In a way, we have a new Mars mission coming up that has been off of the radar for many of us, I think. JWST will be, if all goes well, operational before the next Mars opposition in 2022. JWST is not going "to" Mars (although it will be about 3% closer to Mars than terrestrial telescopes), but it has spectral capabilities strikingly superior to anything we have ever sent to Mars, and its spatial resolution will still be abundantly adequate for differentiating different regions, atmospheric layers, etc.

An overview here, not new, but new to me: