Analysis of the Anisotropic Heat-Protective Material Application Effectiveness in the Implementation of Trajectories with Multiple Re-entries into the Atmosphere

2021 ◽  
pp. 56-68
Author(s):  
V.V. Leonov ◽  
V.S. Zarubin ◽  
M.A. Ayrapetyan
Keyword(s):  
Thermal Protection ◽  
Structural Elements ◽  
The Moon ◽  
Protective Material ◽  
Heat Flows ◽  
Earth’S Atmosphere ◽  
Earth's Atmosphere ◽  
Protection Coating ◽  
Thermal Protection Coatings ◽  
Thermal Protection Coating

In the case of full implementation of the programs of studying and developing the Moon, announced in recent years (“Luna”, Artemis, Chang’e), significant increase in cargo turnover between the Moon and the Earth is expected. Therefore the research and development of appropriate spacecrafts and their structural elements is believed to be promising, especially thermal protection coatings ensuring spacecraft safety during movement (descent) in the dense atmosphere layers. A special characteristic of the trajectory of the spacecraft returning from the Moon’s orbit is the closeness of the speed of its entry into the Earth’s atmosphere to the parabolic one. This circumstance significantly complicates solving the problem of creating thermal protection for such a vehicle, because of higher convective and radiative heat flows compared to those acting on orbital landers. The analysis showed that when implementing the trajectory of the return of spacecraft with multiple re-entries into the Earth’s atmosphere, a trajectory can be selected (at least for cargo flights) so that the intensity of heat exchange on the surface of the coating does not exceed the permissible level. In this case, use of modern and advanced anisotropic heat-protective composite materials can reduce the spacecraft surface temperature to a level that does not cause destruction of the thermal protection coating.

scholarly journals MODIFIED EPOXY COMPOSITION FOR PRODUCTION OF THERMAL PROTECTION COATING

2020 ◽  
pp. 88-96
Author(s):  
Alexandr Maramygin ◽  
Keyword(s):  
Thermal Protection ◽  
Polymerization Process ◽  
Polymer Composition ◽  
Production Cycle ◽  
Practical Implementation ◽  
Epoxy Composition ◽  
Materials Used ◽  
Protection Coating ◽  
Thermal Protection Coatings ◽  
Thermal Protection Coating

The material summed up in this article is recommended for engineers of aerospace industry, as well as can be of inter-est for the production personnel. The article covers the production of “scale-like” outer thermal protection coatings on the basis of syntactic materials with tumescent characteristics used in the production of special purpose equipment. The research per-formed sums up the results of the practical implementation of the technology adaptative method in the conditions of the real outer thermal protection coatings production. This work describes a typical technological process of “scale-like” outer thermal protection coating production from the panels based on syntactic material, including the stages of separate panels production with the help of shape-generating molding tools and forming of thermal protection coating by laying and molding-on of separate panels on the pressure restraint layer of the aircraft. The author proves the effectiveness of technology adaptative method us-age on the example of modification processes of pattern polymer composition being the basis of syntactic material. The re-search describes the solutions for the production cycle optimization via improvement of technological properties of the materials used. The work also contains the results of the researches, including spectral and thermochemical analyses of polymer compo-sitions modified by polyisocyanates, and describes the research techniques of their properties. Quasi-eutectic compositions of aliphatic and aromatic amines are received, which, being used as curative of reactive epoxiurethane polymers produced on the basis of epoxy-diane oligomers and polyisocyanates, enable to divide the polymerization process into two stages. The method described in the article provides the elimination of panel defects on the stage of molding-on due to implementation of mode separation in polymerization processes, which contributes towards the quality and reliability of thermal protection coating.

scholarly journals High-resolution spectroscopy and spectropolarimetry of the total lunar eclipse January 2019

2020 ◽  
Vol 635 ◽  
pp. A156
Author(s):  
K. G. Strassmeier ◽  
I. Ilyin ◽  
E. Keles ◽  
M. Mallonn ◽  
A. Järvinen ◽  
...  
Keyword(s):  
Large Scale ◽  
Solar Spectrum ◽  
High Resolution Spectroscopy ◽  
Strong Increase ◽  
Lunar Eclipse ◽  
The Sun ◽  
The Moon ◽  
Earth’S Atmosphere ◽  
The Earth ◽  
Earth's Atmosphere

