Future Venus Missions Options

[Phil Stooke]

Oh well, might as well start that new topic since it's already well advanced in the Juno area...

My perspective on landers is as follows. All the landers we've had so far were dropped blind onto an essentially unknown surface. Any future landers can be targeted for specific terrains. It really is not true that we have had representative landings. Even a descent image or two, a panoramic photo plus a bit of surface composition, from a simple Venera-class lander just updated a bit, would be useful if we could put several down at well chosen targets. My choices would be:

Examples of the main plains units (smooth, fractured, ridged)

tesserae

high elevation radar-bright tesserae

large fresh lava flow unit ('fluctus')

crater dark parabola

crater ejecta outflow unit

dunes area.

And I have always assumed, rightly or wrongly, that it would be relatively easy to put these down, so they ought to be fairly inexpensive as planetary landers go.

Phil

[Phil Stooke]

I think the whole issue of earth-based identification of craters on Mars is frequently misrepresented.

If I look up at the Moon without a telescope I can see Mare Crisium... it's a dark circular patch which lies in a crater, a big crater which we often call a basin, but a crater nonetheless. But I'm not seeing the crater, the depression, I'm only seeing the dark floor. I simply don't believe that Mellish or Barnard or anyone else ever saw a crater. They only saw - at most - circular albedo markings. The idea that they were craters was pure guesswork, based on the appearance of Plato, Crisium etc. on the Moon. The best proof of this is the case of Nix Olympica, a prominent circular bright spot, trumpeted as a crater when Mariners 6 and 7 appeared to resolve it as a crater with a central peak. But it wasn't.

Phil