I was going to make this a scene link but it was too short to make an note for it so here it is:
Daphne lay sprawled out on the bed, staring up at the ceiling, thinking about the planet she’d never come back to.
I'd say it's a good start! Definitely makes the reader ask 'what planet? wait, planet?' My only critiques would be to replace the comma with an 'and' (commas will kill your writing and you can actually remove most of them when you go back through and edit -if you tend to overuse them, like myself ^^; ) and to clarify the last little bit at the end. From what I'm reading, she's currently on the planet or had just recently left? Definitely think about the different feeling between 'come back to' and 'go back to' and what they imply.
Solid. My first book ever's opening line was horrible. It was something like "As So-and-so made his way down the dimly lit tunnel, his back ached and his knees buckled under the weight he was carrying." I dunno, I cringe every time. It took me like ten rewrites to get THAT, too.
I personally like that you show exactly what this book is from the get-go. I also agree with Fanta's advice.