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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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29 records · Page 2
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NASA NTRS2005

Single visit completeness optimization

The Terrestrial Planet Finder Coronagraph (TPF-C) is a NASA pre-phase. A orbiting telescope with the goal of detecting and characterizing visible and near-IR light refelected from terrestrial planets. We use observational completeness, defined as the fraction of potentially observable planets that are detected, to determine how well the proposed telescope meets the mission goals. Single visit completeness is optimized by slecting the length of observation per target that maximizes the completeness for the ensemble of stars. In this memo we describe the integration time calculations and two approaches to single visit optimization.

optimization↗
NASA NTRS2005

Occulting focal plane masks for Terrestrial Planet Finder Coronagraph: design, fabrication, simulations and test results

Occulting focal plane masks for the Terrestrial Planet Finder Coronagraph (TPF-C) could be designed with continuous gray scale profile of the occulting pattern such as 1-sinc2 on a suitable material or with micron-scale binary transparent and opaque structures of metallic pattern on glass. We have designed, fabricated and tested both kinds of masks. The fundamental characteristics of such masks and initial test results from the High Contrast Imaging Test bed (HCIT) at JPL are presented.

adaptive optics↗
NASA NTRS2007

Beam Combination for Stellar Imager and its Application to Full-Aperture Imaging

Stellar Imager (SI) will be a Space-Based telescope consisting of 20 to 30 separated apertures. It is designed for UV/Optical imaging of stellar surfaces and asteroseismology. This report describes details of an alternative optical design for the beam combiner, dubbed the Spatial Frequency Remapper (SFR). It sacrifices the large field of view of the Fizeau combiner. In return, spectral resolution is obtained with a diffraction grating rather than an array of energy-resolving detectors. The SFR design works in principle and has been implemented with MIRC at CHARA for a small number of apertures. Here, we show the number of optical surfaces can be reduced and the concept scales gracefully to the large number of apertures needed for Stellar Imager. We also describe a potential application of this spatial frequency remapping to improved imaging with filled aperture systems. For filled-aperture imaging, the SFR becomes the core of an improved aperture masking system. To date, aperture-masking has produced the best images with ground-based telescopes but at the expense of low sensitivity due to short exposures and discarding most of the light collected by the telescope. This design eliminates the light-loss problem previously claimed to be inherent in all aperture-masking designs. We also argue that at least in principle, the short-integration time limit can also be overcome. With these improvements, it becomes an ideal camera for TPF-C; since it can form speckle-free images in the presence of wavefront errors, it should significantly relax the stability requirements of the current designs.

Mozurkewich, D.↗
NASA NTRS2007

The SIM PlanetQuest Science Program

SIM PlanetQuest (hereafter, just SIM) is a NASA mission to measure the angular positions of stars with unprecedented accuracy. We outline the main astrophysical science programs planned for SIM, and related opportunities for community participation. We focus especially on SIM's ability to detect exoplanets as small as the Earth around nearby stars. The planned synergy between SIM and other planet-finding missions including Kepler and GAIA, and planet-characterizing missions including the James Webb Space Telescope (JWST), Terrestrial Planet Finder--Coronagraph (TPF-C), and Terrestrial Planet Finder--Interferometer (TPF-I), is a key element in NASA's Navigator Program to find Earth-like planets, determine their habitability, and search for signs of life in the universe. SIM's technology development is now complete and the project is proceeding towards a launch in the next decade.

SIM PlanetQuest (SIM)↗
NASA NTRS2011

An Integral-Field Spectrograph for a Terrestrial Planet Finding Mission

We describe a conceptual design for an integral field spectrograph for characterizing exoplanets that we developed for NASA's Terrestrial Planet Finder Coronagraph (TPF-C), although it is equally applicable to an external-occulter mission. The spectrograph fulfills all four scientific objectives of a terrestrial planet finding mission by: (1) Spectrally characterizing the atmospheres of detected planets in search of signatures of habitability or even biological activity; (2) Directly detecting terrestrial planets in the habitable zone around nearby stars; (3) Studying all constituents of a planetary system including terrestrial and giant planets, gas and dust around sun-like stars of different ages and metallicities; (4) Enabling simultaneous, high-spatial-resolution, spectroscopy of all astrophysical sources regardless of central source luminosity, such as AGN's, proplyds, etc.

