Main page Anti Greenhouse Technology.
The use of micro helium balloons could be the only feasible way to terraform a hot Inner Planet. All other known methods fail to, are too expensive or have too many side effects to be used on a planet closer to the Sun then Venus.
A micro helium balloon is a small balloon (smaller then 1 cm in diameter), filled with helium (or hydrogen, see below) and coated with a reflective material. In theory, such balloons can be even smaller, up to 1 mm.
Helium is the best gas for this, because it is inert. Hydrogen can be used. It is lighter then helium and is found almost anywhere (in water and many chemical compounds), but it's flammable. Still, if the number of balloons don't exceed a certain limit and a large scale fire is impossible, hydrogen could be a better option then helium.
The balloons need to be made of a material able to sustain high temperature variations, which on some planets and atmospheres might vary between -150 and +500 C. The material must have some degree of elasticity, but not too much. Being more rigid, it cannot change much of its volume. So, balloons will tend to stay at a specified height, where atmospheric pressure has a certain value. This way, they will not escape into upper atmosphere and break apart and also they will not fall too close to the ground.
Also, they must resist small impacts. For larger, conventional ones, this was a major problem, but for microballoons it will not be, given their small mass.
The half-life of a balloon must be as long as possible, at least 50 years. This way, settlers will be able to replenish them.
How they work Edit
The most important feature of each balloon is its reflective surface and each one will behave like a tiny mirror. Depending on what the host star is, they can be metal-white or have different colors.
In case of B - type stars, which generate much of their light in ultraviolet, balloons might be covered with an UV reflective surface. In addition, they could transform part of blue and UV light into red or yellow light. This technology exists and is used in every neon, which in fact produces almost only blue light, which is transformed into a light more suitable for human eye.
Another option is to make balloons partially transparent. They will reflect only certain light wavelengths (for example part of visible and UV), but will allow heat to pass through.
Since these balloons are not very elastic, they will keep almost the same volume and will tend to fly at a certain altitude, where atmospheric pressure equals their density. This way, they can be placed at a height above the highest mountains, above majority of clouds (to protect them from lightning) and above conventional airplane lines.
It is possible to use them in the opposite way: by coating them with a substance that allows light to pass but reflects far infrared, they will behave like Greenhouse Gases. The main advantage is that balloons will stay high enough, while majority of greenhouse gasses, having a higher mass, will tend to go to the surface.
Major advantages Edit
Small balloons, having little mass, will better survive collisions with other balloons. When they break, they will only bring to the ground very small debris.
The main advantage is that covering the sky with small balloons will require far lesser materials then covering the same sky with big balloons. Economy will be made mostly on helium, which is very rare on rocky planets:
- A balloon with a radius of 1 km has a volume of 4.2 billion cubic meters and will protect 3.14 million square meters of land.
- A balloon with a radius of 1 m has a volume of 4.2 square meters and will protect 3.14 square meters of land. To protect the same surface like a 1km radius balloon, we will need one million balloons of one meter radius, but only 4.2 million cubic meters of helium (about 1000 times less helium).
- A balloon with a radius of 1 cm will have a volume of 0.0000042 square meters and will protect 0.000314 square meters of land. To protect the same surface like a 1 km wide balloon, we will need 10 billion small balloons, but with only 42000 cubic meters of helium (about 100000 times less).
Talking about materials, large balloons require stronger materials, while smaller ones not. The surface of a sphere is equal with the surface of a circle with the same radius. As a direct result, the surface of all balloons is equal to the surface of ground they cover (suppose they are at the same height) and is not inferred by size of a balloon. Given the fact that smaller balloons require thinner walls, building micro-balloons is less expensive and less resource consuming.
In some cases, it would be wise to create balloons with different mass, so that they will form two or more different layers. This way we can first deflect a certain type of radiation (for example UV), while the lower layer can reflect a part of visible light.
Balloons have a certain half-life. They will need to be replenished. This process is resource consuming. The costs of maintaining a layer of microballoons might be expensive.
Another major problem is that spaceships will have to pass through the balloon layer. Given their small size, it is not expected that ships will suffer from impact, but this might create temporary holes in the layer.
Another major problem is that balloons will be randomly moved by air currents. It is possible that at some point, density of balloons will not be constant. If less light is received for a few seconds or minutes, there should not be a problem. However, if the opposite happens and light passes unfiltered to the surface, on a planet closer to the Sun then Mercury, a minute is more then enough for temperatures to rise above 100 C. Such holes between balloons are predictable to happen fast, without a warning and also close fast. People traveling will need to have something to protect themselves, like an umbrella coated with aluminum. Vehicles and buildings will also need to be cover with something similar. In forests, pastures and crops, fires might ignite this way. Houses will need to be built of non-combustible materials. Holes in the balloon layer will not last more then a few minutes, so the atmosphere will absorb heat fast. After the incident, life can continue like before.
Another potential risk is that balloons might conduce electricity and stimulate lighting. They might interfere somehow with magnetic fields.
The sky Edit
On an inner planet covered with a layer of micro-balloons, the sky will be different then what we are used to see on Earth. They are too small to be seen individual, but they will tend to group. We might see something like a cloud, but with a different structure, with parts that are white, shiny, but also with darker or completely dark areas. If the layer is high enough, we should not see dark areas, but the blue sky instead, while whiter areas will be visible like clouds.
The sun would not be visible as a globe, but small parts of it will be seen through small gaps in the layer. In addition, the layer should be whiter closer to where the sun should be seen on the sky. Tiny gaps are formed and closed fast. The sun should appear as a multitude of blinking lights.
At dusk and dawn, we should not see the amazing colors we are used with, but instead, a more gray-themed landscape.
During night, there will be much darkness. Stars can be seen only occasionally, when they are in the same direction with a gap in the layer. Since gaps are small and are formed and destroyed fast, two parsons at 10 m one from another might not see a star at the same time. There is a possibility that balloons will interact with solar winds and magnetic fields and will create a dim light, similar with a pale aurora.
It is possible that during night water can condense and even freeze on the balloons. If this happens, their mass will increase and they will move down. The effects on the climate will be interesting, but also this will create interesting views of the sky.
On some planets, where the parent stars don't give enough light in each spectra as needed for plants, balloons might be colored. If this is the case, the majority of them should be white, with a small amount having a certain color. As air currents might temporarily arrange balloons in different structures, clouds of various colors can appear on the sky. This becomes very interesting if balloons have different mass and are placed on different layers.
Extrapolating this, balloons can be used also to generate a greenhouse effect, only that in such a scenario they allow light to pass and reflect heat. The major difference is that on an outer planet air currents are very slow and the layer will tend to be uniform. On the other hand, gravity will tend to merge balloons into unstable clusters. This will be an interesting phenomena which might be visible as almost invisible, diffuse clouds.
Even more, it is possible to use colored tiny balloons to create views that are impossible in nature, like a green sky. The very rich in the far future, with enough funds to order a terraformed planet at command, would be very pleased of this.
The use of microballoons can be controversial and might have many unforeseen risks, but as for now, it is the only feasible technology able to terraform a hot inner planet, more heated by its sun then Mercury is from ours.