DOCSLIB.ORG

Terrestrial Planet Finder Interferometer Science Working Group Report

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Terrestrial Planet Finder Interferometer Science Working Group Report JPL Publication 07-1 Terrestrial Planet Finder Interferometer Science Working Group Report Edited by: P. R. Lawson, O. P. Lay, K. J. Johnston, and C. A. Beichman Jet Propulsion Laboratory California Institute of Technology Pasadena, California National Aeronautics and Space Administration Jet Propulsion Laboratory California Institute of Technology Pasadena, California 1 March 2007 This research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise, does not constitute or imply its endorsement by the United States Government or the Jet Propulsion Laboratory, California Institute of Technology. ii Abstract Over the past two years, the focus of the project for the interferometric version of the Terrestrial Planet Finder (TPF-I) has been on the development of the scientific rational for the mission, the assessment of TPF-I architectures, the laboratory demonstration of key technologies, and the development of a detailed technology roadmap. The Science Working Group (SWG), in conjunction with European colleagues working on the European Space Agency’s (ESA’s) Darwin project, has reaffirmed the goals of TPF-I as part of a broad vision for the detection and characterization of Earth-like planets orbiting nearby stars and for the search for life on those planets. The SWG also helped to assess the performance of different interferometric configurations for TPF-I/Darwin. Building on earlier SWG reports, this document restates the scientific case for TPF-I, assesses suitable target stars and relevant wavelengths for observation, discusses dramatic new capabilities for general astrophysical observations, and summarizes how Spitzer has improved our knowledge of the incidence of zodiacal emission on the search for planets. This document discusses in some detail on laboratory advances in interferometric nulling and formation flying. Laboratory experiments have now achieved stable narrow- and broad-band nulling the levels of 10-6 and 2.0×10-5, respectively. A testbed has demonstrated formation flying using two realistic spacecraft mockups. With a suitably funded program of technology development, as summarized herein and described in more detail in the Technology Plan for the Terrestrial Planet Finder Interferometer (2005), the National Aeronautics and Space Administration (NASA) and ESA would be able to start within the coming decade a full-scale TPF-I/Darwin mission capable of finding Earths orbiting more than 150 nearby stars, or a scaled back interferometer capable of studying more than 30 stars. Finding evidence for life on just one of those planets would revolutionize our understanding of our place in the cosmos. iii iv Approvals Prepared by: ___________________ ______ Approved by: ___________________ ______ NASA/JPL Peter R. Lawson date Daniel R. Coulter date TPF-I Systems Manager, Project Manager, Terrestrial Planet Finder Terrestrial Planet Finder Approved by: ___________________ ______ Approved by: ___________________ ______ TPF-I SWG NASA/JPL Kenneth Johnston date Wesley A. Traub date TPF-I SWG Co-Chair, Chief Scientist, US Naval Observatory Navigator Program Approved by: ___________________ ______ Approved by: ___________________ ______ TPF-I SWG NASA/JPL Charles Beichman date Michael Devirian date TPF-I SWG Co-Chair, Manager, California Institute of Technology Navigator Program v vi Acknowledgements Twenty-two representatives from the astronomical community and one ex officio member were named to the TPF-Interferometer Science Working Group (TPF-I SWG). They work closely with the TPF project to develop the science rationale for the mid-IR observing program, to help guide the appropriate technology, and to interface with their counterparts on the European Space Agency's Terrestrial Exoplanet Science Advisory Team and Darwin project. As representatives of the broad astronomical community, the TPF-I SWG acts as the science conscience of the project, ensuring that the broad TPF-I science goals are worthy of the mission and that the mission will be able to fulfill them. Specific tasks of the TPF-I SWG includes, but are not limited to: 1. Refining, as necessary, TPF-I science goals as embodied in the Design Reference Mission and assessing the impact of altering mission design parameters (orbit, mission duration, telescope size, instrument complement, etc.) on these science goals. 2. Assessing design concepts, technology, and implementation plans relative to the overall scientific performance of the mission. 3. Assisting NASA in explaining the goals of TPF-I to the larger astronomy community and in preparing materials for review by external scientific advisory groups and oversight committees. 