Vacuum tubes for venus rover?

[ELS122]

Couldn't tubes be used for the venus rover? they could work at ~500C... of course they would need to be specifically built to handle the environment but I dont see why it couldn't work.
the cathode would need less energy to heat it too since the temperature difference would be small... noise currents would be huge but still...
also you could build the tubes in a planar design which would allow for them to be much more compact for digital circuitry.
And if the cathode heater is still drawing too much energy, you could heat it up with a solar heater, or if that's still too much energy, you could use a radioactive tickler.
The hardest thing about them would probably be the chamber for the tubes, since there would be like 400bar of pressure that would need to be sealed.
Tubes seem like a much better choice over mechanical.

[tom66]

So many issues with this idea:

It would be difficult to design tubes to handle the harsh environment of any launch and landing with multiple-G loads and wild temperature swings. 

What exactly would the tubes do?  The functionality would be limited to the most basic measurements transmitted over an analogue radio interface.  That means no photography, no complex scientific measurements, no data recording...

If tubes do survive the high temperature operation regime, great, but what about their power supply (batteries), the other passive components required, insulation on wires etc...? 

A better option would be to build an insulated box with a cooling system to allow ordinary microelectronics to work.  I worked on a project a long time ago that had electronics running at 200C, we could not buy anything we needed that was rated that high, so we batch tested the highest grades of components and found what worked.  We found that for instance a PIC microcontroller rated at 125C could in fact operate at up to 200C if you got lucky with the part.  You would have to derate everything (we were running at a few MHz) and the quiescent current was ludicrous (I seem to remember 50mA) and it's likely to only have a short lifespan, but it did still operate. 

[ELS122]

So many issues with this idea:

It would be difficult to design tubes to handle the harsh environment of any launch and landing with multiple-G loads and wild temperature swings. 

What exactly would the tubes do?  The functionality would be limited to the most basic measurements transmitted over an analogue radio interface.  That means no photography, no complex scientific measurements, no data recording...

If tubes do survive the high temperature operation regime, great, but what about their power supply (batteries), the other passive components required, insulation on wires etc...? 

A better option would be to build an insulated box with a cooling system to allow ordinary microelectronics to work.  I worked on a project a long time ago that had electronics running at 200C, we could not buy anything we needed that was rated that high, so we batch tested the highest grades of components and found what worked.  We found that for instance a PIC microcontroller rated at 125C could in fact operate at up to 200C if you got lucky with the part.  You would have to derate everything (we were running at a few MHz) and the quiescent current was ludicrous (I seem to remember 50mA) and it's likely to only have a short lifespan, but it did still operate.

Wrong on so many levels.
It's not impossibly hard to design tubes that can handle multiple G's... GLASS tubes were used in jets after all...
And if you have a design for a tube that can handle 400 bar of pressure, it obviously will be no problem to make it handle a few G's of acceleration.

Even just transmission would be a BIG deal. so you're implying it's not worth the effort to have an RF transmitter on a venus rover instead of whatever mechanical comms link is on current designs? Furthermore, tubes could store data, tubes can do calculations, and tubes could image things too.

Insulation could be glass or ceramic insulation.

yeah but what about the wire? 

[coppice]

Have you actually read the history of the USSR's Venus landers. You don't have to ponder the topic. You can read what has been achievable with vacuum tube electronics, including a vacuum tube camera, a tough pressure vessel, and material choices to tolerate the extremely acidic environment. Spoiler: after several landings, and learning what the lander needed to tolerate, their best effort was a lander with a camera that lasted for a little more than 2 hours before heat and corrosion killed it. Its not entirely clear if corrosion or heat got to it first.

There has been a recent surge in Venus probe activity. Most are looking at further mapping from orbit or exploring the upper atmosphere with balloon like probes, rather than going down to the brutal surface conditions.

[coppercone2]

i think its a giant waste of time because venus would be like the most expensive planet to go to. far away AND corrosive. Anything corrosion resistant becomes mega expensive. Out of the problems from regolith and mars, venus is 10x worse. And it would even suck to go there because its extra dangerous, for a EVA. 

