Speculating on the current conditions of defunct probes.

[Minmus Taster]

I'm particularly interested in what's left of the old 'Venera' probes, would they have been totally destroyed by now?

Another interesting one is the 'Huygens' on Titan, it is supposed to have landed in a dried up riverbed so is it possible it was swept away to another location? It was designed to float after all.

[Nuke]

i expect a puddle of metal but with russian big metal ball construction that puddle is probably contained by the lander hull.

[SunlitZelkova]

16 hours ago, Minmus Taster said:

Another interesting one is the 'Huygens' on Titan, it is supposed to have landed in a dried up riverbed so is it possible it was swept away to another location? It was designed to float after all.

If it's dried up it's unlikely it will get wet again? I think.

16 hours ago, Minmus Taster said:

I'm particularly interested in what's left of the old 'Venera' probes, would they have been totally destroyed by now?

If it was built to survive at all, it's likely still there.

A sunk submarine doesn't disappear from the water just because it sinks, it only does so if it goes below crush depth. And this thing was designed to go to Venusian "crush depth" and survive.

[darthgently]

3 hours ago, SunlitZelkova said:

 

A sunk submarine doesn't disappear from the water just because it sinks, it only does so if it goes below crush depth. And this thing was designed to go to Venusian "crush depth" and survive

Corrosion?  I imagine it is a loose pile of reduced flakes and dust with a few parts made of odd materials still recognizable.It could have been swallowed completely by a molten volcanic outflow by now also

Edited February 27 by darthgently

[darthgently]

2 hours ago, SunlitZelkova said:

If it's dried up it's unlikely it will get wet again? I think.

I thought Titan [edit: am I confusing with Enceladus?] had methane geysers and rains and cracks in the ground opening and refreezing sporadically.

Also, don't assume the "dry river beds" in Arizona stay dry, for example.  They are called "washes" for a reason

[farmerben]

It might be fairly well preserved.  Certain components will have melted but probably not all of it.

[StrandedonEarth]

1 hour ago, darthgently said:

Corrosion?  I imagine it is a loose pile of reduced flakes and dust with a few parts made of odd materials still recognizable.It could have been swallowed completely by a molten volcanic outflow by now also

IIRC the atmosphere has a good proportion of sulfuric acid (although I'm not sure if that it true at ground level) so I think this is the most likely condition of Venera...

[kerbiloid]

On 2/26/2024 at 7:15 PM, Minmus Taster said:

old 'Venera' probes, would they have been totally destroyed by now?

Since Venera-7 the lander balls were made of titanium, so they don't care of that puny Venus.

The previous ones were aluminium, so their balls are  smashed, and are metal scrap. But still far from melting point.

As any plastic has probably decayed, they are metal scrap, shaped as a lander.

 

[darthgently]

26 minutes ago, kerbiloid said:

Since Venera-7 the lander balls were made of titanium, so they don't care of that puny Venus.

Sulphuric acid does reduce titanium above room temperatures, so consider the far higher than room temperatures at Venus' surface.   Heat accelerates chemical reactions, so maybe think super pressure cooker with strong acid tossed in.  Maybe some kind of ceramic but I wouldn't figure Ti to still be there

[kerbiloid]

8 minutes ago, darthgently said:

Sulphuric acid does reduce titanium above room temperatures, so consider the far higher than room temperatures at Venus' surface

Quote

about 65 kg m⁻³

 

At the surface of Venus, the temperature is 464 °C, hot enough to melt lead. Atmospheric density at the surface is about 65 kg m⁻³ or 6.5% the density of liquid water¹. Atmospheric composition is 96.5% CO₂ and 3.5% N₂ (by volume)².

It's much less concentrated around it, than in any solution.

[darthgently]

21 minutes ago, kerbiloid said:

It's much less concentrated around it, than in any solution.

But look at what mere rain water does on Earth materials at our pressures .  Now make it rain an acid solution at much higher temps and pressures for decades.  Never mind the volcanic gasses on the surface. HF,  HCl etc.  I'm still picturing reduced flakes and dust at this point, but who knows?

 

[kerbiloid]

30 minutes ago, darthgently said:

But look at what mere rain water does on Earth materials at our pressures

Water is not gas. It's by orders of magnitude denser, and it's a polar solvent.

While CO2 is mostly inert to the metals in absence of water, and the sulfuric ions in it are just traces.

[darthgently]

12 minutes ago, kerbiloid said:

Water is not gas. It's by orders of magnitude denser, and it's a polar solvent.

While CO2 is mostly inert to the metals in absence of water, and the sulfuric ions in it are just traces.

