Density spikes in Titan’s upper ionosphere

2020 ◽  
Author(s):  
Niklas Edberg ◽  
Jan-Erik Wahlund ◽  
Erik Vigren
Keyword(s):  
Langmuir Probe ◽  
Initial Result ◽  
Early Earth ◽  
Sudden Increase ◽  
The Moon ◽  
Plasma Properties ◽  
Density Peaks ◽  
Time Period ◽  
Upper Ionosphere ◽  
Measured Density

<p>Titan, the largest moon of Saturn, has a dense and nitrogen-rich atmosphere, which is similar to that of early Earth before lived evolved. Solar EUV radiation and energetic particles ionizes the atmosphere and thereby forming a layer of plasma, the ionosphere, in the uppermost part of the atmosphere. The Cassini spacecraft flew past the moon Titan 127 times during its 14-year mission in the Saturn system. During most of these close flybys Cassini entered the ionosphere and some reached the ionospheric peak, located at some 1400 km above the moon surface. With the Langmuir probe instrument, we could study the plasma properties, e.g. ion and electron density, temperature etc., and a very dynamic ionospheric structure was found. In particular, significant and apparently sporadic density spikes in the upper ionosphere were found. These density peaks are manifested as a sudden increase in the measured density by some 10-100 cm<sup>-3</sup> over a time period of roughly minutes. These have so far been left unattended in our studies of Titan. We will present some statistics on their appearance and initial result on the mechanism forming them.</p> <p> </p> <p> </p>

scholarly journals The Upsurge and Impact of COVID 19 in India: Health Issues and Remedial Measures

2021 ◽  
pp. 28-34
Author(s):  
Kanchi Isswani
Keyword(s):  
Sudden Increase ◽  
The Novel ◽  
Health Issues ◽  
Public Places ◽  
Frontline Workers ◽  
Time Period ◽  
Essential Services ◽  
Novel Coronavirus ◽  
Major Decision ◽  
Better Than

The novel Coronavirus was something that nobody was prepared for. It was that part of the syllabus which was always neglected. The contagious disease which started in the Wuhan region of China had started to settle in various parts of the World. The outbreak of this disease has reached such a huge number that all the countries witnessed lockdown in some form or the other. Some people have witnessed destruction of mankind while some have even leisured this time to their fullest but as it has been always said “Prevention is better than cure”. Prevention of covid 19 in all the nations was one of the major steps which was taken in the year 2020. In India it all started in the year of 2019 December when the first ever case of covid 19 was reported in the state of Kerala followed by Rajasthan, Maharashtra and Delhi. Following such a situation and then sudden increase in the no of cases all over the country a major decision was taken that was of Complete lockdown excluding the emergency and essential services. Before taking the step of lockdown, as a gesture of respect to the frontline workers, government of India announced Tali Bajao movement. In the period of lockdown Certain norms were even made mandatory that were wearing a mask, maintenance of hand sanitation and following social distancing of 1.5 meters in public places. All the educational institutes and teachings were even suspended during the time period of lockdown as it could have become a hub for the virus to spread. With time, the restrictions which were laid down in lockdown were started to be reduced in the phase wise manner and finally India noticed its very first Unlock period. In all this scenario mankind has dealt with various situations and have emerged to be a better person. All these steps were crucial to control the spread of Novel Coronavirus and prevention from the already spread cases.

Fly Me to the Moon: A Survey of American Historical and Contemporary Simulation Entertainments

1997 ◽  
Vol 6 (5) ◽  
pp. 565-580 ◽  
Author(s):  
Judith Maloney
Keyword(s):  
The United States ◽  
World's Fair ◽  
Technological Innovations ◽  
The Moon ◽  
Social Functions ◽  
Time Period ◽  
The Social ◽  
Group Experiences ◽  
Historical Antecedents ◽  
Selection Of

Simulation experiences captivate the imagination of today's entertainment-seeking public. Once located exclusively at a few venues, these simulations are increasingly prevalent in a variety of locales including malls and casinos. While today's public may view these entertainments as novel, these forms of simulation have rich historical antecedents that can be traced to entertainment and technological innovations of the nineteenth century. Focusing on American examples from the time period of 1820 to the present, this paper examines a wide variety of immersive entertainments that attempted to simulate an experience, environment, or event so realistically that viewers accepted the imitation as authentic and realistic. This paper examines cycloramas, panoramas, historic recreations, and a selection of mechanical rides from amusement parks and world's fair midways that provided group experiences. An examination of the social functions of these precursors strengthens our understanding of the significance of contemporary simulation entertainments in the United States.

