Orbital Debris Ontology Toward an Orbital Space

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Presentation Summary. • What is ... A branch of metaphysics (philosophical inquiry into the nature of the world). – Generic or ..... References. [1] An Ontological Architecture for Orbital Debris Data , Rovetto, Earth Science Informatics, 2015.

Orbital Debris Ontology Robert J. Rovetto [email protected] ([email protected]) ORCID Presented at Center for Orbital Debris Education and Research (CODER) University of Maryland, November 15-17, 2016 1

Presentation Summary • • • • • • •

What is Ontology? Orbital Debris (OD) Ontology of Orbital Debris Project Summary Orbital Data Sharing The Orbital Debris Ontology (ODO) & others Project Status

Robert Rovetto, [email protected]


Ontology – what is it? • Philosophical Ontology – A branch of metaphysics (philosophical inquiry into the nature of the world) – Generic or abstract characterizations of what does or can exist • often results in categorizations & classification systems

– An Ontology = a general theory of a subject matter or domain of interest

• Formal Ontology – Often uses concepts from philosophical ontology, and logical formalisms (logics) to generically (domain-neutrally) represent a domain

• Computational or Applied Ontology & Ontology Engineering – An interdisciplinary discipline that creates terminology-based computational representations to model knowledge or a domain of interest – Provides meaning to data by labeling data elements with ontology categories – May draw upon philosophical and formal ontology – A Computational Ontology = a computable terminology/vocabulary that is formally defined, and often formed into a taxonomy, the totality of which expresses a conceptualization or representation of a domain of interest – Tom Gruber: an explicit specification of a conceptualization – Uses logics: FOL, HOL, CLIF, KIF, OWL, DL etc. Robert Rovetto, [email protected]


Computational Ontologies Related to • Computer science, Information Science, Informatics, Comp.Linguistics • Database (DB) management • Linked-data, Semantic web, “big data” • Artificial Intelligence Purposes • Express and Represent general knowledge – Makes implicit knowledge and assumptions explicit

• • • • •

Organize information, Annotate data, Data-extraction Limit complexity (but they can be complex themselves), Minimize ambiguity Specify a generic data model representation of a DB or its subject matter in order to export, translate, query and unify data across distinct systems [6] To Facilitate: data sharing & integration; DB/Systems interoperability Sematic interoperability, Knowledgebase and Vocabulary Reuse

Can be used for any data-intensive discipline, application, community or domain, e.g., space (astronautics, astrodynamics, astronomy, SSA, orbital debris …)  Robert Rovetto, [email protected]


Orbital Debris Domain • Debris entities in orbit about Earth – Types: Defunct Spacecraft, Mission-related Debris, Orbital Debris Fragment, Payload Debris, Rocket Body Debris, Spacecraft Ejecta, …

• A global hazard to persons, existing space assets, and the future of spaceflight – Precedent: collisions b/w artificial satellites – Present & Future Concern: Cascade effect, Kessler Syndrome

• Deficiencies in current orbital data management (slide 17) • This calls for improving SSA & our knowledge of OD envir. • Efforts & Solutions – OD mitigation and remediation R&D – International cooperation/efforts • IADC guidelines 5

– Growing SSA networks – …

Orbital Debris Questions & Concerns • How to: detect, identify, re-identify, & track (SSA activities) – synchronic vs. diachronic identity (philosophical distinction)

• Prediction of debris formation, orbital conjunctions (collision/risk potential) • How to manage and leverage orbital/SSA data to gain a bigger picture of the orbital space environment (see slide 17) • Mitigation & Remediation methods • Location - Orbital regions • Spatial & temporal position over time • Quantity, Size, Material composition, Ownership, responsibility, … – Physical properties, Social properties, …

• Causal Origins, actual and potential Effects on other objects in orbit • Do any groupings or patterns emerge? – E.g., based on causal interrelationships and properties – Patterns of orbital interaction & behavior (with other OD & space weather)?

Answers to these questions help answer the question: How can we ontologically characterize OD and OD data? Robert Rovetto, [email protected]


Ontology of Orbital Debris • What is orbital debris ontology? • What is the ontology of orbital debris? – Ontological inquiry into the field of orbital debris: orbital debris objects, their origins, properties, causal interactions, OD SSA, policy, etc. – Formal, philosophical & computational investigation into ontologically characterizing the orbital debris domain – Generic ‘nature’ of OD & related phenomena…or high-level characterizations thereof

• Since OD is part of the orbital space environment, we must consider broader orbital space ontology[3][4][5] Robert Rovetto, [email protected]


‘Ontologizing’ Orbital Debris Tasks in ontology development 1. 2.

