Originally posted by sonhouse
Great news indeed. So I wonder why NASA didn't think of this say, 40 years ago?
They did. Its called the space shuttle.
The problem was, the idea started out well, but then got ruined by requirements. For example the military required it to have a very large cargo bay. But overall, the space shuttle was quite successful - just very very costly. Although it was reusable, servicing it for each flight cost more than building a new falcon 9.
Another factor might be computers, but I don't think so. I think computers from the 80's were probably sufficient to land a falcon 9.
SpaceX built the falcon rockets from the very beginning with re usability in mind. They spent extra on the rocket design to make it reusable, and carry extra fuel for the return journey which results in smaller payloads for the rocket size. But the planning and investment is paying off.