The new evidence suggesting a wetter Venusian history comes from a series of experiments documenting the chemical stability of tremolite for several billion years at temperatures similar to that of Venus' surface, about 740 degrees Kelvin - roughly 870 degrees Fahrenheit.
Tremolite is a mineral that forms in the presence of water.
If tremolite or some other hydrous mineral can be detected on the surface of Venus, then it can be concluded that Earth's once-wet neighbor lost its water over time, putting to rest an enduring question in planetary science. We have shown that tremolite can withstand extreme temperatures and remain intact for billions of years. If we can go to Venus and find tremolite, or some other hydrous mineral, then we would have proof that Venus had water in its past. Johnson and Fegley's research on the decomposition rate of tremolite shows that the evidence is in the rocks. When you go backpacking, you want to know where you are going and what you need to carry.