gerald A. Evans
Christopher M. Booth


Applying the Precautionary Principle to Wireless Technology: Policy Dilemmas and Systemic Risks

Paul Ben Ishai
Hillel Z. Baldwin
Linda S. Birnbaum
Tom Butler
Kent Chamberlin
Devra Lee Davis

Environment Science and Policy for Sustainable Development

Abstract: Recent decades have seen a huge rise in human exposure to microwave radiation due to the widespread use of mobile and wireless services that enable smartphones and watches, tablets, laptops and digital devices in the home and workplace. The health and safety standards to protect humans from exposure to harmful levels of microwave radiation can be traced to the 1950s. However, research now demonstrates the existence of many adverse health effects, including cancers and neurological disorders, at levels of everyday use by children and adults. We argue that it is long past the time for governments to apply the Precautionary Principle to protect children and adults, especially pregnant women, and to ensure safer levels of exposure for all.


History of Cliometrics


Emphasizing Understandability, Flexibility, and Verifiability in a Spacecraft Fault Management Autonomy System

George Cancro
Russel Turner
Chris Monaco
D. WILSON
L. Nguyen
Michael Pekala

Abstract: Surveying the current state of practice of spacecraft autonomy, one can detect many different attributes of the various autonomy systems currently employed to maintain the safety of the spacecraft. In an effort to move beyond the state of practice, Johns Hopkins University Applied Physics Lab has focused on three of these attributes not found together in current systems: Understandability, Flexibility and Verifiability. Understandability defines the ability to specify and review the autonomy system in such a way that any non-software domain expert or system engineer can understand the design. Flexibility defines the ability to modify the design pre- and post-launch in parts without patching or without complete code uploads. Verifiability defines the ability to exhaustively and rapidly verify correct autonomy system behavior before it is uploaded to the spacecraft. With the goal of attain


Dynamic Bayesian Networks for Fault Detection, Identification, and Recovery in Autonomous Spacecraft

IEEE Transactions on Systems Man and Cybernetics Systems

Abstract: This paper describes how to exploit the modeling features and inference capabilities of dynamic Bayesian networks (DBN), in designing and implementing an innovative approach to fault detection, identification, and recovery (FDIR) for autonomous spacecrafts (e.g., a Mars rover). In particular, issues like partial observability, uncertain system evolution and system-environment interaction, as well as the prediction and mitigation of imminent failures can be naturally addressed by the proposed approach. The DBN framework can augment the modeling and analytical power of standard FDIR methodologies, while still being able to be integrated into the usual system modeling procedures (like, for instance, fault tree analysis). An FDIR cycle composed of the tasks of diagnosis (identification of the current state of the system), prognosis (identification of the future state under the current condit


Model-based fault management for spacecraft autonomy

Abstract: Autonomous health monitoring is a key enabling technology for future space missions. One approach to developing this capability is through model-based fault management. This method seeks to leverage system models in order to enable rapid algorithm development, reduce the burden of verification and validation, and ensure that a large set of possible faults can be detected and identified. Here, a high fidelity model of a spacecraft attitude control system is used to as step towards validating the performance of Marple, a model-based fault management system. The ultimate goal is to validate this autonomous fault management capability for use on robotic and manned missions and this work is a step to that end.


Formal methods for the validation of fault tolerance in autonomous spacecraft

Sandra Ayache
Eric Conquet
Pascal Humbert
C. Rodrı́guez
Joseph Sifakis
R. Nicholas Gerlich

Abstract: One of the major challenges to be faced in the design of new-generation spacecrafts comes with the requirement to increase the capacity of autonomous operation, in particular in presence of abnormal events. Formal methods are becoming more accepted in the space industry as a possible way to manage induced systems complexity. The Data Management System Design Validation (DDV) study has accomplished an experimental junction between the spacecraft autonomy trends and emerging formal methodologies. A methodological framework applicable to the early life cycle phases of fault-tolerant systems engineering has been defined. It focuses on the verification of fault tolerance properties using model-based formalisms. The Specification and Design Language (SDL) was selected for this study as the best suited language with respect to the application. This work has resulted in an executable specificati


Fault Tolerance for Spacecraft Attitude Management

AIAA Guidance, Navigation, and Control Conference

Abstract: We present an autonomy architecture called Fault Tolerant Remote Agent that integrates symbolic reasoning from AI planning/scheduling with physics-based fault-tolerant control. Application to spacecraft attitude management in the presence of diverse failure classes is studied. We first review fault tolerance in AI and control-theoretic contexts and introduce an architecture in which the capabilities of each can be integrated into a more comprehensive fault management framework. We then present fault identification and reconfiguration algorithms for a spacecraft attitude control case study. Simulation results demonstrate good recovery by the spacecraft for situations in which controllability is not lost. These simulations also illustrate how logic-based and physics-based algorithms cooperatively achieve a more comprehensive fault management capability than would be possible with either al


Human–Autonomy Teaming: Definitions, Debates, and Directions

Joseph B. Lyons
Katia Sycara
Michael Lewis
August Capiola

Abstract: Researchers are beginning to transition from studying human-automation interaction to human-autonomy teaming. This distinction has been highlighted in recent literature, and theoretical reasons why the psychological experience of humans interacting with autonomy may vary and affect subsequent collaboration outcomes are beginning to emerge (de Visser et al., 2018; Wynne and Lyons, 2018). In this review, we do a deep dive into human-autonomy teams (HATs) by explaining the differences between automation and autonomy and by reviewing the domain of human-human teaming to make inferences for HATs. We examine the domain of human-human teaming to extrapolate a few core factors that could have relevance for HATs. Notably, these factors involve critical social elements within teams that are central (as argued in this review) for HATs. We conclude by highlighting some research gaps that researchers


Fault protection in a component-based spacecraft architecture

DSpace@MIT (Massachusetts Institute of Technology)

Abstract: As spacecraft become more complex and autonomous, the need for reliable fault protection will become more prevalent. When coupled with the additional requirement of limiting cost, the task of implementing fault protection on spacecraft becomes extremely challenging. The current state-of-the-art Cassini fault protection software, for example, is a testament to the complexity and difficulty of implementing fault protection on spacecraft. This paper describes how domain knowledge about spacecraft fault protection can be captured and stored in a reusable, component-based spacecraft architecture. The spacecraft-level fault protection strategy for a new spacecraft can then be created by composing generic component specifications, each with component-level fault protection included. The resulting fault protection design can be validated by formal analysis and simulation before any costly implem


Fault protection architecture for the command and data subsystem on the Cassini spacecraft

Abstract: Cassini is a NASA/JPL spacecraft that is planned to be launched in 1997 for a 10.7 year mission (6.7 in transit, 4 in orbit) to the planet Saturn. This paper focuses on one subsystem on the spacecraft, the Command and Data Subsystem (CDS). Overviews are presented of the Cassini and CDS avionics and then the internal fault protection architecture for the subsystem is described. This description covers fault detections, error filtering, event activation rules, and response triggering for the following key subsystem regions: (1) Command and Data Electronics Assemblies, (2) 1553B Bus and Remote Terminal Communication Interface Units, (3) Remote Engineering Units, and (4) Solid State Recorders.


