Characterizing exoearths at wavelength about 10 micron offers many benefits over visible coronagraphy. Apart from providing direct access to a number of significant bio-signatures, direct-imaging in the mid-infrared can provide 1000 times or more relaxation to contrast requirements while greatly shortening the time-scales over which the system must be stable. This in turn enables tremendous relief to optical manufacturing, control and stability tolerances bringing them inline with current technology state of the art. In this paper, we explore a reference design that co-optimizes a large, segmented, linearized aperture telescope using one-dimensional phase-induced aperture apodization to provide highcontrast imaging for spectroscopic analysis. By rotating about a parent star, the chemical signatures of its planets are characterized while affording additional means for background suppression.
Detection of Earth sized extra-solar planets by the transit method requires measurement of quite small variations (~8x10-5) in the brightness of candidate stars. Noise contributed by hot pixels in CCD detectors operating in the space environment, among other noise sources, must be understood and controlled in order to design transit experiments like the Kepler Mission, which will attempt to measure the distribution of planets as small as the Earth around solar type stars from space. We have analyzed the hot pixel statistics for CCD detectors on several operating space instruments and conclude that neither the amplitude nor the variability of hot pixels will significantly impair the ability of the Kepler Mission to detect transits of earth sized planets transiting solar type stars. The Kepler Mission is currently in the design stage and is expected to begin operation in 2007.
KEYWORDS: Stars, Planets, Space operations, Photometry, Charge-coupled devices, Data centers, System on a chip, Aerospace engineering, Space telescopes, Signal to noise ratio
The Kepler Mission is a search for terrestrial planets specifically designed to detect Earth-size planets in the habitable zones of solar-like stars. In addition, the mission has a broad detection capability for a wide range of planetary sizes, planetary orbits and spectral types of stars. The mission is in the midst of the developmental phase with good progress leading to the preliminary design review later this year. Long lead procurements are well under way. An overview in all areas is presented including both the flight system (photometer and spacecraft) and the ground system. Launch is on target for 2007 on a Delta II.
George Rieke, Erick Young, James Cadien, Charles Engelbracht, Karl Gordon, Douglas Kelly, Frank Low, Karl Misselt, Jane Morrison, James Muzerolle, G. Rivlis, John Stansberry, Jeffrey Beeman, Eugene Haller, David Frayer, William Latter, Alberto Noriega-Crespo, Deborah Padgett, Dean Hines, J. Douglas Bean, William Burmester, Gerald Heim, Thomas Glenn, R. Ordonez, John Schwenker, S. Siewert, Donald Strecker, S. Tennant, John Troeltzsch, Bryce Unruh, R. Warden, Peter Ade, Almudena Alonso-Herrero, Myra Blaylock, Herve Dole, Eiichi Egami, Joannah Hinz, Emeric LeFloch, Casey Papovich, Pablo Perez-Gonzalez, Marcia Rieke, Paul Smith, Kate Su, Lee Bennett, David Henderson, Nanyao Lu, Frank Masci, Misha Pesenson, Luisa Rebull, Jeonghee Rho, Jocelyn Keene, Susan Stolovy, Stefanie Wachter, William Wheaton, Paul Richards, Harry Garner, M. Hegge, Monte Henderson, Kim MacFeely, David Michika, Chris Miller, Mark Neitenbach, Jeremiah Winghart, R. Woodruff, E. Arens, Charles Beichman, Stephen Gaalema, Thomas Gautier, Charles Lada, Jeremy Mould, Gerry Neugebauer, Karl Stapelfeldt
The Multiband Imaging Photometer for Spitzer (MIPS) provides long wavelength capability for the mission, in imaging bands at 24, 70, and 160 microns and measurements of spectral energy distributions between 52 and 100 microns at a spectral resolution of about 7%. By using true detector arrays in each band, it provides both critical sampling of the Spitzer point spread function and relatively large imaging fields of view, allowing for substantial advances in sensitivity, angular resolution, and efficiency of areal coverage compared with previous space far-infrared capabilities. The Si:As BIB 24 micron array has excellent photometric properties, and measurements with rms relative errors of 1% or better can be obtained. The two longer wavelength arrays use Ge:Ga detectors with poor photometric stability. However, the use of 1.) a scan mirror to modulate the signals rapidly on these arrays, 2.) a system of on-board stimulators used for a relative calibration approximately every two minutes, and 3.) specialized reduction software result in good photometry with these arrays also, with rms relative errors of less than 10%.