4. Producing a Science Requirements Document. This document will include the prioritized science objectives and requirements for the planet finding and characterization and general astrophysics aspects of the TPF-I mission. The duration of the appointments of each TPF-I SWG member is approximately 3 years. The Terrestrial Planet Finder Interferometer Science Working Group Report has been assembled with the efforts of many individuals. In addition to the members of the TPF-I SWG listed in Table 1, the editors are pleased to acknowledge contributions by Stefan Martin, Robert Peters, Robert Gappinger, Alexander Ksendzov, Kent Wallace, Rosemary Diaz, Kurt Liewer, Frank Loya, Marty Marcin, Andrew Booth, Gary Blackwood, Eric Bloemhof, Dan Coulter, Jim DeCino, Serge Dubovitsky, Philip Dumont, Andy Eatchel, Nick Elias, Steven Gunter, Curt Henry, Louise Hamlin, Ron Holm, Mike Lieber, Chris Lindensmith, Martin Lo, Ken Marsh, David Miller, Chia-Yen Peng, Ben Platt, George Purcell, Robert Smythe, Jeff Tien, John Treichler, Velu Velusamy, Brent Ware, and Matthew Wette. The editors are also most grateful for the assistance of Roger Carlson at JPL Publications. vii Table 1. Members of the TPF-I Science Working Group (2005–2008) Name Institution Michelson Science Center, California Institute of Akeson, Rachel Technology (CalTech) Bally, John University of Colorado Beichman, Charles (ex officio) Michelson Science Center, CalTech Crisp, David Jet Propulsion Laboratory Danchi, William Goddard Space Flight Center (GSFC) Falkowski, Paul Rutgers University Fridlund, Malcolm ESA/ESTEC Hinz, Phil University of Arizona Hollis, Jan M. (Mike) GSFC Hyland, David Texas A&M University Johnston, Kenneth (chair) US Naval Observatory Lane, Ben Massachusetts Institute of Technology (MIT) Laughlin, Gregory UC Santa Cruz Liseau, Rene Stockholm Observatory, Sweden Mennesson, Bertrand Jet Propulsion Laboratory Monnier, John University of Michigan Noecker, Charley Ball Aerospace Quillen, Alice University of Rochester Röttgering, Huub Leiden University, Netherlands Serabyn, Gene Jet Propulsion Laboratory Wilner, David Harvard-Smithsonian Center for Astrophysics Woolf, Nick University of Arizona viii Table of Contents 1 Introduction.........................................................................................................1 1.1 Purpose and Scope ........................................................................................................................... 2 1.2 Science Objectives........................................................................................................................... 4 1.3 Development of the Interferometer Architecture............................................................................. 4 1.4 References........................................................................................................................................ 7 2 Exoplanet Science ...............................................................................................9 2.1 Science Requirements...................................................................................................................... 9 2.1.1 Planetary Detection and Characterization.......................................................................... 9 2.1.2 Observing Modes............................................................................................................. 13 2.1.3 Mission Summary............................................................................................................ 14 2.2 Wavelength Coverage.................................................................................................................... 14 2.3 Physical Characterization............................................................................................................... 15 2.3.1 Temperature, Radius, and Albedo ................................................................................... 15 2.3.2 Orbital Flux Variation...................................................................................................... 16 2.4 Biomarkers..................................................................................................................................... 17 2.4.1 Biomarker Signatures in the Mid Infrared....................................................................... 18 2.4.2 Resolution Needed........................................................................................................... 20 2.4.3 Planets Around Different Stars........................................................................................ 20 2.4.4 Detection of Water..........................................................................................................
