Cross-link Radio Occultation measurements of the Venus Atmosphere by using multiple small satellites

Abstract:

Radio occultation measurements are usually conducted concurrently with optical measurements. Radio waves are transmitted from the spacecraft, refracted in the planetary atmosphere, and received at a ground station. From the measured atmospheric Doppler shift, we can obtain a vertical temperature profile with a high accuracy (measurement error ~ 0.1 K) and a high vertical resolution (~1 km). This is useful for us to investigate the atmospheric structure in the vertical direction. In the case of a conventional radio occultation measurement, however, the observational region and chance are limited by the orbit of a spacecraft and the spatial positions of a spacecraft, a planet and the Earth. One of the methods to overcome this weak point is a cross-link radio occultation technique among the multiple spacecraft.

We consider the cross-link radio occultation measurements of the Venus atmosphere by using multiple small satellites in terms of both engineering and science. It is assumed that they are conducted by one main satellite and two sub satellites. As a result of the trade-off between the fuel consumption for orbit insertion and transfer and the number of observation point, it is expected that the number of measurements would be 179 in the rotation period of Venus super-rotation (4 Earth days) and the observation points could distribute globally. This enables us to obtain four-dimensional data of temperature and pressure. If the submillimeter, ultra-violet and infrared imaging measurements were also conducted, we would investigate the cloud physics and the photochemistry as well as the atmospheric structure and dynamics. In addition, we might be able to create more precise Venusian meteorological model by using a data assimilation technique. In this presentation, we are going to talk about the current status and the future prospect of this conceptual study.