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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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At least 199 records · Page 11
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NASA NTRS2005

HEBS and Binary 1-sinc masks simulations, HCIT experiments and results

Based on preliminary experiments and results with a binary 1-sinc mask in the HCIT early in August 2004, we planned for a detailed experiment to compare the performance of HEBS and Binary masks under nearly identical conditions in the HCIT. This report details the design and fabrication of the masks, simulated predictions, and experimental results.

HCIT↗
NASA NTRS2005

TPF coronagraph instrument design

For the past 2 years, NASA has invested substantial resources to study the design and performance of the Terrestrial Planet Finder Coronagraph (TPF-C). The work, led by the Jet Propulsion Laboratory with collaboration from Goddard Space Flight Center and several university and commercial entities, encompasses observatory design, performance modeling, materials characterization, primary mirror studies, and a significant technology development effort including a high-contrast imaging testbed that has achieved 1e-9 contrast in a laboratory experiment.

extra-solar planets↗
NASA NTRS2003

RF optics design

Explore the source record for details and available documents.

DSN array↗
NASA NTRS2004

Terrestrial Planet Finder Coronagraph overview of technology development & system design

Astronomers have discovered over 150 planets orbiting other stars. NASA mission; Find and characterize terrestrial (or rocky) exo-planets that might harbor life (like Earth)liquid water on the planet (habitable zone). An atmosphere that indicates the presence of life water, oxygen, ozone, carbon dioxide, chlorophyll, and methane. Two missions under development: A coronagraph and an interferometer.

Balasubramanian, Kunjuthapatham↗
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 NTRS2006

Analysis of the Optical Design for the SAFIR Telescope

SAFIR, the Single Aperture Far Infra Red Observatory, is a very powerful space mission that will achieve background-limited sensitivity in the far infrared-submillimeter spectral region. Many processes of enormous interest to astronomers can best be studied in this wavelength range, but require the demanding combination of high sensitivity, good angular resolution, and spectroscopic capability. SAFIR is a 10m class telescope to offering good angular resolution, cooled to below 5 K in order to achieve background-limited sensitivity, and equipped with a complement of large-format cameras and broadband spectrometers. Successful operation of such a facility is critically dependent on achieving the level of sensitivity expected, but this is rendered difficult by potential pickup from unwanted sources of radiation. This problem is exacerbated by the fact that the emission from the optical system itself is minimal due to its low temperature, thus emphasizing the importance of minimizing pickup from unwanted astronomical sources of radiation, including the emission from dust in our solar system (analogous to the zodiacal light, hence 'zodi'), and the emission from warm dust in the Milky Way (Galactic 'cirrus').

antenna radiation patterns↗
NASA NTRS2007

Stardust in STARDUST - the C, N, and O Isotopic Compositions of Wild 2 Cometary Matter in Al foil Impacts

In January 2006, the STARDUST mission successfully returned dust samples from the tail of comet 81P/Wild 2 in two principal collection media, low density silica aerogel and Al foil. While hypervelocity impacts at 6.1 km/s, the encounter velocity of STARDUST, into Al foils are generally highly disruptive for natural, silicate-dominated impactors, previous studies have shown that many craters retain sufficient residue to allow a determination of the elemental and isotopic compositions of the original projectile. We have used the NanoSIMS to perform C, N, and O isotope imaging measurements on four large (59-370 microns diameter) and on 47 small (0.32-1.9 microns diameter) Al foil impact craters as part of the STARDUST Preliminary Examination. Most analyzed residues in and around these craters are isotopically normal (solar) in their C, N, and O isotopic compositions. However, the debris in one large crater shows an average 15N enrichment of approx. 450 %, which is similar to the bulk composition of some isotopically primitive interplanetary dust particles. A 250 nm grain in another large crater has an O-17 enrichment with approx. 2.65 times the solar O-17/O-16 ratio. Such an O isotopic composition is typical for circumstellar oxide or silicate grains from red giant or asymptotic giant branch stars. The discovery of this circumstellar grain clearly establishes that there is authentic stardust in the cometary samples returned by the STARDUST mission. However, the low apparent abundance of circumstellar grains in Wild 2 samples and the preponderance of isotopically normal material indicates that the cometary matter is a diverse assemblage of presolar and solar system materials.

Stadermann, Frank J.↗
NASA NTRS2007

SEM-EDS Analyses of Small Craters in Stardust Aluminum Foils: Implications for the Wild-2 Dust Distribution

Aluminium foils were used on Stardust to stabilize the aerogel specimens in the modular collector tray. Part of these foils were fully exposed to the flux of cometary grains emanating from Wild 2. Because the exposed part of these foils had to be harvested before extraction of the aerogel, numerous foil strips some 1.7 mm wide and 13 or 33 mm long were generated during Stardusts's Preliminary Examination (PE). These strips are readily accommodated in their entirety in the sample chambers of modern SEMs, thus providing the opportunity to characterize in situ the size distribution and residue composition - employing EDS methods - of statistically more significant numbers of cometary dust particles compared to aerogel, the latter mandating extensive sample preparation. We describe here the analysis of nearly 300 impact craters and their implications for Wild 2 dust.

Borg, J.↗