The problem of immigration to space

The following is purely personal understanding.

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1。 The investment in building a space station is relatively large. For immigrants, its scale is almost impossible, and the problem of building materials alone is very nerve-racking.

2。 It is relatively practical to transfer to other planets or satellites in the solar system, but not many planets can do it. Like Europa and Titan, the heat source can't be guaranteed from the beginning. At present, there is no need to consider mercury and venus, and the asteroid belt is too far from the sun to ensure the heat source. In the end, only the moon and Mars can plan their development plans, which are of course the advantages of the moon.

3。 Earth-like planets outside the solar system, needless to say, I think it is several orders of magnitude more difficult than the space station.