Precisely what I was thinking, I wonder what's all the discussion about, the MOM will be inserted into a highly elliptical orbit around Mars, with a planned periapsis of 365 km (227 mi) and apoapsis of 80,000 km (50,000 mi) [1]. It will not even come close Mars's atmosphere. Wouldn't that take contamination out of the question completely?
[1] http://en.wikipedia.org/wiki/Mars_Orbiter_Mission