Jet Propulsion Laboratory

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.

A Measurement of the Polarization-Temperature Angular Cross-Power Spectrum of the Cosmic Microwave Background from the 2003 Flight of BOOMERANG

Abstract: We present a measurement of the polarization-temperature angular cross power spectra, langTErang and langTBrang, of the cosmic microwave background. The result is based on ~200 hr of data from eight polarization-sensitive bolometers operating at 145 GHz during the 2003 flight of BOOMERANG. We detect a significant langTErang correlation in the l-range between 50 and 950 with a statistical significance of >3.5 σ. Contamination by polarized foreground emission and systematic effects are negligible in comparison with statistical uncertainties. The spectrum is consistent with previous detections and with the "concordance model" that assumes adiabatic initial conditions. This is the first measurement of polarization-temperature angular cross-power spectra using bolometric detectors.

Sensor web: a new instrument concept

Abstract: The confluence of the rapidly expanding sensor, computation, and telecommunication industries has allowed for a new instrument concept: the Sensor Web. A Sensor Web consists of intra-communicating, spatially-distributed sensor pods that are deployed to monitor and explore environments. It is capable of automated reasoning for it can perform intelligent autonomous operations in uncertain environments, respond to changing environmental conditions, and carry out automated diagnosis and recovery. Sensor Webs could have as much an impact on the uses of sensors as the Internet did on the uses of computers. Sensor Webs are often confused with distributed sensors or sensor networks. The unique feature of the Sensor Web is that information gathered by one pod is shared and used by other pods. In contrast, sensor networks merely gather data and information gathered by a particular pod on such a network does not influence the behavior of another pod. Thus, sensor networks collect data while Sensor Webs can react and modify their behavior on the basis of the collected data. This paper will outline the potential of the Sensor Web concept and describe the Jet Propulsion Laboratory Sensor Webs Project. In particular, a prototype Sensor Web deployed at the Huntington Botanical Gardens will be discussed.© (2001) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Validation of Tropospheric Emission Spectrometer (TES) nadir ozone profiles using ozonesonde measurements

Abstract: We compare Tropospheric Emission Spectrometer (TES) version 2 (V002) nadir ozone profiles with ozonesonde profiles from the Intercontinental Chemical Transport Experiment Ozonesonde Network Study, the World Ozone and Ultraviolet Data Center, the Global Monitoring Division of the Earth System Research Laboratory, and the Southern Hemisphere Additional Ozonesonde archives. Approximately 1600 coincidences spanning 72.5°S-80.3°N from October 2004 to October 2006 are found. The TES averaging kernel and constraint are applied to the ozonesonde data to account for the TES measurement sensitivity and vertical resolution. TES sonde differences are examined in six latitude zones after excluding profiles with thick high clouds. Values for the bias and standard deviation are determined using correlations of mean values of TES ozone and sonde ozone in the upper troposphere (UT) and lower troposphere (LT). The UT biases range from 2.9 to 10.6 ppbv, and the LT biases range from 3.7 to 9.2 ppbv, excluding the Arctic and Antarctic LT where TES sensitivity is low. A similar approach is used to assess seasonal differences in the northern midlatitudes where the density and frequency of sonde measurements are greatest. These results are briefly compared to TES V001 ozone validation work which also used ozonesondes but was carried out prior to improvements in the radiometric calibration and ozone retrieval in V002. Overall, the large number of TES and sonde comparisons indicate a positive bias of approximately 3-10 ppbv for the TES V002 nadir ozone data set and have helped to identify areas of potential improvement for future retrieval versions.

ABUNDANT CIRCUMSTELLAR SILICA DUST AND SiO GAS CREATED BY A GIANT HYPERVELOCITY COLLISION IN THE ∼12 MYR HD172555 SYSTEM

Abstract: The fine dust detected by infrared (IR) emission around the nearby {beta} Pic analog star HD172555 is very peculiar. The dust mineralogy is composed primarily of highly refractory, nonequilibrium materials, with approximately three quarters of the Si atoms in silica (SiO{sub 2}) species. Tektite and obsidian lab thermal emission spectra (nonequilibrium glassy silicas found in impact and magmatic systems) are required to fit the data. The best-fit model size distribution for the observed fine dust is dn/da = a {sup -3.95{+-}}{sup 0.10}. While IR photometry of the system has stayed stable since the 1983 IRAS mission, this steep a size distribution, with abundant micron-sized particles, argues for a fresh source of material within the last 0.1 Myr. The location of the dust with respect to the star is at 5.8 {+-} 0.6 AU (equivalent to 1.9 {+-} 0.2 AU from the Sun), within the terrestrial planet formation region but at the outer edge of any possible terrestrial habitability zone. The mass of fine dust is 4 x 10{sup 19}-2 x 10{sup 20} kg, equivalent to a 150-200 km radius asteroid. Significant emission features centered at 4 and 8 {mu}m due to fluorescing SiO gas are also found. Roughly 10{sup 22}more » kg of SiO gas, formed by vaporizing silicate rock, is also present in the system, and a separate population of very large, cool grains, massing 10{sup 21}-10{sup 22} kg and equivalent to the largest sized asteroid currently found in the solar system's main asteroid belt, dominates the solid circumstellar material by mass. The makeup of the observed dust and gas, and the noted lack of a dense circumstellar gas disk, strong stellar X-ray activity, and an extended disk of {beta} meteoroids argues that the source of the observed circumstellar materials is a giant hypervelocity (>10 km s{sup -1}) impact between large rocky planetesimals, similar to the ones which formed the Moon and which stripped the surface crustal material off of Mercury's surface.« less