After an 18 year old teenager who was born and raised on a safe space colony on Mars visits the post-apocalyptic Earth for the first time, he needs to find out,where he really belongs ? with his family up on the Mars, or down here on the Earth.

https://en.wikipedia.org/wiki/The_Space_Between_Us_(film)

Read other loglines and study the ?Formula? tab ? there?s a specific structure loglines require.

As Richiev has stated, you need to include what it is that makes him want to stay on earth. Not only is that the incident that starts the whole adventure but it also establishes what sort of film we're looking at, helps to provide stakes, can hint at antagonistic forces working against him, and makes us understand his goal. That's how important this one detail is.

Dkpough1's feedback is spot on too. As far as the goal goes, making a decision is an internal struggle. Imagine watching someone make a decision - it could take seconds, minutes, or days but you'd still just be watching someone thinking. For a visual medium this is a really boring thing to see so make his goal something tangible and visual. This goal can be used to represent the internal goal - in Stand By Me for example, the journey to find the body represents the characters coming of age.

Without the inciting incident and corresponding goal it's difficult to understand what the stakes are so focus on those two bits first and, if you get them right, chances are everything else will fall into place.

Hope this helps.