What would the Venus landers look like today?

Question

Between 1966 and 1985, several probes, mostly of Soviet design, successfully landed on Venus. Many of them continued operating long enough to send back audio, images, and various measurements, though none survived for longer than about two hours.

Given what we know about Venus's atmosphere, including the tremendously high temperature and pressure, what would the probes that made a soft landing look like today if we could see them up close? Would they appear more or less intact, or crumpled like a crushed tin can, or even partly melted like Salvador Dalí's drooping clocks? Would the surfaces show any signs of dust, abrasion, or oxidation?

For reference, there exist various photos of replicas of the Venus landers as well as artists' impressions of the landers on the Venusian surface. (I don't embed these images here as I can't find any good ones that are freely licensed.)

Also note that while an earlier question here about Venus treats the topic of landers getting crushed by atmospheric pressure, its time frame is limited to the exact point when the lander fails. My question is more about what happens to the lander in the long term, after many decades of neglect.

Answer 1

Let's talk about the major materials that made up the Venera landers. https://space.stackexchange.com/a/9965/25 has a great summary of what the landers were made of, they are composed of include Titanium, gold, fiberglass, KG-25 an high-temperature polyurethane foam, and PTKV-260. There are a bunch of other materials, likely including some glass and other things that have the potential, but a complete list of materials isn't available. Most of those wouldn't work.

The titanium already showed signs of oxidation when the probes were working. It is safe to assume that continued. Gold does not oxidize and should have remained. Any fluids and foams would have likely dissolved, just not leaving much. Aluminum likely remained mostly intact, although weakened somewhat through some extra oxidation, it has probably collapsed. It will eventually succumb to the sulfuric acid. Iron will have dissolved in any sulfuric acid that makes it to the surface.

This paper suggests gold, iridium, silicon dioxide, aluminum nitride, silicon nitride, and aluminum oxide are all good materials to use on Venus. I can't find any reference to any of these being used except for gold, and most likely silicon dioxide. Any of these materials would have survived. Most of the rest would be some kind of oxidized mess, although I do suspect that most of it would at least remain close. There is a slight surface wind on Venus which would have blown away the really badly damaged components, but much of them would have only been oxidized versions of what was already there.

Any parts that did survive would be covered in dust, due to the wind. The images we have seen of the surface of Venus show very few rocks, and most of those are pretty small. It is likely that any light wires would have been blown around, along with the severely degraded components. The glass from lenses would have likely remained, along with at least a part of the electronics, but would probably be covered in dust.

Some of the later missions made use of special materials, which probably helped them survive more intact. I can't find any details, but they seem mostly to have been used for the electronics. Aluminum and even iron will last long enough to serve its purpose on Venus, and the limiting factor never was keeping the structure together.

Bottom line, very little is likely left, and what is left would be scattered and covered in dust.

Answer 2

Many thanks to the contributors, fascinating reading.

Something I don't see mentioned here: metal creep. I am drawing on engineering undergrad courses in materials science, crystallography, etc. from 40 yrs ago.

Creep is defined here: https://en.wikipedia.org/wiki/Creep_(deformation)

"In materials science, creep (sometimes called cold flow) is the tendency of a solid material to undergo slow deformation while subject to persistent mechanical stresses. It can occur as a result of long-term exposure to high levels of stress that are still below the yield strength of the material. Creep is more severe in materials that are subjected to heat for long periods and generally increase as they near their melting point."

If the landers are mostly intact, perhaps some components of would look saggy, a little or a lot, inside and out.

I expect the landers are upright and mostly intact, and badly damaged on close inspection.

Inside the spherical pressure shell: whatever can melt has melted, then dripped or fallen into pool/pile at the bottom, some solid pieces snagging on still-attached parts on the way down.

If Venus is geologically active, ground tremors over decades - even small ones - would perhaps cause parts made fragile to fall off. This paints a mental picture of long periods of increasing fragility followed by sudden small collapses if/when a tremor occurs.

It would be interesting to see a rendered image of the present state, produced by a running fine-grained software materials-based model of a lander, aged according to its environment.

Remarkable project, Venera.