The Experts below are selected from a list of 111 Experts worldwide ranked by ideXlab platform

Barry Smith - One of the best experts on this subject based on the ideXlab platform.

  • formal ontology for natural language processing and the integration of biomedical databases
    International Journal of Medical Informatics, 2006
    Co-Authors: Jonathan Simon, James Matthew Fielding, Mariana Casella Dos Santos, Barry Smith
    Abstract:

    Summary The central hypothesis underlying this communication is that the methodology and conceptual rigor of a philosophically inspired formal ontology can bring significant benefits in the development and maintenance of application ontologies [A. Flett, M. Dos Santos, W. Ceusters, Some Ontology Engineering Procedures and their Supporting Technologies, EKAW2002, 2003]. This hypothesis has been tested in the collaboration between Language and Computing (L&C), a company specializing in software for supporting natural language processing especially in the medical field, and the Institute for Formal Ontology and Medical Information Science (IFOMIS), an academic research institution concerned with the theoretical foundations of ontology. In the course of this collaboration L&C's ontology, LinKBase ® , which is designed to integrate and support reasoning across a plurality of external databases, has been subjected to a thorough auditing on the basis of the principles underlying IFOMIS's Basic Formal Ontology (BFO) [B. Smith, Basic Formal Ontology, 2002. http://ontology.buffalo.edu/bfo]. The goal is to transform a large terminology-based ontology into one with the ability to support reasoning applications. Our general procedure has been the implementation of a meta-ontological Definition Space in which the Definitions of all the concepts and relations in LinKBase ® are standardized in the framework of first-order logic. In this paper we describe how this principles-based standardization has led to a greater degree of internal coherence of the LinKBase ® structure, and how it has facilitated the construction of mappings between external databases using LinKBase ® as translation hub. We argue that the collaboration here described represents a new phase in the quest to solve the so-called "Tower of Babel" problem of ontology integration [F. Montayne, J. Flanagan, Formal Ontology: The Foundation for Natural Language Processing, 2003. http://www.landcglobal.com/].

  • Reference ontologies for biomedical ontology integration and natural language processing
    2004
    Co-Authors: Jonathan Simon, James Matthew Fielding, Mariana Casella Dos Santos, Barry Smith
    Abstract:

    The central hypothesis of the collaboration between Language and Computing (L&C) and the Institute for Formal Ontology and Medical Information Science (IFOMIS) is that the methodology and conceptual rigor of a philosophically inspired formal ontology greatly benefits application ontologies.[1] To this end LinKBase®, L&C’s ontology, which is designed to integrate and reason across various external databases simultaneously, has been submitted to the conceptual demands of IFOMIS’s Basic Formal Ontology (BFO).[2] With this project we aim to move beyond the level of controlled vocabularies to yield an ontology with the ability to support reasoning applications. Our general procedure has been the implementation of a meta-ontological Definition Space in which the Definitions of all the concepts and relations in LinKBase® are standardized in a framework of first-order logic. In this paper we describe how this standardization has already led to an improvement in the LinKBase® structure that allows for a greater degree of internal coherence than ever before possible. We then show the use of this philosophical standardization for the purpose of mapping external databases to one another, using LinKBase® as translation hub, with a greater degree of success than possible hitherto. We demonstrate how this offers a genuine advance over other application ontologies that have not submitted themselves to the demands of philosophical scrutiny.

Jonathan Simon - One of the best experts on this subject based on the ideXlab platform.

  • formal ontology for natural language processing and the integration of biomedical databases
    International Journal of Medical Informatics, 2006
    Co-Authors: Jonathan Simon, James Matthew Fielding, Mariana Casella Dos Santos, Barry Smith
    Abstract:

    Summary The central hypothesis underlying this communication is that the methodology and conceptual rigor of a philosophically inspired formal ontology can bring significant benefits in the development and maintenance of application ontologies [A. Flett, M. Dos Santos, W. Ceusters, Some Ontology Engineering Procedures and their Supporting Technologies, EKAW2002, 2003]. This hypothesis has been tested in the collaboration between Language and Computing (L&C), a company specializing in software for supporting natural language processing especially in the medical field, and the Institute for Formal Ontology and Medical Information Science (IFOMIS), an academic research institution concerned with the theoretical foundations of ontology. In the course of this collaboration L&C's ontology, LinKBase ® , which is designed to integrate and support reasoning across a plurality of external databases, has been subjected to a thorough auditing on the basis of the principles underlying IFOMIS's Basic Formal Ontology (BFO) [B. Smith, Basic Formal Ontology, 2002. http://ontology.buffalo.edu/bfo]. The goal is to transform a large terminology-based ontology into one with the ability to support reasoning applications. Our general procedure has been the implementation of a meta-ontological Definition Space in which the Definitions of all the concepts and relations in LinKBase ® are standardized in the framework of first-order logic. In this paper we describe how this principles-based standardization has led to a greater degree of internal coherence of the LinKBase ® structure, and how it has facilitated the construction of mappings between external databases using LinKBase ® as translation hub. We argue that the collaboration here described represents a new phase in the quest to solve the so-called "Tower of Babel" problem of ontology integration [F. Montayne, J. Flanagan, Formal Ontology: The Foundation for Natural Language Processing, 2003. http://www.landcglobal.com/].

  • Reference ontologies for biomedical ontology integration and natural language processing
    2004
    Co-Authors: Jonathan Simon, James Matthew Fielding, Mariana Casella Dos Santos, Barry Smith
    Abstract:

    The central hypothesis of the collaboration between Language and Computing (L&C) and the Institute for Formal Ontology and Medical Information Science (IFOMIS) is that the methodology and conceptual rigor of a philosophically inspired formal ontology greatly benefits application ontologies.[1] To this end LinKBase®, L&C’s ontology, which is designed to integrate and reason across various external databases simultaneously, has been submitted to the conceptual demands of IFOMIS’s Basic Formal Ontology (BFO).[2] With this project we aim to move beyond the level of controlled vocabularies to yield an ontology with the ability to support reasoning applications. Our general procedure has been the implementation of a meta-ontological Definition Space in which the Definitions of all the concepts and relations in LinKBase® are standardized in a framework of first-order logic. In this paper we describe how this standardization has already led to an improvement in the LinKBase® structure that allows for a greater degree of internal coherence than ever before possible. We then show the use of this philosophical standardization for the purpose of mapping external databases to one another, using LinKBase® as translation hub, with a greater degree of success than possible hitherto. We demonstrate how this offers a genuine advance over other application ontologies that have not submitted themselves to the demands of philosophical scrutiny.

Keith Warfield - One of the best experts on this subject based on the ideXlab platform.

  • Designing astrophysics missions for NASA’s Space Launch System
    Journal of Astronomical Telescopes Instruments and Systems, 2016
    Co-Authors: H. Philip Stahl, Randall C. Hopkins, Andrew Schnell, David A. Smith, Angela Jackman, Keith Warfield
    Abstract:

    Large Space telescope missions have always been limited by their launch vehicle’s mass and volume capacities. The Hubble Space Telescope was specifically designed to fit inside the Space Shuttle and the James Webb Space Telescope was specifically designed to fit inside an Ariane 5. Astrophysicists desire even larger Space telescopes. NASA’s “Enduring Quests Daring Visions” report calls for an 8- to 16-m Large UV-Optical-IR (LUVOIR) Surveyor mission to enable ultrahigh-contrast spectroscopy and coronagraphy. Association of Universities for Research in Astronomy’s “From Cosmic Birth to Living Earth” report calls for a 12-m class High-Definition Space Telescope to pursue transformational scientific discoveries. NASA’s “Planning for the 2020 Decadal Survey” calls for a Habitable Exoplanet Imaging (HabEx) and an LUVOIR as well as Far-IR and an X-ray Surveyor missions. Packaging larger Space telescopes into existing launch vehicles is a significant engineering complexity challenge that drives cost and risk. NASA’s planned Space Launch System (SLS), with its 8- or 10-m diameter fairings and ability to deliver 35 to 45 mt of payload to Sun-Earth-Lagrange-2, mitigates this challenge by fundamentally changing the design paradigm for large Space telescopes. This paper introduces the mass and volume capacities of the planned SLS, provides a simple mass allocation recipe for designing large Space telescope missions to this capacity, and gives three specific mission concept implementation examples: a 4-m monolithic off-axis telescope, an 8-m monolithic on-axis telescope, and a 12-m segmented on-axis telescope.

