Venus stratospheric sounder: first in situ measurements in upper cloud region

In spite of intensive ground-based and space observations, many major questions about the Venus are still unanswered. Among them are the nature, pattern and evolution of the atmospheric circulation in the troposphere and stratosphere, the nature and distribution of the UV-absorber, and the structure and composition of the stratospheric clouds. There is no accurate data on the vertical structure of the lowest 12 km . The stratosphere, with exception of the probes’ accelerometer data, has been essentially unexplored with in situ measurements. It is also unknown if any noticeable changes in the structure and circulation of the atmosphere have occurred since the last VEGA mission in 1985. Future missions, such as the Venus Surface Sample Return Mission, require improved knowledge of the Venus atmospheric environment where these missions need to operate with much better accuracy and less risk than before. The proposed Venus Statospheric Sounder Mission could serve as a low-cost effective precursor to this more ambitious project. The main element of the mission is the balloon-borne sonde that will ascend to 80– 82 km altitude after aerial deployment and inflation at 55– 60 km and will transmit data direct to Earth on the way through the atmosphere. The basic set of instruments may include pressure and temperature sensors, nephelometer, and sensors to measure the chemical composition of clouds. Differential Very Long Base Interferometry tracking of the balloon will give an accurate wind profile of the atmosphere of Venus. It will be the first mission that will provide data on the Venus stratosphere with high vertical resolution. The mission is lightweight and can be delivered on the Micromission Probe Vehicle.