Vacuum Balloon Sun Shield

I just read an article indicating that "GeoEngineering", modifying the Earth's environment on a global scale, is now entering mainstream thought as Something We Might Need To Do (see link). The problem is global warming, and the time-frame for putting a solution in place appears to be shrinking faster than originally calculated. Remember that while rainfall patterns will change with global warming, that is not as big a threat to civilization as the icecaps melting would be, causing the oceans to rise 60 meters and drown seaside cities all over the world. Modern civilization should therefore consider preventing that to be something of a priority.

In the longest term the best solution is to get all those millions of tons of carbon dioxide gas out of the atmosphere, because putting it there is the root of the problem. This is so much more easily said than done, though, that no method of doing it can be implemented quickly enough, before it is too late.

In the medium term the best solution is probably to put some sort of shade in place in Space, between the Sun and the Earth, to block a small percentage of impinging sunlight. But we don't have the tech to do that as quickly as we need to do SOMETHING. We are thus stuck with doing something in the Earthly environment on a large scale -- "geoengineering", that is.

When possible, "large scale" should mean "mass production", which can involve many of the tools that our modern civilization has available. And it is perhaps fitting that the same productivity that has led to this problem might be employed to solve it. We just need a solution that doesn't destroy any ecosystems, and can last a long time. An example of something that probably won't work well is to build a forest of mirrors north of the "tree line". Often snow-covered, that darkish landscape is now exposed and absorbing sunlight; mirrors could prevent that and thus keep down the temperatures there. But for it to not get any sun, by being shaded all year long, means what little ecosystem it has will be destroyed, Not A Good Thing. Also, there is no equivalent amount of stable landscape near the South Pole, on which to mount an equivalent number of mirrors, to protect that region. And dust in the air would gradually reduce the effectiveness of the mirrors, anyway, unless they were cleaned often. We need a better approach!

In this Idea, "better" involves putting the system in place and then mostly forgetting about it. It can fall into the "out of sight, out of mind" category. It should not significantly interfere with the day-to-day activities of any life-form.

As you may already know, a "vacuum balloon" is a simple solid spherical hollow shell that has no air inside it at all. If the weight of the shell is less than the weight of an equal-volume amount of air, it will be bouyed upward, exactly like submarine is buoyed upward when it reduces its weight-to-volume ratio by replacing water in its ballast tanks with air. The main problem that vacuum balloons have is, ordinary air pressure causes them to be crushed. But who says we have to make them where the air pressure is ordinary?

Let us do our construction of vacuum balloons in two stages. At ground level a factory can make them almost complete, hollow spheres with one small hole each. We then transport them to high altitude, evacuate them, seal them, and release them. Now the shells only have to resist the much lower air pressure of the high altitude.

Let us assume here that by dealing with the air-pressure problem in that way, we can make these shells out of some ordinary lightweight metal like aluminum. Highly reflective, a mirror in any direction, each one we can make float at high altitude would reflect some sunlight away from the Earth. Impermeable to atmospheric gases, they could float/aloft for many years. ENOUGH of them can successfully combat global warming!

It is important to pick an altitude that is higher than most clouds. We should prefer an altitude that is even higher than most jets fly, just to prevent collisions --although the jets would probably not be damaged; they are built to survive impacts with much-more-solid birds. No, we want to prevent collisions so they stay aloft longer!

A possible difficulty here involves the "place" at which we do the necessary work at high altitude, evacuating and sealing the balloons. Mount Everest might qualify, but we don't want to release all our vacuum balloons at that latitude. We would prefer that most of them, in fact, be released near the Poles, to reduce the sunlight that is melting the icecaps. Atmospheric wind-circulation patterns might even keep most of them over the poles, too.

What we cannot do is release them while flying a jet at a thousand kilometers per hour; they are too fragile for that. We need a relatively stationary high-altitude platform, to which we can easily transport the prepared but non-evacuated shells. A tethered aerostat might qualify (with additional balloons holding up the tether, which is used as a conveyor to transport the shells). No aerostat yet exists that is large enough to be a factory such as we need, but that is much more due to a lack of money than a lack of technology. As the urgency of the need to solve the global warming problem becomes more apparent, the money should become avaliable for solutions, perhaps including this one.