|
Post by vegetal on Feb 1, 2017 2:47:29 GMT
So, I was a reading about the Venera missions launched by the Soviet Union, and it's interesting - the environment is so harsh on the surface that none of the probes lasted for long.
The atmo pressure is stupid high and temperatures are something like 700 K I guess. So, is it even possible with current tech to build a lasting probe to land there? Like, a few months or so?
I have the impression that pressure wouldn't be so problematic, you can toughen up parts, equalize interior and exterior pressure in many spots, and seal the most sensitive ones in a pressure vessel. But temperature....I don't know. Losing heat to an environment that is already that hot would require quite a bit of energy (I'm too rusty to calculate that), and if that's not possible...then what? I don't think any electronics would be able to survive.
What do you think guys and gals?
|
|
|
Post by coaxjack on Feb 1, 2017 2:59:35 GMT
I'm sure there's a solution to all of the problems encountered in that environment-but things that are engineered to be that robust tend to be really heavy. Considering how much delta-v it takes to get to Venus in the first place, massive payload and large dV requirements usually also mean large amounts of money as well. There are probably JPL scientists with some ideas to do exactly what you're describing, but NASA's budget is pretty anemic right now unfortunately, excluding any sort of off-the wall kind of mission like this.
|
|
|
Post by theholyinquisition on Feb 1, 2017 3:48:47 GMT
So, I was a reading about the Venera missions launched by the Soviet Union, and it's interesting - the environment is so harsh on the surface that none of the probes lasted for long. The atmo pressure is stupid high and temperatures are something like 700 K I guess. So, is it even possible with current tech to build a lasting probe to land there? Like, a few months or so? I have the impression that pressure wouldn't be so problematic, you can toughen up parts, equalize interior and exterior pressure in many spots, and seal the most sensitive ones in a pressure vessel. But temperature....I don't know. Losing heat to an environment that is already that hot would require quite a bit of energy (I'm too rusty to calculate that), and if that's not possible...then what? I don't think any electronics would be able to survive. What do you think guys and gals? Venus is the closest known approximation of Hell. It's probably the most hostile body in the solar system to human life (short of the Sun.) Quite frankly, we don't care about venus enough for that.
|
|
|
Post by teeth on Feb 1, 2017 4:16:51 GMT
If you really wanted to survey it on the visual spectrum, you could do a floating balloon rather than a probe. To get pictures of the surface it could lower a camera below the cloud layer by winch, then pull it back up when it starts getting too hot. It's pointless though, we already have an accurate map of the planet from satellites and there isn't much worth doing there.
|
|
|
Post by vegetal on Feb 1, 2017 4:22:30 GMT
I'm sure there's a solution to all of the problems encountered in that environment-but things that are engineered to be that robust tend to be really heavy. Considering how much delta-v it takes to get to Venus in the first place, massive payload and large dV requirements usually also mean large amounts of money as well. There are probably JPL scientists with some ideas to do exactly what you're describing, but NASA's budget is pretty anemic right now unfortunately, excluding any sort of off-the wall kind of mission like this. Actually, delta V requirements are quite low. The transfer takes just 640 m/s beyond Earth escape, and the capture can be executed with some massive aerobraking. The trip is also quite short, a few weeks I think. And come on guys, I'm not talking about financial motivation, that's boring. I wanna think about the challenge. The early probes were just 1 ton, later ones were heavier, but maybe we could do better with current technology?
|
|
|
Post by n2maniac on Feb 1, 2017 6:16:37 GMT
Are you suggesting something that could run for weeks or months on the surface? If so, the challenges are:
-Electronics temperature limits: the exhaust temperature of these cannot be much above 340K with any practical technological development (we aren't going to fabricate a CPU on diamond to run hotter). It will need to be actively cooled to a fairly high heat rejection temperature (740K). Requires at least a custom refrigerant loop, insulated box, custom parts, and a specially made high temperature motor with lube that is likely solid at lower temperatures. -Power source: solar is a no-go at the surface (temperature and actual low solar intensity below the clouds), gotta go nuclear with a high heat rejection temperature (again, 740K). This is getting up to the point that the internal parts of real-life RTGs are designed for, so efficiency will be poor (but should be able to work). Combined with the refrigeration loop power consumption, this is gonna get FAT. -Corrosion and pressure (at high temperatures): The outer shell has a taxing combination of problems to survive. If every internal component can be designed for high pressure operation, this will reduce the weight and strength requirements on the corrosion protection. This may be hard to do simultaneously with insulation that works and is lightweight, however. -Part qualification: every part exposed to the outside pretty much has to have some weird custom aspect to it. Getting vendors to make this will be a PITA. -Link budget: assuming this is unmanned and you want it to transmit data back, you have to do that. There are minimum practical limits to the SWAP of a usable uplink (which will limit its minimum size).
