Satellites and Pluto

1999 ◽  
Author(s):  
Yuk L. Yung ◽  
William B. DeMore
Keyword(s):  
Solar System ◽  
The Other ◽  
The Moon ◽  
Small Bodies ◽  
Planetary Body ◽  
Galilean Moons ◽  
Satellites Of Jupiter ◽  
Tidal Heating ◽  
Pioneer 10 ◽  
Active Volcanoes

The presence of an atmosphere on a small planetary body the size of the Moon is surprising. Loss of material by escape would have depleted the atmosphere over the age of the solar system. Since these objects are not large enough to possess, or to sustain for long, a molten core, continued outgassing from the interior is not expected. However, it is now known that four small bodies in the outer solar system possess substantial atmospheres: lo, Titan, Triton, and Pluto. These atmospheres range from the very tenuous on lo (of the order of a nanobar) to the very massive on Titan (of the order of a bar). The atmospheric pressures on Triton and Pluto are of the order of 10 μbar. Perhaps the most interesting questions about these atmospheres concern their unusual origin and their chemical evolution. lo is the innermost of the four Galilean satellites of Jupiter, the other three being Ganymede, Europa, and Callisto. All the Galilean moons are comparable in size, but there is no appreciable atmosphere on the other moons. The first indications that lo possesses an atmosphere came in 1974 with the discovery of sodium atoms surrounding the satellite and the detection of a well-developed ionosphere from the Pioneer 10 radio occultation experiment. The Voyager encounter in 1979 established the existence of active volcanoes as well as SOa gas. These are the only extraterrestrial active volcanoes discovered to date, and they owe their existence to a curious tidal heating mechanism associated with the 2:1 resonance between the orbits of lo and Europa.

scholarly journals Features of the geochemistry of the Moon and the Earth, determined by the mechanism of formation of the Earth – Moon system (report at the 81st international meteorite conference, Moscow, july 2018)

2019 ◽  
Vol 64 (8) ◽  
pp. 762-776
Author(s):  
E. M. Galimov
Keyword(s):  
Solar System ◽  
Volatile Components ◽  
Kinetic Regime ◽  
The Moon ◽  
Mechanism Of Formation ◽  
Planetary Body ◽  
Moon System ◽  
The Earth ◽  
Reversible Nature ◽  
Dust Condensation

This article discusses some features of geochemistry of the Earth and the Moon, which manifests the specificity of the mechanism of their formation by fragmentation of protoplanetary gas-dust condensation (Galimov & Krivtsov, 2012). The principal difference between this model and other hypotheses of the Earth-Moon system formation, including the megaimpact hypothesis, is that it assumes the existence of a long stage of the dispersed state of matter, starting with the formation of protoplanetary gas-dust condensation, its compression and fragmentation and ending with the final accretion to the formed high-temperature embryos of the Earth and the Moon. The presence of the dispersed state allows a certain way to interpret the observed properties of the Earth-Moon system. Partial evaporation of solid particles due to adiabatic heating of the compressing condensation leads to the loss of volatiles including FeO. Computer simulations show that the final accretion is mainly performed on a larger fragment (the Earth’s embryo) and only slightly increases the mass of the smaller fragment (the Moon embryo).This explains the relative depletion of the Moon in iron and volatile and the increased concentration of refractory components compared to the Earth. The reversible nature of evaporation into the dispersed space, in contrast to the kinetic regime, and the removal of volatiles in the hydrodynamic flow beyond the gas-dust condensation determines the loss of volatiles without the effect of isotopes fractionation. The reversible nature of volatile evaporation also provides, in contrast to the kinetic regime, the preservation of part of the high-volatile components, such as water, in the planetary body, including the Moon. It follows from the essence of the model that at least a significant part of the Earth’s core is formed not by segregation of iron in the silicate-metal melt, but by evaporation and reduction of FeO in a dispersed medium, followed by deposition of clusters of elemental iron to the center of mass. This mechanism of formation of the core explains the observed excess of siderophilic elements in the Earth’s mantle. It also provides a plausible explanation for the observed character of iron isotopes fractionation (in terms of δ57Fe‰) on Earth and on the Moon. It solves the problem of the formation of iron core from initially oxide (FeO) form. The dispersed state of the substance during the period of accretion suggests that the loss of volatiles occurred during the time of accretion. Using the fact that isotopic systems: U–Pb, Rb–Sr, 129J–129Xe, 244Pu–136Xe, contain volatile components, it is possible to estimate the chronology of events in the evolution of the protoplanetary state. As a result, agreed estimates of the time of fragmentation of the primary protoplanetary condensation and formation of the embryos of the Earth and the Moon are obtained: from 10 to 40 million years, and the time of completion of the earth’s accretion and its birth as a planetary body: 110 – 130 million years after the emergence of the solar system. The presented interpretation is consistent with the fact that solid minerals on the Moon have already appeared at least 60 million years after the birth of the solar system (Barboni et al., 2017), and the metal core in the Earth and in the Moon could not have formed before 50 million years from the start of the solar system, as follows from the analysis of the Hf-W system (Kleine et al., 2009). It is shown that the hypothesis of megaimpact does not satisfy many constraints and does not create a basis for the explanation of the geochemistry of the Earth and the Moon.