Four institutions are collaborating to design and build three near identical R ~2700 cross-dispersed near-infrared spectrographs for use on various 5-10 meter telescopes. The instrument design addresses the common observatory need for efficient, reliable near-infrared spectrographs through such features as broad wavelength coverage across 6 simultaneous orders (0.8 - 2.4 microns) in echelle format, real-time slit viewing through separate optics and detector, and minimal moving parts. Lastly, the collaborators are saving money and increasing the likelihood of success through economies of scale and sharing intellectual capital.
KEYWORDS: Systems engineering, Stars, Performance modeling, Space operations, Photometry, Signal to noise ratio, Data modeling, Data acquisition, Planets, Error analysis
The Kepler mission will launch in 2007 and determine the distribution of earth-size planets (0.5 to 10 earth masses) in the habitable zones (HZs) of solar-like stars. The mission will monitor > 100,000 dwarf stars simultaneously for at least 4 years. Precision differential photometry will be used to detect the periodic signals of transiting planets. Kepler will also support asteroseismology by measuring the pressure-mode (p-mode) oscillations of selected stars. Key mission elements include a spacecraft bus and 0.95meter, wide-field, CCD-based photometer injected into an earth-trailing heliocentric orbit by a 3-stage Delta II launch vehicle as well as a distributed Ground Segment and Follow-up Observing Program. The project is currently preparing for Preliminary Design Review (October 2004) and is proceeding with detailed design and procurement of long-lead components. In order to meet the unprecedented photometric precision requirement and to ensure a statistically significant result, the Kepler mission involves technical challenges in the areas of photometric noise and systematic error reduction, stability, and false-positive rejection. Programmatic and logistical challenges include the collaborative design, modeling, integration, test, and operation of a geographically and functionally distributed project. A very rigorous systems engineering program has evolved to address these challenge. This paper provides an overview of the Kepler systems engineering program, including some examples of our processes and techniques in areas such as requirements synthesis, validation & verification, system robustness design, and end-to-end performance modeling.
The instruments of the Space Infrared Telescope Facility (SIRTF) are cooled directly by liquid helium, while the optical system is cooled by helium vapor. The greater the power dissipation into the liquid helium, the more vapor is produced, and the colder the telescope. Observations at shorter wavelengths do not require telescope temperatures as low as those required at shorter wavelengths. By taking advantage of this, it may be possible to extend the helium and mission lifetime by 10% or even 20%
The Astrobiology Explorer (ABE) is a MIDEX mission concept under study at NASA's Ames Research Center in collaboration with Ball Aerospace & Technologies, Corp. ABE will conduct IR spectroscopic observations to address important problems in astrobiology, astrochemistry, and astrophysics. The core observational program would make fundamental scientific progress in understanding the distribution, identity, and evolution of ices and organic matter in dense molecular clouds, young forming stellar systems, stellar outflows, the general diffuse ISM, HII regions, Solar System bodies, and external galaxies. The ABE instrument concept includes a 0.6 m aperture Cassegrain telescope and two moderate resolution (R equals 2000-3000) spectrographs covering the 2.5-16 micron spectral region. Large format (1024x1024 pixel or larger) IR detector arrays and bandpass filters will allow each spectrograph to cover an entire octave of spectral range or more per exposure without any moving parts. The telescope will be cooled below 50 K by a cryogenic dewar shielded by a sunshade. The detectors will be cooled to ~8K. The optimum orbital configuration for achieving the scientific objectives of the ABE mission is a low background, 1 AU Earth driftaway orbit requiring a Delta II launch vehicle. This configuration provides a low thermal background and allows adequate communications bandwidth and good access to the entire sky over the ~1-2 year mission lifetime.
In this paper we describe the main subsystems that constitute the Mt. Palomar Prime Focus InfraRed Camera (PFIRCAM), together with some of the characterization data obtained for the focal plane array. This camera is currently a facility instrument at the 200-inch Mt. Palomar Observatory. It helps to satisfy the observational needs of astronomers in the spectral range of 1 micrometers to 2.5 micrometers by utilizing a HgCdTe NICMOS3 array. The camera has a plate scale of 0.54 arcsec/pixel for an overall FOV of 138 X 138 arcsec.
A NICMOS II array, a NIR (0.80 - 2.6 micron) imaging system, was integrated into the California Institute of Technology Palomar Observatory camera. The Palomar camera system which consists of six discrete subsystems including a focal plane, an electrical interface, data acquisition electronics, a dewar, dewar optics, and the software is described. The performance and calibration data for each subsystem are presented. Emphasis is placed on test data on the focal plane performance.
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