Probability for cosmic masses of the main asteroid belt to approach the Earth

2021 ◽  
Author(s):  
T. Salnikova ◽  
A. Samokhin
Keyword(s):  
Asteroid Belt ◽  
The Earth ◽  
Main Asteroid Belt

Thermal consequences of impact bombardments to silicate crusts of terrestrial-type exoplanets

2021 ◽  
Author(s):  
Stephen J. Mojzsis ◽  
Oleg Abramov
Keyword(s):  
Extrasolar Planets ◽  
Unit Area ◽  
Production Functions ◽  
Asteroid Belt ◽  
Earth Planet ◽  
Cross Sectional ◽  
The Earth ◽  
Main Asteroid Belt ◽  
Gravitational Compression ◽  
Impactor Velocity

<p><strong>Introduction. </strong>Post-accretionary impact bombardment is part of planet formation and leads to localized, regional [e.g., 1-3], or even wholesale global melting of silicate crust [e.g., 4]; less intense bombardment can also create hydrothermal oases favorable for life [e.g, 5]. Here, we generalize the effects of late accretion bombardments to extrasolar planets of different masses (0.1-10M<sub>⊕</sub>). One example is Proxima Centauri b, estimated at ~2× M<sub>⊕</sub> [6]. We model a 0.1M<sub>⊕ </sub>“mini-Earth”<sub></sub>and “super-Earth” at 10M<sub>⊕</sub>, the approximate upper limit for a “mini-Neptune” [7]. Output predicts lithospheric melting and subsurface habitable volumes.</p><p><strong>Methods. </strong>The model [1,2] consists of (i) stochastic cratering; (ii) analytical thermal expressions for each crater [e.g., 8,9]; and (iii) a 3-D thermal model of the lithosphere, where craters cool by conduction and radiation.</p><p>We analyze impact bombardments using our solar system’s mass production functions for the first 500 Myr [10]. Surface temperatures and geothermal gradients are set to 20 °C and 70 °C/km [2]. Total delivered mass for Earth is 7.8 × 10<sup>21</sup> kg, and scaled to other planets based on cross-sectional areas, with 1.7 × 10<sup>21</sup> kg for mini-Earth, 1.2 × 10<sup>22</sup> kg for Proxima Centauri b, and 3.6 × 10<sup>22</sup> kg for super-Earth. The impactors' SFD is based on our main asteroid belt [11]. Impactor and target densities are set to 3000 kg m<sup>-3</sup> and planetary bulk densities are assumed to be 5510 kg m<sup>-3</sup>, omitting gravitational compression [7]. Impactor velocity was estimated at 1.5 × v<sub>esc</sub> for each planet, with 7.8 km s<sup>-1</sup> for mini-Earth,  16.8 km s<sup>-1</sup> for the Earth, 21.1 km s<sup>-1</sup> for Proxima Centauri b, and 36.1 km s<sup>-1</sup> for super-Earth.</p><p><strong>Results. </strong>We assume fully formed crusts, so melt volume immediately increases due to impacts. Super-Earth reaches a maximum of ~45% of the lithosphere in molten state, whereas mini-Earth reaches a maximum of only ~5%.  This is due to much higher impact velocities and cratering densities on the super-Earth compared to mini-Earth. We also show the geophysical habitable volumes within the upper 4 km of a planet’s crust as the bombardment progresses. Impacts sterilize the majority of the habitable volume on super-Earth; however, due to its large total volume, the total habitable volume is still higher than on other planets despite the more intense bombardment in terms of energy delivered per unit area.</p><p><strong>References:</strong> [1] Abramov, O., and S.J. Mojzsis (2009) Nature, 459, 419-422. [2] Abramov et al. (2013) Chemie der Erde, 73, 227-248. [3] Abramov, O., and S. J. Mojzsis (2016) Earth Planet Sci. Lett., 442, 108-120. [4] Canup, R. M. (2004) Icarus, 168, 433-456. [5] Abramov, O., and D. A. Kring (2004) J. Geophys. Res., 109(E10). [6] Tasker, E. J. et al. (2020). Astronom. J., 159(2), 41. [7] Marcy, G. W. et al. (2014). PNAS, 111(35), 12655-12660. [8] Kieffer S. W. and Simonds C. H. (1980) Rev. Geophys. Space Phys., 18, 143-181. [9] Pierazzo E., and H.J. Melosh (2000). Icarus, 145, 252-261. [10] Mojzsis, S. J. et al. (2019). Astrophys. J., 881(1), 44. [11] Bottke, W. F. et al. (2010) Science, 330, 1527-1530.</p>

scholarly journals Physics of Celestial Scale Dumbbells

2017 ◽  
Vol 9 (5) ◽  
pp. 12
Author(s):  
Leonardo Golubovic ◽  
Steven Knudsen
Keyword(s):  
Outer Space ◽  
Satellite Orbit ◽  
Asteroid Belt ◽  
Geosynchronous Satellite ◽  
The Earth ◽  
Dwarf Planets ◽  
Basic Physics ◽  
Main Asteroid Belt ◽  
Space Elevators ◽  
Top Mass

