LIR: Longwave Infrared Camera onboard the Venus orbiter Akatsuki

Fukuhara, Tetsuya; Taguchi, Makoto; Imamura, Takeshi; Nakamura, Masato; Ueno, Munetaka; Suzuki, Makoto; Iwagami, N.; Sato, Mitsuteru; Mitsuyama, Kazuaki; Hashimoto, George L.; Ohshima, Ryo; Kouyama, T.; Ando, Hiroki; Futaguchi, Masahiko

doi:10.5047/eps.2011.06.019

Cited by 54 publications

(51 citation statements)

References 35 publications

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“…Akatsuki images are from JAXA The Akatsuki orbiter launched by Japan in May 2010 (Nakamura et al 2007(Nakamura et al , 2016 is beginning to investigate this relationship after a successful orbital insertion around Venus on 7 December 2015, with routine observations beginning in April 2016. The first image of Venus obtained from orbit from the LIR camera (Fukuhara et al 2011) in the 8-12 μm wavelengths shows small scale temperature detail (Fig. 38) which has been previously seen in high resolution thermal infrared images from the Subaru telescope (Sato et al 2014).…”

Section: Absorbers Of Solar Radiation In the Clouds And Cloud Top Temmentioning

confidence: 99%

“…Wild et al (2013) discuss Earth's mean energy balance using both surface stations and spacecraft observations and infer new estimates of global mean surface radiation. Data from the LIR camera on Akatsuki orbiter (Fukuhara et al 2011) measure the emitted radiation by Venus between 8-12 μm. These data are still being gathered and soon analysis of these data should result in newer estimates of the emitted radiation emitted by Venus as a function of latitude.…”

Section: Global Radiative Energy Balancementioning

confidence: 99%

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Venus Atmospheric Thermal Structure and Radiative Balance

et al. 2018

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From the discovery that Venus has an atmosphere during the 1761 transit by M. Lomonosov to the current exploration of the planet by the Akatsuki orbiter, we continue to learn about the planet's extreme climate and weather. This chapter attempts to provide a comprehensive but by no means exhaustive review of the results of the atmospheric thermal structure and radiative balance since the earlier works published in Venus and Venus II books from recent spacecraft and Earth based investigations and summarizes the gaps in [1411][1412][1413][1414] 1986). Thus, most of the new information about the atmospheric thermal structure has come from different remote sensing (Earth based and spacecraft) techniques using occultations (solar infrared, stellar ultraviolet and orbiter radio occultations), spectroscopy and microwave, short wave and thermal infrared emissions. The results are restricted to altitudes higher than about 40 km, except for one investigation of the near surface static stability inferred by Meadows and Crisp (J. Geophys. Res. 101:4595-4622, 1996) from 1 μm observations from Earth. Little information about the lower atmospheric structure is possible below about 40 km altitude from radio occultations due to large bending angles. The gaps in our knowledge include spectral albedo variations over time, vertical variation of the bulk composition of the atmosphere (mean molecular weight), the identity, properties and abundances of absorbers of incident solar radiation in the clouds. The causes of opacity variations in the nightside cloud cover and vertical gradients in the deep atmosphere bulk composition and its impact on static stability are also in need of critical studies. The knowledge gaps and questions about Venus and its atmosphere provide the incentive for obtaining the necessary measurements to understand the planet, which can provide some clues to learn about terrestrial exoplanets.

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Section: Absorbers Of Solar Radiation In the Clouds And Cloud Top Temmentioning

confidence: 99%

Section: Global Radiative Energy Balancementioning

confidence: 99%

Venus Atmospheric Thermal Structure and Radiative Balance

et al. 2018

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“…The UVI is designed to measure ultraviolet radiation scattered from the cloud top altitudes in two bands centered at 283 and 365 nm . The LIR detects thermal radiation emitted from the cloud tops over a rather wide wavelength region of 8-12 μm, and this enables mapping of the cloud top temperatures Fukuhara et al 2011). Unlike other imagers onboard AKAT-SUKI, LIR takes images of both the dayside and nightside equally.…”

