Investigation of the YORP effect on asteroid (162173) Ryugu – An application of FEM approach thermophysical model

2021 ◽  
Author(s):  
Ryota Nakano ◽  
Masatoshi Hirabayashi
2018 ◽  
Vol 14 (A30) ◽  
pp. 15-15
Author(s):  
Oleksiy Golubov ◽  
Daniel J. Scheeres ◽  
Yurij N. Krugly
Keyword(s):  

AbstractHere, we discuss the YORP equilibria, to which asteroids can come as the result of their evolution due to the YORP effect.


2008 ◽  
Vol 490 (1) ◽  
pp. 387-391 ◽  
Author(s):  
M. Micheli ◽  
P. Paolicchi
Keyword(s):  

Science ◽  
2007 ◽  
Vol 316 (5822) ◽  
pp. 274-277 ◽  
Author(s):  
P. A. Taylor ◽  
J.-L. Margot ◽  
D. Vokrouhlicky ◽  
D. J. Scheeres ◽  
P. Pravec ◽  
...  
Keyword(s):  

1969 ◽  
Vol 156 ◽  
pp. 1135 ◽  
Author(s):  
D. F. Winter ◽  
J. M. Saari

2019 ◽  
Vol 631 ◽  
pp. A149
Author(s):  
A. Rożek ◽  
S. C. Lowry ◽  
M. C. Nolan ◽  
P. A. Taylor ◽  
L. A. M. Benner ◽  
...  

Context. The potentially hazardous asteroid (85990) 1999 JV6 has been a target of previously published thermal-infrared observations and optical photometry. It has been identified as a promising candidate for possible Yarkovsky-O’Keefe-Radzievskii-Paddack (YORP) effect detection. Aims. The YORP effect is a small thermal-radiation torque considered to be a key factor in spin-state evolution of small Solar System bodies. In order to detect YORP on 1999 JV6 we developed a detailed shape model and analysed the spin-state using both optical and radar observations. Methods. For 1999 JV6, we collected optical photometry between 2007 and 2016. Additionally, we obtained radar echo-power spectra and imaging observations with Arecibo and Goldstone planetary radar facilities in 2015, 2016, and 2017. We combined our data with published optical photometry to develop a robust physical model. Results. We determine that the rotation pole resides at negative latitudes in an area with a 5° radius close to the south ecliptic pole. The refined sidereal rotation period is 6.536787 ± 0.000007 h. The radar images are best reproduced with a bilobed shape model. Both lobes of 1999 JV6 can be represented as oblate ellipsoids with a smaller, more spherical component resting at the end of a larger, more elongated component. While contact binaries appear to be abundant in the near-Earth population, there are only a few published shape models for asteroids in this particular configuration. By combining the radar-derived shape model with optical light curves we determine a constant-period solution that fits all available data well. Using light-curve data alone we determine an upper limit for YORP of 8.5 × 10−8 rad day−2. Conclusions. The bifurcated shape of 1999 JV6 might be a result of two ellipsoidal components gently merging with each other, or a deformation of a rubble pile with a weak-tensile-strength core due to spin-up. The physical model of 1999 JV6 presented here will enable future studies of contact binary asteroid formation and evolution.


2016 ◽  
Vol 685 ◽  
pp. 389-393
Author(s):  
Maria A. Anisimova

This paper presents the thermophysical model of crystallization of the coating at the conditions of imperfect contact between the coating and sunstrate. The model takes into account the heat exchange of coating with the environment and with the substrate. The influence of thermal resistance of the interface and concentration of filler in the coating on the change of temperature during cooling is investigated.


2007 ◽  
Vol 134 (5) ◽  
pp. 1750-1768 ◽  
Author(s):  
David Nesvorný ◽  
David Vokrouhlický
Keyword(s):  

Author(s):  
Nicholas P. G. Lumley ◽  
Emory Ford ◽  
Eric Minford ◽  
Jason M. Porter

Highly porous ceramic fiber insulations are beginning to be considered as a replacement for firebrick insulations in high temperature, high pressure applications by the chemical process industry. However, the implementation of such materials has been impeded by a lack of experimental data and predictive models, especially at high gas pressure. The goal of this work was to develop a general, applied thermophysical model to predict effective thermal conductivity, keff, of porous ceramic fiber insulation materials and to determine the temperature, pressure, and gas conditions under which natural convection is a possible mode of heat transfer. A model was developed which calculates keff as the sum of conduction, convection, and radiation partial conductivities. The model was validated using available experimental data, including laboratory measurements made by this research effort. Overall, it was concluded that natural convection is indeed possible for the most porous insulations at pressures exceeding 10 atm. Furthermore, keff for some example insulations was determined as a function of temperature, pressure, and gas environment.


2020 ◽  
Author(s):  
Thomas G. Müller ◽  
Martin J. Burgdorf ◽  
Stefan A. Buehler ◽  
Marc Prange

<p>We present a thermophysical model (TPM) of the Moon which matches the observed, global, disk-integrated thermal flux densities of the Moon in the mid-infrared wavelength range for a phase angle range from -90° to +90°.<br />The model was tested and verified against serendipitous multi-channel HIRS measurements of the Moon obtained by different meteorological satellites (NOAA-11, NOAA-14, NOAA-15, NOAA-17, NOAA-18, NOAA-19, MetOp-A, MetOp-B). The sporadic intrusions of the Moon in the deep space view of these instruments have been extracted in cases where the entire Moon was within the instruments' field of view. The HIRS long-wavelengths channels 1-12 cover the range from 6.5 to 15 μm, the short-wavelengths channels 13-19 are in the 3.7 to 4.6 μm range.</p> <p>The model is based on an asteroid TPM concept (Lagerros 1996, 1997, 1998; Müller & Lagerros 1998, 2002), using the known global properties of the Moon (like size, shape, spin properties, geometric albedo, thermal inertia, surface roughness, see Keihm 1984; Racca 1995; Rozitis & Green 2011; Hayne et al. 2017), combined with a model for the spectral hemispherical emissivity which varies between 0.6 and 1.0 in the HIRS wavelength range (Shaw 1998; ECOSTRESS data base: https://ecostress.jpl.nasa.gov/). The spectral emissivity as well as characteristics of the surface roughness are crucial to explain the well-calibrated measurements.</p> <p>Our Moon model fits the flux densities for the currently available 22 epochs (each time up to 19 channels) with an absolute accuracy of 5-10%. The phase curves at the different wavelengths are well explained. The spectral energy distributions are very sensitive to emissivity and roughness properties. Here, we see minor variations in the model fits, depending on the origin (phase and aspect angle related) of the thermal emission. We also investigated the influence of reflected sunlight at short wavelengths.</p> <p>Our TPM of the Moon has a wide range of applications: (i) for Earth-observing weather satellites in the context of field of view and photometric calibration (e.g., Burgdorf et al. 2020); (ii) for interplanetary space missions (e.g., Hayabusa2, OSIRIS-REx or BepiColombo) with infrared instruments on board for an in-space characterization of instrument properites (e.g., Okada et al. 2018); (iii) to shed light on the thermal mid-infrared properties of the lunar surface on a global scale; and, (iv) to benchmark thermophysical model techniques for asteroids in the regime below 10 μm (e.g., observed by WISE in the W1 and W2 bands at 3.4 and 4.6 μm, by Spitzer-IRAC at 3.55 and 4.49 μm or from ground in M band at around 5 μm).</p> <p><br />References:<br />Burgdorf M., et al. 2020, Remote Sens. 12, 1488; Hayne, P. et al. 2017, JGRE 122, 237; Keihm, S.J. 1984, Icarus 60, 568; Lagerros 1996,  A&A 310, 1011; Lagerros 1997, A&A 325, 1226; Lagerros 1998, A&A 332, 1123; Müller & Lagerros 1998, A&A 338, 340; Müller & Lagerros 2002, A&A 381, 324; Okada T. et al. 2018, P&SS 158, 46; Racca G. 1995, P&SS 43, 835; Rozitis & Green 2011, MNRAS 415, 2042.</p> <p> </p>


2020 ◽  
Author(s):  
Edoardo Rognini ◽  
Alessandro Mura ◽  
Maria Teresa Capria ◽  
Angelo Zinzi ◽  
Anna Milillo ◽  
...  

<div> <p>The BepiColombo mission is the first European mission to Mercury; the spacecraft will reach its destination in December 2025, and will study in detail the surface, the exosphere and the magnetosphere of the planet. </p> </div> <div> <p>We have developed a thermophysical model with the aim to analyze the dependence of the temperature of the surface and of the layers close to it on the assumptions on the thermophysical properties of the soil. The code solves the one-dimensional heat equation, assumes purely conductive heat propagation and no internal heat sources; the surface is assumed to be composed of a regolith layer with high porosity and density increasing with depth. The illumination conditions are calculated by using a Mercury shape model and the SPICE routines [1]. </p> </div> <div> <p>The model will help us to interpret the data that will be provided by the instruments onboard the BepiColombo mission. Preliminary calculations have been carried out to analyze the thermal response of the soil as a function of thermal conductivity. The model is currently also used to study the sodium content in the planet's exosphere, whose origin is under investigation [2]; the MESSENGER mission has measured the exospheric sodium content as a function of time, detecting an increase at the "cold poles" (so called because of their lower than average temperature). We therefore want to study the effect of surface temperatures on the sodium content in the exosphere; for this purpose, the temperature distribution calculated with the code is used together with an atmospheric circulation model that calculates the exospheric sodium content [3]. </p> </div> <div> <p>A simplified version of the thermophysical code is almost ready to be available to the scientific community through MATISSE [4], the software developed at the SSDC in ASI and available at https://tools.ssdc.asi.it/Matisse. </p> </div> <p>[1] Acton, C. H. (1996), Planetary and Space Science, 44, 65-70<br />[2] Cassidy, T., et al. (2016), GRL, 43, 11 121-128<br />[3] Mura, A., et al. (2009), Icarus, 1, 1-11<br />[4] Zinzi, A., et al. (2016), Astronomy & Computing, 15, 16-28</p>


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