Read the first two chapters and I'm intrigued.
The brother/sister dynamic on a starship is interesting and I can't help but like the bright-eyed, fresh-faced science officer. Let's see if she can keep up that high spirit and naiveté once out in space.
You haven't given us many clues yet as of the setting of this story. If feels a bit like Alternative timeline Trek but I could be wrong.
Also agree with Sgt_G. It would help to have paragraph breaks to distinguish the dialogue. As it is I got a little confused on who was talking. Don't worry about short paragraphs. I personally prefer reading less blocky writing as it makes things flow better, in my view.