Spoiler alert-----
The two astronauts who re-entered could have gotten that colony flight up and running with the underground survivors right? That would have been a pretty interesting bit of plot.
It felt like the movie kind of dragged. Like the plot wasn't leading anywhere substantial. The graphics and CGI were great, and the ending was a little nice sentimental touch, but I felt the overall idea could have been improved upon.
The universe of the movie needed to be developed more, and the characters as well. I didn't feel invested enough in the tragedy of what happened to Earth, or in the characters individually.
It felt like disconnected bits of struggle, which needed to be solved before the plot could actually progress.