Fuelling the skies

In the second blogpost of the space series, we have seen that methane is likely a dream come true for spacefarers. Because when it comes to fuel, two things are important. Easy and cheap production of a lot of it. And ease of storage.

We have also seen that methane is the best compromise out there on many counts. And last week we found Venus to be very well placed for very frequent travel between the outpost and Earth. Also, there are plenty of volatile elements in huge quantities that are hard to find in the inner solar system. 

In 1978, the Pioneer Venus Multiprobe launched for its long exploration flight to Venus. It made a very strange discovery. It detected very large amounts of methane in the atmosphere from 60km altitude down to the surface. Most of the Venusian atmosphere is CO2 of course. On Earth, atmospheric methane is a little less than 2 parts per million. This makes it 0,0002% of the air we breathe.

On Venus, this number is between 1000 and 6000 parts per million. About 0,1-0,6% of the ambient gas called atmosphere on Venus. This does not sound like much but the Venusian atmosphere is also about 90 times denser than Earth’s. This means that there is between 45,000 and 270,000 times as much Methane in any given m3 of the Venusian atmosphere than in an m3 of Earth’s atmosphere. Thats a pretty meaningful figure I would say.

But where does this methane come from?

There are a couple of theories. Researchers were puzzled. They believed for a long time that methane is an organic gas. Hence it can only come into being when biological processes cook it up.

But if you believe that this is what I think, you have not paid attention. Or you just started reading my blog very recently. Some time ago I wrote a post called Terra Methanum. In this post I explained that most of the methane we have on Earth is not biological in origin at all. It’s rather abiological processes deep inside Earth that produce it. 

Its geological activity that produces the methane. And Earth releases vast amounts of it into the atmosphere all the time. But the Earth’s atmosphere also has a process for dealing with methane. It breaks it up rather rapidly into water and CO2. This is due to the presence of large amounts of oxygen and sunlight down to the surface. 

Those breakup processes very likely only work in a limited way on Venus. If they work at all as there is no or very little oxygen to react with. This means that methane once released into the atmosphere would tend to accumulate. And this would explain the higher concentration.

Venus is a geologically very active planet. This leads me to assume that abiotic methane production on the planet must at least be as potent as it is on Earth. If not more so. 

So, we have a source of copious methane production that does not depend on biological processes. We have an atmosphere that due to its composition and opaqueness slows any atmospheric breakup of methane very much.

I am just relating some data we have of course. This also means that I am speculating and all this needs verification. But if I needed a fuelling station in space, I would spend some time and money on this very possibility. Maybe a probe that floats in the Venusian atmosphere and measures those things reliably?

If confirmed, that would mean that methane only needs to be extracted out of the Venusian atmosphere, processed and liquefied. Those processes require energy and again, its Venus that helps on this count. The Venusian planetary surface is the hottest of any terrestrial body in the solar system. In contrast, the upper layer of clouds about 55km from the ground is rather pleasant by contrast. This massive temperature difference means that generators optimized to exploit such differences should work great for power production.

But where would they be situated?

How about a base in the clouds? As seen before, the Venusian atmosphere is composed mainly of CO2. CO2 is a very heavy molecule with a molecular weight of 44,01 g/mol. Whereas oxygen which can be generated from the CO2 itself has a molecular weight of  15,999 g/mol. Pretty decent lift for blimps. 

That being said, as there is no free oxygen in the atmosphere, one could also process the sulphuric acid and extract hydrogen for lift. It has a molecular weight of  2,01588 g/mol. No Hindenburg style explosion is possible as an almost pure CO2 atmosphere does not allow for any of that. Leaks would be rather harmless. On earth thats a huge hazard. Now we have absolutely outstanding lift.

So, we can produce virtually anything we need to fuel rockets and the energy required to do so. As our station is high up in the clouds, pressure and temperature protection need to be only minimal. Life support is also mostly possible with products from the local environment.

Most processes will be automatized. The Venusian gravity is a little less than Earth’s. As the base is already in the clouds, escaping the base should be much less of a problem than on Earth as well. 

The atmosphere is also very thick so there could be a second base maybe about 100 km above the surface. Travel between the bases could be done with blimps. Launch from the upper base would be a rather simple affair. 

Who knows, maybe a skyhook is an option from the upper base. But let’s not go quite that far yet.

Every structure that floats in the clouds of Venus should also be lightweight. Yes, the CO2 ocean below provides great lift but there is no reason to make things heavier than they need be. And here, the carbon in the CO2 comes in handy. It can be made into graphene for carbon fibers. This makes Venus more than a fueling station in space. 

But let’s play devil’s advocate. Let’s assume that those methane measurements were wrong. 

No problem. 

Extract the hydrogen from the sulfuric acid and the carbon from the CO2 and a Sabatier process will get us there.

There is a lot of speculation that Venus had life and then a runaway greenhouse effect made it the hell it is today I doubt that. As Venus is closer to the Sun it receives a lot more solar energy than Earth does. And considering how incredibly dense the atmosphere must always have been, it heated up like a pizza oven.

Terraforming Venus (and also Mars) are science fiction. But in situ resource utilization is not.

Venus is the only place apart from Earth in the inner solar system that offers all volatile elements we need for life in space in massive quantities. The next stop for similar amounts would be at Jupiter. 

Venus would be a great place for a space habitat feeding on the rich atmosphere of our sister world. 

Elon, Jeff – ae both of you paying attention?