I think mars might be like a really bad day in antarctica. Venus is next level. its a sad place

[coppice]

i think its a giant waste of time because venus would be like the most expensive planet to go to. far away AND corrosive.

Exploring Venus has many problems, but its not far away. The cost to get a ship to Venus is considerably lower than any other planet, including Mars.

[coppercone2]

not when it has to be made of triple thick super alloy with quadruple gaskets where you can leave a piece of aluminum on the surface of mars. pretty sure for a rover so long the inside is dust resistant you can let dust inside if the wires good

i think orbiters there might be cheap because their not expected to get in contact with the atmosphere

[coppice]

not when it has to be made of triple thick super alloy with quadruple gaskets where you can leave a piece of aluminum on the surface of mars. pretty sure for a rover so long the inside is dust resistant you can let dust inside if the wires good

That assumes you are trying to reach the surface. There are various current plans to visit the upper atmosphere, with craft designed to float there, above the horrible temperatures, pressures, and corrosion. I'm not clear that conditions in the upper atmosphere are as benign as some of these projects seem to base their thinking on, but time will tell.

[coppercone2]

their still 1000 times easier because you don't have corrosive at 100 atmospheres pressure (1000PSI) like you do at the surface.

it seems like a good start to build that stuff if we want to turn into a civilization with space battle ships that have plate armor though. like quake 2

I think if you put that lander on any other planet it would be considered something like a really armored vehicle. like somethin you would send to spy on alquida

[TimFox]

There were two episodes of the US television series "The six million dollar man" where a Soviet probe developed to survive landing on Venus got loose in Wyoming and the hero had great difficulty keeping it from wreaking havoc wherever it went on the Earth's surface due to its invulnerability.
https://www.imdb.com/title/tt0702050/  et seq

[ELS122]

Have you actually read the history of the USSR's Venus landers. You don't have to ponder the topic. You can read what has been achievable with vacuum tube electronics, including a vacuum tube camera, a tough pressure vessel, and material choices to tolerate the extremely acidic environment. Spoiler: after several landings, and learning what the lander needed to tolerate, their best effort was a lander with a camera that lasted for a little more than 2 hours before heat and corrosion killed it. Its not entirely clear if corrosion or heat got to it first.

There has been a recent surge in Venus probe activity. Most are looking at further mapping from orbit or exploring the upper atmosphere with balloon like probes, rather than going down to the brutal surface conditions.

Didn't know the soviets used tubes. I assumed it was a suicide mission and they just used semiconductors kept cool with just a lot of thermal mass...
Is there any description of the circuit, tubes or components they used?

[tggzzz]

So many issues with this idea:

It would be difficult to design tubes to handle the harsh environment of any launch and landing with multiple-G loads and wild temperature swings. 

WW2 anti aircraft shells had proximity fuses containing 4/5 valves. After being "detonated" out of the barrel, they were spinning at 30000rpm. https://en.m.wikipedia.org/wiki/Proximity_fuze

What exactly would the tubes do?  The functionality would be limited to the most basic measurements transmitted over an analogue radio interface.  That means no photography, no complex scientific measurements, no data recording...

When a MIG25 Foxbat interceptor (a Soviet contemporary of the F15) landed in Japan, the people disassembling it were amazed to find the avionics were based on nuvistor valves.

It is amazing what can be achieved by people with skill and imagination.

[T3sl4co1l]

Thermionics don't really matter. Also, anything that would be applicable, is going to look very different from what you're imagining; consider for example alumina (or even more inert) ceramics, layered with electrodes, machined with cavities, and maybe a tungsten wire spans across one gap for heater, a mesh grid electrode on the next lyer, and plate on top.  Connections are made with metallization, or metal enamel, and sealed with braze or glass frit; the completed assembly is sealed in a high vacuum furnace brazing operation.  Reason being, the miniaturization is much greater, a necessity for any kind of technical mission -- but it's doubtful that anywhere near enough computational power would be practical with such a scheme.  It could manage flight systems, some sensor processing and communication, but nothing like the high-resolution photos or video that are demanded today.

