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  • ASTROPHYSICS  (916)
  • Life and Medical Sciences  (844)
  • Lunar and Planetary Science and Exploration  (410)
  • INSTRUMENTATION AND PHOTOGRAPHY
  • 2015-2019  (367)
  • 1990-1994  (2,036)
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  • 1
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    Properties of Rubble-Pile Asteroid (101955) Bennu from OSIRIS-REx Imaging and Thermal Analysis (2019)
    In:  CASI
    Details
    Publication Date: 2019-08-14
    Description: Establishing the abundance and physical properties of regolith and boulders on asteroids is crucial for understanding the formation and degradation mechanisms at work on their surfaces. Using images and thermal data from NASA's Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer (OSIRIS-REx) spacecraft, we show that asteroid (101955) Bennu's surface is globally rough, dense with boulders, and low in albedo. The number of boulders is surprising given Bennu's moderate thermal inertia, suggesting that simple models linking thermal inertia to particle size do not adequately capture the complexity relating these properties. At the same time, we find evidence for a wide range of particle sizes with distinct albedo characteristics. Our findings imply that ages of Bennu's surface particles span from the disruption of the asteroid's parent body (boulders) to recent in situ production (micrometre-scale particles).
    Keywords: Lunar and Planetary Science and Exploration
    Type: GSFC-E-DAA-TN67770 , Nature Astronomy (e-ISSN 2397-3366); 3; 341–351
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 2
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    OSIRIS-REx Contamination Control Strategy and Implementation (2017)
    In:  CASI
    Details
    Publication Date: 2019-08-13
    Description: OSIRIS-REx will return pristine samples of carbonaceous asteroid Bennu. This manuscript describes how pristine was defined based on expectations of Bennu and on a realistic understanding of what is achievable with a constrained schedule and budget, and how that definition flowed to requirements and implementation. To return a pristine sample, the OSIRIS-REx spacecraft sampling hardware was maintained at Level 100 A/2 and less than 180 nanograms per square centimeter of amino acids and hydrazine on the sampler head through precision cleaning, control of materials, and vigilance. Contamination is further characterized via witness material exposed to the spacecraft assembly and testing environment as well as in space. This characterization provided knowledge of the expected background and will be used in conjunction with archived spacecraft components for comparison with the samples when they are delivered to Earth for analysis. Most of all, the cleanliness of the OSIRIS-REx spacecraft was achieved through communication between scientists, engineers, managers, and technicians.
    Keywords: Lunar and Planetary Science and Exploration
    Type: GSFC-E-DAA-TN41800 , International Conference on the Origin of Life; Jul 16, 2018 - Jul 21, 2018; San Diego, CA; United States
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    NASA TECHNICAL REPORTS
  • 3
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    OSIRIS-REx Contamination Control Strategy and Implementation (2017)
    In:  Other Sources
    Details
    Publication Date: 2019-08-26
    Description: OSIRIS-REx will return pristine samples of carbonaceous asteroid Bennu. This article describes how pristine was defined based on expectations of Bennu and on a realistic understanding of what is achievable with a constrained schedule and budget, and how that definition flowed to requirements and implementation. To return a pristine sample, the OSIRIS-REx spacecraft sampling hardware was maintained at level 100 A/2 and less than 180 ng/cm(exp 2) of amino acids and hydrazine on the sampler head through precision cleaning, control of materials, and vigilance. Contamination is further characterized via witness material exposed to the spacecraft assembly and testing environment as well as in space. This characterization provided knowledge of the expected background and will be used in conjunction with archived spacecraft components for comparison with the samples when they are delivered to Earth for analysis. Most of all, the cleanliness of the OSIRIS-REx spacecraft was achieved through communication among scientists, engineers, managers, and technicians.
    Keywords: Lunar and Planetary Science and Exploration
    Type: GSFC-E-DAA-TN50790 , Space Science Review (ISSN 0038-6308) (e-ISSN 1572-9672); 214; 1; 19
    Format: text
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    NASA TECHNICAL REPORTS
  • 4
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    An unusually strong Einstein ring in the radio source PKS1830 - 211 (1991)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: High-resolution radio images of PKS1830 - 211 are obtained to study the possibility that the double structure is a gravitationally lensed object. The VLBI observations, taken from interferometric radiotelescope networks, reveal an elliptical ring that connects two bright spots of similar composition. Because the lens and the lensed object are closely aligned, and because of the structure of the two spots, the source is concluded to be a radio Einstein ring. The source is found to be close to the galactic plane, and the lens and the lensed object are extragalactic. The source is also found to be unusually bright, suggesting that it is aligned with a bright background source or amplified by some mechanism related to a source that is not so bright.