OD domain research What are the entities of interest? How are they related? (Objects, events, observations, measurements, orbital models, etc.)

3. 4.


Identify & analyze fund. domain concepts, terms/jargon, principles Demarcate the domain (if needed) for content management & modularization Form a terminology of the above / Assert formal classes – Structure or “Taxonomize” onto. terms where possible with relation classes

6. 7. 8.

Define Terms: natural language, logical, and computational definitions Formalizations, axioms, for computability (e.g., FOL, CLIF, OWL, …) Ontology tools: ontology editors to build ontology file, visualizations, etc. 9. Test/Validate the ontology: Competency questions. Queries (e.g., SPARQL). Use instance data from databases. Software analytics. 10. … (May use standard software development methodology)


Coverage of Orbital Debris Domain To ontologically represent OD, needs terms for [1]… – – – – – – – – –

Keplerian/Orbital System concepts (holistic modeling) Events in orbit, e.g., conjunctions Objects in orbit, e.g. debris types, non-debris Physical and Social Properties Orbits, Trajectories (actual and predicated) Causal factors: genesis, effects, potential Scientific concepts/principles: orbital mechanics, etc. Predictive knowledge, Astrodynamic Models Observational measurements

Together this characterizes a broader scope than OD alone—the orbital space environment [3][4] or SSA domain [2]—and can be divided into sub domain ontologies: systems, events, objects, etc. A subset could minimally characterize OD objects alone. Robert Rovetto, [email protected]


Defining ‘Orbital Debris’ Natural Language Def.: • “Artificial objects, including derelict spacecraft and spent launch vehicle orbital stages, left in orbit which no longer serve a useful purpose” [Handbook for Limiting Orbital Debris, 8719.14] • “Space debris are all manmade objects, including their fragments and parts, whether their owners can be identified or not, in Earth orbit or re-entering the dense layers of the atmosphere that are non-functional with no reasonable expectation of their being able to assume or resume their intended functions or any other functions for which they are or can be authorized. [Technical Report On Space Debris, UN] Example Formalizations / Formal Definitions • FOL: instance_of(x, OrbitalDebris) ↔ instanceOf(x, ArtificialObject) ∧ ∃y[ instanceOf(y, Orbit)] ∧ hasOrbit(x, y) ∧ ~∃z[instance_of(z, Function) ∧ hasFunction(x,z)] • Computational (partial def.): Is-a ArtificialObject and (hasOrbit some Orbit) and not (hasPurpose some Purpose) …

Debris Classes to Define Defunct Spacecraft Mission-related Debris Orbital Debris Fragment Payload Debris Rocket Body Debris Spacecraft Ejecta


Orbital Terms My Proposed Generic Orbital Terminology (Subject to revision. Used in my project ontologies, e.g., ODO, SSAO) Orbital System, Keplerian System Orbital Object, Gravitational Orbital Object Orbital Debris Object, Orbital Debris Artifact – Orbital Debris Fragment, Mission-related Debris, etc. Space Debris Object, Space Debris Artifact, Space Object Orbital Debris Role, Space Debris Role Orbital Occurrence, Orbital Event, Orbital Process – Orbital Collision, Orbital Break-up Orbital Property – Orbital Element, Orbital Parameter; Orbital Inclination, etc. Orbit (unity), Orbital Motion, Orbiting Process (motion), Orbits (relation) Orbital Lifetime Orbital Space, Orbital Space Environment Orbital Debris Mitigation Measure/Process … Robert Rovetto, [email protected]


Towards a General-purpose Orbital Terminology & Ontology Why? • Generic but domain-specific = a domain-specific upper-level vocabulary/ontology • Usable by any space data source – b/c captures universal orbital concepts and principles*

• Qualitative descriptions, but can admit quantitative values • Contribute to astrodynamics terminology and standards? • Uses of a generic Orbital Ontology… – *any OD database can input actual or predicted values of orbital parameters of actual satellites – As a learning tool for the relationships between satellites & orbits Project Goal (slide 14,15): Develop a ready-to-use generic Orbital Ontology for space actor users to add instance data (actual satellite orbital data, TLEs). Thanks to Avril Styrman.

– Combine with a visualization/simulation for greater pedagogical utility – Connect w/existing ontologies: NASA SWEET[12], QUDT, etc. – Qualitative spatial reasoning Robert Rovetto, [email protected]


Big Picture - Orbital Ontology

• • • •

Is generic Qualitative Admits quantitative description & values, e.g., values of TLEs, etc. Can be used by or can extend existing space ontologies, e.g., NASA SWEET, QUDT, etc.