Not to mention power systems; even with 300V+ solar panels (or RTG stacks), you've basically got awful-efficiency thermionic switching converters, or mechanical switching -- straight up switching (relays), or [even] old[er]-school vibrator supplies, may well be worthwhile; not sure about arcing at high temperatures though, that might be questionable. Maybe high pressure Ar fill would do or something.

Hm, solar. Light level at the surface IIRC is a fraction of Earth's, maybe like a heavily cloudy day, or on Mars. The cloud layers are VERY thick!  The spectrum is more-or-less visible white (a bit yellowed I think it is?) , meaning solar panels need a bandgap of 1-2eV to function.  But if they're cooking at 500C, even a 2eV bandgap is pretty much useless.  Kind of nuts to think about an RTG in such an environment, but the mechanisms all still work at high temperature AFAIK. Don't know what materials would be applicable. I'm sure PuO2 would still be fine as fuel, probably casing materials will have to improve, especially for chemical resistance.

Battery technology at least is available; Mg-Sb and Na-S chemistries could do at those temperatures.

Would certainly be fascinating if we mined an honest to goodness whole-ass asteroid, separated iridium from the metal fraction, and use that to build things.  Dropping a few care packages worth down to the surface would easily pay for the mission, and such a strong and inert metal would survive fine in the atmosphere.  I'm sure there are easier and cheaper ways to protect such a thing, but more to say it would be neat to do it that way some time.

But, needless to say, they'll probably use something like SiC or GaN, or even diamond if reasonable dopants can be found (perhaps the high temperature enables more options?), and make ICs out of that.  Imagine a PPC CPU crafted of transparent crystal and running at 9V or thereabouts!  It'll probably run slow (10s, maybe 100s MHz?), but have enough data width and memory to be usable.

It would be difficult to design tubes to handle the harsh environment of any launch and landing with multiple-G loads and wild temperature swings. 

Long-solved problem, remarkably; one of many technologies that won the war, the proximity fuze.  They put a homodyne receiver inside a fucking artillery shell; it worked, devastatingly well!  IIRC, the tubes were fairly standard design, subminiature glass, with extra reinforcement.  Power was delivered by a battery whose electrolyte came from a vial (smashed by shock) which then got squished into electrodes by centripetal action.

Tim

[coppercone2]

those mini tubes were forcasted to start coming out some time after 1970 (flat ASIC tube circuit cards)

Well really, if you think about it, you don't need that much stuff. What you would need is a big multiplexer to get as many sensors and experiments as possible to transmit data.


1 way to do things is to try to get the most advanced spectro-instrument to get physical data over. the other way is to get a bunch of general tools to get you interesting information.

for instance, you could setup a materials test where you have hundreds of common components being tested, say under force (bolts, springs, brackets) and see what the life time is before failure from a test that can be as simple as a ohm meter going up. that data might be 10000x more valuable then anything involving spectrometers etc.


I mean what practical use are some of these more advanced instruments when you need to verify basic stuff? You could actually run experiments there, you don't have to try to get advanced data that is supposed to be used for what, variables in a simulator? FOr models we don't know are even accurate?

[tom66]

Fair enough on tube ruggedness, though I still maintain you'd be absolutely nuts to solve this problem with tubes instead of rugged electronics.  Honeywell have microcontrollers and ADCs that can operate at up to 250C junction temperature.  You could probably keep that kind of equipment alive for days in a very high temperature environment with the right design, and it could do genuinely useful things like modulate data onto a digital interface allowing for large amounts of data to be transferred.  Potentially even imagery, if you can find an image sensor that can operate at very high temperatures and a lens that can resist corrosion for long enough.  Perhaps you could keep some electronics alive indefinitely with Peltier devices, some of those can operate up to 300C case temperature, though the power consumption may be an issue.

These types of missions cost billions of dollars to set up, so there's no doubt that whatever is done will be done with the best technology available.  That won't be vacuum tubes!

In terms of sensors, just look at what is on the Curiosity Rover.  I'm assuming you'd want to try and move the probe around rather than have it be stationary (unless you just hope you'll land on somewhere really sciencey).  That implies a computer and robotic control, too.  The other issue you have is link strength.  The probe's signal is unlikely to be very strong, so if you can only transmit analog information, you're limited in the range of information you can accurately convey.  The Curiosity Rover has a 32kbit/s link with Earth and a slightly faster, but far less available link with the MRO at 2Mbit/s.