Fault Tolerant Three-Phase AC Motor Drive Topologies: A Comparison of Features, Cost, and Limitations

B.A. Welchko
T.Α. Lipo
Thomas M. Jahns
Steven E. Schulz

Abstract: This paper compares the many fault tolerant three-phase ac motor drive topologies that have been proposed to provide output capacity for the inverter faults of switch short or open-circuits, phase-leg short-circuits, and single-phase open-circuits. Also included is a review of the respective control methods for fault tolerant inverters including two-phase and unipolar control methods. The output voltage and current space in terms of dq components is identified for each topology and fault. These quantities are then used to normalize the power capacity of each system during a fault to a standard inverter during normal operation. A silicon overrating cost factor is adopted as a metric to compare the relative switching device costs of the topologies compared to a standard three-phase inverter.


A Primer on Architectural Level Fault Tolerance

NASA STI Repository (National Aeronautics and Space Administration)

Abstract: This paper introduces the fundamental concepts of fault tolerant computing. Key topics covered are voting, fault detection, clock synchronization, Byzantine Agreement, diagnosis, and reliability analysis. Low level mechanisms such as Hamming codes or low level communications protocols are not covered. The paper is tutorial in nature and does not cover any topic in detail. The focus is on rationale and approach rather than detailed exposition.


An overview of the fault protection design for the attitude control subsystem of the Cassini spacecraft

Abstract: This paper describes Cassini's fault tolerance objectives, and how those objectives have influenced the design of its attitude control subsystem (ACS). Particular emphasis is placed on the architecture of the software algorithms that are used to detect, locate, and recover from ACS faults, and the integration of these algorithms into the rest of the object-oriented ACS flight software. The interactions of these ACS "fault protection" algorithms with Cassini's system-level fault protection algorithms is also described. We believe that the architecture of the ACS fault protection algorithms provides significant performance and operability improvements over the fault protection algorithms that have flown on previous interplanetary spacecraft.


CloudSat Anomaly Recovery and Operational Lessons Learned

Abstract: In April 2011, NASA’s pioneering cloud profiling radar satellite, CloudSat, experienced a battery anomaly that placed it into emergency mode and rendered it operations incapable. All initial attempts to recover the spacecraft failed as the resultant power limitations could not support even the lowest power mode. Originally part of a six-satellite constellation known as the “A-Train”, CloudSat was unable to stay within its assigned control box, posing a threat to other A-Train satellites. CloudSat needed to exit the constellation, but with the tenuous power profile, conducting maneuvers was very risky. The team was able to execute a complex sequence of operations which recovered control, conducted an orbit lower maneuver, and returned the satellite to safe mode, within one 65 minute sunlit period. During the course of the anomaly recovery, the team developed several bold, innovative opera


The INTEGRAL spacecraft – in-orbit performance

P. L. Jensen
K. Clausen
C. Cassi
F. Ravera
G. Janin
Christoph Winkler

Abstract: The INTEGRAL satellite was successfully launched from Baikonur on 17 October, 2002. INTEGRAL is an observatory for gamma-ray astronomy. The goals are to provide unprecedented high resolution imaging capability for unambiguous identification of gamma ray sources and high energy resolution for line spectroscopy. This paper summarises the actual orbital evolution based on the first 8 months in orbit and provides a status of the on-board limiting life resources. The paper describes the measured in-orbit performance of the INTEGRAL satellite and summarizes the applicable operational constraints for the science user community.


An Approach To Mode and Anomaly Detection with Spacecraft Telemetry Data

Gautam Biswas
Hamed Khorasgani
Gerald Stanje
Abhishek Dubey
Somnath Deb
Sudipto Ghoshal

International Journal of Prognostics and Health Management

Abstract: This paper discusses a mixed method that combines unsupervised learning methods and human expert input for analyzing telemetry data from long-duration robotic space missions. Our goal is to develop more automated methods for detecting anomalies in time series data. Once anomalies are identified using unsupervised learning methods we use feature selection methods followed by expert input to derive the knowledge required for building on-line detectors. These detectors can be used in later phases of the current mission and in future missions for improving operations and overall safety of the mission. Whereas the primary focus in this paper is on developing data-driven anomaly detection methods, we also present a computational platform for data mining and analytics that can operate on historical data offline, as well as incoming telemetry data on-line.


A survey on Fault Detection, Isolation and Recovery (FDIR) module in satellite onboard software

Abstract: The complexity of the avionic systems in satellites is rising as space missions become increasingly more sophisticated. This complexity emphasizes the need for more dependable systems with minimal anomalies. As satellite manufactures seek to convert many hardware implemented functionalities into software, the On-Board Software (OBSW) is becoming a major component in every satellite. Noticeably, more tasks for Fault Detection, Isolation and Recovery (FDIR) are being implemented in software, where the need comes for a well-defined software architecture that supports a cost-effective implementation of the FDIR functions. FDIR was already explained as key functionality of the OBSW. Obviously not all failures are subject to onboard identification and not all failures are subject to onboard recovery. The FDIR concept to be worked out for the spacecraft during the engineering phase follows some


Galileo spacecraft anomaly and safing recovery

Abstract: A high-level anomaly recovery plan which identifies the steps necessary to recover from a spacecraft 'Safing' incident was developed for the Galileo spacecraft prior to launch. Since launch, a total of four in-flight anomalies have lead to entry into a system fault protection 'Safing' routine which has required the Galileo flight team to refine and execute the recovery plan. These failures have allowed the flight team to develop an efficient recovery process when permanent spacecraft capability degradation is minimal and the cause of the anomaly is quickly diagnosed. With this previous recovery experience and the very focused boundary conditions of a specific potential failure, a Gaspra asteroid recovery plan was designed to be implemented in as quickly as forty hours (desired goal). This paper documents the work performed above, however, the Galileo project remains challenged to develop


Geoscience Laser Altimetry System (GLAS) Loop Heat Pipe Anomaly and On Orbit Testing