Some researchers suggest that rainfall of highly acidic water occurs on Venus.  The clouds are acidic water vapor.  But, as noted, who knows?  I haven't been there myself

[SunlitZelkova]

19 hours ago, darthgently said:

I thought Titan [edit: am I confusing with Enceladus?] had methane geysers and rains and cracks in the ground opening and refreezing sporadically.

Also, don't assume the "dry river beds" in Arizona stay dry, for example.  They are called "washes" for a reason

I suppose so. To be completely honest I'm not that all familiar with southwestern geography*. Here in Oregon and Washington a dry riverbed is usually one that ceased to exist millions of years ago.

*Darn you public school system circa the 2000s! (although TBH I don't know if the geography of states that are not your own is ever taught, or was ever taught at all beyond a few simple keywords)

[Piscator]

While it is highly doubtful that any rain of sulphuric acid reaches the surface (since it would boil away long before), the sulphur compounds in the Venusian atmosphere still contribute to its overall corrosiveness in a major way if you can believe this paper. Unfortunately, it doesn't say anything about titanium, but any copper wiring would have turned into a mass of dendritic copper sulphide crystals long ago, it appears. Aluminium seems to be fairly stable but traces of alloyed magnesium oxidize quickly. Steel in general doesn't fare very well either, slowly reacting with the simulated atmosphere to iron and chromium oxides and nickel sulphide, depending on the original composition.

 

PS According to the follow-up study, titanium seems to be quite stable under Venusian surface conditions.

[Hannu2]

18 hours ago, darthgently said:

Some researchers suggest that rainfall of highly acidic water occurs on Venus.  The clouds are acidic water vapor.  But, as noted, who knows?  I haven't been there myself

As far as I know that rain may happen high in atmosphere. But temperatures near surface are well beyond water's and sulfuric acid's boiling point and liquid rain can never reach the surface.

It is difficult to say how dry acid vapor affects to metals based on corrosion in normal conditions on Earth. Usually dry acid vapors are far less corrosive than in humid environment. I planned once a reactor for semiconductor epitaxy. It used HCl gas in 316 stainless steel tubes at several hundreds of C and over 1000 C in quartz tubes. Trick was that it was extremely dry gas (2 % HCl in H2 if I remember correctly). A little bit water vapor in mixture and life of tubing had been minutes.

I think sulfuric acid is also much less reactive on Venus's surface than water solutions commonly used in laboratory or industry. But I do not have an idea how just titanium can handle it.

 

 

[Hannu2]

3 hours ago, Piscator said:

PS According to the follow-up study, titanium seems to be quite stable under Venusian surface conditions.

Interesting articles, thank you for searching them. List of suitable metals seems to be very short and impractical. Titanium seems to be only option for large structures.

[kerbiloid]

We need to deliver a titanium-hull submarine to Venus. It will withstand both pressure and corrosion.

P.S.
Wait... Wasn't it actually a prototype of a venusian combat rover?

[darthgently]

29 minutes ago, Hannu2 said:

As far as I know that rain may happen high in atmosphere. But temperatures near surface are well beyond water's and sulfuric acid's boiling point and liquid rain can never reach the surface.

That makes total sense, thanks.  I'm picturing the atmosphere there as a big separation column now with gradients of pressure and temperature and with gravity at one end.   

Vaporization depends on pressure and temperature as well as the elements and molecules involved so given the images from Venera-? above and what you are saying temperature wins over pressure wrt surface liquid water.  I wonder what precipitates or vapors reach the ground from above?  What is that dust around the probe composed of?  What vapors and liquids emerge from the ground via volcanism?  What could be in liquid form at the surface periodically, aside from lead, and what kind of chemistry exists among all these things at the surface.  It is hard for me to see it as a kind soup to successfully steep in for decades even for titanium which becomes more reactive with temperature and pressure as does nearly everything.  

I wasn't kidding about ceramics and it would be cool if a future Venera or other could find out more over a longer period of time.  Especially if they could land it near enough to a prior probe to use images and even samples of its remains to ascertain longer term chemistry there.  Maybe powered from some chemical gradient available there?  Interesting stuff

[darthgently]

23 minutes ago, kerbiloid said:

We need to deliver a titanium-hull submarine to Venus. It will withstand both pressure and corrosion.

More of a submarine/dirigible hybrid but with the right displacement it should be mobile with needing wheels?  The next Venus probe could be like this with a fully mechanical control system.  A nano Babbage-difference-engine-inspired computer made of nanoscale silicon parts.