  • Potential Large Missions Enabled by Nasa's Space Launch System
    Space Telescopes and Instrumentation 2016: Optical Infrared and Millimeter Wave, 2016
    Co-Authors: H. Philip Stahl, Randall C. Hopkins, Andrew Schnell, David A. Smith, Angela Jackman, Keith Warfield
    Abstract:

    Large Space telescope missions have always been limited by their launch vehicle’s mass and volume capacities. The Hubble Space Telescope (HST) was specifically designed to fit inside the Space Shuttle and the James Webb Space Telescope (JWST) is specifically designed to fit inside an Ariane 5. Astrophysicists desire even larger Space telescopes. NASA’s "Enduring Quests Daring Visions" report calls for an 8- to 16-m Large UV-Optical-IR (LUVOIR) Surveyor mission to enable ultra-high-contrast spectroscopy and coronagraphy. AURA’s “From Cosmic Birth to Living Earth” report calls for a 12-m class High-Definition Space Telescope to pursue transformational scientific discoveries. NASA’s “Planning for the 2020 Decadal Survey” calls for a Habitable Exoplanet Imaging (HabEx) and a LUVOIR as well as Far-IR and an X-Ray Surveyor missions. Packaging larger Space telescopes into existing launch vehicles is a significant engineering complexity challenge that drives cost and risk. NASA’s planned Space Launch System (SLS), with its 8 or 10-m diameter fairings and ability to deliver 35 to 45-mt of payload to Sun-Earth-Lagrange-2, mitigates this challenge by fundamentally changing the design paradigm for large Space telescopes. This paper reviews the mass and volume capacities of the planned SLS, discusses potential implications of these capacities for designing large Space telescope missions, and gives three specific mission concept implementation examples: a 4-m monolithic off-axis telescope, an 8-m monolithic on-axis telescope and a 12-m segmented on-axis telescope.

  • Potential Large Decadal Missions Enabled by Nasas Space Launch System
    2016
    Co-Authors: H. Philip Stahl, Randall C. Hopkins, Andrew Schnell, David A. Smith, Angela Jackman, Keith Warfield
    Abstract:

    Large Space telescope missions have always been limited by their launch vehicle's mass and volume capacities. The Hubble Space Telescope (HST) was specifically designed to fit inside the Space Shuttle and the James Webb Space Telescope (JWST) is specifically designed to fit inside an Ariane 5. Astrophysicists desire even larger Space telescopes. NASA's "Enduring Quests Daring Visions" report calls for an 8- to 16-m Large UV-Optical-IR (LUVOIR) Surveyor mission to enable ultra-high-contrast spectroscopy and coronagraphy. AURA's "From Cosmic Birth to Living Earth" report calls for a 12-m class High-Definition Space Telescope to pursue transformational scientific discoveries. NASA's "Planning for the 2020 Decadal Survey" calls for a Habitable Exoplanet Imaging (HabEx) and a LUVOIR as well as Far-IR and an X-Ray Surveyor missions. Packaging larger Space telescopes into existing launch vehicles is a significant engineering complexity challenge that drives cost and risk. NASA's planned Space Launch System (SLS), with its 8 or 10-m diameter fairings and ability to deliver 35 to 45-mt of payload to Sun-Earth-Lagrange-2, mitigates this challenge by fundamentally changing the design paradigm for large Space telescopes. This paper reviews the mass and volume capacities of the planned SLS, discusses potential implications of these capacities for designing large Space telescope missions, and gives three specific mission concept implementation examples: a 4-m monolithic off-axis telescope, an 8-m monolithic on-axis telescope and a 12-m segmented on-axis telescope.

H. Philip Stahl - One of the best experts on this subject based on the ideXlab platform.

  • Designing astrophysics missions for NASA’s Space Launch System
    Journal of Astronomical Telescopes Instruments and Systems, 2016
    Co-Authors: H. Philip Stahl, Randall C. Hopkins, Andrew Schnell, David A. Smith, Angela Jackman, Keith Warfield
    Abstract:

