The main menu is well laid out for ease of use, but lots of unused space to the left. The menu could have been down the left side of the screen thus creating more space for your sun and potentially more planets in the scene. The typeface used is clear and easy to read, although with this much unused space the title could have been much larger.
For the object scene the theme of the buttons seems to change from black and white to red, a more consistent colour scheme should be applied. The design of the rocket is fantastic, but I think it should start slightly smaller to not take up so much of the screen as its out of frame to begin with. Background from the menu screen could have been used behind the rocket to reiterate space theme.
The interactions are good, but the orbit path is slightly off centre and runs way out of frame, once shrunk down, the orbit button becomes a far better interaction. Up and down move increments are far to small and almost unnoticeable, but overall very well designed.
Well done Jack