[Hannu2]

4 hours ago, kerbiloid said:

We need to deliver a titanium-hull submarine to Venus. It will withstand both pressure and corrosion.

P.S.
Wait... Wasn't it actually a prototype of a venusian combat rover?

 

If density of atmosphere is 65 kg/m^3 it would not be a bad idea. Mass of 1 m^3 sphede made from 0.5 mm titanium sheet is about 11 kg. If it was filled with hydrogen at ambient pressure hydrogen would take about 3-4 kg and submarine or balloon or whatever would lift about 50 kg control systems and scientific payload.

Or maybe also machine gun but it may take couple of decades before anyone on Earth think Venus is worth conquering.

Edited February 28 by Hannu2

[Nuke]

11 hours ago, SunlitZelkova said:

I suppose so. To be completely honest I'm not that all familiar with southwestern geography*. Here in Oregon and Washington a dry riverbed is usually one that ceased to exist millions of years ago.

*Darn you public school system circa the 2000s! (although TBH I don't know if the geography of states that are not your own is ever taught, or was ever taught at all beyond a few simple keywords)

rivers in the desert are usually dry most of the year but they can turn into roaring torrents during the monsoon season late summer early fall. i actually rather liked that time of year, you can go outside in the warm rain and splash in puddles and the like.  not like here in se alaska where you can get hypothermia fast if you get a little wet.

Edited February 28 by Nuke

[Nuke]

13 hours ago, darthgently said:

More of a submarine/dirigible hybrid but with the right displacement it should be mobile with needing wheels?  The next Venus probe could be like this with a fully mechanical control system.  A nano Babbage-difference-engine-inspired computer made of nanoscale silicon parts.

silicon carbide semiconductors may be able to give you a computer of sorts. it will be slow, and you will need ceramic pcbs with gold traces, so it wont be cheap. bigger problem is the camera. while you can use an old school camera tube, i dont think there is a transparent lens material that will last very long. power is another issue. you cant use solar, you cant really use batteries either. you might be able to do a cryogen battery, where you use the venutian heat to provide the hot side and boiling ln2 to provide the cold side on a silicon carbide peltier device (which im not even sure would work with that material) but i cant imagine that running for very long. a vertical axis wind turbine might work and provide direct mechanical power through a titanium gear train. not sure if you could make a generator, not sure if there is a material with a high enough curie point for a permanent magnet. assuming electromagnets still work (they work on the sun) you would need a gold coil induction motor. you cant even use the regular enamel coating, you would have to somehow embed gold wire into a ceramic substrate. at least ceramic bearings are a thing, but you would need to land in a way where you don't shatter them.

[darthgently]

20 minutes ago, Nuke said:

silicon carbide semiconductors may be able to give you a computer of sorts. it will be slow, and you will need ceramic pcbs with gold traces, so it wont be cheap. bigger problem is the camera. while you can use an old school camera tube, i dont think there is a transparent lens material that will last very long. power is another issue. you cant use solar, you cant really use batteries either. you might be able to do a cryogen battery, where you use the venutian heat to provide the hot side and boiling ln2 to provide the cold side on a silicon carbide peltier device (which im not even sure would work with that material) but i cant imagine that running for very long. a vertical axis wind turbine might work and provide direct mechanical power through a titanium gear train. not sure if you could make a generator, not sure if there is a material with a high enough curie point for a permanent magnet. assuming electromagnets still work (they work on the sun) you would need a gold coil induction motor. you cant even use the regular enamel coating, you would have to somehow embed gold wire into a ceramic substrate. at least ceramic bearings are a thing, but you would need to land in a way where you don't shatter them.

As long as the coils don't heat up so much from drive current to reach 1000C or so gold could be a good choice.

Power is a problem for sure.  Even an RTG or nuked sterling generator could be challenged by the high temp of the cold sink available there.

As for camera lenses, why not pin-hole cameras?  Light gathering would seriously suffer, but maybe an array of hundreds of pinhole cameras and some insect eye inspired signal fusion processing?

[Nuke]

2 minutes ago, darthgently said:

As long as the coils don't heat up so much from drive current to reach 1000C or so gold could be a good choice.

Power is a problem for sure.  Even an RTG or nuked sterling generator could be challenged by the high temp of the cold sink available there.

As for camera lenses, why not pin-hole cameras?  Light gathering would seriously suffer, but maybe an array of hundreds of pinhole cameras and some insect eye inspired signal fusion processing?

a one pixel cameras can be used in a scanning mechanical arrangement. it might take a long time to scan a frame but it will give you some images.