C. L. Baker
C. Dan Butler
Peggy L. Jester
Eric Grob

41st International Conference on Environmental Systems

Abstract: The Geoscience Laser Altimetry System (GLAS) is the sole instrument on the ICESat Satellite. On day 230 of 2003, the GLAS Component Loop Heat Pipe (CLHP) entered a slow circulation mode that resulted in the main electronics box reaching its hot safing temperature, after which the entire instrument was turned off. The CLHP had a propylene working fluid and was actively temperature controlled via a heater on the compensation chamber. The slow circulation mode happened right after a planned propulsive yaw maneuver with the spacecraft. It took several days to recover the CLHP and ensure that it was still operational. The recovery occurred after the entire instrument was cooled to survival temperatures and the CLHP compensation chamber cycled on a survival heater. There are several theories as to why this slow circulation mode exhibited itself, including: accumulation of Non-Condensible Gas (


Low Earth Orbit Satellite Security and Reliability: Issues, Solutions, and the Road Ahead

Pingyue Yue
Jianping An
Jiankang Zhang
Jia Ye
Gaofeng Pan
Shuai Wang

Abstract: Low Earth Orbit (LEO) satellites undergo a period of rapid development driven by ever-increasing user demands, reduced costs, and technological progress. Since there is a lack of literature on the security and reliability issues of LEO Satellite Communication Systems (SCSs), we aim to fill this knowledge gap. Specifically, we critically appraise the inherent characteristics of LEO SCSs and elaborate on their security and reliability requirements. In light of this, we further discuss their vulnerabilities, including potential security attacks launched against them and reliability risks, followed by outlining the associated lessons learned. Subsequently, we discuss the corresponding security and reliability enhancement solutions, unveil a range of trade-offs, and summarize the lessons gleaned. Furthermore, we shed light on several promising future research directions for enhancing the secu


The Heliospheric Imagers Onboard the STEREO Mission

C. J. Eyles
R. A. Harrison
C. J. Davis
N. R. Waltham
B. M. Shaughnessy
H. Mapson-Menard


Radio science investigations by VeRa onboard the Venus Express spacecraft

B. Häusler
M. Pätzold
G. L. Tyler
R. A. Simpson
M. K. Bird
V. Dehant


A Review of Anomaly Detection in Spacecraft Telemetry Data

Asma Fejjari
Alexis Delavault
Robert Camilleri
Gianluca Valentino

Abstract: Telemetry data play a pivotal role in ensuring the success of spacecraft missions and safeguarding the integrity of spacecraft systems. Therefore, the timely detection and subsequent notification of any abnormal events related to the functionality of spacecraft subsystems are crucial to ensure their safe operation. In recent years, several anomaly detection methods have been developed to monitor spacecraft telemetry data and detect anomalies. This manuscript provides a comprehensive literature review of the existing anomaly detection methods for spacecraft telemetry data. It exposes the challenges faced by such systems, highlights the strengths and limitations of each anomaly detection method, and assesses and compares the performance of these approaches in detecting anomalies. Initial results show that GCN and TCN models have achieved promising precision up to 94%. The paper concludes w


Enabling Onboard Detection of Events of Scientific Interest for the Europa Clipper Spacecraft

Kiri L. Wagstaff
Gary Doran
A. G. Davies
Saadat Anwar
Srija Chakraborty
M. E. Cameron

Abstract: Data analysis and machine learning methods have great potential to aid in planetary exploration. Spacecraft often operate at great distances from the Earth, and the ability to autonomously detect features of interest onboard can enable content-sensitive downlink prioritization to increase mission science return. We describe algorithms that we designed to assist in three specific scientific investigations to be conducted during flybys of Jupiter's moon Europa: the detection of thermal anomalies, compositional anomalies, and plumes of icy matter from Europa's subsurface ocean. We also share the unique constraints imposed by the onboard computing environment and several lessons learned in our collaboration with planetary scientists and mission designers.


A Review of the Space Environment Effects on Spacecraft in Different Orbits

Abstract: The space environment consists of various complex phenomena, which could have a strong influence on the spacecraft operation in different aspects. Since the very beginning of space exploration, numerous studies have been done on the space environment. However, most of the existing literature focuses on the investigation of the details of environmental phenomena, while the space environment has rarely been discussed from the perspective of orbits types. Therefore, a comprehensive review on analyzing and comparing the environmental characteristics among diverse orbits in space is of great significance. In this paper, the main components of the space environment are introduced, including the neutral atmosphere, the plasma environment, the radiation environment, the macroscopic particle environment, the geomagnetic field, the temperature field, and the solar activities. The relations of the


Investigating Mercury’s Environment with the Two-Spacecraft BepiColombo Mission

Anna Milillo
M. Fujimoto
Go Murakami
J. Benkhoff
Joe Zender
Sae Aizawa

Abstract: Abstract The ESA-JAXA BepiColombo mission will provide simultaneous measurements from two spacecraft, offering an unprecedented opportunity to investigate magnetospheric and exospheric dynamics at Mercury as well as their interactions with the solar wind, radiation, and interplanetary dust. Many scientific instruments onboard the two spacecraft will be completely, or partially devoted to study the near-space environment of Mercury as well as the complex processes that govern it. Many issues remain unsolved even after the MESSENGER mission that ended in 2015. The specific orbits of the two spacecraft, MPO and Mio, and the comprehensive scientific payload allow a wider range of scientific questions to be addressed than those that could be achieved by the individual instruments acting alone, or by previous missions. These joint observations are of key importance because many phenomena in Me


The Energetic Particle Spectrometer HEP onboard the GEOTAIL Spacecraft.

T. Doke
Masayuki Fujii
M. Fujimoto
K. Fujiki
Toshihumi Fukui
F. Gliem

Journal of geomagnetism and geoelectricity

Abstract: The instruments for the HEP (High Energy Particle) experiments of the GEOTAIL mission, launched in July 1992, consist of 5 spectrometers (LD, BD, MI-1, MI-2 and HI). The LD (Low energy particle Detector) and the BD (Burst Detector) are mainly used to measure electrons, protons, helium and oxygen ions which reflect plasma dynamics in the magnetotail region. On the other hand, MI-1, MI-2 (Medium energy Isotope telescope-1, -2) and HI (High energy Isotope telescope) are used to measure the isotope abundance of solar flare particles and cosmic ray particles which reflect physical conditions of interplanetary space and origin of these particles. In this paper, the objectives of these experiments, the details of the instruments and preliminary results from the observation in the magnetotail are given. The preliminary results obtained by the LD and BD show that a highly collimated beam of energ