Load more

Recommended publications
  • Michael Garcia Hubble Space Telescope Users Committee (STUC)
    Hubble Space Telescope Users Committee (STUC) April 16, 2015 Michael Garcia HST Program Scientist [email protected] 1 Hubble Sees Supernova Split into Four Images by Cosmic Lens 2 NASA’s Hubble Observations suggest Underground Ocean on Jupiter’s Largest Moon Ganymede file:///Users/ file:///Users/ mrgarci2/Desktop/mrgarci2/Desktop/ hs-2015-09-a-hs-2015-09-a- web.jpg web.jpg 3 NASA’s Hubble detects Distortion of Circumstellar Disk by a Planet 4 The Exoplanet Travel Bureau 5 TESS Transiting Exoplanet Survey Satellite CURRENT STATUS: • Downselected April 2013. • Major partners: - PI and science lead: MIT - Project management: NASA GSFC - Instrument: Lincoln Laboratory - Spacecraft: Orbital Science Corp • Agency launch readiness date NLT June 2018 (working launch date August 2017). • High-Earth elliptical orbit (17 x 58.7 Earth radii). Standard Explorer (EX) Mission PI: G. Ricker (MIT) • Development progressing on plan. Mission: All-Sky photometric exoplanet - Systems Requirement Review (SRR) mapping mission. successfully completed on February Science goal: Search for transiting 12-13, 2014. exoplanets around the nearby, bright stars. Instruments: Four wide field of view (24x24 - Preliminary Design Review (PDR) degrees) CCD cameras with overlapping successfully completed Sept 9-12, 2014. field of view operating in the Visible-IR - Confirmation Review, for approval to enter spectrum (0.6-1 micron). implementation phase, successfully Operations: 3-year science mission after completed October 31, 2014. launch. - Mission CDR on track for August 2015 6 JWST Hardware Progress JWST remains on track for an October 2018 launch within its replan budget guidelines 7 WFIRST / AFTA Widefield Infrared Survey Telescope with Astrophysics Focused Telescope Assets Coronagraph Technology Milestones Widefield Detector Technology Milestones 1 Shaped Pupil mask fabricated with reflectivity of 7/21/14 1 Produce, test, and analyze 2 candidate 7/31/14 -4 10 and 20 µm pixel size.
    [Show full text]
  • The Discovery of Exoplanets
    L'Univers, S´eminairePoincar´eXX (2015) 113 { 137 S´eminairePoincar´e New Worlds Ahead: The Discovery of Exoplanets Arnaud Cassan Universit´ePierre et Marie Curie Institut d'Astrophysique de Paris 98bis boulevard Arago 75014 Paris, France Abstract. Exoplanets are planets orbiting stars other than the Sun. In 1995, the discovery of the first exoplanet orbiting a solar-type star paved the way to an exoplanet detection rush, which revealed an astonishing diversity of possible worlds. These detections led us to completely renew planet formation and evolu- tion theories. Several detection techniques have revealed a wealth of surprising properties characterizing exoplanets that are not found in our own planetary system. After two decades of exoplanet search, these new worlds are found to be ubiquitous throughout the Milky Way. A positive sign that life has developed elsewhere than on Earth? 1 The Solar system paradigm: the end of certainties Looking at the Solar system, striking facts appear clearly: all seven planets orbit in the same plane (the ecliptic), all have almost circular orbits, the Sun rotation is perpendicular to this plane, and the direction of the Sun rotation is the same as the planets revolution around the Sun. These observations gave birth to the Solar nebula theory, which was proposed by Kant and Laplace more that two hundred years ago, but, although correct, it has been for decades the subject of many debates. In this theory, the Solar system was formed by the collapse of an approximately spheric giant interstellar cloud of gas and dust, which eventually flattened in the plane perpendicular to its initial rotation axis.