Project Summary • Origins in 2011. Ontology to facilitate OD data-sharing to help solve the OD problem [1]. Independent efforts & opportunity search since then. Hat tip to David Vallado, AGI*. • Develop & implement the Orbital Debris Ontology (ODO)[1] and related ontologies, perhaps part of a broader space ontology, e.g.,: – Orbital Space Ontology (OSO/OSEO[3][4], or NESEO[2]) – The Space Situational Awareness Domain Ontology (SSAO)[2] • To Improve peaceful SSA via data-sharing • Ontology-supported Space Applications: find space applications & problems that may benefit from use of these ontologies (e.g. [8]) • Develop scientifically accurate knowledge models of the domain • Advance formal & philosophical analysis of the field • Project URL (landing page): www.purl.org/space-ontology *2011 said community needs more OD data exchange/integration Robert Rovetto, [email protected]


Specific Goals Project Summary (2) • Space terminologies (for OD, astrodynamics, SSA, astronautics) • Orbital and astronautical concept analysis • Space object Classification & Characterization • Formal models of OD, Orbits, etc. • Ontologies for SSA, OD, astronautics • Ontology-based Visualizations • Semantic & Systems Interoperability (among SSA and related space information systems) • Data sharing & Integration, DB interoperability Robert Rovetto, [email protected]


Orbital Data • Sources – – – –

Satellite Operators, Amateur observers, Academia U.S. DoD, Spacetrak, Celestrak, Space Data Association ESA SSA network, NASA, CNES, Roscosmos, India, China …

• Potential for international cooperation & datasharing • Database terms can be labeled with ontological classes, providing meaning to the data, making it both human and machine-readable • Goals: knowledge sharing, data fusion & extraction; Knowledge representation & reasoning; etc Robert Rovetto, [email protected]


Orbital/SSA Data Problems & Concepts • Deficiencies of contemporary Orbital Data – – – –

Varying data quality Low accuracy of publicly-accessible orbital information No unified international mechanism for catalogues and identifying orbital objects Multiple databases. Potentially conflicting information. Distinct data sources are not integrated. [2016 UN paper [9] [10] ]

• Relevant Concepts – International Civil Space Situational Awareness System (Weeden & Kelso 2009 [11]) – Novel Approaches to International Cooperation and Data Sharing for SSA, IAC-12B5.1.( Kretzenbacher, et al. 2012) [14] – Ontological Models To Support Planning Operations (Bonasso et al. 2013)[13] – NASA SWEET ontologies[12], IVOA Astro. Ontology[7]

• Potential Solutions –

International partnerships, Data-sharing, Advances in SSA (infrastructure, coverage, precision), Advances in astrodynamics standards, Advances in space information modeling & data management  ontology may play a part

Robert Rovetto, [email protected]


Ontology-based Data-sharing among Space Object Catalogues

[1] An Ontological Architecture for Orbital Debris Data (Rovetto, Earth Science Informatics, 2015) (edited figure) 18

Project Architecture Concepts

Poster presented at AMOS 2016 [3], and similar at [4]


Modular Ontology Architecture Concepts for Domain Demarcation (subject to revision, merging, etc.) Ontologies: • Orbital Space Ontology (as a global ontology, or a ontology of core terms, for the following) • The Orbital Debris Ontology (ODO)[1] • The Space Situational Awareness Ontology (Rovetto & T.S. Kelso [2]) • Orbital Event & Process Ontology (specific to occurrences in orbit) • Orbital Object Ontology, or Space Object Ontology (Rovetto, paper under review) • Astrodynamics Modeling/Models Ontology • Space Weather Ontology • … Combined each sub-domain ontology should form a holistic picture of the orbital space environment. Contact me if interested in using, contributing to, or funding development of one of the ontologies. Some may extend and import classes from, say, Astronomical Object Type Ontology (IVOA)[7], NASA SWEET ontologies [12], etc. Robert Rovetto, [email protected]


ODO: The Orbital Debris Ontology

Landing Page/Description Page: www.purl.org/space-ontology/odo (presently links to… https://rrovetto.github.io/The-Orbital-Debris-Ontology/) Near Future Location of OWL file : www.purl.org/space-ontology/odo.owl


Ontologizing an Orbital Scenario

Figure from [3]


Example Ontology Architecture

[5] Ontology Architectures for the Orbital Space Environment and Space Situational Awareness Domain, Rovetto, 2016 See slide 24 for space ontology architecture scenario.