A Case Study of How Natural Phenomena Were Justified in Medieval Science: The Situation of Annular Eclipses in Medieval Astronomy

2014 ◽  
Vol 27 (1) ◽  
pp. 33-47 ◽  
Author(s):  
S. Mohammad Mozaffari
Keyword(s):  
Observational Evidence ◽  
General Level ◽  
Natural Phenomena ◽  
The Moon ◽  
Medieval Period ◽  
Complex Situation ◽  
Islamic Period ◽  
Medieval Science ◽  
Time Period

ArgumentThe present paper is an attempt to understand how medieval astronomers working within the Ptolemaic astronomical context in which the annular eclipse is an unjustified and impossible phenomenon, could know, define, justify, and later make attempts that led to success in predicting annular solar eclipses. As a context-based study, it reviews the situation of annular eclipses with regard to the medieval hypotheses applied to the calculation of the angular diameters of the sun and the moon, which was basic for contemplating the possibility of annular eclipses. This gives the premises and the preliminary insights that were necessary to clarify the complex situation of the annular eclipse in the late medieval Islamic period and to explain the historical mechanisms leading to justifying the phenomenon during that period. This was, first due to a convincing and efficient observational evidence which, of course, was available only to a number of medieval astronomers and significantly for only a limited time period, and, second, the result of an amazing interaction amongst various astronomical traditions available to them. At a more general level, the research aims to inspect or, at least, to give some impressions of the essential conditions, i.e., identification of phenomenon, empirical evidence, and the justifying underlying tradition, under which it became possible in the tradition-based science of the `medieval period to permit a not-already-defined and tradition-opposed phenomenon to be posed and justified.

scholarly journals How Much Did the Moon Heat Young Earth?

Eos ◽  
2022 ◽  
Vol 103 ◽  
Author(s):  
Jure Japelj
Keyword(s):  
Surface Temperature ◽  
Early Earth ◽  
The Moon ◽  
Global Volcanism ◽  
Tidal Heating

Tidal heating may have raised the surface temperature of early Earth and triggered global volcanism, a new study says.

scholarly journals Titan's ionosphere in the magnetosheath: Cassini RPWS results during the T32 flyby

2009 ◽  
Vol 27 (11) ◽  
pp. 4257-4272 ◽  
Author(s):  
P. Garnier ◽  
J-E. Wahlund ◽  
L. Rosenqvist ◽  
R. Modolo ◽  
K. Ågren ◽  
...  
Keyword(s):  
Plasma Wave ◽  
Significant Influence ◽  
Langmuir Probe ◽  
Cold Plasma ◽  
The Moon ◽  
Plasma Environment ◽  
Cassini Mission ◽  
Electrical Conductivities ◽  
Low Altitude ◽  
Detailed Picture

Abstract. The Cassini mission has provided much information about the Titan environment, with numerous low altitude encounters with the moon being always inside the magnetosphere. The only encounter taking place outside the magnetopause, in the magnetosheath, occurred the 13 June 2007 (T32 flyby). This paper is dedicated to the analysis of the Radio and Plasma Wave investigation data during this specific encounter, in particular with the Langmuir probe, providing a detailed picture of the cold plasma environment and of Titan's ionosphere with these unique plasma conditions. The various pressure terms were also calculated during the flyby. The comparison with the T30 flyby, whose geometry was very similar to the T32 encounter but where Titan was immersed in the kronian magnetosphere, reveals that the evolution of the incident plasma has a significant influence on the structure of the ionosphere, with in particular a change of the exo-ionospheric shape. The electrical conductivities are given along the trajectory of the spacecraft and the discovery of a polar plasma cavity is reported.

The vaporization behavior of carbon and hydrogen from the early global magma ocean

2021 ◽  
Author(s):  
Natalia Solomatova ◽  
Razvan Caracas
Keyword(s):  
First Principles ◽  
Atmospheric Pressure ◽  
Considerable Effect ◽  
Early Earth ◽  
The Moon ◽  
Magma Ocean ◽  
Cooling History ◽  
History Of ◽  
Carbon Molecules ◽  
Dense Atmosphere