Design of the Remote Agent experiment for spacecraft autonomy

Douglas E. Bernard
Gregory A. Dorais
Charles Fry
Edward B. Gamble
Bob Kanefsky
James Kurien

Abstract: This paper describes the Remote Agent flight experiment for spacecraft commanding and control. In the Remote Agent approach, the operational rules and constraints are encoded in the flight software. The software may be considered to be an autonomous "remote agent" of the spacecraft operators in the sense that the operators rely on the agent to achieve particular goals. The experiment will be executed during the flight of NASA's Deep Space One technology validation mission. During the experiment, the spacecraft will not be given the usual detailed sequence of commands to execute. Instead, the spacecraft will be given a list of goals to achieve during the experiment. In flight, the Remote Agent flight software will generate a plan to accomplish the goals and then execute the plan in a robust manner while keeping track of how well the plan is being accomplished. During plan execution, the R


An Autonomous Spacecraft Agent Prototype

Barney Pell
Douglas E. Bernard
Steve Chien
Erann Gat
Nicola Muscettola
P. Pandurang Nayak


titleRemote agent prototype for spacecraft autonomy/title

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE

Abstract: NASA has recently announced the New Millennium Program (NMP) to develop 'faster, better, cheaper' spacecraft in order to establish a 'virtual presence' in space. A crucial element in achieving this vision is onboard spacecraft autonomy, requiring us to automate functions which have traditionally been achieved on ground by humans. These include planning activities, sequencing spacecraft actions, tracking spacecraft state, ensuring correct functioning, recovering in cases of failure and reconfiguring hardware. In response to these challenging requirements, we analyzed the spacecraft domain to determine its unique properties and developed an architecture which provided the required functionality. This architecture integrates traditional real-time monitoring and control with constraint-based planning and scheduling, robust multi-threaded execution, and model-based diagnosis and reconfigurati


Autonomy in materials research: a case study in carbon nanotube growth

Pavel Nikolaev
Daylond Hooper
Frederick Webber
Rahul Rao
Kevin Decker
Michael Krein

Abstract: Abstract Advances in materials are an important contributor to our technological progress, and yet the process of materials discovery and development itself is slow. Our current research process is human-centred, where human researchers design, conduct, analyse and interpret experiments, and then decide what to do next. We have built an Autonomous Research System (ARES)—an autonomous research robot capable of first-of-its-kind closed-loop iterative materials experimentation. ARES exploits advances in autonomous robotics, artificial intelligence, data sciences, and high-throughput and in situ techniques, and is able to design, execute and analyse its own experiments orders of magnitude faster than current research methods. We applied ARES to study the synthesis of single-walled carbon nanotubes, and show that it successfully learned to grow them at targeted growth rates. ARES has broad im


Model Based Autonomy - How Model without Human Expertise Can Facilitate Fault Diagnosis and Other Spacecraft Tasks ? -

Shinichi Nakasuka
Shiro Ogasawara
Masayuki TAKATA
Taizo Yamamoto

Abstract: A model based fault diagnosis system for satellites is proposed which autonomously infers the cause of failure from telemetry-type time history data using functional models of satellite subsystems. The key research issue is how and to what extent a model without human expertise can solve the fault diagnosis problem. The evaluation results of the prototype system indicate that though non-deterministic search process guided by some weak logic can solve the problem within practical time to some extent, it still has severe limitations coming from the lack of capability to measure the similarity of two telemetry data. Extraction and utilization of attributes useful for diagnosis task is a promising approach, and one method is proposed for autonomously defining such important attributes from telemetry data.


Advanced model-based FDIR techniques for aerospace systems: Today challenges and opportunities


Model-based off-nominal state isolation and detection system for autonomous fault management

Abstract: This paper presents a model-based fault management (FM) system designed to provide off-nominal state detection and isolation capabilities that are key components to assessing spacecraft state awareness. The ability to autonomously isolate spacecraft failures to component levels will enable faster and more targeted responses and recovery thereby reducing down time. The use of model-based systems and practices is being explored by the FM community as a viable approach to developing more capable, autonomous systems in order to meet mission objectives. Model-based systems can provide better fault identification than traditional methods of fault detection such as limit-checking. They also lend themselves to more straight-forward approaches to verification and validation. We have chosen a particular model-based technique called Constraint Suspension for autonomous fault detection and isolation


OPS-SAT Spacecraft Autonomy with TensorFlow Lite, Unsupervised Learning, and Online Machine Learning

Georges Labrèche
David J. Evans
Dominik Marszk
Tom Mladenov
Vasundhara Shiradhonkar
Tanguy Soto

Abstract: OPS-SAT is a 3U CubeSat launched on December 18, 2019, it is the first nanosatellite to be directly owned and operated by the European Space Agency (ESA). The spacecraft is a flying platform that is easily accessible to European industry, institutions, and individuals for rapid prototyping, testing, and validation of their software and firmware experiments in space at no cost and no bureaucracy. Equipped with a full set of sensors and actuators, it is conceived to break the “has never flown, will never fly” cycle. OPS-SAT has spearheaded many firsts with in-orbit applications of Artificial Intelligence (AI) for autonomous operations. AI is of rising interest for space-segment applications despite limited technology demonstrators on-board flying spacecrafts. Past missions have restricted AI to inferring models trained on the ground prior to being uplinked to a spacecraft. Th


FDIR Strategies For Autonomous Satellite Formations - A Preliminary Report

Charles Castel
Jean-François Gabard
Catherine Tessier
B. Laborde
Raymond Soumagne

National Conference on Artificial Intelligence

Abstract: This paper focuses on FDIR (Fault Detection, Isolation and Recovery) strategies for autonomous satellite formations. Anomalies that impact the formation geometry, the scien-tific mission and communications are considered. Three cen-tralised, one mixed and two distributed strategies are charac-terised in terms of knowledge, algorithm and communication requirements. Preliminary Petri net- based simulations al-low the dynamics of the spacecraft states and the FDIR task progress to be shown and the spacecraft communication links to be displayed. First results on the robustness of the strate-gies wrt an anomaly that would affect the FDIR itself or the communication links are presented.