Section: Methodsmentioning

confidence: 99%

“…The LIR image shows the thermal radiation emitted from the cloud top altitudes with a single band-pass filter of 8-12 μm Fukuhara et al 2011). This is a composite image that was made by superimposing 32 raw images to improve the signal-to-noise ratio.…”

Section: First Images Of Venus By the Camerasmentioning

confidence: 99%

AKATSUKI returns to Venus

et al. 2016

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AKATSUKI is the Japanese Venus Climate Orbiter that was designed to investigate the climate system of Venus. The orbiter was launched on May 21, 2010, and it reached Venus on December 7, 2010. Thrust was applied by the orbital maneuver engine in an attempt to put AKATSUKI into a westward equatorial orbit around Venus with a 30-h orbital period. However, this operation failed because of a malfunction in the propulsion system. After this failure, the spacecraft orbited the Sun for 5 years. On December 7, 2015, AKATSUKI once again approached Venus and the Venus orbit insertion was successful, whereby a westward equatorial orbit with apoapsis of ~440,000 km and orbital period of 14 days was initiated. Now that AKATSUKI's long journey to Venus has ended, it will provide scientific data on the Venusian climate system for two or more years. For the purpose of both decreasing the apoapsis altitude and avoiding a long eclipse during the orbit, a trim maneuver was performed at the first periapsis. The apoapsis altitude is now ~360,000 km with a periapsis altitude of 1000-8000 km, and the period is 10 days and 12 h. In this paper, we describe the details of the Venus orbit insertion-revenge 1 (VOI-R1) and the new orbit, the expected scientific information to be obtained at this orbit, and the Venus images captured by the onboard 1-µm infrared camera, ultraviolet imager, and long-wave infrared camera 2 h after the successful initiation of the VOI-R1.

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“…LIR (Taguchi et al, 2007;Fukuhara et al, in press) detects thermal emission from the cloud top in a wavelength region 8-12 µm to map the cloud-top temperature, which is typically ∼230 K. Unlike other imagers onboard Akatsuki, LIR is able to take images of both dayside and nightside with equal quality. The cloud-top temperature map will reflect mostly the cloud height distribution, whose detailed structure is unknown except in the northern high latitudes observed by Pioneer Venus OIR and the southern high latitudes observed by Venus Express VIRTIS .…”

Section: Longwave Infrared Camera (Lir)mentioning

confidence: 99%

Overview of Venus orbiter, Akatsuki

et al. 2011

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The Akatsuki spacecraft of Japan was launched on May 21, 2010. The spacecraft planned to enter a Venusencircling near-equatorial orbit in December 7, 2010; however, the Venus orbit insertion maneuver has failed, and at present the spacecraft is orbiting the Sun. There is a possibility of conducting an orbit insertion maneuver again several years later. The main goal of the mission is to understand the Venusian atmospheric dynamics and cloud physics, with the explorations of the ground surface and the interplanetary dust also being the themes. The angular motion of the spacecraft is roughly synchronized with the zonal flow near the cloud base for roughly 20 hours centered at the apoapsis. Seen from this portion of the orbit, cloud features below the spacecraft continue to be observed over 20 hours, and thus the precise determination of atmospheric motions is possible. The onboard science instruments sense multiple height levels of the atmosphere to model the three-dimensional structure and dynamics. The lower clouds, the lower atmosphere and the surface are imaged by utilizing nearinfrared windows. The cloud top structure is mapped by using scattered ultraviolet radiation and thermal infrared radiation. Lightning discharge is searched for by high speed sampling of lightning flashes. Night airglow is observed at visible wavelengths. Radio occultation complements the imaging observations principally by determining the vertical temperature structure.

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LIR: Longwave Infrared Camera onboard the Venus orbiter Akatsuki

Cited by 54 publications

References 35 publications

Venus Atmospheric Thermal Structure and Radiative Balance

Venus Atmospheric Thermal Structure and Radiative Balance

AKATSUKI returns to Venus

Overview of Venus orbiter, Akatsuki

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