    [Show full text]
  • Modeling Super-Earth Atmospheres in Preparation for Upcoming Extremely Large Telescopes
    Modeling Super-Earth Atmospheres In Preparation for Upcoming Extremely Large Telescopes Maggie Thompson1 Jonathan Fortney1, Andy Skemer1, Tyler Robinson2, Theodora Karalidi1, Steph Sallum1 1University of California, Santa Cruz, CA; 2Northern Arizona University, Flagstaff, AZ ExoPAG 19 January 6, 2019 Seattle, Washington Image Credit: NASA Ames/JPL-Caltech/T. Pyle Roadmap Research Goals & Current Atmosphere Modeling Selecting Super-Earths for State of Super-Earth Tool (Past & Present) Follow-Up Observations Detection Preliminary Assessment of Future Observatories for Conclusions & Upcoming Instruments’ Super-Earths Future Work Capabilities for Super-Earths M. Thompson — ExoPAG 19 01/06/19 Research Goals • Extend previous modeling tool to simulate super-Earth planet atmospheres around M, K and G stars • Apply modified code to explore the parameter space of actual and synthetic super-Earths to select most suitable set of confirmed exoplanets for follow-up observations with JWST and next-generation ground-based telescopes • Inform the design of advanced instruments such as the Planetary Systems Imager (PSI), a proposed second-generation instrument for TMT/GMT M. Thompson — ExoPAG 19 01/06/19 Current State of Super-Earth Detections (1) Neptune Mass Range of Interest Earth Data from NASA Exoplanet Archive M. Thompson — ExoPAG 19 01/06/19 Current State of Super-Earth Detections (2) A Approximate Habitable Zone Host Star Spectral Type F G K M Data from NASA Exoplanet Archive M. Thompson — ExoPAG 19 01/06/19 Atmosphere Modeling Tool Evolution of Atmosphere Model • Solar System Planets & Moons ~ 1980’s (e.g., McKay et al. 1989) • Brown Dwarfs ~ 2000’s (e.g., Burrows et al. 2001) • Hot Jupiters & Other Giant Exoplanets ~ 2000’s (e.g., Fortney et al.
    [Show full text]
  • PEAS: the PLANET AS EXOPLANET ANALOG SPECTROGRAPH. E. C. Martin1 and A
    Exoplanets in our Backyard 2020 (LPI Contrib. No. 2195) 3006.pdf PEAS: THE PLANET AS EXOPLANET ANALOG SPECTROGRAPH. E. C. Martin1 and A. J. Skemer1, 1Department of Astronomy & Astrophysics, University of California, Santa Cruz, CA ([email protected]) Introduction: Exoplanets are abundant in our Galaxy • Produce 2D surface maps of Venus, Mars, Jupi- and yet characterizing them remains a technical chal- ter, Saturn, Uranus, Neptune lenGe. Solar System planets provide an opportunity to • Produce fiducial measurements that will be used test the practical limitations of exoplanet observations to plan instruments for future exoplanet mis- with hiGh siGnal-to-noise data, and ancillary data (such sions, such as HabEx/LUVOIR and TMT. as 2D maps and in situ measurements) that we cannot Long term: access for exoplanets. However, data on Solar System • Time-series observations of Solar System plan- planets differ from exoplanets in that Solar System ets to explore variability and weather patterns planets are spatially resolved while exoplanets are all on planets unresolved point-sources. • Comparison to historical data (e.g. [4]) There have been several recent efforts to validate techniques for interpreting exoplanet observations by • Study planetary seismoloGy (oscillation modes) binning images of Solar System planets to a single of Solar System planets pixel: For example, Cowan et al. [1] used images from the EPOXI mission to study Earth’s Globally averaGed PEAS Instrument Design Planetary light collect- properties as it rotated; MayorGa et al. [2] used data ed by the telescope will be split into a spectroGraph from the Cassini spacecraft’s fly-by of Jupiter to ob- system and an imaGinG system for simultaneous obser- serve Globally averaGed reflected liGht phase curves; vations.
    [Show full text]
  • The Exoplanet Revolution
    FEATURES THE EXOPLANET REVOLUTION l Yamila Miguel – Leiden Observatory, Leiden, The Netherlands – DOI: https://doi.org/10.1051/epn/2019506 Hot Jupiters, super-Earths, lava-worlds and the search for life beyond our solar system: the exoplanet revolution started almost 30 years ago and is now taking off. re there other planets like the Earth out discovered the astonishing number of 4000 exoplanets, there? This is probably one of the oldest and counting. Every new discovery shows an amazing questions of humanity. For centuries and diversity that impacts in the perception and understand- Auntil the 90s, we only knew of the existence ing of our own solar system. of 8 planets. But today we live in a privileged time. For the first time in history we know that there are other How to find exoplanets? planets orbiting distant stars. Finding exoplanets is an extremely difficult task. These The first planet orbiting a star similar to the Sun was planets shine mostly due to the reflection of the stellar . Artist’s impression discovered in 1995 -only 24 years ago- and it started light in their atmospheres and their light is incredibly of COROT-7b. a revolution in Astronomy. Today astronomers have weak compared to that of their host stars. For this reason, © ESO/L. Calçada EPN 50/5&6 41 FEATURES THE Exoplanet REVolution observing exoplanets directly is extremely difficult and allows astronomers to calculate the planet’s density, astronomers had to develop indirect techniques that infer important to start assessing planetary compositions the presence of the planet. and diversity. Two of the most successful techniques to discov- er exoplanets are the "Transits" and "Radial Veloci- The Exoplanet Zoo ties" techniques.