A Particle Filtering Approach for Fault Detection and Isolation of UAV IMU Sensors: Design, Implementation and Sensitivity Analysis

Egidio D’Amato
V. Nardi
Immacolata Notaro
Valerio Scordamaglia

Abstract: Sensor fault detection and isolation (SFDI) is a fundamental topic in unmanned aerial vehicle (UAV) development, where attitude estimation plays a key role in flight control systems and its accuracy is crucial for UAV reliability. In commercial drones with low maximum take-off weights, typical redundant architectures, based on triplex, can represent a strong limitation in UAV payload capabilities. This paper proposes an FDI algorithm for low-cost multi-rotor drones equipped with duplex sensor architecture. Here, attitude estimation involves two 9-DoF inertial measurement units (IMUs) including 3-axis accelerometers, gyroscopes and magnetometers. The SFDI algorithm is based on a particle filter approach to promptly detect and isolate IMU faulted sensors. The algorithm has been implemented on a low-cost embedded platform based on a Raspberry Pi board. Its effectiveness and robustness were


Fault detection, isolation and recovery (FDIR) in satellite onboard software

Shahrokh Jalilian
Fatemeh SalarKaleji
Tofig Kazimov

Abstract: The complexity of the avionic systems in satellites is rising as space missions become increasingly more sophisticated. This complexity emphasizes the need for more dependable systems with minimal anomalies. As satellite manufactures seek to convert many hardware implemented functionalities into software, the On-Board Software (OBSW) is becoming a major component in every satellite. Noticeably, more tasks for Fault Detection, Isolation and Recovery (FDIR) are being implemented in software, where the need comes for a well-defined software architecture that supports a cost-effective implementation of the FDIR functions. FDIR was already explained as key functionality of the OBSW. Obviously not all failures are subject to onboard identification and not all failures are subject to onboard recovery. The FDIR concept to be worked out for the spacecraft during the engineering phase follows some


A novel methodology to construct digital twin models for spacecraft operations using fault and behaviour trees

Abstract: Successful satellite data reception requires the nominal operation of the ground stations in charge of their health monitoring as much as the spacecrafts themselves. Although the concept of Model-Based Diagnosis (MBD) in the field of autonomous systems -such as satellites, has long been researched and developed, that is not the case for their ground systems. Both satellites and ground stations operate autonomously. The latter however, are not equipped with the advanced Fault Detection, Isolation and Recovery (FDIR) capabilities one finds today on-board all orbiting spacecrafts. The aim of the study presented in this paper is the improvement of ground stations' operational diagnostics by providing the operators with ad-hock, Operations-Dedicated Models (ODMs). The latter serve as a basis for the construction of the system's Digital Twin (DT) models. These models allow the operators react


Application of Deep Learning for Spacecraft Fault Detection and Isolation

Research Repository (Delft University of Technology)

Abstract: Spacecraft require high availability, autonomous operation, and a high degree of mission success. Spacecraft use sensors, such as star trackers and GPS, and actuators, such as reaction wheels, to reach and maintain a correct attitude and position. Failures in these components will have a significant negative impact on the success of the mission, or may even cause total loss of mission. Fault Detection, Isolation and Recovery (FDIR) aims to detect and isolates faults and recover them before they develop into failures. This makes it an important factor in the success of a satellite’s mission. It is also a determining factor in the level of autonomy if a system does not require ground intervention to perform FDIR. Development of FDIR methods is a difficult task, of which the success depends largely on the knowledge of the system and suffers under noisy environments. This research aims to ex


Web-Based Survival Analysis Tool Tailored for Medical Research (KMplot): Development and Implementation

Abstract: BACKGROUND: Survival analysis is a cornerstone of medical research, enabling the assessment of clinical outcomes for disease progression and treatment efficiency. Despite its central importance, no commonly used spreadsheet software can handle survival analysis and there is no web server available for its computation. OBJECTIVE: Here, we introduce a web-based tool capable of performing univariate and multivariate Cox proportional hazards survival analysis using data generated by genomic, transcriptomic, proteomic, or metabolomic studies. METHODS: We implemented different methods to establish cut-off values for the trichotomization or dichotomization of continuous data. The false discovery rate is computed to correct for multiple hypothesis testing. A multivariate analysis option enables comparing omics data with clinical variables. RESULTS: We established a registration-free web-based su


Cox Analysis of Survival Data with Non-Proportional Hazard Functions

Journal of the Royal Statistical Society Series D (The Statistician)


Survival Analysis: A Self-Learning Text

Abstract: Introduction to Survival Analysis.- Kaplan-Meier Survival Curves and the Log-Rank Test.- The Cox Proportional Hazards Model and Its Characteristics.- Evaluating the Proportional Hazards Assumption.- The Stratified Cox Procedure.- Extension of the Cox Proportional Hazards Model for Time-Dependent Variables.- Parametric Survival Models.- Recurrent Events Survival Analysis.- Competing Risks Survival Analysis.


DeepSurv: personalized treatment recommender system using a Cox proportional hazards deep neural network

Jared Katzman
Uri Shaham
Alexander Cloninger
Jonathan Bates
Tingting Jiang
Yuval Kluger

Abstract: BACKGROUND: Medical practitioners use survival models to explore and understand the relationships between patients' covariates (e.g. clinical and genetic features) and the effectiveness of various treatment options. Standard survival models like the linear Cox proportional hazards model require extensive feature engineering or prior medical knowledge to model treatment interaction at an individual level. While nonlinear survival methods, such as neural networks and survival forests, can inherently model these high-level interaction terms, they have yet to be shown as effective treatment recommender systems. METHODS: We introduce DeepSurv, a Cox proportional hazards deep neural network and state-of-the-art survival method for modeling interactions between a patient's covariates and treatment effectiveness in order to provide personalized treatment recommendations. RESULTS: We perform a nu


A Proportional Hazards Model for the Subdistribution of a Competing Risk

Journal of the American Statistical Association

Abstract: Abstract With explanatory covariates, the standard analysis for competing risks data involves modeling the cause-specific hazard functions via a proportional hazards assumption. Unfortunately, the cause-specific hazard function does not have a direct interpretation in terms of survival probabilities for the particular failure type. In recent years many clinicians have begun using the cumulative incidence function, the marginal failure probabilities for a particular cause, which is intuitively appealing and more easily explained to the nonstatistician. The cumulative incidence is especially relevant in cost-effectiveness analyses in which the survival probabilities are needed to determine treatment utility. Previously, authors have considered methods for combining estimates of the cause-specific hazard functions under the proportional hazards formulation. However, these methods do not all


Introduction to the Analysis of Survival Data in the Presence of Competing Risks

Peter C. Austin
Douglas S. Lee
Jason P. Fine

Abstract: Competing risks occur frequently in the analysis of survival data. A competing risk is an event whose occurrence precludes the occurrence of the primary event of interest. In a study examining time to death attributable to cardiovascular causes, death attributable to noncardiovascular causes is a competing risk. When estimating the crude incidence of outcomes, analysts should use the cumulative incidence function, rather than the complement of the Kaplan-Meier survival function. The use of the Kaplan-Meier survival function results in estimates of incidence that are biased upward, regardless of whether the competing events are independent of one another. When fitting regression models in the presence of competing risks, researchers can choose from 2 different families of models: modeling the effect of covariates on the cause-specific hazard of the outcome or modeling the effect of covari


