Saturn in hot water: viscous evolution of the Enceladus torus

The detection of outgassing water vapor from Enceladus is one of the great breakthroughs of the Cassini mission. The fate of this water once ionized has been widely studied; here we investigate the effects of purely neutral-neutral interactions within the Enceladus torus. We find that, thanks in part to the polar nature of the water molecule, a cold (~180 K) neutral torus would undergo rapid viscous heating and spread to the extent of the observed hydroxyl cloud, before plasma effects become important. We investigate the physics behind the spreading of the torus, paying particular attention to the competition between heating and rotational line cooling. A steady-state torus model is constructed, and it is demonstrated that the torus will be observable in the millimeter band with the upcoming Herschel satellite. The relative strength of rotational lines could be used to distinguish between physical models for the neutral cloud.Comment: submitted to Icarus updated: references fixe

WASTE WATERS IN ‘DUGA RESA COTTON INDUSTRY’

SAŽETAK: Otpadne vode zagađuju rijeke, mora, jezera i podzemlje – podzemne vode. Samim time ugrožen je opstanak života na Zemlji. Otpadne vode pospješuju razvoj mikroorganizama. Mikroorganizmi troše kisik što dovodi do uginuća riba, a i do razvoja patogenih mikroba. U članku se želi staviti težište na problem zaštite okoliša od nastalih otpadnih voda u Pamučnoj industriji Duga Resa. Tekstilna industrija stvara otpadne vode u procesnoj proizvodnji. Takve zagađene otpadne vode treba pročistiti prije ispuštanja u vodotokove. Način predtretmana - pročišćavanja otpadnih voda u tekstilnoj industriji može biti neutralizacijski, oksidacijski ili redukcijski postupak (kemijska razgradnja). Uz to postoje fizikalna razgradnja (taloženje, filtracija, adsorpcija, itd.), fizikalno-kemijska razgradnja (koagulacija/flokulacija, aeracija, ekstrakcija, spaljivanje, osmoza, elektroliza, itd.) i biološka razgradnja (aerobna, anaerobna). Odabir vrste pročišćavanja ovisi o sastavu i vrsti otpadnih voda. Tek nakon pročišćavanja otpadne vode mogu se ispuštati u kanalizacijski sustav. Zakon propisuje kvalitetu otpadnih voda. Time se pridonosi kvaliteti zaštite ljudi i okoliša.Waste waters pollute rivers, lakes, seas and ground waters. This threatens the existence of life on Earth. Waste waters facilitate the growth of micro-organisms that consume oxygen, causing fish perishing and the growth of pathogenic microbes. This paper puts emphasis on the problem of environmental protection against waste waters generated by ‘Duga Resa Cotton Industry’. The textile industry generates waste waters in the production process. Such polluted waste waters should be purified before discharging into watercourses. The method of pre-treatment or purification of waste waters in the textile industry can be a neutralization, oxidation or reduction procedure. Moreover, there are physical degradation methods (depositing, filtration, absorption, etc.), physical and chemical degradation methods (coagulation/flocculation, aeration, extraction, combustion, osmosis, electrolysis, etc.) and biological degradation methods (aerobic, anaerobic, by means of activated carbon and fungi). The selection of the purification method depends on the composition and type of waste waters. Only after purification can waste waters be discharged into the sewerage. The law prescribes the quality of waste waters, thus raising the quality of people and environmental protection

The roles of charge exchange and dissociation in spreading Saturn's neutral clouds

Neutrals sourced directly from Enceladus's plumes are initially confined to a dense neutral torus in Enceladus's orbit around Saturn. This neutral torus is redistributed by charge exchange, impact/photodissociation, and neutral-neutral collisions to produce Saturn's neutral clouds. Here we consider the former processes in greater detail than in previous studies. In the case of dissociation, models have assumed that OH is produced with a single speed of 1 km/s, whereas laboratory measurements suggest a range of speeds between 1 and 1.6 km/s. We show that the high-speed case increases dissociation's range of influence from 9 to 15 Rs. For charge exchange, we present a new modeling approach, where the ions are followed within a neutral background, whereas neutral cloud models are conventionally constructed from the neutrals' point of view. This approach allows us to comment on the significance of the ions' gyrophase at the moment charge exchange occurs. Accounting for gyrophase: (1) has no consequence on the H2O cloud; (2) doubles the local density of OH at the orbit of Enceladus; and (3) decreases the oxygen densities at Enceladus's orbit by less than 10%. Finally, we consider velocity-dependent, as well as species-dependent cross sections and find that the oxygen cloud produced from charge exchange is spread out more than H2O, whereas the OH cloud is the most confined.Comment: Accepted to the Journal of Geophysical Research, 49 pages, 10 figure

