Thank you, Tanada. I was waiting for someone to inject some reality into the whining.
Q: Do you think we will ever inhabit other planets?
A: That's not even the right question. There are no other local planets that are compatible with human life. And as others have pointed out, the energy required for star travel is prohibitively high.
Planets are not where anybody should want to live, anyway. They are uncontrolled, and full of diseases and parasites and predators. They are subject to weather events that kill people and destroy property. Worst of all, the one planet suitable for mankind in this solar system is overpopulated with humans already, and rapidly swirling around the drain at present. Worst of all, planets have limited supplies of water, food, raw materials for industries, and energy. Lastly, they have space limitations that will constrain the human species to a population somewhere in the billions, or at very best the tens of billions.
I am confident that we will occupy space off this world. I will touch briefly on a topic, a single paragraph, and then give anyone interested a line of further research.
The first space habitats were constructed in Low Earth Orbits. They were temporary homes, the US SpaceLab and the Russian Mir space "stations". LEO is also the logical place for the first permanent space habitats - which may or may not include the present International Space Station. LEO is the logical place to exploit space when limited to vehicles and habitats constructed on the surface of the Earth. The logical culmination is dozens - perhaps hundreds of habitats in LEO, because it is close, easy and cheap to access, and yet still has access to microgravity and pretty hard vacuums, as well as solar energy - all three being of interest in the manufacturing of new crystals, composite materials, and nanostructures such as Buckyballs. (Read up on the ISS experiments past, present, and planned for the future, then search "Bigelow Aerospace".)
Almost as accessible as LEO are the Lagrange points in the Earth/moon system. There are five points where the Earth/Moon gravity is in equilibrium, and no fuel is required for station-keeping, as it is in LEO. These are numbered L1 through L5 as follows:
....where M1 is the Earth and M2 the Earth's Moon (not to scale, of course).
L4 and L5 are the most useful of these and sometime in the next few decades I expect to see habitats constructed at both, using raw materials from the near-Earth asteroids (of which over 7000 have been identified so far). There are effectively unlimited water and materials off-Earth already, including the asteroid belt and Trojan asteroids (both nickel-iron and carbonaceous bodies), water ice from the rings of Saturn (more water than on Earth, and 99.9% pure), even more water (more than millions of planets the size of Earth) in the Oort Cloud, and the endless 24X7 solar energy in orbit. In fact there has been an active Engineering effort at designing these space habitats, an organization called the "L5 Society" since the 1970's. (Further reading would be "O'Neill Colony", "Asteroid Mining", "Saturn's Rings", "Oort Cloud", etc.).
I am virtually certain that once we have a foothold in space, that within the next two centuries, the exponential population growth that is stalling out from resource depletion on Earth will resume in the space of our own Solar System. I estimate the human carrying capacity of the Solar System - based just on the materials discovered already - to be in the hundreds of
Trillions.
It is inevitable, it will happen, and we are on the verge already. The only question being, will the end of cheap oil cause some catastrophe such as a nuclear war that will interrupt the steady progress towards the goals I have described, that is occurring today, without any of you even noticing. In other words, I am questioning whether or not we will remain alive long enough to escape the dirty and dangerous place we inhabit today.
After we leave, nobody should care about this planet or any other, ever again. Only a fool would live on the surface of a world when the alternative is a 100% human designed and human constructed space habitat.