Monday, September 25, 2017

Harvesting from Gas Giants

There has been some small amount of discussion here on Earth about mining extraplanetary resources. One subject was the He3 on the moon, which makes an excellent fusion fuel. Another has been precious metals or rare earths on asteroids. These are all high value to weight materials, found on places without deep gravitational wells. The idea would be very simple. Go out and mine them where they are found, ship them back via rocket, and land them somehow on Earth.

An alien civilization might start with such things in their early days of harvesting interplanetary resources, but what about the gas giants? Assuming their solar system has one or more gas giants, like we have Jupiter and Saturn, these planets represent the large majority of planetary mass in the solar system, meaning they might be the location of the largest amount of resources. We do not yet understand the composition of the core of these planets, as their atmospheres are too thick to see though and too dense to fly a probe into and survive. We hardly know the radius of the solid cores, or if indeed there is a well-defined one. We know what we see, the upper atmosphere, which for Jupiter and Saturn, is a banded pattern with a great amount of wind shear and turbulence. The banded patterns likely come from the mixing of lower layers of the atmosphere due to convective circulation forced by rotation, akin to Coriolis forces. The lower layers have a different composition due to the gravity gradient and therefore a different albedo shows where they are circulated upwards.

Is there any way that energy might be harvested from a planet such as Jupiter and brought back to the home planet, such as Earth, with a positive return? There must be a total amount of energy expended to both obtain the energy at the gas giant and then transport it back to the home planet and down to the surface there and this has to be less than the energy provided. These calculations cannot be done now, as we are short a hundred years or so of engineering, but some ideas as to the sources can be guessed. One source is the simplest: hydrogen. Hydrogen brought to a planet with a surplus of oxygen is an excellent fuel, only making water when combusted. One idea for alien planets is that their energy on the surface would be transported and used as hydrogen gas, but whether it is or not, hydrogen for power plants is still a viable concept.

The upper atmosphere of Jupiter and all gas giants is mostly hydrogen, with a bit of helium mixing in. Helium does not much degrade the fuel ability of hydrogen, and might be fairly valuable on the home planet in its own right, so bringing back a bit of an admixture with helium is not a bad idea. Gas giants are gas giants because they are large enough to retain hydrogen for time comparable with the age of the solar system or the universe, so any large enough planet should be mostly hydrogen at the top of its atmosphere. Skimming into that exosphere with a large tank and a large scoop should pick up hydrogen quite nicely. It might be compressed a bit more before shipping it back to the home planet, to whatever degree minimizes the tank mass per hydrogen mass.

The energy cost for shipping some tank back to the home planet is not connected to the energy for a space ship, as shuttle orbits can be used which are immensely efficient, needing only steering propulsion. There would have to be energy expended to bring the tank of hydrogen up to match the velocity of the ship transporting it, and then energy expended when the tank was dropped off into an orbit around the home planet. An empty tank would have to be attached in place of the full tank to the shuttle craft, and this could be managed as a momentum transfer, so that only the energy to decelerate the mass of hydrogen is necessary, plus some energy for steering and aligning orbits.

Once in orbit around the home planet, the hydrogen would have to be brought down to the home planet’s surface. Reusable shuttle craft is one idea, burning some of the hydrogen with atmospheric oxygen to land calmly and gently. We have only begun to perfect the art of reusable surface-to-orbit shuttles, but they obviously can be done. Another more exotic idea is to have a large diameter pipe oriented vertically, from geostationary orbit down to the surface. This idea has been discussed as a space elevator, but it is even simpler to have a hollow pipe though which hydrogen could flow. Obviously, there would be great bending moment on the pipe from the atmosphere, but if that is solved, it would likely be more efficient that reusable shuttles.

Other sources are much more difficult to harvest, but might be possible. There are tremendous wind forces on Jupiter, and likely gas giants in other solar systems. There is no clear way to put something down on the core surface to capture the wind energy and then transform it into a transportable form and bring it up through the entire atmosphere back to orbit where it could be returned to the home planet. Instead, some form of long tether between two floating objects, at different altitude, might serve to provide enough differential wind velocity to harvest power electrically. We have not mastered the art of transmitting power over long distances even on Earth or from Earth orbit to Earth surface, but it does seem to be remotely possible that a tethered platform could transmit power to an orbiting satellite, which would then put it into some form where it could be transported back to the home planet. Batteries are an inefficient form of energy storage, and chemical fuel in the form of carbon bonds is much more energy-dense. Shipping water and carbon dioxide on the shuttle back to the gas giant, where they were transformed to octane or something similar, and then shipping by shuttle back to the home planet would use very little energy in transferring orbits. The octane might be burned in home planet orbit and the exhaust packaged and reshipped to the gas giant.

Another less thought of form of energy harvesting is from the magnetic field of the gas giant. If the alien solar system had rapidly rotating gas giants, they should have strong magnetic fields, although we frankly do not understand the mechanisms for planetary magnetic fields very well. A huge loop of conductor, orbiting at low orbit over the gas giant and oriented perpendicularly to the field lines, should capture a large current which could be transformed and transferred in much the same way as electrical power captured from wind shear forces.