    [Show full text]
  • Exploring Exoplanet Populations with NASA's Kepler Mission
    SPECIAL FEATURE: PERSPECTIVE PERSPECTIVE SPECIAL FEATURE: Exploring exoplanet populations with NASA’s Kepler Mission Natalie M. Batalha1 National Aeronautics and Space Administration Ames Research Center, Moffett Field, 94035 CA Edited by Adam S. Burrows, Princeton University, Princeton, NJ, and accepted by the Editorial Board June 3, 2014 (received for review January 15, 2014) The Kepler Mission is exploring the diversity of planets and planetary systems. Its legacy will be a catalog of discoveries sufficient for computing planet occurrence rates as a function of size, orbital period, star type, and insolation flux.The mission has made significant progress toward achieving that goal. Over 3,500 transiting exoplanets have been identified from the analysis of the first 3 y of data, 100 planets of which are in the habitable zone. The catalog has a high reliability rate (85–90% averaged over the period/radius plane), which is improving as follow-up observations continue. Dynamical (e.g., velocimetry and transit timing) and statistical methods have confirmed and characterized hundreds of planets over a large range of sizes and compositions for both single- and multiple-star systems. Population studies suggest that planets abound in our galaxy and that small planets are particularly frequent. Here, I report on the progress Kepler has made measuring the prevalence of exoplanets orbiting within one astronomical unit of their host stars in support of the National Aeronautics and Space Admin- istration’s long-term goal of finding habitable environments beyond the solar system. planet detection | transit photometry Searching for evidence of life beyond Earth is the Sun would produce an 84-ppm signal Translating Kepler’s discovery catalog into one of the primary goals of science agencies lasting ∼13 h.
    [Show full text]
  • Report by the ESA–ESO Working Group on Extra-Solar Planets
    Report by the ESA–ESO Working Group on Extra-Solar Planets 4 March 2005 Summary Various techniques are being used to search for extra-solar planetary signatures, including accurate measurement of radial velocity and positional (astrometric) dis- placements, gravitational microlensing, and photometric transits. Planned space experiments promise a considerable increase in the detections and statistical know- ledge arising especially from transit and astrometric measurements over the years 2005–15, with some hundreds of terrestrial-type planets expected from transit mea- surements, and many thousands of Jupiter-mass planets expected from astrometric measurements. Beyond 2015, very ambitious space (Darwin/TPF) and ground (OWL) experiments are targeting direct detection of nearby Earth-mass planets in the habitable zone and the measurement of their spectral characteristics. Beyond these, ‘Life Finder’ (aiming to produce confirmatory evidence of the presence of life) and ‘Earth Imager’ (some massive interferometric array providing resolved images of a distant Earth) arXiv:astro-ph/0506163v1 8 Jun 2005 appear as distant visions. This report, to ESA and ESO, summarises the direction of exo-planet research that can be expected over the next 10 years or so, identifies the roles of the major facilities of the two organisations in the field, and concludes with some recommendations which may assist development of the field. The report has been compiled by the Working Group members and experts (page iii) over the period June–December 2004. Introduction & Background Following an agreement to cooperate on science planning issues, the executives of the European Southern Observatory (ESO) and the European Space Agency (ESA) Science Programme and representatives of their science advisory structures have met to share information and to identify potential synergies within their future projects.
