It's not just "very hard", it's utterly impossible for a civilization of our level. Making a small colony on Mars is far more doable, even though that's pretty

It's not just "very hard", it's utterly impossible for a civilization of our level. Making a small colony on Mars is far more doable, even though that's pretty dubious. But Mars at least doesn't have a sulfuric acid atmosphere with crushing deep-sea pressure and a temperature hot enough to melt lead. The idea of terraforming that is just silly. It would be easier to build a generation ship to travel to other star systems.