My adviser asked me to come up with a research topic for a PhD student. As I'm expected to graduate in early 2016, my mentor considered this a good "exercise" for a tenure track career. Of course, this is not intended to be final, I am supposed to propose to my adviser this topic and then it will be decided whether it is good enough to suggest a direction of a student's research.
Based on the field of interest, I intend to propose a problem which I find interesting (and would gladly research myself, if the time permitted). To that purpose, I defined a number of milestones, covering some likely scenarios in the research progress. I also prepared around 20 papers, some of which serve as an introduction to the problems of the field of interest, while others are state-of-the-art approaches closely related to the topic.
This is basically more than I had when I begun my research. So, in that regard, I'm confident that I did a reasonable job so far. Of course, if you have any remarks, don't hesitate to add them.
My problem is that it would currently be very hard for me to come up with more than 2-3 topics prepared in that way.
Also, I can't help but wonder whether the topic I would suggest is "good enough" to lead the student to conduct quality research and eventually to a PhD. In this particular case, my mentor will shape the topic and guide the student so there is no worry. Besides that, I am confident that the suggested topic is a problem in the field, as I thought and investigated it a long before the request came from my adviser.
I find it a bit hard to believe that I'll always have such problems ready in my head, so I assume that I'll have to start from somewhere in forming one.
So, what methodology should I follow when defining research topics?