Current Constraints on Ancient Venus

Tessera terrain on Venus is complexly deformed and stratigraphically older than the plains with a crater age 1 to 1.4x the global average of 0.5 – 1 Gy. As such, the Venus tesserae are likely our only record of the first 80% of the history of the planet. Determination of specific rock types in the tesserae will provide critical insights into an early period of Venus’ history. Several observations demonstrate that the tesserae were formed during an extinct epoch. They were formed during a high strain rate and higher heat flow. The Venus Express data show that tesserae have a lower ~1μm emissivity than the plains, which indicate that the tesserae have a lower FeO content and this may have formed due to plate recycling on a planet with surface water. The tesserae have a range of morphologies indicating lateral accretion and assembly. In this talk, I will discuss our present understanding of this terrain as we look forward to three missions to Venus in the coming decade.