The Daily Post had a Daily Prompt today called Longing For Gravity, and this is what it said:
You are on a mission to Mars.
Because of the length of of the journey, you will never be able to return to Earth.
What about our blue planet will you miss the most?
(Thank you for the wonderful prompt suggestion, K. Renae P.!)
And this is my response:
Because Mars is currently so inhospitable, I would miss some of the natural environment of Earth the most, because most of that is lacking on Mars at this time: