A century from now, if earth's population continues to grow, our descendants may wish to expand the amount of land that is available for settlement.

Thrusters may open up new alternatives in considering how best to use earth's available resources.

Huge land masses are presently not very useful because they are too far north. See map.

Reducing, even eliminating, the tilt wouldn't make the Northern land masses accessible, because they would still be locked into deep cold.

There are at least two possibilities that might be worth exploring:

One possibility is to change the orientation to maximize the amount of land surface that is comfortable and arable.

Whether we can reorient the entire planet, or just slide the mantle, we could bring these less useful landmasses into temperate climates and expand the useful land available for settlement.

Another possibility is to find ways to expand the amount of ice stored at the poles. This would lower the levels of the seas, and give us much more land around our coasts. I hope our scientists explore ways to expand the polar ice caps and how to make them grow. Changing the earth's orbit to make it a little cooler everywhere is one way, but the price may be too high to consider, unless we are otherwise forced to do it to contain global warming, or avoid a collision.

Changing the earth's spin rate might have the same effect, and it would be a great deal easier to do. (See NASA announcement.) It should be reasonably easy to discover whether we gain or lose heat by changing the spin rate, or whether it is a zero sum game.

During the next century, we might even explore low tech, brute force methods of adding to the ice caps. For example, pumping seawater down through the mantle into the molten core to create steam upwind of Antarctica might give the air there the moisture it needs to create snow and deepen the ice pack. Those who have visited Iceland may resonate to this idea.

We might even consider locating some thrusters in polar locations where the heat generated by the thrusting could be used to generate steam, which might help with increasing moisture available for ice creation. This might be practical if our scientists determine that continuous low levels of thrust are better than thrusters that operate in bursts.