For at topic to be manageable:

1. It must not be too broad.

If your topic is too broad, there will be too many sources to consult.

If you simply search for the topic "cell phones," you will find thousands of articles to sift through.

Most good research topics usually contain more than one concept, which helps to focus the topic. Rather than writing about cell phones in general, you may want to focus on the effect of cell phones on hearing in teenagers (3 separate concepts: cell phones, hearing, teenagers).

2. There must be sufficient source material.

If you research an event that happened very recently, there may not be enough scholarly material to learn from. If you've learned about the information cycle, you know that scholarly research material is published some time after an event occurs or an idea is developed.

Consider broadening to an event from the past that has been researched and critiqued.

Rather than writing only about the Haiti earthquake, consider looking at the social toll that earthquakes can take.

If your topic is too narrow and specific, there won't be enough research for you to draw from.

You may pick the most interesting topic ever, but if it hasn't been studied yet, you may not find any published information to support your thesis.

BE FLEXIBLE --Once you do some initial searching, you may decide to broaden your topic, narrow your topic, or select a new topic altogether.

From the Purdue OWL:

Research topics are often fluid, and dictated more by the student's ongoing research than by the original chosen topic. Such fluidity is common in research, and should be embraced as one of its many characteristics.

http://owl.english.purdue.edu/owl/resource/658/03