scholarly journals Geometric correction for thermographic images of asteroid 162173 Ryugu by TIR (thermal infrared imager) onboard Hayabusa2

2021 ◽  
Vol 73 (1) ◽  
Author(s):  
Takehiko Arai ◽  
Tatsuaki Okada ◽  
Satoshi Tanaka ◽  
Tetsuya Fukuhara ◽  
Hirohide Demura ◽  
...  
Keyword(s):  
Surface Roughness ◽  
High Surface ◽  
Thermal Inertia ◽  
Thermal Infrared ◽  
Shape Model ◽  
Infrared Imager ◽  
Least Squares Fit ◽  
Temperature Maps ◽  
Pixel Scale ◽  
Thermal Infrared Imager

AbstractThe thermal infrared imager (TIR) onboard the Hayabusa2 spacecraft performed thermographic observations of the asteroid 162173 Ryugu (1999 JU$$_3$$ 3 ) from June 2018 to November 2019. Our previous reports revealed that the surface of Ryugu was globally filled with porous materials and had high surface roughness. These results were derived from making the observed temperature maps of TIR using a projection method onto the shape model of Ryugu as geometric corrections. The pointing directions of TIR were calculated using an interpolation of data from the SPICE kernels (NASA/NAIF) during the periods when the optical navigation camera (ONC) and the light detection and ranging (LIDAR) observations were performed. However, the mapping accuracy of the observed TIR images was degraded when the ONC and LIDAR were not performed with TIR. Also, the orbital and attitudinal fluctuations of Hayabusa2 increased the error of the temperature maps. In this paper, to solve the temperature image mapping problems, we improved the correction method by fitting all of the observed TIR images with the surface coordinate addressed on the high-definition shape model of Ryugu (SFM 800k v20180804). This correction adjusted the pointing direction of TIR by rotating the TIR frame relative to the Hayabusa2 frame using a least squares fit. As a result, the temperature maps spatially spreading areas were converged within high-resolved $$0.5^\circ$$ 0 . 5 ∘ by $$0.5^\circ$$ 0 . 5 ∘ maps. The estimated thermal inertia, for instance, was approximately 300$$\sim$$ ∼ 350 Jm$$^{-2}$$ - 2 s$$^{-0.5}$$ - 0.5 K$$^{-1}$$ - 1 at the hot area of the Ejima Saxum. This estimation was succeeded in case that the surface topographic features were larger than the pixel scale of TIR. However, the thermal inertia estimation of smooth terrains, such as the Urashima crater, was difficult because of surface roughness effects, where roughness was probably much smaller than the pixel scale of TIR.

scholarly journals Geometric Correction for Thermographic Images of Asteroid 162173 Ryugu by TIR (Thermal Infrared Imager) onboard Hayabusa2

2021 ◽  
Author(s):  
Takehiko Arai ◽  
Tatsuaki Okada ◽  
Satoshi Tanaka ◽  
Tetsuya Fukuhara ◽  
Hirohide Demura ◽  
...  
Keyword(s):  
Thermal Inertia ◽  
Thermal Infrared ◽  
Correction Method ◽  
Geometric Correction ◽  
Shape Model ◽  
Mapping Procedure ◽  
Infrared Imager ◽  
Least Squares Fit ◽  
Pixel Scale ◽  
Thermal Infrared Imager

Abstract The thermal infrared imager (TIR) onboard the Hayabusa2 spacecraft performed thermographic observations of the asteroid 162173 Ryugu (1999 JU3) from June 2018 to November 2019. Our previous reports showed the surface temperature and thermal inertia maps of Ryugu. At that time, the mapping procedure from observed TIR images to the shape model of Ryugu has been developed as a geometric correction method. The method used the shape model derived from the observed images by the optical. navigation camera (ONC), a numerical geometry toolkit, SPICE kernels (NASA/NAIF) based on the spacecraft attitude data derived from ONC images, and the measured altitudes by the light detection and ranging (LIDAR). The pointing directions of TIR were calculated using an interpolation of data from SPICE kernels during the periods when the ONC or LIDAR observation was performed. Still, the mapping accuracy of the observed TIR images was degraded when the ONC and LIDAR observations were not performed with TIR. In this paper, to solve the problem of the mapping procedure, we improved the correction method by matching the TIR images, which carried out a one-to-one correspondence between the observed points in the TIR images and the surface nodes addressed on the shape model of Ryugu. This geometric correction adjusted the pointing direction of TIR by rotating the TIR frame relative to the base of the Hayabusa2 frame using a least squares fit. The resulting temperature maps spatially spreading more than 10° were improved after the correction, and high-resolved 0.5° by 0.5° maps were constructed. The geometric correction was effective for characteristic regions where the terrain was comparable to the pixel scale of TIR, such as the Ejima Saxum. The estimated thermal inertia of the bottom of Ejima Saxum was approximately 300 Jm-2s-0.5K-1. Thus this estimation was succeeded in case that the surface topographic features were the pixel scale of TIR. However, the thermal inertia estimation of smooth terrains, such as the Urashima crater, was difficult because of surface roughness effects, where roughness was probably less than the pixel scale of TIR.

scholarly journals Geometric Correction for Thermal Imaging of Asteroid Ryugu Observed by TIR onboard Hayabusa2

2020 ◽  
Author(s):  
Takehiko Arai ◽  
Tatsuaki Okada ◽  
Satoshi Tanaka ◽  
Tetsuya Fukuhara ◽  
Hirohide Demura ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Thermal Inertia ◽  
Small Scale ◽  
Geometric Correction ◽  
Roughness Effects ◽  
Shape Model ◽  
Topographic Features ◽  
Infrared Imager ◽  
Least Squares Fit ◽  
Thermophysical Model

Abstract The thermal infrared imager (TIR) onboard the Hayabusa2 spacecraft performed thermographic observations of the asteroid 162173 Ryugu (1999 JU3) from June 2018 to November 2019. In this study, we performed a geometric correction for TIR images by making a one-to-one correspondence between the observed areas and the surface coordinates derived from a shape model of Ryugu. The pointing direction, which is an alignment direction of TIR, was adjusted by rotating the TIR frame relative to the base of the Hayabusa2 frame using a least-squares fit. This geometric correction allows us to identify observed local areas within one pixel, which corresponds to 5 m error in a 5 km altitude observation. The corrected temperature images projected onto the shape model were constructed. Hot temperature regions were found at the base of Ejima Saxum and Otohime Saxum, for instance. A simulation result indicates that multiple radiations from the surrounding terrains generate hot regions. The estimated thermal inertia of the base of Ejima Saxum as characteristic shape area is approximately 300 Jm -2 s -0.5 K -1 within the error bars of the observed temperature profile. This estimation is succeeded by performing the geometric correction in case that the surface topographic features are greater than the spatial resolution of the pixel. However, thermal inertia estimations of smooth terrains, such as the floor of Urashima crater, were difficult probably because of surface roughness effects. Our results suggest the necessity to develop a hybrid thermophysical model that implements large- and small-scale surface roughness.

Correlation Between Ion Contents in Acupuncture Points and Propagated Sensation a long with Channel

2021 ◽  
Author(s):  
Fu Shin Lee ◽  
Tai An Chiang ◽  
Jou Ying Lee ◽  
Chen I Lin
Keyword(s):  
Thermal Infrared ◽  
Experimental Results ◽  
Intense Pulse Light ◽  
X Ray ◽  
Pulse Light ◽  
Infrared Imager ◽  
Significant Temperature ◽  
Light Beams ◽  
X Ray Absorption ◽  
Thermal Infrared Imager

Background: Propagated sensation along with channels are phenomena that occur because of stimulations during acupuncture therapies and tend to transmit the stimulating signals along the meridians. From the Western medicine aspect, researchers consider the phenomena as neurotransmissions initiated by nerves, and various ions regulate the physiological functions of the nervous systems.Objective: The object of this research is to investigate the key characteristics of ions at acupoints and the mechanism of propagated sensation along with channels, which are crossing meridians in traditional Chinese medicine (TCM).Methods: This research first conduct experiments by applying intense pulse light beams, which replace the traditional acupuncture treatments, on designated acupoints of studied human subjects, and employ a thermal infrared imager to monitor the temperature responses, which are induced by post sensation, in adjacent regions of the acupoints. Meanwhile, the research applies a synchrotron radiation technique on adult SD (Sprague Dawley) rats, and the study analyses the output responses with an X-ray Absorption Fine Spectroscopy (XAFS) to investigate the ion distributions in the relevant acupoints, which might trigger the propagated sensation crossing meridians.Results: Experimental results demonstrate that significant temperature increases simultaneously at the stimulated acupoints and certain other acupoints, whether in the same meridians. Moreover, XAFS experimental results indicate significantly high levels of calcium, potassium, and sulfide ions at the stimulated acupoint regions. On the contrary, the measured chloride ions level at the regions is correspondingly lower.Conclusions: The thermal infrared imager monitoring show significant temperature variations of crossing-meridian acupoints after implementing the intense pulse light beams on designated acupoints, and it implies the occurring of prolonged sensation along with channels using acupuncture therapies. The x-ray absorption spectrum demonstrates significant differences in ion amounts and distributions between the acupoints and non-acupoints, and acupuncture therapies result in ion concentrations in the correlated regions inducing propagated sensation crossing meridians in TCM. Hence, the stimulated acupoints operate as ion reservoirs to provide high-concentration of specific ions to trigger the crossing-meridian post sensation.

Temperature Field Measurement of Turning Tool with Thermal Infrared Imager

2011 ◽  
Vol 305 ◽  
pp. 265-268
Author(s):  
Yan Ming Quan ◽  
Hao Xu ◽  
Zhi Yong Ke
Keyword(s):  
Temperature Field ◽  
High Temperature ◽  
Thermal Infrared ◽  
Rake Face ◽  
Surface Emissivity ◽  
Thermal Images ◽  
Infrared Imager ◽  
Measurement Results ◽  
Carbide Insert ◽  
Thermal Infrared Imager

The variety of surface emissivity of carbide insert P10 against temperature raise is calibrated with antitheses. The influence of high temperature object near the carbide insert and the open measurement environment of the thermal infrared imager on the calibrated values are investigated. Then the thermal images of turning tool’s rake face are continuously captured by an infrared imager in the designed turning experiment. In the analysis of thermal images, the influence of measurement environment is taken into consideration and varied emissivity values are used to analyze the temperature in different areas of the rake face. A series of measurement results of temperature field in the rake face are achieved and they are consistent with the conventional rules of turning researches.

scholarly journals Analysis of theoretical model of thermal infrared imager based on the substrate-free focal plane array

2011 ◽  
Vol 60 (5) ◽  
pp. 054401
Author(s):  
Jiang Xing-Kai ◽  
Zhang Qing-Chuan ◽  
Shi Hai-Tao ◽  
Mao Liang ◽  
Cheng Teng ◽  
...  
Keyword(s):  
Theoretical Model ◽  
Focal Plane ◽  
Thermal Infrared ◽  
Focal Plane Array ◽  
Infrared Imager ◽  
Thermal Infrared Imager
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