Scenario Orbital Debris Ontology Architecture


These ontologies are intended to provide • Thorough high-level representation of the domain • Accurately-defined terminology and classification system for orbitology, orbital objects, events; SSA processes; astronautical, astrodynamics & general orbital concepts; etc. • Formal models of orbits • A data model for space applications and databases to draw upon. – Should help minimize coding complexity

• … Robert Rovetto, [email protected]


Project Status • • • •

Under development & subject to revision Independent efforts. Approx. 4-5+ publications Interdisciplinary: needs comp sci., astrodynamicists, … experts. Tasks: domain research; ontology demarcation, structuring, merging; definitions, formalizations • Project Landing Page: www.purl.org/space-ontology (presently forwards to... http://rrovetto.github.io/Orbital-Space-Ontology-Project/)

• Example User/Application: – An ontology-driven orrery, D. O’Neil, NASA MSFC [8] uses the SSAO

• SEEKING: – Funded opportunities to sustainably develop, including… • A space degree studentship (e.g., as a BS, MS or PhD project) • Contract work, Employment, Paid internships • Univ. Professors or Companies to apply to research grants

– Partners, contributors, co-authors, subject-matter experts, team, …

• Contact me if you would like to use or contribute to the project/ontologies Robert Rovetto, [email protected]


References [1] An Ontological Architecture for Orbital Debris Data , Rovetto, Earth Science Informatics, 2015. DOI:10.1007/s12145-015-0233-3 [2] Preliminaries of a Space Situational Awareness Ontology , Rovetto & Kelso, AIAA/AAS Space Flight Mechanics Meeting, 2016. [3] The Orbital Space Environment and Space Situational Awareness Domain Ontology – Towards an International Information System for Space Data, Rovetto, AMOS 2016 (Poster presentation & Paper) [4] Orbital Space Environment and Space Situational Awareness Domain Ontology, Rovetto, CEUR workshop proceedings for Joint Ontology Workshops, & FOIS Early Career Symposium; Annecy, France, July 2016. [5] Ontology Architectures for the Orbital Space Environment and Space Situational Awareness Domain, Rovetto, International Workshop on Ontology Modularity, Contextuality, and Evolution at FOIS, July 2016. [6] ‘Ontology’, Tom Gruber, http://tomgruber.org/writing/ontology-definition-2007.htm [7] International Virtual Observatory Alliance (IVOA) [8] Ontology-driven Orrery , Daniel O’Neil, NASA , Marshal Space Flight Center. Github (work in progress) [9] Bringing the UN information platform into the pragmatic perspective , PPT by Delegation of the Russian Federation, 59th session of COPUOS, 8-17 June 2016, Vienna, Austria [10] Considerations on the set of prime requirements and factors that should shape the policy of international information-sharing serving safety of space operations, A/AC.105/L.303, Working paper by Russian Federation; United Nations General Assembly, COPUOS, 59th session Vienna, 8-17 June 2016. [11] Analysis of the Technical Feasibility of Building an International Civil Space Situational Awareness System, IAC-09.A6.5.2 B. Weeden, T.S. Kelso, 2009. [12] NASA Semantic Web for Earth and Environmental Terminology (SWEET) ontologies, JPL, Caltech. [13] Ontological Models To Support Planning Operations (Bonasso et al. 2013), NASA page

[14] Novel Approaches to International Cooperation and Data Sharing for SSA, IAC-12-B5.1., Kretzenbacher, et al., 2012.

Acknowledgements Daniel A. O’Neil, Alan Ruttenberg, Avril Styrman


Thank you for listening Thanks to CODER reviewers, Dr. Sedwick & the CODER team Questions, Comments? SEEKING … funded opportunities, partners, a space degree studentship, subject-matter experts, grant proposal sponsors/co-authors, & contributors, or a team.

Contact me with partnership inquiries, offers, & discussion. Contact me if you are interested in using, or contributing to, one of the ontologies Robert Rovetto: [email protected] ([email protected]) Project landing webpage: Orbital Debris Ontology: ODO owl file: SSA Ontology descr. page: SSAO owl file:

www.purl.org/space-ontology www.purl.org/space-ontology/odo www.purl.org/space-ontology/odo.owl www.purl.org/space-ontology/ssao www.purl.org/space-ontology/ssao.owl

Presented at Center for Orbital Debris Education and Research (CODER), University of Maryland, November 15, 2016