Hi. I’m not much of an artist, but it doesn’t look like you have any replies yet, so here are my thoughts.
Her face looks a bit flat, although that could be a natural thing.
Her lips are perhaps a little too big, or bright. She wouldn’t be wearing lipstick in space, right?
The spaceships look textureless compared to her suit. Even her face seems to have less detail. Her pupils make her look like she’s looking up – at nothing really. Maybe if you made her look down, or at some significant sight (perhaps the mountains?), and changed her mouth expression a little bit so she looked like she was sad to be leaving the planet, it would make it more interesting? She does look a little sad, but it could be improved. Aside from the “mountains” the ground is pretty much flat. I would like to see more of the planet. The smoke coming from the rocket on the left looks great, and her suit looks great. It’s awesome for a picture without a reference. Good work