    [Show full text]
  • Stsci Newsletter: 2011 Volume 028 Issue 02
    National Aeronautics and Space Administration Interacting Galaxies UGC 1810 and UGC 1813 Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA) 2011 VOL 28 ISSUE 02 NEWSLETTER Space Telescope Science Institute We received a total of 1,007 proposals, after accounting for duplications Hubble Cycle 19 and withdrawals. Review process Proposal Selection Members of the international astronomical community review Hubble propos- als. Grouped in panels organized by science category, each panel has one or more “mirror” panels to enable transfer of proposals in order to avoid conflicts. In Cycle 19, the panels were divided into the categories of Planets, Stars, Stellar Rachel Somerville, [email protected], Claus Leitherer, [email protected], & Brett Populations and Interstellar Medium (ISM), Galaxies, Active Galactic Nuclei and Blacker, [email protected] the Inter-Galactic Medium (AGN/IGM), and Cosmology, for a total of 14 panels. One of these panels reviewed Regular Guest Observer, Archival, Theory, and Chronology SNAP proposals. The panel chairs also serve as members of the Time Allocation Committee hen the Cycle 19 Call for Proposals was released in December 2010, (TAC), which reviews Large and Archival Legacy proposals. In addition, there Hubble had already seen a full cycle of operation with the newly are three at-large TAC members, whose broad expertise allows them to review installed and repaired instruments calibrated and characterized. W proposals as needed, and to advise panels if the panelists feel they do not have The Advanced Camera for Surveys (ACS), Cosmic Origins Spectrograph (COS), the expertise to review a certain proposal. Fine Guidance Sensor (FGS), Space Telescope Imaging Spectrograph (STIS), and The process of selecting the panelists begins with the selection of the TAC Chair, Wide Field Camera 3 (WFC3) were all close to nominal operation and were avail- about six months prior to the proposal deadline.
    [Show full text]
  • An Implementation Concept for the ASPIRE Mission
    An Implementation Concept for the ASPIRE Mission. W. D. Deininger* ([email protected]), W. Purcell,* P. Atcheson,*G. Mills,* S. A Sandford,** R. P. Hanel,** M. McKelvey,** and R. McMurray** *Ball Aerospace & Technologies Corp. (BATC) P. O. Box 1062 Boulder, CO, USA 80306-1062 **NASA Ames Research Center Moffett Field, CA, USA 94035 Abstract—The Astrobiology Space Infrared Explorer complex and tied to the cyclic process whereby these (ASPIRE) is a Probe-class mission concept developed as elements are ejected into the diffuse interstellar medium part of NASA’s Astrophysics Strategic Mission Concept (ISM) by dying stars, gathered into dense clouds and studies. 1 2 ASPIRE uses infrared spectroscopy to explore formed into the next generation of stars and planetary the identity, abundance, and distribution of molecules, systems (Figure 1). Each stage in this cycle entails chemical particularly those of astrobiological importance throughout alteration of gas- and solid-state species by a diverse set of the Universe. ASPIRE’s observational program is focused astrophysical processes: hocks, stellar winds, radiation on investigating the evolution of ices and organics in all processing by photons and particles, gas-phase neutral and phases of the lifecycle of carbon in the universe, from ion chemistry, accretion, and grain surface reactions. These stellar birth through stellar death while also addressing the processes create new species, destroy old ones, cause role of silicates and gas-phase materials in interstellar isotopic enrichments, shuffle elements between chemical organic chemistry. ASPIRE achieves these goals using a compounds, and drive the universe to greater molecular Spitzer-derived, cryogenically-cooled, 1-m-class telescope complexity.
    [Show full text]
  • Adaptive Nulling for the Terrestrial Planet Finder Interferometer Robert D
    Adaptive nulling for the Terrestrial Planet Finder Interferometer Robert D. Peters*, Oliver P. Lay, Akiko Hirai, Muthu Jeganathan Jet Propulsion Laboratory, California Institute of Technology 4800 Oak Grove Drive, Pasadena CA 91109 ABSTRACT Deep, stable starlight nulls are needed for the direct detection of Earth-like planets and require careful control of the intensity and phases of the beams that are being combined. We are testing a novel compensator based on a deformable mirror to correct the intensity and phase at each wavelength and polarization across the nulling bandwidth. We have successfully demonstrated intensity and phase control using a deformable mirror across a 100nm wide band in the near- IR, and are in the process of conducting experiments in the mid-IR wavelengths. This paper covers the current results and in the mid-IR. Keywords: Nulling interferometry, planet detection, deformable mirror, dispersion compensator, nulling, amplitude and phase correction, adaptive nuller 1. INTRODUCTION Direct detection of Earth like planets around nearby stars requires a combination of starlight suppression and high angular resolution (< 0.1 arcsec). The technique of nulling interferometry1 has been proposed at mid-infrared wavelengths for both the European Darwin mission2 and NASA’s Terrestrial Planet Finder - Interferometer (TPF-I)3. The latter is also developing a visible coronagraph architecture (TPF-C). For the case of the mid-IR interferometer, the light from the star must be suppressed by a factor of 105 or more over the bandwidth of interest, currently 7 - 17 μm. All designs under consideration include a single-mode spatial filter (SMSF) through which the combined light is passed before being detected.