Applied survival analysis regression modeling of time to event data

David W. Hosmer
Stanley Lemeshow
Susanne May

Abstract: THE MOST PRACTICAL, UP-TO-DATE GUIDE TO MODELLING AND ANALYZING TIME-TO-EVENT DATANOW IN A VALUABLE NEW EDITION Since publication of the first edition nearly a decade ago, analyses using time-to-event methods have increase considerably in all areas of scientific inquiry mainly as a result of model-building methods available in modern statistical software packages. However, there has been minimal coverage in the available literature to9 guide researchers, practitioners, and students who wish to apply these methods to health-related areas of study. Applied Survival Analysis, Second Edition provides a comprehensive and up-to-date introduction to regression modeling for time-to-event data in medical, epidemiological, biostatistical, and other health-related research. This book places a unique emphasis on the practical and contemporary applications of regression modeling rather than the mathe


Applying Cox Regression to Competing Risks

Abstract: Two methods are given for the joint estimation of parameters in models for competing risks in survival analysis. In both cases Cox's proportional hazards regression model is fitted using a data duplication method. In principle either method can be used for any number of different failure types, assuming independent risks. Advantages of the augmented data approach are that it limits over-parametrisation and it runs immediately on existing software. The methods are used to reanalyse data from two well-known published studies, providing new insights.


Mario A. Cleves
William Gould
Roberto G. Gutierrez
Yulia Marchenko

Abstract: An Introduction to Survival Analysis Using Stata, Third Edition is the ideal tutorial for professional data analysts who want to learn survival analysis for the first time or who are well versed in survival analysis but are not as dexterous in using Stata to analyze survival data. This text also serves as a valuable reference to those readers who already have experience using Stata’s survival analysis routines. The third edition has been updated for Stata 11, and it includes a new chapter on competing-risks analysis. This chapter describes the problems posed by competing events (events that impede the failure event of interest), and covers estimation of cause-specific hazards and cumulative incidence functions. Other enhancements include the handling of missing values by multiple imputation in Cox regression, a new-to-Stata-11 system for specifying categorical (factor) variables and thei


Frailty Models in Survival Analysis

Abstract: Frailty Models in Survival Analysis, by Andreas Wienke, Boca Raton, Chapman & Hall/CRC, 2010, xxi + 301 pp., £63.99 or US$ 99.95 (hardback), ISBN 978-1-4200-7388-1 Frailty models are extensions of ...


A standard procedure for creating a frailty index

Samuel D. Searle
Arnold Mitnitski
Evelyne A. Gahbauer
Thomas M. Gill
Kenneth Rockwood

Abstract: BACKGROUND: Frailty can be measured in relation to the accumulation of deficits using a frailty index. A frailty index can be developed from most ageing databases. Our objective is to systematically describe a standard procedure for constructing a frailty index. METHODS: This is a secondary analysis of the Yale Precipitating Events Project cohort study, based in New Haven CT. Non-disabled people aged 70 years or older (n = 754) were enrolled and re-contacted every 18 months. The database includes variables on function, cognition, co-morbidity, health attitudes and practices and physical performance measures. Data came from the baseline cohort and those available at the first 18-month follow-up assessment. RESULTS: Procedures for selecting health variables as candidate deficits were applied to yield 40 deficits. Recoding procedures were applied for categorical, ordinal and interval variab


Penalized Survival Models and Frailty

Terry M. Therneau
Patricia M. Grambsch
V. Shane Pankratz

Journal of Computational and Graphical Statistics

Abstract: Interest in the use of random effects in the survival analysis setting has been increasing. However, the computational complexity of such frailty models has limited their general use. Although fitting frailty models has traditionally been difficult, standard algorithms for fitting Cox semiparametric and parametric regression models can be readily extended to include penalized regression. We demonstrate that solutions for gamma shared frailty models can be obtained exactly via penalized estimation. Similarly, Gaussian frailty models are closely linked to penalized models. Fitting frailty models with penalized likelihoods can be made quite efficient by taking advantage of computational methods available for penalized models. We have implemented penalized regression for the coxph function of S-Plus and illustrate the algorithms with examples using the Cox model.


Bivariate frailty model for the analysis of multivariate survival time


Time-varying covariates and coefficients in Cox regression models

Zhongheng Zhang
Jaakko Reinikainen
Kazeem Adeleke
Marcel E. Pieterse
Karin Groothuis‐Oudshoorn

Abstract: Time-varying covariance occurs when a covariate changes over time during the follow-up period. Such variable can be analyzed with the Cox regression model to estimate its effect on survival time. For this it is essential to organize the data in a counting process style. In situations when the proportional hazards assumption of the Cox regression model does not hold, we say that the effect of the covariate is time-varying. The proportional hazards assumption can be tested by examining the residuals of the model. The rejection of the null hypothesis induces the use of time varying coefficient to describe the data. The time varying coefficient can be described with a step function or a parametric time function. This article aims to illustrate how to carry out statistical analyses in the presence of time-varying covariates or coefficients with R.


Survival and Event History Analysis: A Process Point of View

Odd O. Aalen
Oernulf Borgan
Håkon K. Gjessing


Survival analysis for recurrent event data: an application to childhood infectious diseases

Abstract: Many extensions of survival models based on the Cox proportional hazards approach have been proposed to handle clustered or multiple event data. Of particular note are five Cox-based models for recurrent event data: Andersen and Gill (AG); Wei, Lin and Weissfeld (WLW); Prentice, Williams and Peterson, total time (PWP-CP) and gap time (PWP-GT); and Lee, Wei and Amato (LWA). Some authors have compared these models by observing differences that arise from fitting the models to real and simulated data. However, no attempt has been made to systematically identify the components of the models that are appropriate for recurrent event data. We propose a systematic way of characterizing such Cox-based models using four key components: risk intervals; baseline hazard; risk set, and correlation adjustment. From the definitions of risk interval and risk set there are conceptually seven such Cox-base


