Mazanek and his team members are Aerospace Engineers
The quote may be found here:
http://www.spaceref.com/news/viewsr.html?pid=18122
An analysis of alternative Mars propulsion systems was done many years ago in th Soveit Union.
That team of engineers favored solar power, because it had an unlimited lifetime, and would not have to be discarded, which is what would have to be donee to nuclear systems after they became radioactive.