The physics of manmade celestial scale objects, such as Space Elevators connecting the Earth with outer space, has recently attracted increased attention of diverse researchers. In this article we review basic physics of celestial scale dumbbells such as the Analemma Tower suspended from an asteroid orbiting the Earth (Clouds, 2017). Celestial dumbbells involve two large masses (top and bottom) connected by strings. The two masses move geosynchronously with the Earth, with the bottom mass remaining close to the Earth and the top mass moving above the Earth’s geosynchronous satellite orbit. Appealing examples of celestial scale dumbbells are untied Rotating Space Elevators (RSE) (Knudsen & Golubovic, 2015). Physics of untied rotating space elevators. European Physical Journal Plus 130, 243.]. Celestial scale dumbbells exhibit rich and interesting nonlinear dynamics caused by instabilities of dumbbell geosynchronous motion discussed in this review article. We also point out that celestial scale dumbbells are physically feasible (in terms of nowadays available materials strengths) on dwarf planets in the main asteroid belt of the Solar system such as Ceres.

scholarly journals On a possibility of transfer of asteroids from the 2:1 mean motion resonance with Jupiter to the Centaur zone

2021 ◽  
Author(s):  
Kazantsev Anatolii ◽  
Kazantseva Lilia
Keyword(s):  
Terrestrial Planet ◽  
Numerical Calculations ◽  
Asteroid Belt ◽  
Time Interval ◽  
Transfer Time ◽  
Mean Motion ◽  
Resonant Orbits ◽  
Main Asteroid Belt ◽  
Absolute Magnitudes ◽  
Mean Motion Resonance

ABSTRACT The paper analyses possible transfers of bodies from the main asteroid belt (MBA) to the Centaur region. The orbits of asteroids in the 2:1 mean motion resonance (MMR) with Jupiter are analysed. We selected the asteroids that are in resonant orbits with e > 0.3 whose absolute magnitudes H do not exceed 16 m. The total number of the orbits amounts to 152. Numerical calculations were performed to evaluate the evolution of the orbits over 100,000-year time interval with projects for the future. Six bodies are found to have moved from the 2:1 commensurability zone to the Centaur population. The transfer time of these bodies to the Centaur zone ranges from 4,600 to 70,000 yr. Such transfers occur after orbits leave the resonance and the bodies approach Jupiter Where after reaching sufficient orbital eccentricities bodies approach a terrestrial planet, their orbits go out of the MMR. Accuracy estimations are carried out to confirm the possible asteroid transfers to the Centaur region.

scholarly journals Forming terrestrial planets and delivering water

2015 ◽  
Vol 11 (A29B) ◽  
pp. 427-430
Author(s):  
Kevin J. Walsh
Keyword(s):  
Planet Formation ◽  
Semimajor Axis ◽  
Giant Planet ◽  
Terrestrial Planet ◽  
Giant Planets ◽  
Asteroid Belt ◽  
Terrestrial Planets ◽  
The Earth ◽  
Building Models ◽  
Rich Material

AbstractBuilding models capable of successfully matching the Terrestrial Planet's basic orbital and physical properties has proven difficult. Meanwhile, improved estimates of the nature of water-rich material accreted by the Earth, along with the timing of its delivery, have added even more constraints for models to match. While the outer Asteroid Belt seemingly provides a source for water-rich planetesimals, models that delivered enough of them to the still-forming Terrestrial Planets typically failed on other basic constraints - such as the mass of Mars.Recent models of Terrestrial Planet Formation have explored how the gas-driven migration of the Giant Planets can solve long-standing issues with the Earth/Mars size ratio. This model is forced to reproduce the orbital and taxonomic distribution of bodies in the Asteroid Belt from a much wider range of semimajor axis than previously considered. In doing so, it also provides a mechanism to feed planetesimals from between and beyond the Giant Planet formation region to the still-forming Terrestrial Planets.