Introducing Survival and Event History Analysis

Abstract: The Fundamentals of Survival and Event History Analysis Introduction: What Is Survival and Event History Analysis? Key Concepts and Terminology Censoring and Truncation Mathematical Expression and Relation of Basic Statistical Functions How Do the Survivor, Density and Hazard Function Relate? Why Use Survival and Event History Analysis? Overview of Survival and Event History Models Exercises Using R and Other Computer Programs for Survival and Event History Analysis Introduction: Computer Programs for Survival and Event History Analysis Conducting Serious Data Analysis: Life Lessons Why Use R? Downloading R on Your Personal Computer Add-On Packages Running R Determining and Setting your Working Directory Help and Documentation Importing Data Into R Working With Data: Opening and Accessing Variables from a Data Frame Saving Output as File, Workspace and History and Quitting R Exercises Yo


The Cox Proportional Hazards Model


Proportional hazards model


Cox Proportional Hazards


Survival Analysis with Competing Risks and Semi-competing Risks Data


Classical Regression Models for Competing Risks


Satellite Communications in the New Space Era: A Survey and Future Challenges

Oltjon Kodheli
Eva Lagunas
Nicola Maturo
Shree Krishna Sharma
Bhavani Shankar
Jesús Fabián Mendoza Montoya

Abstract: Satellite communications (SatComs) have recently entered a period of renewed interest motivated by technological advances and nurtured through private investment and ventures. The present survey aims at capturing the state of the art in SatComs, while highlighting the most promising open research topics. Firstly, the main innovation drivers are motivated, such as new constellation types, on-board processing capabilities, non-terrestrial networks and space-based data collection/processing. Secondly, the most promising applications are described, i.e., 5G integration, space communications, Earth observation, aeronautical and maritime tracking and communication. Subsequently, an in-depth literature review is provided across five axes: i) system aspects, ii) air interface, iii) medium access, iv) networking, v) testbeds & prototyping. Finally, a number of future challenges and the respective


The CHEOPS mission

W. Benz
C. Broeg
A. Fortier
N. Rando
T. Beck
M. Beck

Abstract: Abstract The CHaracterising ExOPlanet Satellite (CHEOPS) was selected on October 19, 2012, as the first small mission (S-mission) in the ESA Science Programme and successfully launched on December 18, 2019, as a secondary passenger on a Soyuz-Fregat rocket from Kourou, French Guiana. CHEOPS is a partnership between ESA and Switzerland with important contributions by ten additional ESA Member States. CHEOPS is the first mission dedicated to search for transits of exoplanets using ultrahigh precision photometry on bright stars already known to host planets. As a follow-up mission, CHEOPS is mainly dedicated to improving, whenever possible, existing radii measurements or provide first accurate measurements for a subset of those planets for which the mass has already been estimated from ground-based spectroscopic surveys. The expected photometric precision will also allow CHEOPS to go beyond


CONTESTED AUTONOMY

Abstract: Commitments to truth and to “transparency,” or public accountability, are two central normative aspects of professional journalism. This article considers ways in which both are challenged and complemented by popular communicators, particularly bloggers, in today's media environment. While all professions claim autonomy over articulation and enactment of their own norms, definitions of professional constructs are now open to reinterpretation, and oversight of professional behavior is increasingly shared.


Technology readiness levels for machine learning systems

Alexander Lavin
Ciarán Lee
Alessya Visnjic
Siddha Ganju
Dava Newman
S. Ganguly

Abstract: The development and deployment of machine learning systems can be executed easily with modern tools, but the process is typically rushed and means-to-an-end. Lack of diligence can lead to technical debt, scope creep and misaligned objectives, model misuse and failures, and expensive consequences. Engineering systems, on the other hand, follow well-defined processes and testing standards to streamline development for high-quality, reliable results. The extreme is spacecraft systems, with mission critical measures and robustness throughout the process. Drawing on experience in both spacecraft engineering and machine learning (research through product across domain areas), we've developed a proven systems engineering approach for machine learning and artificial intelligence: the Machine Learning Technology Readiness Levels framework defines a principled process to ensure robust, reliable, a


The NASA Integrated Vehicle Health Management Technology Experiment for X-37

Mark Schwabacher
Jeff Samuels
Lee Brownston
Daniel Clancy

Abstract: The NASA Integrated Vehicle Health Management (IVHM) Technology Experiment for X-37 was intended to run IVHM software on-board the X-37 spacecraft. The X-37 is intended to be an unpiloted vehicle that would orbit the Earth for up to 21 days before landing on a runway. The objectives of the experiment were to demonstrate the benefits of in-flight IVHM to the operation of a Reusable Launch Vehicle, to advance the Technology Readiness Level of this IVHM technology within a flight environment, and to demonstrate that the IVHM software could operate on the Vehicle Management Computer. The scope of the experiment was to perform real-time fault detection and isolation for X-37's electrical power system and electro-mechanical actuators. The experiment used Livingstone, a software system that performs diagnosis using a qualitative, model-based reasoning approach that searches system-wide interact


Technology Readiness Levels for Machine Learning Systems

Alexander Lavin
Ciarán Lee
Alessya Visnjic
Siddha Ganju
Dava Newman
Sujoy Ganguli


The Solar Probe Plus Mission: Humanity’s First Visit to Our Star

N. J. Fox
M. Velli
S. D. Bale
R. B. Decker
Andrew Driesman
R. A. Howard

Abstract: Solar Probe Plus (SPP) will be the first spacecraft to fly into the low solar corona. SPP’s main science goal is to determine the structure and dynamics of the Sun’s coronal magnetic field, understand how the solar corona and wind are heated and accelerated, and determine what processes accelerate energetic particles. Understanding these fundamental phenomena has been a top-priority science goal for over five decades, dating back to the 1958 Simpson Committee Report. The scale and concept of such a mission has been revised at intervals since that time, yet the core has always been a close encounter with the Sun. The mission design and the technology and engineering developments enable SPP to meet its science objectives to: (1) Trace the flow of energy that heats and accelerates the solar corona and solar wind; (2) Determine the structure and dynamics of the plasma and magnetic fields at


Integrated Software and Sensor Health Management for Small Spacecraft

Johann Schumann
Ole J. Mengshoel
Timmy Mbaya

Abstract: Despite their size, small spacecraft have highly complex architectures with many sensors and computer-controlled actuators. At the same time, size, weight, and budget constraints often dictate that small spacecraft are designed as single-string systems, which means that there are no or few redundant systems. Thus, all components, including software, must operate as reliably. Faults, if present, must be detected as early as possible to enable (usually limited) forms of mitigation. Telemetry bandwidth for such spacecraft is usually very limited. Therefore, fault detection and diagnosis must be performed on-board. Further restrictions include low computational power and small memory. In this paper, we discuss the use of Bayesian networks (BNs) to monitor the health of on-board software and sensor systems, and to perform advanced on-board diagnostic reasoning. Advanced compilation techniques