    Large Space telescope missions have always been limited by their launch vehicle’s mass and volume capacities. The Hubble Space Telescope was specifically designed to fit inside the Space Shuttle and the James Webb Space Telescope was specifically designed to fit inside an Ariane 5. Astrophysicists desire even larger Space telescopes. NASA’s “Enduring Quests Daring Visions” report calls for an 8- to 16-m Large UV-Optical-IR (LUVOIR) Surveyor mission to enable ultrahigh-contrast spectroscopy and coronagraphy. Association of Universities for Research in Astronomy’s “From Cosmic Birth to Living Earth” report calls for a 12-m class High-Definition Space Telescope to pursue transformational scientific discoveries. NASA’s “Planning for the 2020 Decadal Survey” calls for a Habitable Exoplanet Imaging (HabEx) and an LUVOIR as well as Far-IR and an X-ray Surveyor missions. Packaging larger Space telescopes into existing launch vehicles is a significant engineering complexity challenge that drives cost and risk. NASA’s planned Space Launch System (SLS), with its 8- or 10-m diameter fairings and ability to deliver 35 to 45 mt of payload to Sun-Earth-Lagrange-2, mitigates this challenge by fundamentally changing the design paradigm for large Space telescopes. This paper introduces the mass and volume capacities of the planned SLS, provides a simple mass allocation recipe for designing large Space telescope missions to this capacity, and gives three specific mission concept implementation examples: a 4-m monolithic off-axis telescope, an 8-m monolithic on-axis telescope, and a 12-m segmented on-axis telescope.

  • Potential Large Missions Enabled by Nasa's Space Launch System
    Space Telescopes and Instrumentation 2016: Optical Infrared and Millimeter Wave, 2016
    Co-Authors: H. Philip Stahl, Randall C. Hopkins, Andrew Schnell, David A. Smith, Angela Jackman, Keith Warfield
    Abstract:

    Large Space telescope missions have always been limited by their launch vehicle’s mass and volume capacities. The Hubble Space Telescope (HST) was specifically designed to fit inside the Space Shuttle and the James Webb Space Telescope (JWST) is specifically designed to fit inside an Ariane 5. Astrophysicists desire even larger Space telescopes. NASA’s "Enduring Quests Daring Visions" report calls for an 8- to 16-m Large UV-Optical-IR (LUVOIR) Surveyor mission to enable ultra-high-contrast spectroscopy and coronagraphy. AURA’s “From Cosmic Birth to Living Earth” report calls for a 12-m class High-Definition Space Telescope to pursue transformational scientific discoveries. NASA’s “Planning for the 2020 Decadal Survey” calls for a Habitable Exoplanet Imaging (HabEx) and a LUVOIR as well as Far-IR and an X-Ray Surveyor missions. Packaging larger Space telescopes into existing launch vehicles is a significant engineering complexity challenge that drives cost and risk. NASA’s planned Space Launch System (SLS), with its 8 or 10-m diameter fairings and ability to deliver 35 to 45-mt of payload to Sun-Earth-Lagrange-2, mitigates this challenge by fundamentally changing the design paradigm for large Space telescopes. This paper reviews the mass and volume capacities of the planned SLS, discusses potential implications of these capacities for designing large Space telescope missions, and gives three specific mission concept implementation examples: a 4-m monolithic off-axis telescope, an 8-m monolithic on-axis telescope and a 12-m segmented on-axis telescope.

  • Potential Large Decadal Missions Enabled by Nasas Space Launch System
    2016
    Co-Authors: H. Philip Stahl, Randall C. Hopkins, Andrew Schnell, David A. Smith, Angela Jackman, Keith Warfield
    Abstract:

    Large Space telescope missions have always been limited by their launch vehicle's mass and volume capacities. The Hubble Space Telescope (HST) was specifically designed to fit inside the Space Shuttle and the James Webb Space Telescope (JWST) is specifically designed to fit inside an Ariane 5. Astrophysicists desire even larger Space telescopes. NASA's "Enduring Quests Daring Visions" report calls for an 8- to 16-m Large UV-Optical-IR (LUVOIR) Surveyor mission to enable ultra-high-contrast spectroscopy and coronagraphy. AURA's "From Cosmic Birth to Living Earth" report calls for a 12-m class High-Definition Space Telescope to pursue transformational scientific discoveries. NASA's "Planning for the 2020 Decadal Survey" calls for a Habitable Exoplanet Imaging (HabEx) and a LUVOIR as well as Far-IR and an X-Ray Surveyor missions. Packaging larger Space telescopes into existing launch vehicles is a significant engineering complexity challenge that drives cost and risk. NASA's planned Space Launch System (SLS), with its 8 or 10-m diameter fairings and ability to deliver 35 to 45-mt of payload to Sun-Earth-Lagrange-2, mitigates this challenge by fundamentally changing the design paradigm for large Space telescopes. This paper reviews the mass and volume capacities of the planned SLS, discusses potential implications of these capacities for designing large Space telescope missions, and gives three specific mission concept implementation examples: a 4-m monolithic off-axis telescope, an 8-m monolithic on-axis telescope and a 12-m segmented on-axis telescope.

