Downside..... sixteen months in total confinement with your spouse.
Plus-side..... going into space and becoming the first humans to enter Mars orbit.
Any takers?
http://news.sky.com/story/1057890/mars-mission-tito-project-seeks-married-pair
By the way, it's in 2018 - so if you're not married yet, I guess there's still time!
Cedars