    [Show full text]
  • Measuring Extended Structure in Stars Using the Keck Interferometer Nuller
    Measuring Extended Structure in Stars using the Keck Interferometer Nuller Chris Koreskoa M. Mark Colavitab Eugene Serabynb Andrew Boothb and Jean Garciab aMichelson Science Center, IPAC, Caltech, Pasadena, CA 91125, USA; bJet Propulsion Laboratory, Caltech, Pasadena, CA 91109, USA ABSTRACT The Keck Interferometer Nuller is designed to detect faint off-axis mid-infrared light a few tens to a few hundreds of milliarcseconds from a bright central star. The starlight is suppressed by destructive combination along the long (85 m) baseline, which produces a fringe spacing of 25 mas at a wavelength of 10 µm, with the central null crossing the position of the star. The strong, variable mid-infrared background is subtracted using interferometric phase chopping along the short (5 m) baseline. This paper presents an overview of the observing and data reduction strategies used to produce a calibrated measurement of the off-axis light. During the observations, the instrument cycles rapidly through several calibration and measurement steps, in order to monitor and stabilize the phases of the fringes produced by the various baselines, and to derive the fringe intensity at the constructive peak and destructive null along the long baseline. The data analysis involves removing biases and coherently demodulating the short-baseline fringe with the long-baseline fringe tuned to alternate between constructive and destructive phases, combining the results of many measurements to improve the sensitivity, and estimating the part of the null leakage signal which is associated with the finite angular size of the central star. Comparison of the results of null measurements on science target and calibrator stars permits the instrumental leakage - the “system null leakage” - to be removed and the off-axis light to be measured.
    [Show full text]
  • System Design and Technology Development for the Terrestrial
    System design and technology development for the Terrestrial Planet Finder infrared interferometer Gary Blackwood*, Eugene Serabyn, Serge Dubovitsky, MiMi Aung, Steven M. Gunter, Curt Henry Jet Propulsion Laboratory ABSTRACT This paper describes the technical program that will demonstrate the viability of two mid-infrared interferometer architectures being developed for the Terrestrial Planet Finder (TPF) to support a mission concept downselect in 2006. The TPF science objectives are to survey a statistically significant number of nearby solar-type stars for radiation from terrestrial planets, to characterize these planets and to then perform spectroscopy for detection of biomarkers. A 4- telescope, 36-m Structurally-Connected Interferometer using a dual-chopped Bracewell nuller will meet the minimum science requirement to completely survey 30 nearby stars and partially survey 120 others. A Formation-Flying Interferometer will meet the full science requirement to completely survey 150 stars, and involves a trade between dual- chopped Bracewell, degenerate Angel Cross, and the Darwin bow-tie input pupil. The system engineering trades for the connected structure and formation-flying architectures are described. The top technical concems for these architectures are mapped to technology developments that will retire these concems prior to the project downselect between a mid- infrared nulling interferometer and a visible coronagraph. Keywords: interferometry, terrestrial planets, nulling, formation-flying, cryogenic structures 1. INTRODUCTION The goals of the Terrestrial Planet Finder (TPF) are to detect and characterize terrestrial-sized planets around nearby stars for signs of habitability and for evidence of life. The TPF science requirements are to survey a statistically meaningful number of solar-type stars for radiation from terrestrial planets, to characterize these planets and their orbital parameters, and to then perform follow-up spectroscopy on promising targets.
    [Show full text]