Ask HN: How is it that a vuln. scanner (Nexpose) requires 50 GB of HD space?

I'd like to see if anyone can shed some light on this... I was installing the community version of the Nexpose vulnerability scanner and had about 40 GB of free space, when at some point the installer stops saying Nexpose requires at least 50 GB (!) of free space (or "just" 10 GB for the community edition)... Can anyone possibly tell me what all that data is about in a vulnerabily scanner? Isn't vulnerability scanning mostly about comparing service banners to detect exploitable ones? Yeah maybe there is also some big word dictionary in the package? But 50 GB of service banners and dictionary seems just ridiculous? Thanks.