We basically have a huge generation gap with Venus, and we really need something to launch in the early- to mid-2020s so we can maintain some kind of continuity.”
I’m not a planetary scientist, but I’m still disappointed that two proposed Venus missions lost out to two more (still-interesting looking) asteroid missions in the latest NASA mission selections.
Because I am interested in how plate tectonics works, and in that respect Venus is an important outlier. It is the same size, and has the same basic composition, as the Earth, which means it must have a hot interior and almost certainly has a convecting mantle. But as well as being a lander-melting hellhole, Venus also lacks any obvious plates or plate boundaries; so how does Venus’s internal heat get out? Sending back a radar mapper (which was one of the proposed missions) would offer the intriguing possibility of observing surface changes since the Magellan mission, which might reveal signs of tectonic and volcanic activity. Understanding how it is different is the first step to understanding why Earth became Earth and Venus became Venus – which is an increasingly important question as we start peering towards ‘Earth-like’ exoplanets.
That said, the very nature of Venus makes designing missions that have a good chance of answering that question very challenging. It has taken years of roving on Mars to start getting the basics of Mars’s geological history worked out. It is hard to see such insights flowing so easily from a Venus lander that may last only days.