scispace - formally typeset
Search or ask a question
Institution

Jet Propulsion Laboratory

FacilityLa Cañada Flintridge, California, United States
About: Jet Propulsion Laboratory is a facility organization based out in La Cañada Flintridge, California, United States. It is known for research contribution in the topics: Mars Exploration Program & Telescope. The organization has 8801 authors who have published 14333 publications receiving 548163 citations. The organization is also known as: JPL & NASA JPL.


Papers
More filters
Journal ArticleDOI
TL;DR: The Ulysses solar wind plasma experiment has been observed to reach speeds in the 700 to 800 km/s range with a magnetic polarity indicating an origin in the large south polar coronal hole as mentioned in this paper.
Abstract: We present speed observations from the Ulysses solar wind plasma experiment through 50 deg south latitude. The pronounced speed modulation arising from solar rotation and the tilt of the heliomagnetic current sheet has nearly disappeared. Ulysses is now observing wind speeds in the 700 to 800 km/s range, with a magnetic polarity indicating an origin in the large south polar coronal hole. The strong compressions, rarefractions, and shock waves previously seen have weakened or disappeared. Occasional coronal mass ejections characterized by low plasma density caused by radial expansion have been observed. The coronal configuration was simple and stable in 1993, indicating that the observed solar wind changes were caused by increasing spacecraft latitude. Trends in prevailing speed with increasing latitude support previous findings. A decrease in peak speed southward of 40 deg latitude may indicate that the fastest solar wind comes from the equatorial extensions of the polar coronal holes.

128 citations

Journal ArticleDOI
Jason Glenn1, A. Conley1, Matthieu Béthermin2, Bruno Altieri3, A. Amblard4, V. Arumugam5, Herve Aussel6, T. Babbedge7, Andrew Blain8, James J. Bock8, James J. Bock9, Alessandro Boselli10, V. Buat10, N. Castro-Rodríguez11, N. Castro-Rodríguez12, Antonio Cava11, Antonio Cava12, Pierre Chanial7, David L. Clements7, L. Conversi3, Asantha Cooray4, Asantha Cooray8, Charles D. Dowell9, Charles D. Dowell8, Eli Dwek13, Stephen Anthony Eales14, David Elbaz6, Timothy P. Ellsworth-Bowers1, M. Fox7, Alberto Franceschini15, Walter Kieran Gear14, Matthew Joseph Griffin14, Mark Halpern16, Evanthia Hatziminaoglou, Edo Ibar17, Kate Gudrun Isaak14, Rob Ivison5, Rob Ivison17, Guilaine Lagache2, Glenn Laurent18, L. R. Levenson8, L. R. Levenson9, Nanyao Y. Lu8, Suzanne C. Madden6, Bruno Maffei19, G. Mainetti15, Lucia Marchetti15, G. Marsden16, Hien Nguyen8, Hien Nguyen9, B. O'Halloran7, S. J. Oliver20, Alain Omont21, Mat Page22, P. Panuzzo6, Andreas Papageorgiou14, C. P. Pearson23, C. P. Pearson24, Ismael Perez-Fournon12, Ismael Perez-Fournon11, Michael Pohlen14, Dimitra Rigopoulou25, Dimitra Rigopoulou24, D. Rizzo7, Isaac Roseboom20, Michael Rowan-Robinson7, M. Sanchez Portal3, Benjamin L. Schulz8, Douglas Scott16, Nick Seymour22, D. L. Shupe8, A. J. Smith20, Jamie Stevens26, M. Symeonidis22, Markos Trichas7, K. E. Tugwell22, Mattia Vaccari15, Ivan Valtchanov3, Joaquin Vieira8, L. Vigroux21, Lian-Tao Wang20, Robyn L. Ward20, Gillian S. Wright17, C. K. Xu8, Michael Zemcov9, Michael Zemcov8 
21 Nov 2010
TL;DR: In this article, the authors analyzed three fields from the Herschel Multi-tiered Extragalactic Survey (HerMES) programme in all three SPIRE bands (250, 350 and 500 μm) and derived parametrized galaxy number count models to a depth of ∼2 mJy beam−1, approximately four times the depth of previous analyses at these wavelengths, using a probability of deflection [P(D)] approach for comparison to theoretical number count model.
Abstract: Dusty, star-forming galaxies contribute to a bright, currently unresolved cosmic far-infrared background Deep Herschel-Spectral and Photometric Imaging Receiver (SPIRE) images designed to detect and characterize the galaxies that comprise this background are highly confused, such that the bulk lies below the classical confusion limit We analyse three fields from the Herschel Multi-tiered Extragalactic Survey (HerMES) programme in all three SPIRE bands (250, 350 and 500 μm); parametrized galaxy number count models are derived to a depth of ∼2 mJy beam−1, approximately four times the depth of previous analyses at these wavelengths, using a probability of deflection [P(D)] approach for comparison to theoretical number count models Our fits account for 64, 60 and 43 per cent of the far-infrared background in the three bands The number counts are consistent with those based on individually detected SPIRE sources, but generally inconsistent with most galaxy number count models, which generically overpredict the number of bright galaxies and are not as steep as the P(D)-derived number counts Clear evidence is found for a break in the slope of the differential number counts at low flux densities Systematic effects in the P(D) analysis are explored We find that the effects of clustering have a small impact on the data, and the largest identified systematic error arises from uncertainties in the SPIRE beam

127 citations

Journal ArticleDOI
01 Apr 1995-Icarus
TL;DR: In this paper, the tropospheric methane molar fraction (f(sub CH4, t) and the ortho/para hydrogen ratio are derived for Uranus and Neptune based on new determinations of spectroscopic parameters for key hydrogen features as reported by D. W/ Ferguson et al. (1993).

127 citations

Journal ArticleDOI
TL;DR: In this article, the authors presented a catalog of 74 galaxies detected serendipitously during a campaign of spectroscopic observations of the Hubble Deep Field North (HDF) and its environs.
Abstract: We present a catalog of 74 galaxies detected serendipitously during a campaign of spectroscopic observations of the Hubble Deep Field North (HDF) and its environs. Among the identified objects are five candidate Ly? emitters at z 5, a galaxy cluster at z = 0.85, and a Chandra source with a heretofore undetermined redshift of z = 2.011. We report redshifts for 25 galaxies in the central HDF, 13 of which had no prior published spectroscopic redshift. Of the remaining 49 galaxies, 30 are located in the single-orbit HDF flanking fields. We discuss the redshift distribution of the serendipitous sample, which contains galaxies in the range 0.10 < z < 5.77 with a median redshift of z = 0.85, and we present strong evidence for redshift clustering. By comparing our spectroscopic redshifts with optical/IR photometric studies of the HDF, we find that photometric redshifts are in most cases capable of producing reasonable predictions of galaxy redshifts. Finally, we estimate the line-of-sight velocity dispersion and the corresponding mass and expected X-ray luminosity of the galaxy cluster, we present strong arguments for interpreting the Chandra source as an obscured active galactic nucleus, and we discuss in detail the spectrum of one of the candidate z 5 Ly? emitters.

127 citations

Journal ArticleDOI
01 Nov 2012-Nature
TL;DR: The surface of the asteroid Vesta has prominent near-infrared absorption bands characteristic of a range of pyroxenes, confirming a direct link to the basaltic howardite–eucrite–diogenite class of meteorites.
Abstract: Whereas space weathering of some airless bodies, such as the Moon, occurs through the accumulation on regolith of nanophase metallic particles, spectroscopic data show that space weathering of the asteroid Vesta occurs through the small-scale mixing of diverse surface components, which gradually generates locally homogenized upper regolith. Between 16 July 2011 and 5 September 2012, NASA's space probe Dawn was orbiting Vesta, a protoplanet thought to have survived virtually intact since an early phase of Solar System formation. In this issue of Nature, two groups report on the encounter. Carle Pieters and co-workers find that space weathering on Vesta has followed a different course from that observed on the Moon and on Itokawa, the asteroid sampled in an Earth-return mission. On Vesta, weathering involved fine-scale regolith (soil) mixing that has removed clear traces of recent impact deposits. There are no signs of the nanophase metallic-particle deposits seen on the Moon and Itokawa. Thomas McCord and co-authors describe two main types of material on Vesta's surface: bright and dark. The bright material may be uncontaminated indigenous Vesta basaltic soil, with the darker material derived from low-albedo impactors. Dawn has now moved on and is due to rendezvous with the protoplanet Ceres in February 2015. The surface of the asteroid Vesta has prominent near-infrared absorption bands characteristic of a range of pyroxenes, confirming a direct link to the basaltic howardite–eucrite–diogenite class of meteorites1,2,3. Processes active in the space environment produce ‘space weathering’ products that substantially weaken or mask such diagnostic absorption on airless bodies observed elsewhere4,5, and it has long been a mystery why Vesta’s absorption bands are so strong. Analyses of soil samples from both the Moon6 and the asteroid Itokawa7 determined that nanophase metallic particles (commonly nanophase iron) accumulate on the rims of regolith grains with time, accounting for an observed optical degradation. These nanophase particles, believed to be related to solar wind and micrometeoroid bombardment processes, leave unique spectroscopic signatures that can be measured remotely8,9,10 but require sufficient spatial resolution to discern the geologic context and history of the surface, which has not been achieved for Vesta until now. Here we report that Vesta shows its own form of space weathering, which is quite different from that of other airless bodies visited. No evidence is detected on Vesta for accumulation of lunar-like nanophase iron on regolith particles, even though distinct material exposed at several fresh craters becomes gradually masked and fades into the background as the craters age. Instead, spectroscopic data reveal that on Vesta a locally homogenized upper regolith is generated with time through small-scale mixing of diverse surface components.

127 citations


Authors

Showing all 9033 results

NameH-indexPapersCitations
B. P. Crill148486111895
George Helou14466296338
H. K. Eriksen141474104208
Charles R. Lawrence141528104948
W. C. Jones14039597629
Gianluca Morgante13847898223
Jean-Paul Kneib13880589287
Kevin M. Huffenberger13840293452
Robert H. Brown136117479247
Federico Capasso134118976957
Krzysztof M. Gorski132380105912
Olivier Doré130427104737
Mark E. Thompson12852777399
Clive Dickinson12350180701
Daniel Stern12178869283
Network Information
Related Institutions (5)
California Institute of Technology
146.6K papers, 8.6M citations

90% related

Goddard Space Flight Center
63.3K papers, 2.7M citations

90% related

Lawrence Livermore National Laboratory
48.1K papers, 1.9M citations

86% related

University of California, Santa Cruz
44.1K papers, 2.7M citations

85% related

University of Colorado Boulder
115.1K papers, 5.3M citations

84% related

Performance
Metrics
No. of papers from the Institution in previous years
YearPapers
2023177
2022416
2021359
2020348
2019384
2018445