scholarly journals XII. Radiation in the solar system: its effect on temperature and its pressure on small bodies

1904 ◽  
Vol 202 (346-358) ◽  
pp. 525-552 ◽  
Keyword(s):  
Solar System ◽  
Power Law ◽  
Effective Temperature ◽  
Interplanetary Space ◽  
The Other ◽  
Fourth Power ◽  
The Sun ◽  
Planetary Surfaces ◽  
Solar Constant ◽  
Small Bodies

When a surface is a full radiator and absorber its temperature can be determined at once by the fourth-power law if we know the rate at which it is radiating energy. If it is radiating what it receives from the sun, then a knowledge of the solar constant enables us to find the temperature. We can thus make estimates of the highest temperature which a surface can reach when it is only receiving heat from the sun. We can also make more or less approximate estimates of the temperatures of the planetary surfaces by assuming conditions under which the radiation takes place, and we can determine, fairly exactly, the temperatures of very small bodies in interplanetary space. These determinations require a knowledge of the constant of radiation and of either the solar constant or the effective temperature of the sun, either of which, as is well known, can be found from the other by means of the radiation constant. It will be convenient to give here the values of these quantities before proceeding to apply them to our special problems.

Bakerian Lecture - The origin of the solar system

1952 ◽  
Vol 214 (1118) ◽  
pp. 281-291 ◽  
Keyword(s):  
Solar System ◽  
The Moon ◽  
Small Bodies ◽  
Surface Features ◽  
Planets And Satellites ◽  
Origin Of The Moon

Some of the principal theories of the origin of the planets and satellites are discussed. The principal topics are the nebular theory (Roche’s form), tidal theories, collision theories; disk theories; densities of the planets; fission theories of the origin of the moon; origin of small bodies; initial temperatures; constitutions of the planets; the moon’s surface features.

scholarly journals Constraining the Evolutionary History of the Moon and the Inner Solar System: A Case for New Returned Lunar Samples

2019 ◽  
Vol 215 (8) ◽  
Author(s):  
Romain Tartèse ◽  
Mahesh Anand ◽  
Jérôme Gattacceca ◽  
Katherine H. Joy ◽  
James I. Mortimer ◽  
...  
Keyword(s):  
Solar System ◽  
Large Scale ◽  
Lunar Regolith ◽  
The Moon ◽  
Planetary Body ◽  
The Past ◽  
Lunar Samples ◽  
History Of ◽  
Magma Oceans ◽  
Robotic Missions

AbstractThe Moon is the only planetary body other than the Earth for which samples have been collected in situ by humans and robotic missions and returned to Earth. Scientific investigations of the first lunar samples returned by the Apollo 11 astronauts 50 years ago transformed the way we think most planetary bodies form and evolve. Identification of anorthositic clasts in Apollo 11 samples led to the formulation of the magma ocean concept, and by extension the idea that the Moon experienced large-scale melting and differentiation. This concept of magma oceans would soon be applied to other terrestrial planets and large asteroidal bodies. Dating of basaltic fragments returned from the Moon also showed that a relatively small planetary body could sustain volcanic activity for more than a billion years after its formation. Finally, studies of the lunar regolith showed that in addition to containing a treasure trove of the Moon’s history, it also provided us with a rich archive of the past 4.5 billion years of evolution of the inner Solar System. Further investigations of samples returned from the Moon over the past five decades led to many additional discoveries, but also raised new and fundamental questions that are difficult to address with currently available samples, such as those related to the age of the Moon, duration of lunar volcanism, the lunar paleomagnetic field and its intensity, and the record on the Moon of the bombardment history during the first billion years of evolution of the Solar System. In this contribution, we review the information we currently have on some of the key science questions related to the Moon and discuss how future sample-return missions could help address important knowledge gaps.