Context. Observations of the Earthshine off the Moon allow for the unique opportunity to measure the large-scale Earth atmosphere. Another opportunity is realized during a total lunar eclipse which, if seen from the Moon, is like a transit of the Earth in front of the Sun. Aims. We thus aim at transmission spectroscopy of an Earth transit by tracing the solar spectrum during the total lunar eclipse of January 21, 2019. Methods. Time series spectra of the Tycho crater were taken with the Potsdam Echelle Polarimetric and Spectroscopic Instrument (PEPSI) at the Large Binocular Telescope in its polarimetric mode in Stokes IQUV at a spectral resolution of 130 000 (0.06 Å). In particular, the spectra cover the red parts of the optical spectrum between 7419–9067 Å. The spectrograph’s exposure meter was used to obtain a light curve of the lunar eclipse. Results. The brightness of the Moon dimmed by 10.m75 during umbral eclipse. We found both branches of the O2 A-band almost completely saturated as well as a strong increase of H2O absorption during totality. A pseudo O2 emission feature remained at a wavelength of 7618 Å, but it is actually only a residual from different P-branch and R-branch absorptions. It nevertheless traces the eclipse. The deep penumbral spectra show significant excess absorption from the Na I 5890-Å doublet, the Ca II infrared triplet around 8600 Å, and the K I line at 7699 Å in addition to several hyper-fine-structure lines of Mn I and even from Ba II. The detections of the latter two elements are likely due to an untypical solar center-to-limb effect rather than Earth’s atmosphere. The absorption in Ca II and K I remained visible throughout umbral eclipse. Our radial velocities trace a wavelength dependent Rossiter-McLaughlin effect of the Earth eclipsing the Sun as seen from the Tycho crater and thereby confirm earlier observations. A small continuum polarization of the O2 A-band of 0.12% during umbral eclipse was detected at 6.3σ. No line polarization of the O2 A-band, or any other spectral-line feature, is detected outside nor inside eclipse. It places an upper limit of ≈0.2% on the degree of line polarization during transmission through Earth’s atmosphere and magnetosphere.

Novel Concept of Advanced Thermal Protection Coating Based on Fullerenes

2001 ◽  
Author(s):  
Raouf O. Loutfy ◽  
Eugene M. Wexler
Keyword(s):  
Thermal Conductivity ◽  
Experimental Study ◽  
Elevated Temperatures ◽  
Thermal Protection ◽  
Temperature Decrease ◽  
Cold Surface ◽  
Novel Concept ◽  
Protection Coating ◽  
High Emissivity ◽  
Thermal Protection Coating

Abstract Experimental study has been carried out to investigate thermal protection properties of thin fullerene coatings subjected to external heating. It was shown that due to low thermal conductivity and high emissivity, micron-scale fullerene films were capable of withstanding elevated temperatures (up to 800°C) resulting in over 100°C temperature decrease on the “cold” surface of the underlying substrate. Based on obtained results, practically important recommendations are made.

scholarly journals Restoring the top-of-atmosphere reflectance during solar eclipses: a proof of concept with the UV Absorbing Aerosol Index measured by TROPOMI

2020 ◽  
Author(s):  
Victor Trees ◽  
Ping Wang ◽  
Piet Stammes
Keyword(s):  
Air Quality ◽  
Color Change ◽  
Solar Limb ◽  
Correction Method ◽  
The Moon ◽  
Earth’S Atmosphere ◽  
Earth's Atmosphere ◽  
Solar Eclipses ◽  
Limb Darkening ◽  
Aerosol Index

Abstract. Solar eclipses reduce the measured top-of-atmosphere (TOA) reflectances as derived by Earth observation satellites, because the solar irradiance that is used to compute these reflectances is commonly measured before the start of the eclipse. Consequently, air quality products that are derived from these spectra, such as the ultraviolet (UV) Absorbing Aerosol Index (AAI), are distorted or undefined in the shadow of the Moon. The availability of air quality satellite data in the penumbral and antumbral shadow during solar eclipses, however, may be of particular interest to users studying solar eclipses and their effect on the Earth's atmosphere. Given the time and location of a point on the Earth's surface, we explain how to compute the eclipse obscuration fraction taking into account wavelength dependent solar limb darkening. With the calculated obscuration fractions, we restore the TOA reflectances and the AAI in the penumbral shadow during the annular solar eclipses on 26 December 2019 and 21 June 2020 measured by the TROPOMI/S5P instrument. We verify the calculated obscuration with the observed obscuration using an uneclipsed orbit. In the corrected products, the signature of the Moon shadow disappeared. Not taking into account solar limb darkening, however, would result in a maximum underestimation of the obscuration fraction of 0.06 at 380 nm on 26 December 2019, and in a maximum Moon shadow signature in the AAI of 6.7 points increase. We find that the Moon shadow anomaly in the uncorrected AAI is caused by a reduction of the measured reflectance at 380 nm, rather than a color change of the measured light. We restore common AAI features such as the sunglint and desert dust, and we confirm the restored AAI feature on 21 June 2020 at the Taklamakan desert by measurements of the GOME-2C satellite instrument on the same day but outside the Moon shadow. We conclude that the correction method of this paper can be used to detect real AAI rising phenomena and has the potential to restore any other product that is derived from TOA reflectance spectra. This would resolve the solar eclipse anomalies in satellite air quality measurements in the penumbra and antumbra, and would allow for studying the effect of the eclipse obscuration on the composition of the Earth's atmosphere from space.

Heating of Two-Layer Thermal Protection Coating at Hypersonic Flow around a Spherical Blunting

2021 ◽  
Vol 64 (1) ◽  
pp. 87-96
Author(s):  
V. S. Zarubin ◽  
V. N. Zimin ◽  
V. V. Leonov ◽  
V. S. Zarubin
Keyword(s):  
Hypersonic Flow ◽  
Thermal Protection ◽  
Protection Coating ◽  
Thermal Protection Coating
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