[iMo]

You may put some electronics into a, say, 10cm thick Aerogel box and put it inside the oven at 400-500C. You may do it at home..

https://en.wikipedia.org/wiki/Aerogel

[Alex Eisenhut]

It would be difficult to design tubes to handle the harsh environment of any launch and landing with multiple-G loads and wild temperature swings. 

And yet it was done in WWII to put tubes inside proximity fuzes in artillery shells, where the stresses make a rocket launch almost unmeasurable by comparison.

http://www.navweaps.com/index_tech/tech-075.php

A vacuum tube is still faithfully relaying information from Voyager.

https://spinoff.nasa.gov/Traveling-Wave-Tubes-Travel-Far

Or the various pencil triodes in the Saturn rockets...

That implies a computer and robotic control, too. 

Yes, put that in orbit and the rover as an remote-controlled car.

If you want it done, I'd say reach out to James Cameron and tell him he can't do it...

[coppercone2]

i think that the most important thing for venus is to figure out what works there and what does not rather then just trying to explore to make it cheaper to build stuff for there because we can probobly learn tricks about structures and materials from endurance studies that are cheap and low tech, so that we can have a mars duration exploration mission not some sad 1 week thing

like you can just send a device there with 500 different styles of seals to see which one works the best etc

even stupid stuff like fly wheels just spinning to test shaft seals for wheels at different RPM, weight, etc.

but i still stand by the fact that its not smart to try to focus on that. I really think that any kind of payoff from venus is 'far out'.

like we got an idea of how much we can get from a rover for the duration of curiosity. its not even that much good data! interesting but if we got 2 weeks of that from a venus probe, what the hell use is that?

like if you know that you got not much from 11 years, what the hell do you think we might get from some uber expensive venus rover that lasts 2 weeks?


the rover told us mars might have been kinda alive at some point, a primordial fizzle or something. i think we should want something from there. to determine the feasibly of tera forming or mining or at least a research station, even if robotic. Or some kinda semi local terraforming thing (like living near a ice pocket in a crater). it seems promising. what can we get from venus??


what are the pressing questions that scientists have about venus right now?


**************



to me its like if in 1500, people went crazy focusing on exploring antactica rather then going to the north americas because they found its possible to get there from the southern most tip of africa. . Maybe it can be a bit closer if you look at it a certain way, but DAMN like what is the incentive???


east coast to europe : 4200 miles
cape of africa to antarctica : 3200 miles.


would it have been worth it to focus on that just because its closer??

its been closer for like 200 years since its been like properly discovered, and we got 0 resources from it and its still almost impossible to survive there and the slightly further place turned into a sprawling modern civilization made from like 20 countries. From the looks of things its such a desolate dump that we might be on mars BEFORE there is something in antarctica. Maybe a oil recovery operation. IMO close does not mean its a good choice! people are still more interested in the god damn moon then antarctica lol

[BrianHG]

What's wrong with using silicon carbide cmos circuits.  I think the current record are simple logic ICs and power electronics working at >460deg C. (NASA has already tested prototype silicon carbide ICs in a Venus simulated environment, they lasted 22 days at full surface Venus temperatures and pressure.)  With a little effort, they may achieve the 500deg, so no need for crummy tubes when you can use simple low gate count ICs, maybe something like an 8bit MCU.

Also, don't expect to get a lot of current to drive any type of electro-mechanical actuator from a vacuum tube which is already at 500deg.

Power is also an issue.

Why not just forgo the electronics all together?  No electronics to fail.
100% mechanical rover concept designs exist, where the rover is a bunch of different tuned resonant microwave cavities where an orbiting satellite beams the power to make the rover do things and uses reflections for the rover's sensors.

A hybrid design of mechanical and silicon carbide electronics venus probe:

[tszaboo]

i think its a giant waste of time because venus would be like the most expensive planet to go to. far away AND corrosive.

Exploring Venus has many problems, but its not far away. The cost to get a ship to Venus is considerably lower than any other planet, including Mars.

If you can aerobrake, you can transfer to Venus and Mars with almost the same amount of deltaV. It takes less energy to go to Venus or Mars then to land on the Moon. Taking off is a whole different calculation, we probably never be able to lift off anything other than soil samples.

[coppercone2]

that's another good point, martian and moon gravity allows sample retrieval, and moon. Thin or no atmosphere and low gravity force.

Venus has 92% gravity force and massive atmospheric drag, even if you get a material resistant to it. On the plus side, some kinda teflon balloon might be able to get goods off the surface easier. But holy shit, the engineering is insane compared to Mars.

Since Venus has pretty thick gasses, buoyant force becomes powerful.

I think we need 500 years more before its worth while.


i wonder if you can put some kind of reactor in a venus rover to convert the atmospheric gas to hydrogen to make a balloon. If it lasts long enough it maybe can split HF or HCl into hydrogen ions.. plasma exchange membrane?


Could a oxygen balloon float in a CO2 atmosphere? If you broke up the CO2. On mars its too thin, but on Venus if its really blanketed maybe you can get a fair bit away from the ground to try to escape. Or a nitrogen balloon (nitrogen is lighter then oxygen molecularly).

Density of CO2 is 1.95, N2 is 1.25. That is substantial. oxygen is 1.43.

Both N2 and O2 should float a balloon.

But for comparison, 0.083 g/L is hydrogen.

So for a typical hydrogen balloon on earth you have a ratio of  15 densities. A nitrogen balloon on venus would be 1.56 densities.

On the plus side, if you made some kinda hydrogen isolator from rock or trace gasses, you would have a ratio of 23.61 . So you would have substantial balloon power.


If a rover is advanced enough, you could drop hydrogen bottles from orbit so it can find them and fill up.


The hinderburg would have a cargo capacity of 18.36 tons on Venus, rather then 12 tons on earth, from this simple math.


I think thats interesting because rocket assisted with balloons are easier on venus, since you can carry a heavier rocket for the same size balloon. 50% is a big number in engineering for cargo capacity IMO.

[CatalinaWOW]

There was some effort put into integrated thermionic devices in the late 1970s and 1980s.  Those doing the work got funding by pointing out applications like down hole instrumentation in oil wells, space applications including the lunar surface at lunar noon, and nuclear warfare where EMP robustness was at a premium.  Their concepts include ceramic substrates with fired on resistors, chip capacitors and simple planar structures for the tubes.

All of it faded out of view.  No fundamental physics barriers, but I suspect it died for the reasons mentioned in the comments here - multiple orders of magnitude less circuit density relative to silicon ICs, loss of the downhole market to solid state approaches, and thankfully, the receding likelihood of nuclear warfare, and finally to small a market to drive development in competition with silicon ICs.

[SeanB]

Remember the Venera landers used vacuum tube television cameras, simply because CCD arrays were still experimental devices, and while CCD and CMOS sensors have taken over, trying to use them at 100C means lots of noise in the image. A robust camera and vacuum tube amplifier, because they needed high power to transmit, using a low gain very poor direction antenna, simply because the signal had to be received on Earth, even at any angle. That the landers lasted so long on the final iterations was because of experience with the older ones, each failing at some point during descent, and providing information of composition, temperature and pressure before crushing. The last ones had a massive block of wax in them, cooled down during the voyage by allowing it to be exposed to the dark side of the craft, and then sealed before entry, so that it would handle the input heat loading, along with multiple insulating layers and other thermal barriers to keep interior at operating temperatures. Yes not a long life, but they all failed from either thermal stress, or from corrosion breaching seals, long before the batteries gave out.

[SiliconWizard]

Wasn't going to Venus the next fantasy of OceanGate's cofounder (the one who's not dead)?

Venus is a living hell, I'm very curious to see who's gonna successfuly land a rover on there, that won't die within minutes. The electronics really isn't the main issue even.

[khach]

Nitrides based electronics for Venus
https://dspace.mit.edu/handle/1721.1/128350