Orbital Space Environment and Space
   Situational Awareness Domain Ontology
                                   Robert ROVETTOa,1
   a
       University of Maryland Alumnus (2007); University at Buffalo Alumnus (2011);
                   American Public University System/AMU Space studies


1. Introduction

As the population of satellites and other orbital objects in the space environment
increases, the potential for collisions and orbital debris formation does as well. Existing
sensors observe much of the night sky, gathering various sorts of data, but no space
actor has full coverage of the orbital space environment. Although some nations have
data-sharing agreements, not all exchanged data is raw/unmediated, and not all space
actors share data. In toto, this spotlights the need for more precise and complete space
situational awareness (SSA) for the global community.
     Achieving this requires exchanging data and analyzing it to generate knowledge
that can be used to ensure the safety of persons and infrastructure in space and on
Earth’s surface. This data must be updated dynamically in real-time and actionable in
order to protect lives and space assets. Following [1],[2], this project formally studies
and ontologically represents the orbital space and space situational awareness domain.
The domain is that of the orbital and near-Earth space environments; the objects and
phenomena therein; their orbits and orbital properties, motion, causal interrelations;
spacecraft operations; sensor data; observation, detection, prediction and modeling
activities; and scientific disciplines such as astrodynamics.
     Varieties of data include orbital parameters, spacecraft telemetry, and different
sorts of observational sensor data (infrared, optical, etc.). .Existing data sources that
have overlapping data include space debris catalogs, space object catalogs, and other
SSA databases of: space-faring nations, such as the European Space Agency[3], and
NASA (e.g. Orbital Debris Office); private-sector space organizations, such as Space
Data Association; individual sensor and satellite operators; and academia (e.g.,
university observatories).
     In conjunction with additional sensors, space data-exchange will help reduce the
coverage gaps individual space actors may presently have while improving global SSA.
Orbital trajectories, future positions and potential collisions (orbital conjunctions) can
be more accurately determined if more data is made available. Just as with
meteorological forecasts, predictive capabilities become more precise, and we stand to
advance our scientific knowledge about the orbital environment.
     Barriers to sharing SSA data include legal and security concerns, e.g., anonymity,
proprietary information, data related to national security space assets, and international
relations. Additional barriers include the different data formats, and data silos.

       1
           Corresponding Author. Emails: rrovetto@terpalum.umd.edu ; ontologos@yahoo.com
2. Research, Questions and Methodology

     I conceived the orbital debris ontology [1] as part of a potential joint space
ontology to solve space domain problems in 2011. This was further explained and
generalized in [2]. Over time I have accumulated a mass of orbital debris and SSA
domain research to serve as reference and study material. However, given the relative
novelty of applying ontology to this domain, there are limited literature/efforts. Other
work includes: the International Virtual Observatory Alliance and University of
Maryland Astronomical Object Ontology[4], and the NASA SWEET ontologies [5].
     Selected research questions include the following. What are scientifically accurate
formal representations of the domain? Are classical and contemporary ontological
concepts and ontology languages sufficient to faithfully represent the domain? What
ontology architecture and approach/method will best address domain problems? What
domain queries can an ontology answer? Some questions include those of the source of
some orbital debris object, and the type of orbital object. How can dynamic ontologies
benefit the domain? Is the current state of applied ontology able to handle the physics-
intensive aspects of the domain, and if not, what advancements are necessary to do so?
Finally, predictive capability, causal models, astrodynamic models, and probability are
important aspects to taken into account.
     A minimal set of methodological steps includes: domain research; review of
accessible data-sources; identifying domain scenarios, case-studies and problems to
address; assessment of ontology methodologies and designs; whether to reuse existing
ontologies; identify key concepts, terms and domain objects; assert corresponding
ontology classes and interrelations; develop definitions; taxonomy creation; domain
formalization; annotation of one or more data sources; production of an analytics and
software package; validating the ontology by performing queries over data source; and
revision as necessary.


3. Project Goals

     The goals of the project are to create an ontology or ontology suite to formally and
computationally represent the orbital space environment, its objects, relationships, and
the processes that establish and maintain situational awareness of that environment. I
seek a scientifically accurate representation that can annotate domain data and foster
interoperability. This involves creating one or more space terminologies and
taxonomies. A specific practical goal is data-sharing between data sources, as well as
stimulating cooperation among space actors in the development process. I also seek to
make theoretical and philosophical contributions to the domain. An overarching
purpose of the project is to improve SSA and space safety.

[1] R.J.Rovetto, An Ontological Architecture of Orbital Debris Data, Earth Science Informatics 9(1) (2015),
      67-82.
[2] R.J. Rovetto, and T.S. Kelso, Preliminaries of a Space Situational Awareness Ontology, AIAA/AAS
      Space Flight Mechanics meeting, Napa, CA, USA, (2016) forthcoming in Advances in Astronautics,
      Univelt.
[3] European Space Agency (ESA) “Space_Situational_Awareness” URL=
      http://www.esa.int/Our_Activities/Operations/Space_Situational_Awareness
[4] International Virtual Observatory Alliance (IVOA). Ontology of Astronomical Object Types. URL=
      http://www.ivoa.net/documents/Notes/AstrObjectOntology/
[5] NASA Semantic Web for Earth and Environmental Terminology URL= https://sweet.jpl.nasa.gov/