Thread: How long would a modern Venus lander last

The recent events on Venus, which might if they are volcanic in nature suggest a landing mission, got me thinking.Only a handful of Soviet probes have landed on the surface of Venus, and didn't last long. With modern materials, engineering, and larger mass budgets, how long could we expect the next generation of Venus lander to last?As a further question, would a Venus rover be viable at all? Or would any lander last for so little time that it would not be worth driving anywhere?If you can last longer than an hour or so, I would suspect power is an issue also. Does enough sunlight get to the surface of Venus to make any kind of solar power viable?

There is hafium nitride, which melts at almost 6000 degrees f, but it is expensive as hafium ore is rare and very low concentration. Some experiments have been done with high temperature electronics, so a Venus rover might run for a year with an RTG = radiation thermonic generator. The light level is too low for solar panels. The Research and devopment would cost billions Neil

So far as materials science goes, 460 deg C (860 deg F) is not all that hot. In fact, that's actually about 40 deg C cooler than your average self-cleaning oven.

The key here is two-fold: insulation, and a means of cooling the interior. Insulation is required to reduce the rate at which the exterior heat infiltrates into the interior, while a cooling unit keeps the interior at a stable interior temperature. Thus, the insulation reduces the load on the cooling unit, which in turn reduces the power requirements.

Theoretically, you could use infinite insulation, comprised of multiple vacuum layers and reflective strata, but this assumes no heat would be generated from the interior. Alternatively, one could used fused quartz (which doesn't soften until 1665 deg C), and coat that with reflective optics ("glazing") designed to keep the heat flow going mostly in one direction. If this is done with a series of concentric spherical shells, containing only vacuum, the temperature inside will remain cooler than the external temperature. The question is, "how much cooler?"

Assuming triple-glazing, low-e glass, we're looking at SHGC values of, at best, 33%, with VT values of 60%. Thus, 2/3 of the incoming light is shaded (kept outside), while 60% of the interior light passes back to the outside. One might think that this would allow the room to approach absolute zero, but this isn't true, since AZ emits no heat at all, and will absort any heat hitting it. Thus, the internal volume will always have some internal temperature.

Let's assume one could make a sphere where 50% of the energy entering it would be reflected back out, while 50% of the energy already inside would be radiated out. Since energy is proportional to temperature in Kelvins, and equlibrium would be reached at 25% of the external temperature.

Since the external temperature on Venus is 735 deg K, the internal temperature would stabilize at 183.75 deg K, which is -89.4 deg C, or -128.92 deg F.

Uh, any physics majors in the house? I think this isn't right....

Ok, I called a friend and he said I wasn't right, as the incoming amount of radiation is proportional to the external temperature, while the outgoing amount of radiation is proportional to the internal temperature. Thus, incoming will always be 50% of 735 deg K, while the outflowing will always be 50% of whatever the internal temperature is, which results in thermal equlibrium at 735 deg K, i.e. ambient.

Ok, let's change the parameters of the experiment, and allow for a sherical shield which will only admit 30% of the external energy into the interior, while allowing 70% of the internal energy to escape. This stabilizes on a temp of 315 deg K, or 41 deg C, also 107.33 deg F.

So, allowing for coatings which reflect most of the incoming radiation, while emitting more radiation out than they allow in, it's possible to reduce the temperature of the interior by means of radiation alone!

For practical purposes, however, as well as the fact that interior electronics can build up heat rather rapidly and overpower this design. In theory, however, if you had large radiant cooler fins just inside the shell of this device, insulated from the interior except by means of traditional insulation, and an active cooling system inside, with a small thermal connection for powering via thermal...

Oh, heck, this sounds more like a perpetual power generating scheme!

Who can spot the flaw in this design? Is it that there is no way to build a window which emits more energy than it reflects? I'm thinking that might be it. Otherwise we'd have powerless refridgerators built from this glass.

And yet, the converse is true. It's entirely possible to build a device which collects more energy than it radiates or conducts away. It's call "the interior of my car."

Scratching my head on this one... Perhaps I need to take out a provisional patent on this one