    Keywords: ASTROPHYSICS
    Type: Nature (ISSN 0028-0836); 352; 132-134
    Format: text
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    NASA TECHNICAL REPORTS
  • 5
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    Episodes of Particle Ejection from the Surface of the Active Asteroid (101955) Bennu (2019)
    In:  CASI
    Details
    Publication Date: 2020-01-04
    Description: Active asteroids are those that show evidence of ongoing mass loss. We report repeated instances of particle ejection from the surface of (101955) Bennu, demonstrating that it is an active asteroid. The ejection events were imaged by the OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification, and SecurityRegolith Explorer) spacecraft. For the three largest observed events, we estimated the ejected particle velocities and sizes, event times, source regions, and energies. We also determined the trajectories and photometric properties of several gravitationally bound particles that orbited temporarily in the Bennu environment. We consider multiple hypotheses for the mechanisms that lead to particle ejection for the largest events, including rotational disruption, electrostatic lofting, ice sublimation, phyllosilicate dehydration, meteoroid impacts, thermal stress fracturing, and secondary impacts.
    Keywords: Lunar and Planetary Science and Exploration
    Type: GSFC-E-DAA-TN76455 , Science (ISSN 0036-8075) (e-ISSN 1095-9203); 366; 6470; eaay3544
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    NASA TECHNICAL REPORTS
  • 6
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    Spectral Characterization of Analog Samples in Anticipation of OSIRIS-REx's Arrival at Bennu (2017)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: NASA's Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer (OSIRIS-REx) mission successfully launched on September 8th, 2016. During its rendezvous with near-Earth asteroid (101955) Bennu beginning in 2018, OSIRIS-REx will characterize the asteroid's physical, mineralogical, and chemical properties in an effort to globally map the properties of Bennu, a primitive carbonaceous asteroid, and choose a sampling location [e.g. 1]. In preparation for these observations, we spectrally characterized a suite of analog samples across visible, near- and thermal-infrared wavelengths and used these in initial tests of phase detection and abundance determination software algorithms. Here we present the thermal infrared laboratory measurements of the analog sample suite measured under asteroidlike conditions, which are relevant to the interpretation of spectroscopic observations by the OSIRIS-REx Thermal Emission Spectrometer (OTES) [2, 3]. This suite of laboratory measurements of asteroid analogs under asteroid-like conditions is the first of their kind.
    Keywords: Lunar and Planetary Science and Exploration
    Type: JSC-CN-38849 , Lunar and Planetary Science Conference; Mar 20, 2017 - Mar 24, 2017; The Woodlands, TX; United States
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  • 7
    Electronic Resource
    Electronic Resource
    Nuclear protein redistribution in heat-shocked cells (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 154 (1993), S. 402-409 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: An increase was observed in the total protein mass of nuclei isolated from Chinese hamster ovary cells heated at 45°C or 45.5°C. An increase in the fractional recovery of DNA polymerase α and β, and of DNA topoisomerase activity coincided with this increase in the protein mass of nuclei from heated cells. Nuclear protein mass which was soluble in 2.0 M NaCl decreased 0.5 fold, while DNA-associated and nuclear matrix-associated protein mass increased 2.2 and 3.4 fold, respectively. The results indicate that the increase in nuclear protein mass observed in nuclei from heated cells is due in part to an increased binding, or precipitation, of nuclear proteins onto the cell's DNA and nuclear matrix. © 1993 Wiley-Liss, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041540224
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  • 8
    Electronic Resource
    Electronic Resource
    Role for autocrine TGF-β1 in regulating differentiation of a human leukemic cell line toward osteoclast-like cells (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 160 (1994), S. 482-490 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Increasing evidence suggests that transforming growth factor-β (TGF-β) is involved in bone formation during remodeling. Using a recently cloned human leukemic cell line (FLG 29.1 cells) we demonstrate that these cells synthesize and secrete TGF-β1 and that exogenous or autocrine TGF-β1 can induce the same features of osteoclastic-like cells, exerting its effects through the binding to TGF-β specific receptors. Scatchard analysis of 125I-labeled TGF-β1 to FLG 29.1 cells revealed the presence of a single high affinity binding site with a Kd value of ∼25 pM and a binding capacity of ∼900 sites/cell. Affinity labeling experiments showed that FLG 29.1 cells express type I and type II TGF-β receptors. Stimulation of FLG 29.1 cells with low TGF-β1 doses reduced cell proliferation