General discussion after session IV

1988 ◽  
Vol 325 (1587) ◽  
pp. 597-599
Keyword(s):  
Solar System ◽  
The Sun ◽  
The Real ◽  
The Past ◽  
Deep Model ◽  
Remote Measurements ◽  
Error Bars ◽  
Set Up ◽  
The Way

G. Hunt ( PACTEL, London , U. K. ). It is an incredibly important problem to try to understand the Solar System; where we are now, where it has come from. We are looking today at things that happened in the past; the Sun has changed during its lifetime and that upsets some of the chemistry that we are looking at. Professor Gautier’s presentation does raise a number of very important questions of interpretation. The error bars on some of his critical ratios are very large. How can we reduce those error bars? Can this be done as a result of doing remote measurements or must we make in situ observations? Are there more things that we can be doing in the laboratory to improve our spectroscopy, for example? Theories develop more rapidly than observations, that is obviously one of the problems that we are always facing. Something that has been given some attention is the question of the colour of some of the objects we have been looking at. Colour was not mentioned this morning; is it something we should be taking into account. When we make these observations, from Voyager particularly, we are looking right at the very top of the atmosphere, we are looking at the dirt on the skin of the orange type of scenario, yet we are talking about what is happening all the way through. Just how well do we understand those interiors? The weather systems that we think we understand can be explained either by a deep model or a very shallow model. Is that important ? Does it affect the way we interpret these results? These are some of the things that are running through the minds of people as we discuss these factors today, coupled with the fact that when we move away from talking about hydrogen and helium and get involved with other components of the Solar System, things like oxygen, then we really are in difficulties because they have their own chemistry at some depth, and affect the dynamics and the chemistry at these particular levels. Let us just ask ourselves whether are we asking the basic questions, the real questions; have we really set up the ways in which these things can be answered in the next ten years.

scholarly journals Dust Measurements in the Outer Solar System

1994 ◽  
Vol 160 ◽  
pp. 367-380
Author(s):  
Eberhard Grün
Keyword(s):  
Solar System ◽  
Interstellar Dust ◽  
Thermal Emission ◽  
Scattered Light ◽  
Interplanetary Dust ◽  
Dust Particles ◽  
Spatial Density ◽  
Outer Solar System ◽  
The Sun

In-situ measurements of micrometeoroids provide information on the spatial distribution of interplanetary dust and its dynamical properties. Pioneers 10 and 11, Galileo and Ulysses spaceprobes took measurements of interplanetary dust from 0.7 to 18 AU distance from the sun. Distinctly different populations of dust particles exist in the inner and outer solar system. In the inner solar system, out to about 3 AU, zodiacal dust particles are recognized by their scattered light, their thermal emission and by in-situ detection from spaceprobes. These particles orbit the sun on low inclination (i ≤ 30°) and moderate eccentricity (e ≤ 0.6) orbits. Their spatial density falls off with approximately the inverse of the solar distance. Dust particles on high inclination or even retrograde trajectories dominate the dust population outside about 3 AU. The dust detector on board the Ulysses spaceprobe identified interstellar dust sweeping through the outer solar system on hyperbolic trajectories. Within about 2 AU from Jupiter Ulysses discovered periodic streams of dust particles originating from within the jovian system.

scholarly journals The Nasa Solar Probe Mission: In Situ Determination of Interplanetary Out-of-The Ecliptic and Near-Solar Dust Environments

1991 ◽  
Vol 126 ◽  
pp. 29-32
Author(s):  
Bruce T. Tsurutani ◽  
James E. Randolph
Keyword(s):  
Solar Cycle ◽  
Solar System ◽  
Solar Eclipse ◽  
Orbital Period ◽  
High Velocity ◽  
Scientific Community ◽  
The Sun ◽  
Probe Mission

AbstractThe NASA Solar Probe mission will be one of the most exciting dust missions ever flown and will lead to a revolutionary advance in our understanding of dust within our solar system. Solar Probe will map the dust environment from the orbit of Jupiter (5 AU), to within 4 solar radii of the sun’s center. The region between 0.3 AU and 4 Rshas never been visited before, so the 10 days that the spacecraft spends during each (of the two) orbit is purely exploratory in nature. Solar Probe will also reach heliographic latitudes as high as ~ 15 to 28 above (below) the ecliptic on its trajectory inbound (outbound) to (from) the sun. This, in addition to the ESA/NASA Ulysses mission, will help determine the out-of-the-ecliptic dust environment. A post-perihelion burn will reduce the satellite orbital period to 2.5 years about the sun. A possible extended mission would allow data reception for 2 more revolutions, mapping out a complete solar cycle. Because the near-solar dust environment is not well understood (or is controversial at best), and it is very important to have better knowledge of the dust environment to protect Solar Probe from high velocity dust hits, we urgently request the scientific community to obtain further measurements of the near-solar dust properties. One prime opportunity is the July 1991 solar eclipse.

scholarly journals Comet C/2018 V1 (Machholz–Fujikawa–Iwamoto): dislodged from the Oort Cloud or coming from interstellar space?

2019 ◽  
Vol 489 (1) ◽  
pp. 951-961 ◽  
Author(s):  
C de la Fuente Marcos ◽  
R de la Fuente Marcos
Keyword(s):  
Solar System ◽  
Dynamical Evolution ◽  
Oort Cloud ◽  
Interstellar Space ◽  
The Sun ◽  
The Past ◽  
Using Data ◽  
To Receive ◽  
Practical Feasibility

ABSTRACT The chance discovery of the first interstellar minor body, 1I/2017 U1 (‘Oumuamua), indicates that we may have been visited by such objects in the past and that these events may repeat in the future. Unfortunately, minor bodies following nearly parabolic or hyperbolic paths tend to receive little attention: over 3/4 of those known have data-arcs shorter than 30 d and, consistently, rather uncertain orbit determinations. This fact suggests that we may have observed interstellar interlopers in the past, but failed to recognize them as such due to insufficient data. Early identification of promising candidates by using N-body simulations may help in improving this situation, triggering follow-up observations before they leave the Solar system. Here, we use this technique to investigate the pre- and post-perihelion dynamical evolution of the slightly hyperbolic comet C/2018 V1 (Machholz–Fujikawa–Iwamoto) to understand its origin and relevance within the context of known parabolic and hyperbolic minor bodies. Based on the available data, our calculations suggest that although C/2018 V1 may be a former member of the Oort Cloud, an origin beyond the Solar system cannot be excluded. If extrasolar, it might have entered the Solar system from interstellar space at low relative velocity with respect to the Sun. The practical feasibility of this alternative scenario has been assessed within the kinematic context of the stellar neighbourhood of the Sun, using data from Gaia second data release, and two robust solar sibling candidates have been identified. Our results suggest that comets coming from interstellar space at low heliocentric velocities may not be rare.

Austrian Independence and the Innocent Aggressor

2020 ◽  
pp. 132-146
Author(s):  
Karl Kraus
Keyword(s):  
The Real ◽  
Photographic Evidence ◽  
Set Up ◽  
The Way

This chapter shows that the Nazi leadership has adopted the strategy of protesting against “Austrian atrocities.” Against the way their agent inspecteur has been treated there. Against the trivial penalties imposed on their loyal servants. They adduce photographic evidence of real, not just alleged, arrests. And that was why they had no alternative but to close the border, issue travel permits to would-be assassins, set up an Austrian Legion, and foment revolt in the country. The armed incursion into Austria was an internal German matter and “the deterioration of the mood in England can be attributed to the English public's inability to understand Germany's intentions towards Austria”; consequently, there was an alleged conflict between Germany and Austria and alleged interference of Germany in Austrian affairs by the alleged dropping of leaflets on Austrian soil, while the real dropping of leaflets on German soil had contributed to alleged aerial rearmament in Germany, which accounts for the alleged démarche of the powers.

Astromaterials Research of Comet Wild 2: Terameters to Nanometers

MRS Bulletin ◽  
2010 ◽  
Vol 35 (2) ◽  
pp. 150-154 ◽  
Author(s):  
Sean Brennan
Keyword(s):  
Solar System ◽  
Elemental Abundance ◽  
The Sun ◽  
Isotopic Abundance ◽  
Solar System Formation ◽  
Sample Return ◽  
X Ray ◽  
The Past ◽  
Cometary Material ◽  
Sample Return Mission

AbstractStardust, a NASA sample return mission, safely landed in the Utah desert in January 2006 after a seven-year mission, bringing with it the first cometary material from a known parent source, Comet 81P/Wild 2. One of the mission goals is to determine the starting material of the solar system. By sampling a comet, which has spent most of the past 4.6 Gyr beyond the orbit of Neptune, we expect to measure material presumed to be unaffected by the ignition of the sun. The Stardust spacecraft swept through the tail of the comet, collecting hundreds of micron-sized particles from that stream into aerogel, a low-density silica foam. An international team of materials scientists have studied the mineralogy, petrology, and elemental and isotopic abundance of these materials. Our group has studied elemental abundance using an x-ray microprobe; the morphology of the particles was examined using an x-ray microscope, which enables nanotomography of the particles while encased in aerogel. The unexpected conclusions are that much of the material from this comet was formed near the sun, after its ignition, and soon thereafter transported to the outer reaches of the solar system. These results have changed the way astrophysicists think about solar system formation.

scholarly journals Helios spacecraft data revisited: detection of cometary meteoroid trails by following in situ dust impacts

2020 ◽  
Vol 643 ◽  
pp. A96
Author(s):  
Harald Krüger ◽  
Peter Strub ◽  
Max Sommer ◽  
Nicolas Altobelli ◽  
Hiroshi Kimura ◽  
...  
Keyword(s):  
Solar System ◽  
Dust Cloud ◽  
Interplanetary Dust ◽  
Dust Particles ◽  
True Anomaly ◽  
Spatial Density ◽  
The Sun ◽  
Narrow Region ◽  
Spacecraft Data

Context. Cometary meteoroid trails exist in the vicinity of comets, forming a fine structure of the interplanetary dust cloud. The trails consist predominantly of the largest cometary particles (with sizes of approximately 0.1 mm–1 cm), which are ejected at low speeds and remain very close to the comet orbit for several revolutions around the Sun. In the 1970s, two Helios spacecraft were launched towards the inner Solar System. The spacecraft were equipped with in situ dust sensors which measured the distribution of interplanetary dust in the inner Solar System for the first time. Recently, when re-analysing the Helios data, a clustering of seven impacts was found, detected by Helios in a very narrow region of space at a true anomaly angle of 135 ± 1°, which the authors considered as potential cometary trail particles. However, at the time, this hypothesis could not be studied further. Aims. We re-analyse these candidate cometary trail particles in the Helios dust data to investigate the possibility that some or all of them indeed originate from cometary trails and we constrain their source comets. Methods. The Interplanetary Meteoroid Environment for eXploration (IMEX) dust streams in space model is a new and recently published universal model for cometary meteoroid streams in the inner Solar System. We use IMEX to study the traverses of cometary trails made by Helios. Results. During ten revolutions around the Sun, the Helios spacecraft intersected 13 cometary trails. For the majority of these traverses the predicted dust fluxes are very low. In the narrow region of space where Helios detected the candidate dust particles, the spacecraft repeatedly traversed the trails of comets 45P/Honda-Mrkos-Pajdušáková and 72P/Denning-Fujikawa with relatively high predicted dust fluxes. The analysis of the detection times and particle impact directions shows that four detected particles are compatible with an origin from these two comets. By combining measurements and simulations we find a dust spatial density in these trails of approximately 10−8–10−7 m−3. Conclusions. The identification of potential cometary trail particles in the Helios data greatly benefited from the clustering of trail traverses in a rather narrow region of space. The in situ detection and analysis of meteoroid trail particles which can be traced back to their source bodies by spacecraft-based dust analysers provides a new opportunity for remote compositional analysis of comets and asteroids without the necessity to fly a spacecraft to or even land on those celestial bodies. This provides new science opportunities for future missions like DESTINY+ (Demonstration and Experiment of Space Technology for INterplanetary voYage with Phaethon fLyby and dUst Science), Europa Clipper, and the Interstellar Mapping and Acceleration Probe.

scholarly journals Fantastic beginning in the novel by L. I. Borodin “It Never Happened”

2021 ◽  
pp. 73-80
Author(s):  
Ol'ga Stanislavovna Sukhikh
Keyword(s):  
Internal Conflict ◽  
Literary Study ◽  
The Novel ◽  
The Real ◽  
The Past ◽  
Holistic Analysis ◽  
The Fantastic ◽  
The Way

The novel “It Never Happened” by L. I. Borodin is analyzed from the perspective of peculiarities of the embodiment of fantastic beginning therein. The author employs the holistic analysis of the text. The goal of this research consists in studying the synthesis of the fantastic and the real alongside determining the nature of the extraordinary in the novel; analysis of its key function and methods of its introduction into the artistic world. It is established that the synthesis of the fantastic and the real is associated with fact that Borodin does not intend  to create an image of some extraordinary world, but seeks to actualize his emotions and find the way to resolve the internal conflict via fantastic means –  journey of the narrator into the past. The relevance and novelty are defined by the fact that the work of L. I. Borodin has not previously become the object of comprehensive literary study, although it is interesting from the perspective of problematic and poetics, reflection of the theme of guilt, which is meaningful in the works of L. Borodin. It is proven the crucial function of the fantastic in the novel “It Never Happened” is associated with psychologism. The extraordinary in the plotline is a “derivative” from the emotional drama of the narrator, the strongest desire to redeem himself, and repair what was done in childhood.

