Could we see the surface of Venus after the explosion of a H-bomb in its atmosphere?

Question

The dense atmosphere of Venus is mainly composed of carbon dioxide and nitrogen, with clouds made of sulfuric acid droplets, which make optical observation of the surface impossible.

As can be seen on the image above, the cloud layers occur between 30 to 65 km altitude, with the densest layer at about 48.5 km.

Are the thermonuclear weapons of today capable of creating an eye in those cloud layers so we could see the surface of Venus ?

Is it possible to calculate the amount of energy that would be needed to create a hole in the clouds with a diameter of 1000 km, for instance ?

To attain maximum effect the ignition should take place within the cloud layer, probably at about 50 km above the surface.

Answer 1

At Venus there's another problem separate from the cloud problem. Even were there no clouds, you couldn't see the surface of Venus from space at visible wavelengths anyway, due to Rayleigh scattering.

In the past year I've been working on studies of Venus aerial and landed vehicles for doing Venus science, and Rayleigh scattering is a problem at Venus. Rayleigh scattering is the phenomenon that makes Earth's daytime skies blue instead of black—at least, when there are no clouds! The sky is the color it is—"sky blue"—instead of royal blue because Rayleigh scattering doesn't scatter only blue light, it scatters essentially all wavelengths. It just scatters the blue more because the average size scale of the temporary air molecule density enhancements (from "Brownian motion") that give rise to Rayleigh scattering are matched best to the blue wavelengths. All the other wavelengths add up to more-or-less white light, so the color you see is bluish on a white background, more of a pastel blue than a royal blue.

As you get higher in Earth's atmosphere there's less of that scattering overhead so the sky gets darker. Balloons or aircraft that get up over ~70,000' (~22 km) altitude see black sky during daytime. The deeper you get into the atmosphere (the higher the mass density), the more scattering you get.

The magnitude of the scattering at Earth isn't huge. I've been able to see Venus in the sky on a bright, sunny day, in the early afternoon, with my unaided eye. The intensity of the scattered light is less than the intensity of light coming to Earth from Venus. When looking down at Earth from above you can still see Earth's surface because the intensity of the reflected light from the surface is a lot higher than the intensity of the scattered light. (Scattering doesn't just send light downward. It sends some upward, too.)

But just imagine what happens to the scattering intensity as you go deeper into Venus's atmosphere. The pressure goes to 10 bars (very close to 10 times the pressure at Earth's surface)...to 20 bars...to 50 bars...to ~92 bars at the surface. Even with the high temperature there (~735 K, which is ~462 C, ~865 F), the atmosheric mass density is ~67 kg/m^3, more than 50 times what it is at Earth's surface. An atmospheric scientist at the studies I mentioned calculated that at altitudes greater than about 15-20 km at Venus the scattering intensity below is so high that you can't see the surface at visible wavelengths. A 2002 Paper by V.I. Moroz says max of 15 km, even at the 1 micron infrared window (sorry, this paper isn't a freebie download, but you can see that result in the abstract). Part of this is due to the high intensity of scattered light, which produces a noise signal, but some is due to light coming upward from the surface being scattered out too, so that signal is reduced. Some IR wavelengths will get through, because the scattering isn't as pronounced at those wavelengths, but visible light doesn't.

A nuclear bomb won't change this at all.

Answer 2

No, because thermonuclear weapons don't make holes in clouds, they make clouds. First you have a fireball:

And then you get a big mushroom cloud:

Neither the fireball or mushroom cloud are see-through. Even if the bomb managed to push Venus' thick atmosphere out of the way all you'd see is fireball and mushroom cloud before it closed right back up again seconds later. Even if H-bombs did make holes they wouldn't be very big, the largest thermonuclear device tested was the Soviet Tsar Bomba, which yielded 51 Megatons and had a theoretical limit of 100 Megatons. The mushroom cloud went up to 64km and was about half that in diameter. Theoretically you could scale H-bombs up to much higher yields, but then you just get bigger fireballs.

Answer 3

Note: @Conelisinspace's comment reminds me that the clouds don't begin at the surface. Double checking the plot, this happens at roughly ~30 km, at which point the pressure is almost 10x lower, but the (absolute) temperature drops by almost a factor of 2 as well, so we can't quite say we're above 90% of the mass.

However, even if we could, the temperature rise of 0.0001 C would only increase to 0.001 C when a 100 megaton output is averaged over a 1,000 km diameter window, so it still is a half-dozen orders of magnitude away from boiling the water droplets necessary to turn clouds and (presumably) haze transparent. No change in conclusion.

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No, not even close.

These devices don't "blow holes" in the atmosphere, they heat the atmosphere and it expands. So your only chance is to heat it so much that the droplets making it totally opaque are vaporized, turning the atmosphere back into a gas rather than a giant, thick cloud.

According to NASA's fact sheet for Venus the scale height of Venus' atmosphere is about 16 km, which means the density drops with altitude much more slowly than with Earths's ~8 km scale height, combining that with the fact that it starts at 90 times higher density, this explains why the total mass of Venus' atmosphere of about 5E+20 kg is 100 times larger than that of Earth's.

1 ton (of TNT equivalent) is 1 gigacalorie, or 4.184 gigajoules. Let's say you use a really really huge 100 megaton thermonuclear bomb. I don't know if you can get them that big these days. Amazon certainly doesn't carry them.

That's 1E+08 * 4E+09 = 4E+17 Joules, or about 1 miliJoule per kilogram of atmosphere. That's not much. A 500 km radius on the planet has an area of 8E+05 km^2, which is 0.2% of Venus' total area of 4.5E+08 km^2.

That means detonating such a bomb would add about 0.5 Joule per kg of atmosphere in that 1,000 km diameter circle, which would heat it by maybe 0.0001C. Essentially Nothing. No change whatsoever.

It might make a temporarily transparent "bubble" near the surface with a radius of the order of 1 km, that includes only 1 km up as well as to the sides. But no chance that that the atmosphere would be affected all the way to the top.

Answer 4

So I tried another track and it doesn't work either.

If you attempted to use the H-Bomb as a flash bulb to try to produce enough light to bounce off the surface and pass all the way back up without attenuating below our camera sensitivities, it still doesn't work because the reflection is ridiculously dimmer than the original bomb blast.

Those clouds scatter light pretty good.