Analiza informacijskog sustava Odjela za tehničku potporu medicinskih djelatnosti

Završni specijalistički rad prikazuje pravilne korake analize postojećeg informacijskog sustava na primjeru radnog procesa Odjela tehničkih uslužnih i informatičkih djelatnosti kao potpora medicinskim djelatnostima u zdravstvenoj ustanovi. Analiza obuhvaća snimanje postojećeg stanja sustava te izdvajanje promatranog procesa na osnovu kojeg se pristupilo modeliranju poslovnog procesa pomoću dijagrama toka podataka. Pomoću modela poslovnog procesa te obradom dokumenata koji ulaze i izlaze iz sustava u procesu provođenja podrške medicinskom osoblju modeliran je dijagram poslovnih podataka koji prikazuje entitete i veze. Razradom modela poslovnih podataka realiziran je relacijski model podataka koji predstavlja polazište za izgradnju baze podataka koji je osnova svakog informacijskog sustava prilagođenog korisniku i njegovim potrebama

Analiza informacijskog sustava Odjela za tehničku potporu medicinskih djelatnosti

Završni specijalistički rad prikazuje pravilne korake analize postojećeg informacijskog sustava na primjeru radnog procesa Odjela tehničkih uslužnih i informatičkih djelatnosti kao potpora medicinskim djelatnostima u zdravstvenoj ustanovi. Analiza obuhvaća snimanje postojećeg stanja sustava te izdvajanje promatranog procesa na osnovu kojeg se pristupilo modeliranju poslovnog procesa pomoću dijagrama toka podataka. Pomoću modela poslovnog procesa te obradom dokumenata koji ulaze i izlaze iz sustava u procesu provođenja podrške medicinskom osoblju modeliran je dijagram poslovnih podataka koji prikazuje entitete i veze. Razradom modela poslovnih podataka realiziran je relacijski model podataka koji predstavlja polazište za izgradnju baze podataka koji je osnova svakog informacijskog sustava prilagođenog korisniku i njegovim potrebama

Analiza informacijskog sustava Odjela za tehničku potporu medicinskih djelatnosti

Završni specijalistički rad prikazuje pravilne korake analize postojećeg informacijskog sustava na primjeru radnog procesa Odjela tehničkih uslužnih i informatičkih djelatnosti kao potpora medicinskim djelatnostima u zdravstvenoj ustanovi. Analiza obuhvaća snimanje postojećeg stanja sustava te izdvajanje promatranog procesa na osnovu kojeg se pristupilo modeliranju poslovnog procesa pomoću dijagrama toka podataka. Pomoću modela poslovnog procesa te obradom dokumenata koji ulaze i izlaze iz sustava u procesu provođenja podrške medicinskom osoblju modeliran je dijagram poslovnih podataka koji prikazuje entitete i veze. Razradom modela poslovnih podataka realiziran je relacijski model podataka koji predstavlja polazište za izgradnju baze podataka koji je osnova svakog informacijskog sustava prilagođenog korisniku i njegovim potrebama

A Sensitivity Study of the Enceladus Torus

We have developed a homogeneous model of physical chemistry to investigate the neutral-dominated, water-based Enceladus torus. Electrons are treated as the summation of two isotropic Maxwellian distributions$-$a thermal component and a hot component. The effects of electron impact, electron recombination, charge exchange, and photochemistry are included. The mass source is neutral H$_2$O, and a rigidly-corotating magnetosphere introduces energy via pickup of freshly-ionized neutrals. A small fraction of energy is also input by Coulomb collisions with a small population ($<$ 1%) of supra-thermal electrons. Mass and energy are lost due to radial diffusion, escaping fast neutrals produced by charge exchange and recombination, and a small amount of radiative cooling. We explore a constrained parameter space spanned by water source rate, ion radial diffusion, hot-electron temperature, and hot-electron density. The key findings are: (1) radial transport must take longer than 12 days; (2) water is input at a rate of 100--180 kg s$^{-1}$; (3) hot electrons have energies between 100 and 250 eV; (4) neutrals dominate ions by a ratio of 40:1 and continue to dominate even when thermal electrons have temperatures as high as $\approx$ 5 eV; (5) hot electrons do not exceed 1% of the total electron population within the torus; (6) if hot electrons alone drive the observed longitudinal variation in thermal electron density, then they also drive a significant variation in ion composition.Comment: 9 pages text, 3 tables, 9 figure