<p>Estimating the fluxes and speciation of volatiles during the existence of a global magma ocean is fundamental for understanding the cooling history of the early Earth and for quantifying the volatile budget of the present day. Using first-principles molecular dynamics, we predict the vaporization rate of carbon and hydrogen at the interface between the magma ocean and the hot dense atmosphere, just after the Moon-forming impact. The concentration of carbon and the oxidation state of the melts affect the speciation of the vaporized carbon molecules (e.g., the ratio of carbon dioxide to carbon monoxide), but do not appear to affect the overall volatility of carbon. We find that carbon is rapidly devolatilized even under pressure, while hydrogen remains mostly dissolved in the melt during the devolatilization process of carbon. Thus, in the early stages of the global magma ocean, significantly more carbon than hydrogen would have been released into the atmosphere, and it is only after the atmospheric pressure decreased, that much of the hydrogen devolatilized from the melt. At temperatures of 5000 K (and above), we predict that bubbles in the magma ocean contained a significant fraction of silicate vapor, increasing with decreasing depths with the growth of the bubbles, affecting the transport and rheological properties of the magma ocean. As the temperature cooled, the silicate species condensed back into the magma ocean, leaving highly volatile atmophile species, such as CO<sub>2</sub> and H<sub>2</sub>O, as the dominant species in the atmosphere. Due to the greenhouse nature of CO<sub>2</sub>, its concentration in the atmosphere would have had a considerable effect on the cooling rate of the early Earth.</p>

On the Space Weather Effect and CME-Driven Exospheres of the Moon and Ceres

2020 ◽  
Author(s):  
Hua-Shan Shi ◽  
Zheng-Xian Chen ◽  
Wing-Huen Ip
Keyword(s):  
Space Weather ◽  
Time Dependent ◽  
Sudden Increase ◽  
Ion Sputtering ◽  
The Moon ◽  
Weather Effects ◽  
Icy Moons ◽  
Source Mechanisms ◽  
Simulation Results ◽  
Mass Ejection

<p>A number of moon-sized objects in the solar system are characterized by the formation of a surface-bound exosphere. These include the Moon, Ceres, Jupiter’s icy moons, namely, Europa, Ganymede and Callisto, and several of the Saturnian icy moons including Rhea, Dione, and Tethys. There are several major source mechanisms ranging from micrometeoroid bombardment, photo-stimulated desorption, and energetic ion sputtering - in addition to the surface (or subsurface) thermal sublimation in the case of Ceres and the icy Moon. It is interesting that Ceres and the Moon could experience extreme space weather effects when they encounter large solar flare events or coronal mass ejection events. An important consequence is the production of a transient exosphere due to the sudden increase of ion sputtering rates. We have developed time-dependent Monte Carlo models that can be applied to the Moon and Ceres. Some simulation results will be described in this presentation with a view to construct the CME-driven H<sub>2</sub>O and O<sub>2</sub> exosphere of Ceres and the flare-up of the lunar sodium corona and tail emission.</p>

scholarly journals Global nighttime atomic oxygen abundances from resampled GOMOS hydroxyl airglow measurements in the mesopause region

2019 ◽  
Author(s):  
Qiuyu Chen ◽  
Martin Kaufmann ◽  
Yajun Zhu ◽  
Jilin Liu ◽  
Ralf Koppmann ◽  
...  
Keyword(s):  
Atomic Oxygen ◽  
Local Times ◽  
Local Thermal Equilibrium ◽  
Mesopause Region ◽  
Mean Values ◽  
Density Peaks ◽  
Time Period ◽  
Hydroxyl Airglow ◽  
Non Local ◽  
Insight Into

Abstract. This paper presents a new dataset of nighttime atomic oxygen density [O], derived from OH(8–4) ro-vibrational band emissions, using a non-local thermal equilibrium model, with the aim of offering new insight into the atomic oxygen abundances in the mesopause region. The dataset is based on the level-1 atmospheric background measurements observed by the GOMOS instrument on board Envisat. Raw data are reprocessed into monthly zonal mean values in 10° latitude bins with a fixed altitude grid of 3 km. The dataset spans from 70° S to 70° N in latitude and from 80 km to 100 km in altitude, covering a time period from May 2002 to December 2011 at local times of from 10 p.m. to 12 p.m. The atomic oxygen density peaks at about 95 km and the highest values are in the range of 3–8 × 1011 atoms cm−3, depending on latitude and season. There is a rapid decrease of [O] below its peak region. The annual oscillation (AO), semiannual oscillation (SAO), and the solar cycle impact are distinguished from the [O] longtime series variations. This new GOMOS [O] dataset conforms to other published datasets and is consistent with the [O] datasets obtained from the SCIAMACHY OH airglow measurements to within about ±20 %.

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