Radio science investigations by VeRa onboard the Venus Express spacecraft

Häusler, B.; Pätzold, M.; Tyler, G. L.; Simpson, R. A.; Bird, M. K.; Déhant, V.; Barriot, J. P.; Eidel, W.; Mattei, R.; Remus, S.; Selle, J.; Tellmann, S.; Imamura, Takeshi

doi:10.1016/j.pss.2006.04.032

Cited by 90 publications

(83 citation statements)

References 71 publications

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“…Pressure and temperature profiles are derived from the density profiles assuming hydrostatic equilibrium and the ideal gas law. Details about the VeRa instrument are described by Häusler et al (2006Häusler et al ( , 2007. The measurements cover nearly all local times, latitudes and longitudes with a gap in the northern middle latitudes resulting from the highly elliptical orbit of Venus Express.…”

Section: Temperature Structure From Radio Occultations -Vera and Akatmentioning

confidence: 99%

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: Temperature Structure From Radio Occultations -Vera and Akatmentioning

confidence: 99%

Venus Atmospheric Thermal Structure and Radiative Balance

et al. 2018

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“…It represents the scale of the smallest aperture that does not disturb a wave in the actual medium (Häusler et al 2006b). For X-band frequency and D = 10, 000 km, the vertical resolution is about 60 m (Häusler et al 2006b). …”

Section: Radio Sounding Of the Venus' Ionospherementioning

confidence: 99%

Ionospheric inversion of the Venus Express radio occultation data observed by Shanghai 25 m and New Norcia 35 m antennas

Zhang

Jian

et al. 2015

Res. Astron. Astrophys.

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The electron density profile (from 110 km to 400 km) retrieved from the X-band egress observation at Shanghai station, shows a single peak near 147 km with a peak density of about 2 × 10 4 cm −3 at a solar zenith angle of 94• . As a comparison, the VEX radio science (VeRa) observations at New Norcia station were also examined, including S-, X-band and dual-frequency data in the ingress mode. The results show that the electron density profiles retrieved from the S-band data are more analogous to the dual-frequency data in the profile shape, compared with the X-band data. Generally, the S-band results slightly underestimate the magnitude of the peak density, while the X-band results overestimate that. The discrepancy in the X-band profile is probably due to the relatively larger unmodeled orbital errors. It is also expected that the ionopause height is sensitive to the solar wind dynamical pressure in high and intermediate solar activities, usually in the range of 200 km -1000 km on the dayside and much higher on the nightside. Structural variations ("bulges" and fluctuations) can be found in the electron density profiles in intermediate solar activity, which may be caused by the interaction of the solar wind with the ionosphere. Considerable ionizations can be observed in the Venus' nightside ionosphere, which are unexpected for the Martian nightside ionosphere in most cases.

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“…The USO is a heritage from the USOs flown onboard the ESA's Rosetta and Venus Express spacecraft (Häusler et al, 2006).…”

Section: Radio Science (Rs)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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Radio science investigations by VeRa onboard the Venus Express spacecraft

Cited by 90 publications

References 71 publications

Venus Atmospheric Thermal Structure and Radiative Balance

Venus Atmospheric Thermal Structure and Radiative Balance

Ionospheric inversion of the Venus Express radio occultation data observed by Shanghai 25 m and New Norcia 35 m antennas

Overview of Venus orbiter, Akatsuki

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