All in all, energy harvesting from a gas giant might be quite possible for an advanced alien civilization, and this would be manifested by large numbers of shuttle craft going to and from the gas giant and the home planet. These might be visible in very limited circumstances. Nothing else in any of these schemes would even conceivably be visible with a giant telescope from our solar system, but if we could better understand the sources of usable energy in an alien solar system, we might better understand the longevity of the civilization and their propensity for star travel.

Wednesday, September 13, 2017

Civilizations of Intelligent Aliens

If we are going to try and get some insight as to why aliens have not visited us, it would help to know how they think, what they consider important, how they plan their lives, how visionary they are, and many similar questions. Here on Earth we are still somewhat primitive, so we might have some difficulty in imagining how a more advanced society would consider these topics. On Earth, intelligence is very diverse, ranging from what we consider retarded to what we consider genius. On an advanced alien planet, which had passed the genetic grand transition, there might easily be only genius category individuals, or what they consider genius category. Their average might be even higher than our best.

Our society here on Earth is built on the diversity of intelligence. Intelligence makes a big difference in one’s social standing, success, living standards, and interaction with others. It is not so much IQ-measured intelligence, but the ability to solve problems, to be creative, to spot errors, to organize people and projects, to manage things, and so on. We have the people who excel at those tasks running things, and feeding information to the others further down the rungs of the intelligence ladder. Assuming there is a metric which might measure this type of intelligence, you could say that the top 20% or so are in charge of the important organizations, and have influence over all the others.

Our society is organized around this downward flowing of information. The top 20% create it and the lower 80% consume it. This holds in science, technology, governance, business, art, and other segments of our social life. The measure is not ironclad, as there are certainly exceptions, but there is a substantial correlation. This would not be so on a planet with universal high intelligence.

When there is no ranking based on intelligence, how would positions and opportunities be apportioned out? One possibility is a lottery but there are others. How would living standards be decided? Would there be only one living standard and everyone got the same; housing, materials, foods, traveling, and so on? Would there be variations, decided on some random aspects, and would they exist for the whole life of each individual alien, or would an alien experience very different living standards at different times in his/her/its life?

More to the point, without some natural leaders, where every alien could do just as good a job at leading the civilization or its regions or factions, is there any impetus to do great projects, like interstellar voyaging? With no inherent leadership, would some individual alien be chosen and given the mandate to lead the civilization, and if so, would he/she/it decide on something monumental, like an interstellar voyage? On Earth, grandiose projects are usually the project of an individual, although there may be behind-the-scenes motivation and support. The projects are often things which provide that individual with psychological benefits, such as conquests, monuments, or new forms of government. An individual in an alien civilization would be living in a time when he/she/it would already be receiving an abundance of psychological benefits, as the civilization would have supplied those needs just as it supplies all physical needs. Any training would be universal, and not designed to produce individuals who felt a need to do gigantic things. So, from an individual view, there might be no one to lead the civilization to new planets and solar systems.

Perhaps the place of individual leadership would be taken by artificial intelligence. Why would individual aliens want to take on the job of figuring out the details of how to manage the civilization, when it could be automated entirely, and left to some algorithms? But the AI being used for governance would be useful for coordinating the activities of the various robotic systems so that the society would function smoothly and flawlessly, but how would it take over the job of inspiring the aliens to go into interstellar space?

On Earth, we have no serious AI, but we have many people speculating about it, and the usual speculation is that it somehow develops human emotions and starts to act like a super-person. If It was not designed to do that, it would not. At the core of the AI program is a set of metrics and goals, and the AI seeks to take actions and make decisions so that these goals are fulfilled, or the metrics brought to the highest levels. This does not involve star flight.

There would be no individuals who would take on the job of leading a movement to go to space. Everyone would be just as able to envision the idea, see the difficulties, evaluate the benefits, and make a choice. A singular individual, taking on this mission as a human being might, would find little response among other aliens.

In earlier posts, it was discussed how the goal of extraterrestrial travel would have to be encoded into the training that each alien received during his/her/its youth, and then there would be a universal consensus that this task should be part of the civilization’s activities and should be given a portion of the planet’s or solar system’s resources. With that embedded into the tapestry of the civilization’s culture, aliens would expect to devote some part of their time to furthering that goal, or at least to sacrifice some of their resources to it. But the concept that some individual alien would arise in the absence of this portion of their training, and somehow get the idea that he/she/it should lead the civilization into extrasolar space, is more a projection of what we might expect than what might actually happen in an advanced alien civilization. We like to have science fiction stories based around some inspired hero, or we write out histories as it certain individuals made choices and led movements, but these are things that pertain to our civilization with its shortage of intelligence and its dependence on downward communication of ideas and goals. If we try to figure out what happens in an alien civilization by treating it just like Earth with its humans plus some advanced technology, then there will certainly be misunderstandings and possibly even absurd conclusions