Finding faults: A scoping study of fault diagnostics for Industrial Cyber–Physical Systems

Barry Dowdeswell
Roopak Sinha
Stephen G. MacDonell

Abstract: As Industrial Cyber–Physical Systems (ICPS) become more connected and widely-distributed, often operating in safety-critical environments, we require innovative approaches to detect and diagnose the faults that occur in them. We profile fault identification and diagnosis techniques employed in the aerospace, automotive, and industrial control domains. Each of these sectors has adopted particular methods to meet their differing diagnostic needs. By examining both theoretical presentations as well as case studies from production environments, we present a profile of the current approaches being employed and identify gaps. A scoping study was used to identify and compare fault detection and diagnosis methodologies that are presented in the current literature. We created categories for the different diagnostic approaches via a pilot study and present an analysis of the trends that emerged. W


The NASA Roadmap to Ocean Worlds

Amanda R. Hendrix
T. A. Hurford
Laura M. Barge
M. T. Bland
Jeff S. Bowman
W. B. Brinckerhoff

Abstract: In this article, we summarize the work of the NASA Outer Planets Assessment Group (OPAG) Roadmaps to Ocean Worlds (ROW) group. The aim of this group is to assemble the scientific framework that will guide the exploration of ocean worlds, and to identify and prioritize science objectives for ocean worlds over the next several decades. The overarching goal of an Ocean Worlds exploration program as defined by ROW is to "identify ocean worlds, characterize their oceans, evaluate their habitability, search for life, and ultimately understand any life we find." The ROW team supports the creation of an exploration program that studies the full spectrum of ocean worlds, that is, not just the exploration of known ocean worlds such as Europa but candidate ocean worlds such as Triton as well. The ROW team finds that the confirmed ocean worlds Enceladus, Titan, and Europa are the highest priority bo


Planetary habitability: lessons learned from terrestrial analogues

Abstract: Abstract Terrestrial analogue studies underpin almost all planetary missions and their use is essential in the exploration of our Solar system and in assessing the habitability of other worlds. Their value relies on the similarity of the analogue to its target, either in terms of their mineralogical or geochemical context, or current physical or chemical environmental conditions. Such analogue sites offer critical ground-truthing for astrobiological studies on the habitability of different environmental parameter sets, the biological mechanisms for survival in extreme environments and the preservation potential and detectability of biosignatures. The 33 analogue sites discussed in this review have been selected on the basis of their congruence to particular extraterrestrial locations. Terrestrial field sites that have been used most often in the literature, as well as some lesser known o


In-Flight Anomalies and Radiation Performance of NASA Missions - Selected Lessons Learned

Abstract: This presentation addresses in-flight electronic disturbances and radiation, specifically anomaly resolution. The process for anomaly review takes into account the environment, selected parts and design, existing and/or new radiation test data, risk probability and actions to be taken. Noise spikes and the meaning of upset in a fiber optic link are also discussed.


Overview With Results and Lessons Learned of the X-43A Mach 10 Flight

Laurie Marshall
Catherine Bahm
Griffin Corpening
Robert Sherrill

AIAA/CIRA 13th International Space Planes and Hypersonics Systems and Technologies Conference

Abstract: This paper provides an overview of the final flight of the NASA X-43A project. The project consisted of three flights, two planned for Mach 7 and one for Mach 10. The third and final flight, November 16, 2004, was the first Mach 10 flight demonstration of an airframe-integrated, scramjet-powered, hypersonic vehicle. The goals and objectives for the project as well as those for the third flight are presented. The configuration of the Hyper-X stack including the X-43A, Hyper-X launch vehicle, and Hyper-X research vehicle adapter is discussed. The second flight of the X-43A was successfully conducted on March 27, 2004. Mission differences, vehicle modifications and lessons learned from the second flight as they applied to the third flight are also discussed. An overview of flight 3 results is presented.


A Summary of the Rendezvous, Proximity Operations, Docking, and Undocking (RPODU) Lessons Learned from the Defense Advanced Research Project Agency (DARPA) Orbital Express (OE) Demonstration System Mission

Abstract: The Guidance, Navigation, and Control (GN&C) Technical Discipline Team (TDT) sponsored Dr. J. Russell Carpenter, a Navigation and Rendezvous Subject Matter Expert (SME) from NASA's Goddard Space Flight Center (GSFC), to provide support to the Defense Advanced Research Project Agency (DARPA) Orbital Express (OE) rendezvous and docking flight test that was conducted in 2007. When that DARPA OE mission was completed, Mr. Neil Dennehy, NASA Technical Fellow for GN&C, requested Dr. Carpenter document his findings (lessons learned) and recommendations for future rendezvous missions resulting from his OE support experience. This report captures lessons specifically from anomalies that occurred during one of OE's unmated operations.


On-Orbit Results and Lessons Learned from the ASTERIA Space Telescope Mission

Matthew W. Smith
Amanda Donner
Mary Knapp
Christopher M. Pong
Colin H. Smith
Jason Luu

Digital Commons - USU (Utah State University)

Abstract: The Arcsecond Space Telescope Enabling Research in Astrophysics (ASTERIA) was deployed from the International Space Station (ISS) on 20 November 2017, beginning a technology demonstration and opportunistic science mission to advance the state of the art in nanosatellite performance for astrophysical observations. The goal of ASTERIA is to achieve arcsecond-level line-of-sight pointing error and highly stable focal plane temperature control. These capabilities enable precision photometry—i.e. the careful measurement of stellar brightness over time—which in turn allows investigation of astrophysical phenomena such as transiting exoplanets. By the end of the 90-day prime mission, ASTERIA had achieved line-of-sight pointing stability of approximately 0.5 arcseconds root mean square (RMS) over 20-minute observations, pointing repeatability of 1 milliarcsecond RMS from one observation to the n


The TESS science processing operations center

Jon M. Jenkins
Joseph D. Twicken
Sean McCauliff
J. Campbell
Dwight T. Sanderfer
David Christopher Lung

Abstract: The Transiting Exoplanet Survey Satellite (TESS) will conduct a search for Earth's closest cousins starting in early 2018 and is expected to discover ∼1,000 small planets with Rp < 4 R⊕ and measure the masses of at least 50 of these small worlds. The Science Processing Operations Center (SPOC) is being developed at NASA Ames Research Center based on the Kepler science pipeline and will generate calibrated pixels and light curves on the NASA Advanced Supercomputing Division's Pleiades supercomputer. The SPOC will also search for periodic transit events and generate validation products for the transit-like features in the light curves. All TESS SPOC data products will be archived to the Mikulski Archive for Space Telescopes (MAST).