Exploring Venus with Balloons - Science Objectives and Mission Architectures for Small and Medium-Class Missions
Author(s)
Hall, Jeffery L.
Baines, Kevin H.
Zahnle, Kevin J.
Limaye, Sanjay
Atreya, Sushil K.
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Abstract
Following the trailblazing flights of the 1985 twin Soviet VEGA balloons, missions to fly in the skies of Venus have been proposed to both NASA's Discovery Program and ESA's Cosmic Visions amd are currently being planned for NASA's next Frontiers Mission opportunity. Such missions will answer fundamental science issues highlighted in a variety of high-level NASA-authorized science documents in recent years, including the Decadal Study, various NASA roadmaps, and recommendations coming out of the Venus Exploration Analysis Group (VEXAG). Such missions would in particular address key questions of Venus's origin, evolution, and current state, including detailed measurements of (1) trace gases associated with Venus's active photo- and thermo-chemistry and (2) measurements of vertical motions and local temperature which characterize convective and wave processes. As an example of what can be done with small and medium class missions (less than $900M and $500M, respectively), the Venus Aerostatic-Lift Observatories for in-situ Research (VALOR) Discovery and New Frontiers mission concepts will be discussed. Floating in Venus's rapid windstream near an altitude of 55 km, VALOR's twin balloon-borne aerostats will sample rare gases and trace chemicals and measure vertical and horizontal motions and cloud aerosols within Venus's dynamic middle cloud layer. Each balloon will explore a distinctive dynamical/meteorological region within Venus's energetic atmosphere as each circles the globe for over a week, with one drifting in the cloudy north polar region and the other flying in the less-cloudy but more convective temperate region. The New Frontiers concept would carry several drop sondes that would provide vertical profiles from 55 km down to the surface of temperature, pressure, winds, and the abundances of key reactive gases including SO2, CO, and H2O. In addition, each drop sonde would obtain stereoscopic images and spectra of the surface. Each of these VALOR missions would test a variety of scenarios for the origin, formation, and evolution of Venus by sampling all the noble gases and their isotopes, especially the heaviest elements never reliably measured previously, xenon and krypton. Riding the gravity and planetary waves of Venus a la the VEGA balloons in 1985, the VALOR balloons would sample in particular the chemistry and dynamics of Venus's sulfur-cloud meteorology. Tracked by an array of Earth-based telescopes, zonal, meridional, and vertical winds would be measured with unprecedented precision. Such measurements will help in developing our fundamental understanding of (1) the circulation of Venus, including the role of waves in powering the planet's poorly-understood super-rotation, (2) the nature of Venus's sulfur cycle, key to Venus's current climate, and (3) how Earth's neighbor formed and evolved over the aeons.
Sponsor
NASA
Date
2008-06-26
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