Prologue

2016 ◽  
pp. 1-2
Author(s):  
Owen Gingerich
Keyword(s):  
Solar System ◽  
School Children ◽  
The Sun ◽  
The Earth ◽  
System P ◽  
Nicolaus Copernicus ◽  
The Way

In or around 1510 Nicolaus Copernicus, one of the sixteen directors of the northernmost Catholic diocese in Poland, invented the solar system. Wait a minute! you say. Wasn’t the sun always in the middle of the planets? But that wasn’t the way everyone else thought about it. Farmers, professors, priests, and school children all assumed the earth was solidly fixed in the middle of the cosmos. Every day the sun and stars revolved around the earth. The sun also moved, more slowly, in a path against the more distant stars so that it was higher in the sky in the summer and much lower in winter....

In Situ Measurements of Interplanetary Dust in the Inner Solar System

1980 ◽  
Vol 90 ◽  
pp. 277-278
Author(s):  
E. Grün
Keyword(s):  
Solar System ◽  
Ecliptic Plane ◽  
Interplanetary Dust ◽  
Dust Particles ◽  
The Sun ◽  
The South ◽  
Orbit Analysis ◽  
Peak Abundance ◽  
Heliocentric Orbit

The Helios 1 spacecraft was launched in December 1974 into a heliocentric orbit of 0.3 AU perihelion distance. It carries on board a micro-meteoroid experiment which contains two sensors with a total sensitive area of 121 cm2. The ecliptic sensor measures dust particles which have trajectories with elevations from −45° to +55° with respect to the ecliptic plane. The south sensor detects dust particles from −90° to −4°. The ecliptic sensor is covered by a thin film (3000 Å parylene coated with 750 Å aluminium) as protection against solar radiation. The other sensor is shielded by the spacecraft rim from direct sunlight and has an open aperture. Micrometeoroids are detected by the electric charge produced upon impact and the ions are mass analysed in a time-of-flight-spectrometer. During the first 6 orbits of Helios 1 around the sun the experiment registered a total of 168 meteoroids, 52 particles were detected by the ecliptic sensor and 116 particles by the south sensor. Most impacts on the ecliptic sensor were observed when it was pointing in the direction of motion of Helios (apex direction). In contrast to that the south sensor detected most impacts when it was facing in between the solar and antapex directions. Orbit analysis showed that the “apex” particles which are predominantly detected by the ecliptic sensor have eccentricities e < 0.4 or semimajor axes a < 0.5 AU. From comparison with corresponding data from the south sensor it is concluded that the average inclination of these particles is below 30°. The excess of impacts on the south sensor have orbit eccentricities e > 0.5 AU. β-meteoroids which leave the solar system on hyperbolic orbits are directly identified by the imbalance of outgoing (away from the sun) and ingoing particles. Mass analyses of the spectra showed that 40% of the observed spectra have the peak abundance above mass 35 amu which are preliminarily identified as iron meteoroids. 40% of the spectra have the peak abundance below mass 35 amu which correspond to chondritic composition. 20% of the spectra could not be identified in either class.

Air-Cooled Engines in Service

1929 ◽  
Vol 33 (220) ◽  
pp. 269-318
Author(s):  
A. H. R. Fedden
Keyword(s):  
Fuel Consumption ◽  
The Sun ◽  
Oil Consumption ◽  
Missionary Work ◽  
The Past ◽  
New Family ◽  
Aero Engine ◽  
Aero Engines ◽  
The Way

It is now rather more than three years since I last had the honour of presenting a paper before this Society dealing with air-cooled aero engines. At that time the air-cooled engine had not fully won a place “in the sun,” which may be fairly stated to be the case to-day.For some years after the war there was a considerable aversion towards the air-cooled aero engine owing to certain types which had been developed during the war which were supposedly air-cooled, but in reality obtained the greater portion of their cooling by means of exorbitant fuel and oil consumption. As lately as four years ago the practical advantages of the air-cooled engine were only tentatively appreciated by the aircraft constructor, and naturally, owing to his somewhat painful experiences in the past in respect of unreliability and high fuel consumption; it required some missionary work and proof in order to persuade him that the new family of air-cooled engines would really perform in the way their designers claimed for them.

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