Shapes, structures, and evolution of small bodies

Astrodynamics ◽  
2021 ◽  
Vol 5 (4) ◽  
pp. 293-329
Author(s):  
Yun Zhang ◽  
Patrick Michel
Keyword(s):  
Small Bodies

scholarly journals Synthesis of Organic Matter in Aqueous Environments Simulating Small Bodies in the Solar System and the Effects of Minerals on Amino Acid Formation

Life ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 32
Author(s):  
Walaa Elmasry ◽  
Yoko Kebukawa ◽  
Kensei Kobayashi
Keyword(s):  
Amino Acids ◽  
Organic Matter ◽  
Amino Acid ◽  
Solar System ◽  
Acid Formation ◽  
Gel Chromatography ◽  
Small Bodies ◽  
Enhanced Production ◽  
Aqueous Environments ◽  
Heating Duration

The extraterrestrial delivery of organics to primitive Earth has been supported by many laboratory and space experiments. Minerals played an important role in the evolution of meteoritic organic matter. In this study, we simulated aqueous alteration in small bodies by using a solution mixture of H2CO and NH3 in the presence of water at 150 °C under different heating durations, which produced amino acids after acid hydrolysis. Moreover, minerals were added to the previous mixture to examine their catalyzing/inhibiting impact on amino acid formation. Without minerals, glycine was the dominant amino acid obtained at 1 d of the heating experiment, while alanine and β-alanine increased significantly and became dominant after 3 to 7 d. Minerals enhanced the yield of amino acids at short heating duration (1 d); however, they induced their decomposition at longer heating duration (7 d). Additionally, montmorillonite enhanced amino acid production at 1 d, while olivine and serpentine enhanced production at 3 d. Molecular weight distribution in the whole of the products obtained by gel chromatography showed that minerals enhanced both decomposition and combination of molecules. Our results indicate that minerals affected the formation of amino acids in aqueous environments in small Solar System bodies and that the amino acids could have different response behaviors according to different minerals.

Interaction of solid bodies with atmospheres of protoplanets

2018 ◽  
Vol 14 (S345) ◽  
pp. 351-352
Author(s):  
Ernst A. Dorfi ◽  
Florian Ragossnig
Keyword(s):  
Kinetic Energy ◽  
Physical Properties ◽  
Planet Formation ◽  
Frictional Heating ◽  
Protoplanetary Disk ◽  
Small Bodies ◽  
Early Stages ◽  
Break Up ◽  
Solid Bodies ◽  
Stellar Source

AbstractDuring the early stages of planet formation accretion of small bodies add mass to the planet and deposit their energy kinetic energy. Caused by frictional heating and/or large stagnation pressures within the dense and extended atmospheres most of the in-falling bodies get destroyed by melting or break-up before they impact on the planet’s surface. The energy is added to the atmospheric layers rather than heating the planet directly. These processes can significantly alter the physical properties of protoplanets before they are exposed with their primordial atmospheres to the early stellar source when the protoplanetary disk becomes evaporated.

Robust sliding mode guidance and control for soft landing on small bodies

2012 ◽  
Vol 349 (2) ◽  
pp. 493-509 ◽  
Author(s):  
Zhang Zexu ◽  
Wang Weidong ◽  
Li Litao ◽  
Huang Xiangyu ◽  
Cui Hutao ◽  
...  
Keyword(s):  
Sliding Mode ◽  
Soft Landing ◽  
Small Bodies ◽  
Guidance And Control ◽  
And Control

Magmatic and metasomatic processes during formation of the Nb-Zr-REE deposits Khaldzan Buregte and Tsakhir (Mongolian Altai): Indications from a combined CL-SEM Study

1999 ◽  
Vol 63 (2) ◽  
pp. 165-177 ◽  
Author(s):  
U. Kempe ◽  
J. Götze ◽  
S. Dandar ◽  
D. Habermann
Keyword(s):  
Metasomatic Rock ◽  
Metasomatic Alteration ◽  
Small Bodies ◽  
Mongolian Altai ◽  
Mineral Phases ◽  
Internal Structures ◽  
Sem Study ◽  
Backscattered Electron ◽  
Imaging And Spectroscopy ◽  
Electron Imaging

AbstractCathodoluminescence (CL) imaging and spectroscopy, as well as backscattered electron imaging, were used to assign the occurrence of several mineral phases and rock structures in altered nordmarkites and calcite-bearing granites from the Nb-Zr-REE deposits from Khaldzan Buregte and Tsakhir (Mongolian Altai) to three events: (1) intrusion of barren nordmarkites; (2) intrusion of small bodies of calcite-bearing granites with metasomatic alteration of the wall-rocks; and (3) alteration by F-rich fluids.Unusual red and yellow CL caused by Fe3+ and Mn2+ emission centres were detected in microcline and albite. Fe3+ centres were also established (along with others) in quartz, zircon, and possibly in fluorite.Magmatic and metasomatic rock structures and internal structures of the minerals coexist in the samples. The primary magmatic features were in part preserved during alteration. In contrast, the internal and the centre structures may be changed during alteration even in non-replaced mineral phases. Euhedral minerals may be formed by secondary processes as shown for lath-shaped albite. The occurrence of pseudomorphs, the inheritance of elements during replacement, and the mechanical effects of secondary minerals on earlier mineral phases during metasomatic growth are proposed as criteria for the reconstruction of the mineral succession in altered rocks. Snowball structures may be formed as a result of metasomatic alteration rather than as a magmatic intergrowth.

Yarkovsky drift detectability using the Gaia DR2 asteroid astrometry  

2021 ◽  
Author(s):  
Karolina Dziadura ◽  
Dagmara Oszkiewicz ◽  
Federika Spoto ◽  
Przemysław Bartczak
Keyword(s):  
Direct Detection ◽  
Signal To Noise Ratio ◽  
Parameter Determination ◽  
Small Bodies ◽  
Radar Observations ◽  
Orbital Parameters ◽  
Yarkovsky Effect ◽  
Reliable Detection ◽  
Right Ascension ◽  
Gaia Dr2

<div>The orbital motion of small bodies is affected by the Yarkovsky effect (semiminor axes change in time (da/dt)). The first direct detection was only made in 2003 thanks to radar observations. Nowadays there are over a hundred detections for NEAs and only a few for Main-Belt objects, however, the Yarkovsky effect remains difficult to detect for a large group of asteroids.</div> <div>The ESA Gaia mission was claimed to provide extremely precise astrometry of asteroids. Gaia observations were expected to lead to new Yarkovsky detections. In this work, we present the results for the most promising Yarkovsky candidates indexed before the start of the mission.</div> <div>We converted all available data (ground-based optical astrometry, satellite astrometry measurements, radar observations and GAIA DR2 data) to ADES format and then used it for orbit determination. We included the standard error of right ascension (RA), declination (Dec) and correlation of Ra and Dec errors for Gaia astrometry. We found a reliable detection of the Yarkovsky effect with a signal-to-noise ratio (SNR) greater than 3 for 21 asteroids, including 7 confirmations and 14 new detections. In 10 cases the resulting da/dt parameter SNR increased with the usage of the DR2 catalogue data, but no reliable detection can yet be claimed. Furthermore, we present a comparison of our empirical results with expected values estimated using physical and orbital parameters of studied objects. GAIA DR2 asteroids astrometry impacts positively the Yarkovsky drift determination. GAIA DR3 will elongate the observational arc, therefore, contribute to A2 parameter determination.</div>

scholarly journals Effects of cryoprotectants and low temperatures on hatching and abnormal embryo development of Prochilodus lineatus (Characiformes: Prochilodontidae)

2017 ◽  
Vol 15 (3) ◽  
Author(s):  
Raphael S. Costa ◽  
Fabrício M. S. de Souza ◽  
José A. Senhorini ◽  
Rosicleire Veríssimo-Silveira ◽  
Alexandre Ninhaus-Silveira
Keyword(s):  
Embryonic Development ◽  
Low Temperatures ◽  
Survival Rates ◽  
Ice Nucleation ◽  
Small Bodies ◽  
Prochilodus Lineatus ◽  
Morphological Alterations ◽  
Membrane Rupture ◽  
Significant Difference ◽  
Chilling Sensitivity

ABSTRACT This study evaluated the effect of the cryoprotectants and the low temperatures on the embryonic development of Prochilodus lineatus, describing their main morphological alterations. On chilling sensitivity test, the survival rates at the twenty somites stage (20S) were 53.6% at 0ºC, and 100% in 5ºC. To test toxicity, the embryos were exposed to a graded series of 1,2-Propanediol (PROP), dimethyl sulfoxide (Me2SO4) and glycerol (GLY), terminating in a solution of high osmolarity. There was no significant difference in the embryos survival of toxicity test between series of PROP and Me2SO4 in the 6S and 20S. In the cooling protocols, were evaluated the effects of low temperature associated with cryoprotectants. At 5ºC, PROP showed survival rates above 75% in the gastrula stage (G) and above 90% in the 6S and 20S stages. High rates of abnormalities were observed, and the most recurrent were: small bodies, fins presenting uncontrolled cell growth, membrane rupture, and retraction. These results demonstrate the need to use cryoprotectant solutions, even when there is no ice nucleation, and, on the other hand, shows that high cryoprotectant concentrations promote numerous morphological lesions, compromising normal embryonic development.

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