Here's an update from the mouse. Apparently it will be opening in August.
New Adventures Begin at Mission: SPACE in August at Epcot | Disney Parks Blog
And as it was announced at the D23 Expo, in just a few weeks, guests will be able to enjoy new adventures at Mission: SPACE – an updated Orange Mission and a brand-new Green Mission. (Orange is the more intense training experience, while Green is less intense).
The updated Orange Mission will make an even more visually stunning trip to Mars, while the all-new Green adventure will allow guests to blast off for an orbital adventure around planet Earth.
Awesome new poster released as well:
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From D23 we learned ILM is creating the visual effects for the new films. Can't wait to see Mars modeled by the CG pros. Rumors about the green side seem to indicate it'll be more about floating around Earth and a mission that doesn't involve Mars. Should be interesting.