Satellite sputtering in Saturn’s magnetosphere

Abstract The heavy ion plasma and energetic particles continuously sputter the surfaces of the icy satellites embedded in the inner Saturnian magnetosphere. We evaluate satellite sputtering and compare the resulting H2O source distribution with the source distribution expected for the OH cloud recently observed by Hubble Space Telescope. At each satellite we combine, for the ÿrst time, the data from the Plasma Science (PLS) and Low Energy Charged-Particle (LECP) instruments from Voyager 1 and 2, unifying them into a single plasma distribution function. Based on the calculated satellite sources, we conclude that sputtering of the satellite surfaces cannot produce the observed OH cloud and that a large additional source in the inner magnetosphere is needed to fully explain the HST observations

Mass Loss Due to Sputtering and Thermal Processes in Meteoroid Ablation

Conventional meteoroid theory assumes that the dominant mode of ablation is by evaporation following intense heating during atmospheric flight. In this paper we consider the question of whether sputtering may provide an alternative disintegration process of some importance.For meteoroids in the mass range from 10^-3 to 10^-13 kg and covering a meteor velocity range from 11 to 71 km/s, we numerically modeled both thermal ablation and sputtering ablation during atmospheric flight. We considered three meteoroid models believed to be representative of asteroidal (3300 kg m^-3 mass density), cometary (1000 kg m^-3) and porous cometary (300 kg m^-3) meteoroid structures. Atmospheric profiles which considered the molecular compositions at different heights were used in the sputtering calculations. We find that while in many cases (particularly at low velocities and for relatively large meteoroid masses) sputtering contributes only a small amount of mass loss during atmospheric flight, in some cases sputtering is very important. For example, a 10^-10 kg porous meteoroid at 40 km/s will lose nearly 51% of its mass by sputtering, while a 10^-13 kg asteroidal meteoroid at 60 km/s will lose nearly 83% of its mass by sputtering. We argue that sputtering may explain the light production observed at very great heights in some Leonid meteors. The impact of this work will be most dramatic for very small meteoroids such as those observed with large aperture radars.Comment: in pdf form, 48 pgs incl figures and table

Modeling the Seasonal Variability of the Plasma Environment in Saturn's Magnetosphere between Main Rings and Mimas

The detection of O2+ and O+ ions over Saturn's main rings by the Cassini INMS and CAPS instruments at Saturn orbit insertion (SOI) in 2004 confirmed the existence of the ring atmosphere and ionosphere. The source mechanism was suggested to be primarily photolytic decomposition of water ice producing neutral O2 and H2 (Johnson et al., 2006). Therefore, we predicted that there would be seasonal variations in the ring atmosphere and ionosphere due to the orientation of the ring plane to the sun (Tseng et al., 2010). The atoms and molecules scattered out of the ring atmosphere by ion-molecule collisions are an important source for the inner magnetosphere (Johnson et al., 2006; Martens et al. 2008; Tseng et al., 2010 and 2011). This source competes with water products from the Enceladus' plumes, which, although possibly variable, do not appear to have a seasonal variability (Smith et al., 2010). Recently, we found that the plasma density, composition and temperature in the region from 2.5 to 3.5 RS exhibited significant seasonal variation between 2004 and 2010 (Elrod et al., 2011). Here we present a one-box ion chemistry model to explain the complex and highly variable plasma environment observed by the CAPS instrument on Cassini. We combine the water products from Enceladus with the molecules scattered from a corrected ring atmosphere, in order to describe the temporal changes in ion densities, composition and temperature detected by CAPS. We found that the observed temporal variations are primarily seasonal, due to the predicted seasonal variation in the ring atmosphere, and are consistent with a compressed magnetosphere at SOI.Comment: This is submitted to P&S