Characterization of NH4-montmorillonite coexisting with NH4Cl salt at different aggregation states. Application to Ceres.

2021 ◽  
Author(s):  
Victoria Munoz-Iglesias ◽  
Maite Fernández-Sampedro ◽  
Carolina Gil-Lozano ◽  
Laura J. Bonales ◽  
Oscar Ercilla Herrero ◽  
...  
Keyword(s):  
Environmental Conditions ◽  
Spectroscopic Data ◽  
External Surface ◽  
Deionized Water ◽  
Asteroid Belt ◽  
Aqueous Alteration ◽  
Dawn Mission ◽  
Main Asteroid Belt ◽  
Spectroscopic Signatures

<p>Ceres, dwarf planet of the main asteroid belt, is considered a relic ocean world since the Dawn mission discovered evidences of aqueous alteration and cryovolcanic activity [1]. Unexpectedly, a variety of ammonium-rich minerals were identified on its surface, including phyllosilicates, carbonates, and chlorides [2]. Although from the Dawn’s VIR spectroscopic data it was not possible to specify the exact type of phyllosilicates observed, montmorillonite is considered a good candidate owing to its ability to incorporate NH<sub>4</sub><sup>+</sup> in its interlayers [3]. Ammonium-rich phases are usually found at greater distances from the Sun. Hence, the study on their stability at environmental conditions relevant to Ceres’ interior and of its regolith can help elucidate certain ambiguities concerning the provenance of its precursor materials.</p> <p>In this study, it was investigated the changes in the spectroscopic signatures of the clay mineral montmorillonite after (a) being immersed in ammonium chloride aqueous solution and, subsequently, (b) washed with deionized water. After each treatment, samples were submitted to different environmental conditions relevant to the surface of Ceres. For one experiment, they were frozen overnight at 193 K, and then subjected to 10<sup>-5</sup> bar for up to 4 days in a Telstar Cryodos lyophilizer. For the other, they were placed inside the Planetary Atmospheres and Surfaces Chamber (PASC) [4] for 1 day at 100 K and 5.10<sup>-8</sup> bar. The combination of different techniques, i.e., Raman and IR spectroscopies, XRD, and SEM/EDX, assisted the assignment of the bands to each particular molecule. In this regard, the signatures of the mineral external surface were distinguished from the interlayered NH<sub>4</sub><sup>+ </sup>cations. The degree of compaction of the samples resulted crucial on their stability and spectroscopic response, being stiff smectites more resistant to low temperatures and vacuum conditions. In ground clay minerals, a decrease in the basal space with a redshift of the interlayered NH<sub>4</sub><sup>+</sup> IR band was measured after just 1 day of being exposed to vacuum conditions.</p> <p>Acknowledgments</p> <p>This work was supported by the Spanish MINECO projects ESP2017-89053-C2-1-P and PID2019-107442RB-C32, and the AEI project MDM‐2017‐0737 Unidad de Excelencia “María de Maeztu”.</p> <p>References</p> <p>[1] De Sanctis et al.,  Space Sci. Rev. 216, 60, 2020</p> <p>[2] Raponi et al., Icarus 320, 83,  2019</p> <p>[3] Borden and Giese, Clays Clay Miner. 49, 444, 2001</p> <p>[4] Mateo-Marti et al., Life 9, 72, 2019</p>

A ring model of the main asteroid belt for planetary ephemerides

Icarus ◽  
2022 ◽  
pp. 114845
Author(s):  
Shanhong Liu ◽  
Agnés Fienga ◽  
Jianguo Yan
Keyword(s):  
Asteroid Belt ◽  
Ring Model ◽  
Main Asteroid Belt

scholarly journals The Change in Near-Ecliptic Zodiacal Light Brightness with Heliocentric Distance

1985 ◽  
Vol 85 ◽  
pp. 21-25
Author(s):  
G.N. Toller ◽  
J.L. Weinberg
Keyword(s):  
Heliocentric Distance ◽  
Asteroid Belt ◽  
Zodiacal Light ◽  
The Earth ◽  
Pioneer 10

AbstractBackground starlight observed by the Pioneer 10 Imaging Photopolarimeter from beyond the asteroid belt is used to isolate zodiacal light in Pioneer observations at heliocentric distances R between 1 and 3 AU. Near-ecliptic zodiacal light brightness data in the range 65° to 180° elongation ε are used to depict changes in the shape of the zodiacal light with ε and R and are compared to the corresponding views seen from the Earth and from the Helios 1 and 2 spacecraft.

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