I've got a class 17 heavy gravity world in the system next to my home system that I would quite like to colonise before the AI does. However, it will take me 20 weeks to research heavy gravity colonization, and another 38 to research the advanced version of the tech. I know that if I colonise with only the first stage, then the planet will only got 50% of it's land space available, resulting in effectively a class 8 or 9 planet.
However, if I later research the advanced version of the technology, do I get that lost space back? Or does the planet get permanently reduced?