Mr. James C. Marr Profile

James C. Marr

Directorate Chief Engineer

Publications (7)

Proceedings Article | 22 July 2010 Paper

SIM Lite Astrometric Observatory progress report

James Marr, Michael Shao, Renaud Goullioud

Proceedings Volume 7734, 77340H (2010) https://doi.org/10.1117/12.857831

KEYWORDS: Stars, Planets, Interferometers, Space operations, Space telescopes, Telescopes, Planetary systems, Astrophysics, Observatories, Exoplanets

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Proceedings Article | 28 July 2008 Paper

Overview of the SIM PlanetQuest Light mission concept

Renaud Goullioud, J. Catanzarite, F. Dekens, M. Shao, J. Marr

Proceedings Volume 7013, 70134T (2008) https://doi.org/10.1117/12.789988

KEYWORDS: Stars, Interferometers, Telescopes, Space telescopes, Planets, Metrology, Planetary systems, Space operations, Sensors, Interferometry

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Proceedings Article | 28 July 2008 Paper

SIM-Lite: progress report

James Marr-IV, Michael Shao, Renaud Goullioud

Proceedings Volume 7013, 70132M (2008) https://doi.org/10.1117/12.790273

KEYWORDS: Stars, Planets, Interferometers, Space operations, Space telescopes, Telescopes, Astrophysics, Planetary systems, Sensors, Galactic astronomy

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Proceedings Article | 19 September 2007 Paper

SIM PlanetQuest science and technology: a status report

Stephen Edberg, Robert Laskin, James Marr, Stephen Unwin, Michael Shao

Proceedings Volume 6693, 66930D (2007) https://doi.org/10.1117/12.732728

KEYWORDS: Stars, Planets, Galactic astronomy, Astrophysics, Radio optics, Planetary systems, James Webb Space Telescope, Space operations, Motion measurement, Distance measurement

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Optical interferometry will open new vistas for astronomy over the next decade. The Space Interferometry Mission (SIM-PlanetQuest), operating unfettered by the Earth's atmosphere, will offer unprecedented astrometric precision that promises the discovery of Earth-analog extra-solar planets as well as a wealth of important astrophysics. Results from SIM will permit the determination of stellar masses to accuracies of 2% or better for objects ranging from brown dwarfs through main sequence stars to evolved white dwarfs, neutron stars, and black holes. Studies of star clusters will yield age determinations and internal dynamics. Microlensing measurements will present the mass spectrum of the Milky Way internal to the Sun while proper motion surveys will show the Sun's orbital radius and speed. Studies of the Galaxy's halo component and companion dwarf galaxies permit the determination of the Milky Way's mass distribution, including its Dark Matter component and the mass distribution and Dark Matter component of the Local Group. Cosmology benefits from precision (1-2%) determination of distances to Cepheid and RR Lyrae standard candles. The emission mechanism of supermassive black holes will be investigated. Finally, radio and optical celestial reference frames will be tied together by an improvement of two orders of magnitude. Optical interferometers present severe technological challenges. The Jet Propulsion Laboratory, with the support of Lockheed Martin Advanced Technology Center (LM ATC) and Northrop Grumman Space Technology (NGST), has addressed these challenges with a technology development program that is now complete. The requirements for SIM have been satisfied, based on outside peer review, using a series of laboratory tests and appropriate computer simulations: laser metrology systems perform with 10 picometer precision; mechanical vibrations have been controlled to nanometers, demonstrating orders of magnitude disturbance rejection; and knowledge of component positions throughout the whole test assembly has been demonstrated to the required picometer level. Technology transfer to the SIM flight team is now well along.