  • SLS Launched Missions Concept Studies for LUVOIR Mission
    UV Optical IR Space Telescopes and Instruments: Innovative Technologies and Concepts VII, 2015
    Co-Authors: H. Philip Stahl, Randall C. Hopkins
    Abstract:

    NASA’s "Enduring Quests Daring Visions" report calls for an 8- to 16-m Large UV-Optical-IR (LUVOIR) Surveyor mission to enable ultra-high-contrast spectroscopy and coronagraphy. AURA’s “From Cosmic Birth to Living Earth” report calls for a 12-m class High-Definition Space Telescope to pursue transformational scientific discoveries. The multi-center ATLAST Team is working to meet these needs. The MSFC Team is examining potential concepts that leverage the advantages of the SLS (Space Launch System). A key challenge is how to affordably get a large telescope into Space. The JWST design was severely constrained by the mass and volume capacities of its launch vehicle. This problem is solved by using an SLS Block II-B rocket with its 10-m diameter x 30-m tall fairing and estimated 45 mt payload to SE-L2. Previously, two development study cycles produced a detailed concept called ATLAST-8. Using ATLAST-8 as a point of departure, this paper reports on a new ATLAST-12 concept. ATLAST-12 is a 12-m class segmented aperture LUVOIR with an 8-m class center segment. Thus, ATLAST-8 is now a de-scope option.

Randall C. Hopkins - One of the best experts on this subject based on the ideXlab platform.

  • Designing astrophysics missions for NASA’s Space Launch System
    Journal of Astronomical Telescopes Instruments and Systems, 2016
    Co-Authors: H. Philip Stahl, Randall C. Hopkins, Andrew Schnell, David A. Smith, Angela Jackman, Keith Warfield
    Abstract:

    Large Space telescope missions have always been limited by their launch vehicle’s mass and volume capacities. The Hubble Space Telescope was specifically designed to fit inside the Space Shuttle and the James Webb Space Telescope was specifically designed to fit inside an Ariane 5. Astrophysicists desire even larger Space telescopes. NASA’s “Enduring Quests Daring Visions” report calls for an 8- to 16-m Large UV-Optical-IR (LUVOIR) Surveyor mission to enable ultrahigh-contrast spectroscopy and coronagraphy. Association of Universities for Research in Astronomy’s “From Cosmic Birth to Living Earth” report calls for a 12-m class High-Definition Space Telescope to pursue transformational scientific discoveries. NASA’s “Planning for the 2020 Decadal Survey” calls for a Habitable Exoplanet Imaging (HabEx) and an LUVOIR as well as Far-IR and an X-ray Surveyor missions. Packaging larger Space telescopes into existing launch vehicles is a significant engineering complexity challenge that drives cost and risk. NASA’s planned Space Launch System (SLS), with its 8- or 10-m diameter fairings and ability to deliver 35 to 45 mt of payload to Sun-Earth-Lagrange-2, mitigates this challenge by fundamentally changing the design paradigm for large Space telescopes. This paper introduces the mass and volume capacities of the planned SLS, provides a simple mass allocation recipe for designing large Space telescope missions to this capacity, and gives three specific mission concept implementation examples: a 4-m monolithic off-axis telescope, an 8-m monolithic on-axis telescope, and a 12-m segmented on-axis telescope.