and increased cell adhesion and tartrate resistant acid phosphatase (TRAcP) activity. Pretreatment of FLG 29.1 cells with TGF-β1 caused a significant and dose-dependent response to calcitonin. Northern blot of total mRNA and analysis of the conditioned media (CM) showed that TGF-β1 was synthesized by FLG 29.1 cells. TPA treatment, which induces partial differentiation of these cells, markedly increased TGF-β1 mRNA expression and growth factor release. The majority of TGF-β1 secreted by TPA-treated cells was in its latent form. However, anti-TGF-β antibodies inhibited TGF-β1 and TPA-induced growth inhibition, calcitonin responsiveness, and TRAcP activity, suggesting that the TPA effect is mediated in part by autocrine TGF-β1 and indicating that the cells can activate and respond to the TGF-β that they secrete. These findings support a potential autocrine role for TGF-β1 in osteoclast differentiation. © 1994 Wiley-Liss, Inc.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041600311
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  • 9
    Electronic Resource
    Electronic Resource
    Isolation and cultivation of blastocyst-derived stem cell lines from american mink (Mustela vison) (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 33 (1992), S. 418-431 
    Details
    ISSN: 1040-452X
    Keywords: Embryonic stem cells ; Cell differentiation ; Pluripotency ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Ten embryonic stem (ES) cell lines from mink blastocysts were isolated and characterized. All the lines had a normal diploid karyotype; of the ten lines studied, five had the XX and five had the XY constitution. Testing of the pluripotency of the ES-like cells demonstrated that (1) among four lines of genotype XX, an X was late-replicating in three; both Xs were active in about one-third of cells of line MES8, and analysis of glucose-6-phosphate dehydrogenase revealed no dosage compensation for the X-linked gene; (2) when cultured in suspension, the majority of lines were capable of forming “simple” embryoid bodies (EB), and two only showed the capacity for forming “cystic” multilayer EBs. However, formation of ectoderm or foci of yolk sac hematopoiesis, a feature of mouse ES ceils, was not observed in the “cystic” EB; (3) when cultured as a monolayer without feeder, the ES cells differentiated into either vimentin-positive fibroblast-like cells or cytokeratin-positive epithelial-like cells (less frequently); neural cells appeared in two lines; (4) when injected into athymic mice, only one of the four tested lines gave rise to tumors. These were fibrosarcomas composed of fibrobalst-like cells, with an admixture of smooth muscular elements and stray islets of epithelial tissue; (5) when the ES cells of line MES1 were injected into 102 blastocyst cavities and subsequently transplanted into foster mathers, we obtained 30 offspring. Analysis of the biochemical markers and coat color did not demonstrate the presence of chimaeras among offspring. Thus the cell lines derived from mink blastocysts are true ES cells. However, their pluripotential capacities are restricted. © 1992 Wiley-Liss, Inc.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1080330408
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  • 10
    Electronic Resource
    Electronic Resource
    Unusual nuclear structure of the spermatozoon in a marsupial, Sminthopsis crassicaudata (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 37 (1994), S. 78-86 
    Details
    ISSN: 1040-452X
    Keywords: Marsupial ; Sperm head ; Chromatin ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The organization of sperm chromatin in the dasyurid marsupial, Sminthopsis crassicaudata, was investigated using various morphological techniques. Transmission electron microscopy indicates two quite distinct chromatin regions became evident late in spermiogenesis with an outer globular region containing blocks of very electron-dense chromatin. Fluorescent light microscopical studies after staining with DNA dyes and 7-amino actinomycin D of testicular, caput, and cauda epididymal spermatozoa showed that this region fluoresced less brightly than the rest of the nucleus, indicating the presence of fewer DNA binding sites. Freeze fracture showed that the chromatin in most of the nucleus had randomly arranged particles of various sizes, but that of the outer region was composed entirely of small particles. This outer region was more resistant to low concentrations of the ionic detergent, SDS, whereas both guanidine hydrochloride and urea together with sodium chloride generally dispersed all the chromatin except that in the outer globular region and in a localized area of the nucleus beneath the acrosome. This study has thus revealed that the outer globular chromatin of these spermatozoa responds differently to ionic detergents and protein denaturing agents and has a different chromatin organization than most of the rest of the nucleus. The significance of these differences remains, however, to be determined. © 1994 Wiley-Liss, Inc.
    Additional Material: 23 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1080370111
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