Alternatively, you might be able to go really old school and make high temp capable vacuum tubes or special discrete transistors to make a dumb probe operating at ambient conditions with a small RTG to power it, but that sounds kinda lame. However, it should be able to scale down as far as the electronics can.
|
|
|
Post by apophys on Feb 1, 2017 12:28:39 GMT
There's another hazard: lightning. The clouds of Venus are like electrified thunderclouds on Earth. Except that they're made of sulfuric acid.
|
|
|
Post by ash19256 on Feb 1, 2017 18:54:19 GMT
There's another hazard: lightning. The clouds of Venus are like electrified thunderclouds on Earth. Except that they're made of sulfuric acid. Well, at least lightning is a bit simpler to deal with, just set it up so that the probe landing also jams a ground wire into the ground, and then have it raise a lightning rod that's insulated from the electronics and just dumps the bolt into the ground wire.
|
|
|
Post by vegetal on Feb 1, 2017 19:48:34 GMT
I believe miniaturization would be key on the electronics, the least amount of material you would have to cool, the least massive the cooling apparatus would have to be.
The last Venera probes had a bunch of instruments added on the outside, already capable of working in such a harsh environment, stuff like a drill with it's electric motor included. Seems they developed an exotic lubricant for that, molybdenum sulfide I think.
The major problem I see now is powering all that stuff. Like you said, solar is out, and nuclear has this cooling issue. Winds are calm on the surface, so I guess this is out too...
|
|
|
Post by newageofpower on Feb 2, 2017 0:07:54 GMT
I believe miniaturization would be key on the electronics, the least amount of material you would have to cool, the least massive the cooling apparatus would have to be. The last Venera probes had a bunch of instruments added on the outside, already capable of working in such a harsh environment, stuff like a drill with it's electric motor included. Seems they developed an exotic lubricant for that, molybdenum sulfide I think. The major problem I see now is powering all that stuff. Like you said, solar is out, and nuclear has this cooling issue. Winds are calm on the surface, so I guess this is out too... You would need large amounts of electric power to power some hilariously inefficient heat exchangers/heat pump + radiator setup in order to keep the electronics cooled anyways. Might as well run some sort of high temperature, low pressure reactor; 2,000 kelvins and use the atmosphere as the heatsink. The extreme density of the Venusian atmosphere is actually a plus here, you get cooling efficiencies close to using a liquid heat sink.
|
|
|
Post by lawson on Feb 2, 2017 6:29:57 GMT
Alternatively, you might be able to go really old school and make high temp capable vacuum tubes or special discrete transistors to make a dumb probe operating at ambient conditions with a small RTG to power it, but that sounds kinda lame. However, it should be able to scale down as far as the electronics can. I think micro-vacuum tubes are the simplest way to do command and control on the surface of Venus. Already been some demos of the tech as well. (SiC transistors might take the heat as well) Power is definitely going to be a challenge. A high temperature RTG will probably be required. But if the solar illumination on the surface is within a factor of 10 of Earth's surface, solar power probably IS practical.
|
|
|
Post by n2maniac on Feb 2, 2017 7:49:06 GMT
Alternatively, you might be able to go really old school and make high temp capable vacuum tubes or special discrete transistors to make a dumb probe operating at ambient conditions with a small RTG to power it, but that sounds kinda lame. However, it should be able to scale down as far as the electronics can. I think micro-vacuum tubes are the simplest way to do command and control on the surface of Venus. Already been some demos of the tech as well. (SiC transistors might take the heat as well) Power is definitely going to be a challenge. A high temperature RTG will probably be required. But if the solar illumination on the surface is within a factor of 10 of Earth's surface, solar power probably IS practical. Simplest, but going to be very limited in capability. Also, there are limits on how far vacuum tubes scale down (the tubes have to hold a temperature gradient to work). SiC components are typically rated to 450K or so. It is a long cry from 740K. Probably no on solar? The heat also pretty-much makes it a non-starter.
|
|
|
Post by bigbombr on Feb 2, 2017 8:01:00 GMT
What about using geothermal for long term power (Venus is pretty active isn't it?) and optical computers (https://en.wikipedia.org/wiki/Optical_computing) for processing?
|
|
|
Post by shiolle on Feb 2, 2017 8:50:40 GMT
While you are theorizing how hard would it be, NASA is planning to send a rover to the surface of Venus in 2023. It is supposed to have a sail.
|
|
|
Post by lawson on Feb 3, 2017 7:33:02 GMT
Simplest, but going to be very limited in capability. Also, there are limits on how far vacuum tubes scale down (the tubes have to hold a temperature gradient to work). SiC components are typically rated to 450K or so. It is a long cry from 740K. Probably no on solar? The heat also pretty-much makes it a non-starter. Vacuum channel transistor Looks like the current state of the art for tiny vacuum tubes is less than 1um square. Should be small enough to re-create any NMOS microprocessor. Built with tungsten wires on sapphire or diamond, I bet it'd happily operate while glowing. 740K would be a cake walk. NASA appears to be considering solar power for a Venus land sailing rover. Also sounds like NASA already has a solution for hot running electronics. The 450K commercial temperature limits on SiC devices is likely a limit of the standard plastic package, solder, and PCB. Use a ceramic (or glass) and metal package and SiC (or even Silicon) electronics may work just fine at 740K.
|
|