3. Pre-Main Sequence Heating of Planetoids

1977 ◽  
Vol 39 ◽  
pp. 429-437
Author(s):  
C. P. Sonett ◽  
F. L. Herbert
Keyword(s):  
Solar System ◽  
Chemical Reaction ◽  
Electromagnetic Induction ◽  
Main Sequence ◽  
The Moon ◽  
Early Solar System ◽  
Reaction Heat ◽  
Tidal Heating ◽  
Electrical Induction ◽  
Viable Mechanism

The problem of thermal metamorphosis of meteorites, possibly the Moon and Mercury, and perhaps other planetary objects is reviewed. Classical mechanisms of heating include fossil nuclides (especially 26Al), accretional heating, tidal heating, chemical reaction heat, and electrical induction. These various mechanisms involve constraints on the early thermal profiles of the Moon or Mercury. In the case of the meteorites, the primary contenders for a viable mechanism currently are fossil nuclides and electromaqnetic induction, or some combination of these. But the issue of energetic mechanisms in the early solar system remains enigmatic. The fossil nuclide hypothesis leads to constraints upon nucleosynthesis while electromagnetic induction places significant constraints upon electrodynamic effects such as solar spin damping.

From the depths of the Earth

2010 ◽  
Author(s):  
Jan Zalasiewicz
Keyword(s):  
Solar System ◽  
Centrifugal Force ◽  
Outer Layer ◽  
The Moon ◽  
Planetary Body ◽  
The Earth ◽  
The One ◽  
Separate Identity ◽  
Two Bodies

The planet Theia had, like the Earth, formed early, from the mass of dust and rock-melt droplets of the accretionary disc. Theia is calculated to have been about the size of Mars, yet it was to have nothing like that planet’s longevity. Its orbit was close enough to that of Earth for collision to be certain, sooner or later. The two planets came together at something of the order of 40,000 kilometres per hour. Theia lost its separate identity over a few tumultuous minutes, and the Earth was smashed, like a grapefruit hit hard with a hammer. In that conflagration the material of the two planets, having instantly converted into boiling magma and vapour, simply merged. Theia’s core sank to join the Earth’s. Some of the outer layer of both planets splashed out into a cloud of plasma that encircled the suddenly re-formed Earth, and that cloud condensed to form a new companion to our planet—the Moon. It is a fine story, this, of the Moon’s creation through a spectacular planetary collision. It is likely true, too: though it is not certainly so, simply being the hypothesis that now best explains the character of our Earth and its satellite. Like many such stories in science, it is currently the one that best fits the evidence. It has been calculated, on the basis of these two bodies’ mass, momentum and orbit, that it would have been extraordinarily difficult for the Earth to have captured intact a stray planetary body of this size. However, holding onto a mass of ejecta flung out by impact, kept in balance by the twin, opposing forces of gravity and centrifugal force, is a more plausible means of having formed the Moon. More, this concept explains the remarkable isotopic similarity of these two bodies, generated by the intense mixing associated with impact. Mars, by contrast, has very different proportions of, say, the different isotopes of oxygen, because it formed in a different part of the Solar System, where the atoms of the original accretionary disk had been shuffled into different combinations.

scholarly journals Physical Studies of Asteroids By Polarization of the Light

1971 ◽  
Vol 12 ◽  
pp. 95-116 ◽  
Author(s):  
Audouin Dollfus
Keyword(s):  
The Other ◽  
The Moon ◽  
Laboratory Measurements ◽  
Martian Surface ◽  
Dust Deposit ◽  
Asteroidal Belt ◽  
Satellites Of Jupiter ◽  
Celestial Bodies ◽  
Remote Determination

Curves of polarization are available at present for asteroids Vesta, Ceres, Pallas, Iris, Flora, and Icarus. These curves are compared with those of the satellites of Jupiter and Mercury, the Moon, and Mars. Laboratory simulations had already proved that the Moon's surface behaves like a powder of pulverized basalts; the recent confirmation by direct exploration is proving the significance of the method for remote determination of the surface properties of celestial bodies. The simulation of the Martian surface is found on small grained powders oxidized by ferreous limonite or goethite. New laboratory measurements were conducted to prepare the simulation of the asteroidal surfaces. Samples of the lunar surface returned to Earth provide impact-generated regolith and bare rocks superficially pitted and etched by impacts of the types suggested to be found on asteroidal surfaces; they were analyzed polarimetrically.Preliminary interpretations show that Vesta departs significantly from the other asteroids and cannot be covered by frost deposits or by aggregate cosmic dusts; a regolith-type surface generated by impacts or a coating of cohesive grains is indicated.Ceres, Pallas, and Iris are darker, and their polarizations do not suggest a pure regolithic surface, but cohesive grains or aggregates of dust are indicated.Icarus is 108 times smaller in mass; its polarization authorizes a fluffy, loosely aggregated dust deposit; however, a cometary model with stones embedded in ice is perhaps not ruled out on the basis of the present data.The way in which deep-space missions near the asteroidal belt can improve these results is discussed.

