VISTA: Venus in Situ Transfer and Analysis Mission Concept

After Magellan 30 years ago, US Venus exploration has relied on archived data, Earth-based and flyby observations of missions bound elsewhere, and international efforts such as Venus Express (ESA) and Akatsuki (JAXA) until the selection of NASA Discovery missions VERITAS and DAVINCI and participation in ESA's EnVision. These missions will address a significant number of major science questions about the past and present of Venus. Nevertheless, many additional and crucial questions about the history of Venus, including its similarities and differences from Earth, will remain unresolved even after the success of these new missions. Significant divergences in planetary evolution of Venus and Earth require knowledge that is not obtainable by the selected suite of upcoming missions, but can be attained by an innovative approach in the next 20 years if precursor science and technology paves the way. In the same way that the Mars Exploration Rovers, Mars Science Lab, and Perseverance have provided measurements that unravel the mysteries of Mars, the Venus In Situ Transfer and Analysis mission concept (VISTA) provides an opportunity to obtain measurements that cannot be obtained by a simple, short-term mission to Venus. VISTA would provide detailed knowledge of the surface and atmosphere to better understand the origin and evolution of Venus, its geology and former habitability, and the interaction of its surface with the atmosphere. Since the surface environment of Venus is not conducive to long-term missions, we propose a long duration, sky-borne laboratory in the Venus upper atmosphere, maintained at temperatures and pressures favorable for extended laboratory measurements that shed light on the composition and history of minerals and rocks retrieved from the surface. VISTA is a concept for a flagship mission to collect samples from multiple locations on the planet surface, and from the Venus atmosphere, and deliver them to a highly-capable, longlived aerial laboratory for detailed analysis with modern instrumentation. Characterizing the composition, structure, and isotopic ratios of these samples will answer questions of surface composition across multiple geologic provinces. These measurements will help answer questions about the fundamental branch points in the evolution of Venus. Studies of atmospheric aerosols will support models of cloud formation. The longevity of VISTA will provide further information on atmospheric circulation, and provide a platform for detecting rare seismic and volcanic events. Any in situ Venus mission faces significant technical and operational challenges. VISTA shares some challenges with past and current in situ concepts, and presents its own unique challenges (e.g. asset rendezvous, sample processing, and longlived laboratory platform). This paper describes the architecture and trades of the VISTA mission concept for the aerial laboratory, (multiple) sampling landers, ascent vehicles, and sample retrievers.