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

[Guest_BruceMoomaw_*]

Well, to repeat a point I've suggested (somewhere) on this site before: given the great additional difficulty of designing a Venus probe if you have to add an airlock to it to allow it ingest samples into its interior, how much good compositional data can you get on Venus' surface WITHOUT such an airlock. A surprising amount, I suspect. A test has already shown that the LIBS system planned for instantaneous, precise and long-distance element measurements on the MSL rover should work just as well in Venus' environment ( ).

On Mars and on airless worlds, this instrument can probably be combined with a Raman spectrometer (which also uses laser light) for a lot of mineralogy studies (although this system wasn't considered quite ripe enough by the LIBS group right now to add it to their proposal for the MSL's LIBS; it's worked fine in ground tests). I'm not sure whether Raman would work as well at long-range in the super-dense Venusian atmosphere -- it relies on measuring an extremely small trace of backscattered laser light -- but even if it doesn't, you could put the fiber-optic connections to a Raman spectrometer and its laser on a simple arm on the lander to contact the local surface in different places. You could also add other gadgets to that arm: a microscopic imager, and maybe even an abrading wheel to grind the weathering crust off Venusian rocks -- which the lander could probably locate on the surface using a simple hardness sensor on the arm.)

Add a panning near-IR spectrometer to the lander (plus a tiltable flashlamp (or broadband laser) to periodically illuminate the surface and allow that spectrometer to distinguish its reflectance spectra from thermal emission spectra), and maybe also a gamma-ray spectrometer inside the lander's hull, and you could answer damn near every important scientific question about Venus' surface -- except for in-situ age dating -- without ANY airlock, and without any need for instruments that require a long time to gather their data (such as X-ray and Mossbauer spectrometers). An X-ray diffractometer like the one on MSL (which also requires ingested samples) could provide additional mineralogy data, but I question whether it's really essential by itself given the Raman and near-IR spectrometers.