scholarly journals A Possible Mechanism for the Capture of Microparticles by the Earth and Other Planets of the Solar System

1971 ◽  
Vol 13 ◽  
pp. 271-274
Author(s):  
F. Di Benedetto
Keyword(s):  
Solid State ◽  
Solar System ◽  
Neutral Point ◽  
Solid Particles ◽  
The Other ◽  
The Moon ◽  
The Earth ◽  
Maximum Value ◽  
Other Hand ◽  
Solid Form

By application of Lyttleton’s theory for the formation of comets, it is shown that a possible mechanism for the origin and formation of a concentration of cosmic particles around the Earth and the other planets of the solar system exists.In the vicinity of the neutral point, where the velocity of colliding particles is not greater than 6 km/s, it is found that if the solid particles after collision must remain in a solid state, there can be no possibility of accretion for Mercury, Mars, and the Moon, where the maximum value of the “closing-in parameter” p (distance of the center of the planet to the asymptotic trajectory) is less than the radius of the planet.On the other hand, the capture radii of microparticles in solid form varies from a minimum of 2.95 planetary radii for Venus and 3.47 for the Earth, to about 986 for Jupiter.

scholarly journals XIII. Observations on the nature of the new celestial body discovered by Dr. Olbers, and of the comet which was expected to appear last January in its return from the sun

1807 ◽  
Vol 97 ◽  
pp. 260-266 ◽  
Keyword(s):  
Solar System ◽  
Celestial Body ◽  
Great Distance ◽  
The Other ◽  
The Sun ◽  
The Moon ◽  
Heavenly Body ◽  
Valuable Addition ◽  
Late Discovery ◽  
The One

The late discovery of an additional body belonging to the solar system, by Dr. Olbers, having been communicated to me the 20th of April, an event of such consequence engaged my immediate attention. In the evening of the same day I tried to discover its situation by the information I had obtained of its motion; but the brightness of the moon, which was near the full, and at no great distance from the object for which I looked, would not permit a star of even the 5th magnitude to be seen, and it was not till the 24th that a tolerable view could be obtained of that space of the heavens in which our new wanderer was pursuing its hitherto unknown path. As soon as I found that small stars might be perceived, I made several delineations of certain telescopic constellations, the first of which was as represented in figure 1, and I fixed upon the star A, as most likely, from its expected situation and brightness, to be the one I was looking for. The stars in this figure, as well as in all the other delineations I had made, were carefully examined with several magnifying powers, that in case any one of them should hereafter appear to have been the lately discovered object, I might not lose the opportunity of an early acquaintance with its condition. An observation of the star marked A, in particular, was made with a very distinct magnifying power of 460, and says, that it had nothing in its appearance that differed from what we see in other stars of the same size; indeed Dr. Olbers, by mentioning in the communication which I received, that with such magnifying powers as he could use it was not to be distinguished from a fixed star, had already prepared me to expect the newly discovered heavenly body to be a valuable addition to our increasing catalogue of asteroids.

Instrumentation for Nuclear Planetology: Present and Future

2020 ◽  
Author(s):  
Maxim Mokrousov ◽  
Igor Mitrofanov ◽  
Alexander Kozyrev ◽  
Maxim Litvak ◽  
Alexey Malakhov ◽  
...  
Keyword(s):  
Solar System ◽  
Neutron Generator ◽  
Galactic Cosmic Rays ◽  
Field Of View ◽  
The Moon ◽  
Small Bodies ◽  
Nuclear Composition ◽  
Subsurface Layers ◽  
Pros And Cons

<p>The method of remote neutron and gamma spectrometry of bodies in the solar system (the Moon, Mars, and Mercury) has been used for several decades to estimate the nuclear composition of these objects and the hydrogen abundance in their subsurface layers. It is known that many solid planets of Solar system with thin atmospheres, its moons, small bodies and even comets due to bombardment by heavy nucleus of Galactic Cosmic Rays (GRS) produce neutron albedo and characteristic gamma lines. Detection of escaping gammas and neutrons (remote sensing from an orbit or in situ) bringing an information about elemental composition of the subsurface and hydrogen-containing elements (as deep as tens of centimeters). Currently we can classify all nuclear planetology instruments by the field of view (uncollimated and collimated) and by type of soil irradiation (passive – using GRS, and active – using pulsing neutron generator onboard), each of those methods has pros and cons and all of them will be presented. Also, future nuclear planetology instruments and method in design will be presented.</p>

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