Heap, Sara R.↗
NASA NTRS2013

High-Voltage Clock Driver for Photon-Counting CCD Characterization

A document discusses the CCD97 from e2v technologies as it is being evaluated at Goddard Space Flight Center's Detector Characterization Laboratory (DCL) for possible use in ultra-low background noise space astronomy applications, such as Terrestrial Planet Finder Coronagraph (TPF-C). The CCD97 includes a photoncounting mode where the equivalent output noise is less than one electron. Use of this mode requires a clock signal at a voltage level greater than the level achievable by the existing CCD (charge-coupled-device) electronics. A high-voltage waveform generator has been developed in code 660/601 to support the CCD97 evaluation. The unit generates required clock waveforms at voltage levels from -20 to +50 V. It deals with standard and arbitrary waveforms and supports pixel rates from 50 to 500 kHz. The system is designed to interface with existing Leach CCD electronics.

Baker, Robert↗
NASA NTRS2006

The SIM PlanetQuest science program

SIM PlanetQuest (hereafter, just SIM) is a NASA mission to measure the angular positions of stars with unprecedented accuracy. We outline the main astrophysical science programs planned for SIM, and related opportunities for community participation. We focus especially on SIM’s ability to detect exoplanets as small as the Earth around nearby stars. The planned synergy between SIM and other planet-finding missions including Kepler and GAIA, and planetcharacterizing missions including the James Webb Space Telescope (JWST), Terrestrial Planet Finder – Coronagraph (TPF-C), and Terrestrial Planet Finder – Interferometer (TPF-I), is a key element in NASA’s Navigator Program to find Earth-like planets, determine their habitability, and search for signs of life in the universe. SIM's technology development is now complete and the project is proceeding towards a launch early next decade.

Marr, James C. IV↗
NASA NTRS2005

Technology plan for the Terrestrial Planet Finder coronagraph

The Terrestrial Planet Finder (TPF) is envisaged as a series of two space observatories: an 8-m class optical coronagraph, to be launched around 2016; and a mid-infrared formation-flying interferometer, to be launched sometime prior to 2020. The goal of these missions, broadly stated, is to understand the formation and evolution of planets and, ultimately, of life byond our Solar System. In support of this goal, the TPF missions will be capable of (1) searching for and detecting terrestrial planets should they eixst in the habitable zones of nearby stars, (2)characterizing the atmosphere of planets they detect and searching for indicators of the presence of life, (3) undtertaking a program of comparative study of the constituents of planetary systems, and (4) enabling a broad program of general astrophysics. This document details the technology plan for the first of the TPF missions, the Terrestrial Planet Finder Coronagraph (TPF-C).

Lawson, Peter R.↗
NASA NTRS2004

High Contrast Imaging Testbed for the Terrestrial Planet Finder Coronagraph

The Terrestrial Planet Finder (TPF) mission is planning to launch a visible coronagraphic space telescope in 2014. To achieve TPF science goals, the coronagraph must have extreme levels of wavefront correction (less than 1 Angstrom rms over controllable spatial frequencies) and stability to get the necessary suppression of diffracted starlight (approximately l0(exp -10)) contrast at an angular separation approximately 4 (lamda)/D). TPF Coronagraph's primary platform for experimentation is the High Contrast Imaging Testbed, which will provide laboratory validation of key technologies as well as demonstration of a flight-traceable approach to implementation. Precision wavefront control in the testbed is provided by a high actuator density deformable mirror. Diffracted light control is achieved through use of occulting or apodizing masks and stops. Contrast measurements will establish the technical feasibility of TPF requirements, while model and error budget validation will demonstrate implementation viability. This paper describes the current testbed design, development approach, and recent experimental results.

coronagraph↗