Python code snippet attempting to determine possible launch dates which meet the clues offered in the book "The Martian" Created as an exercise for the article on the science of "The Martion" for WRAL-TV. http://www.wral.com/15228560/
2020 is rejected due to the plausability of creating the necessary technology then. 2032 doesn't work because no launch opportunities exist in that year, so 2035 is the answer.
References: Interplanetary Mission Design Handbook: Earth-to-Mars Mission Opportunities 2026 to 2045 by Laura M. Burke, Robert D. Falck, and Melissa L. McGuire, NASA Glenn NASA/TM—2010-216764 http://ntrs.nasa.gov/search.jsp?R=20100037210 The Martian by Andy Weir, specifically Sol1, 16 and 96 entries.