  • Potential Large Missions Enabled by Nasa's Space Launch System
    Space Telescopes and Instrumentation 2016: Optical Infrared and Millimeter Wave, 2016
    Co-Authors: H. Philip Stahl, Randall C. Hopkins, Andrew Schnell, David A. Smith, Angela Jackman, Keith Warfield
    Abstract:

    Large Space telescope missions have always been limited by their launch vehicle’s mass and volume capacities. The Hubble Space Telescope (HST) was specifically designed to fit inside the Space Shuttle and the James Webb Space Telescope (JWST) is specifically designed to fit inside an Ariane 5. Astrophysicists desire even larger Space telescopes. NASA’s "Enduring Quests Daring Visions" report calls for an 8- to 16-m Large UV-Optical-IR (LUVOIR) Surveyor mission to enable ultra-high-contrast spectroscopy and coronagraphy. AURA’s “From Cosmic Birth to Living Earth” report calls for a 12-m class High-Definition Space Telescope to pursue transformational scientific discoveries. NASA’s “Planning for the 2020 Decadal Survey” calls for a Habitable Exoplanet Imaging (HabEx) and a LUVOIR as well as Far-IR and an X-Ray Surveyor missions. Packaging larger Space telescopes into existing launch vehicles is a significant engineering complexity challenge that drives cost and risk. NASA’s planned Space Launch System (SLS), with its 8 or 10-m diameter fairings and ability to deliver 35 to 45-mt of payload to Sun-Earth-Lagrange-2, mitigates this challenge by fundamentally changing the design paradigm for large Space telescopes. This paper reviews the mass and volume capacities of the planned SLS, discusses potential implications of these capacities for designing large Space telescope missions, and gives three specific mission concept implementation examples: a 4-m monolithic off-axis telescope, an 8-m monolithic on-axis telescope and a 12-m segmented on-axis telescope.

  • Potential Large Decadal Missions Enabled by Nasas Space Launch System
    2016
    Co-Authors: H. Philip Stahl, Randall C. Hopkins, Andrew Schnell, David A. Smith, Angela Jackman, Keith Warfield
    Abstract:

    Large Space telescope missions have always been limited by their launch vehicle's mass and volume capacities. The Hubble Space Telescope (HST) was specifically designed to fit inside the Space Shuttle and the James Webb Space Telescope (JWST) is specifically designed to fit inside an Ariane 5. Astrophysicists desire even larger Space telescopes. NASA's "Enduring Quests Daring Visions" report calls for an 8- to 16-m Large UV-Optical-IR (LUVOIR) Surveyor mission to enable ultra-high-contrast spectroscopy and coronagraphy. AURA's "From Cosmic Birth to Living Earth" report calls for a 12-m class High-Definition Space Telescope to pursue transformational scientific discoveries. NASA's "Planning for the 2020 Decadal Survey" calls for a Habitable Exoplanet Imaging (HabEx) and a LUVOIR as well as Far-IR and an X-Ray Surveyor missions. Packaging larger Space telescopes into existing launch vehicles is a significant engineering complexity challenge that drives cost and risk. NASA's planned Space Launch System (SLS), with its 8 or 10-m diameter fairings and ability to deliver 35 to 45-mt of payload to Sun-Earth-Lagrange-2, mitigates this challenge by fundamentally changing the design paradigm for large Space telescopes. This paper reviews the mass and volume capacities of the planned SLS, discusses potential implications of these capacities for designing large Space telescope missions, and gives three specific mission concept implementation examples: a 4-m monolithic off-axis telescope, an 8-m monolithic on-axis telescope and a 12-m segmented on-axis telescope.

  • SLS Launched Missions Concept Studies for LUVOIR Mission
    UV Optical IR Space Telescopes and Instruments: Innovative Technologies and Concepts VII, 2015
    Co-Authors: H. Philip Stahl, Randall C. Hopkins
    Abstract:

    NASA’s "Enduring Quests Daring Visions" report calls for an 8- to 16-m Large UV-Optical-IR (LUVOIR) Surveyor mission to enable ultra-high-contrast spectroscopy and coronagraphy. AURA’s “From Cosmic Birth to Living Earth” report calls for a 12-m class High-Definition Space Telescope to pursue transformational scientific discoveries. The multi-center ATLAST Team is working to meet these needs. The MSFC Team is examining potential concepts that leverage the advantages of the SLS (Space Launch System). A key challenge is how to affordably get a large telescope into Space. The JWST design was severely constrained by the mass and volume capacities of its launch vehicle. This problem is solved by using an SLS Block II-B rocket with its 10-m diameter x 30-m tall fairing and estimated 45 mt payload to SE-L2. Previously, two development study cycles produced a detailed concept called ATLAST-8. Using ATLAST-8 as a point of departure, this paper reports on a new ATLAST-12 concept. ATLAST-12 is a 12-m class segmented aperture LUVOIR with an 8-m class center segment. Thus, ATLAST-8 is now a de-scope option.