Choosing a Supervisor, part 2

This is part two of the post, Choosing a Supervisor.

The second question I suggest you ask yourself with regards to choosing a supervisor is:

2. What is their impact and its timeliness?

Some researchers make their reputation once, so to speak, often early in their careers, then sort of just glide on it their whole lives.

Others reinvent themselves every 5-10 years, either by moving to new fields, writing high-impact books, making new fantastic discoveries or inventing useful new concepts. Perhaps they also co-create a startup and give technology transfer a try.

Do you mind working for someone who "was good back in the 80s" when it is 2010?