A New Look at Venus Clouds

As we all wait for the upcoming launch of the James Webb Space Telescope (JWST), now rescheduled to Christmas Day (or possibly a bit later), it’s worth examining some of the other science it could do. Although I am fascinated by the prospects for exploring the earliest epochs of the universe’s history, there’s another exploration that I like: exoplanet atmospheres. JWST should be able to examine the air at planets around other stars and suss out their atmospheric composition. Atmospheric gases related to life should be seen, which makes JWST a life probe. Kind of interesting, so stay tuned on that.

The Venus Atmosphere

Here in our own solar system, the search for life continues. We know it exists on Earth, and suspect it could have (or maybe still does) exist on Mars. Farther out, Europa and Enceladus remain tantalizing targets in the search for life.

But, what about Venus? Could its atmosphere tell us if life exists there? While there’s no hard evidence yet, despite some interesting finds over the past year or two (phosphine, anyone?), some scientists think it’s possible. I ran across an interesting paper a few days ago about the subject. It describes the research and a hypothesis from a group of scientists at Massachusetts Institute of Technology, Cardiff University (UK), University of Cambridge (UK), Cavendish Laboratory (UK), and the Medical Research Council in the UK. This team looked at some anomalies found in the Venus atmosphere and they came up with a possible pathway for life to explain those anomalies.

Let’s take a closer look, starting with those clouds. The principal component of the Venus clouds is SO2—sulfur dioxide. That makes them very acidic. However, there are some odd atmospheric anomalies just crying out for further examination. One of them is the existence of pockets of ammonia (NH3. The chemical signature for that gas was first found in the 1970s. Its existence remains something of a puzzle to planetary scientists.

The Source for Ammonia

Now, the ammonia isn’t coming from outside of Venus—it’s locally produced. It appears only in those sulfur dioxide clouds and not on the surface. As it is created, the amount of sulfur dioxide drops a little in the areas where the ammonia exists. In addition, there are small pockets of oxygen in the clouds. The question we all want to have the answer to: what’s making it?

There’s no obvious geological or mineralogical source for it. The ammonia doesn’t seem to be a by-product of the volcanic activity on the Venus surface, or of Venus lightning. So, they wondered if it could be due to life in the clouds? Or, are there other explanations that having nothing to do with life? Obviously, we need a lot more data to understand what’s going on.

Life in Venus Clouds

Let’s do a little thought experiment and imagine that the ammonia is due to some life process. The researchers took that idea and came up with a model. They assumed if the ammonia is present in gaseous form, then it would cause a set of chemical reactions in the atmosphere. If life is producing ammonia in the Venus clouds (NOT proven yet), one by-product of the chemical reactions is oxygen. The ammonia itself would dissolve into the droplets of sulfuric acid, which would neutralize them. In other words, that life could change acid rain to someplace where that life could happily exist. Essentially, it could be creating its own habitable zone right there in the Venus clouds.

Now, there’s a lot of research to be done to prove this idea. Or, scientists have to find some other logical explanation for the presence of ammonia and heightened amounts of oxygen gas in the Venus atmosphere. Fortunately, there are plans to send spacecraft to Venus to make extremely detailed studies of its clouds. The Venus Life Finder missions, headed up by MIT’s Sara Seager, will measure them to look at the ammonia and see if there are other signs that might point to life.

If you want to read a more detailed paper on the subject, the researchers have put it up online. You can also read the story at Phys.org, talking about the possible presence of life on Venus.

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