"most space" is correct and usable in written English.
You can use it when you are referring to the largest amount of something. For example, "We need to find the most space available for the new factory."
Most space launch vehicles have three stages.
High-Precision Photometry: MOST space telescope; Kepler mission.
Which articles deserve the most space on your front page?
It was the artist Michael Craig-Martin who observed this week that, "most space is undifferentiated.
The Sun, with seven pages, devoted most space to the story.
Rina Bannerjee's exuberant "Contagious Space, Preserving Pinkeye" uses the most space.
Ford and Mazda say the pair have the most space in their class.
Cosmonauts and most space travelers launching from Baikonur have carried on the tradition since then.
It is a remarkable piece, the music of Bach at its most "Space Odyssey" — now sparkling, now sermonizing.
Of those considered here, the one based on wavelets seems to be the most space efficient and quickest to compute.
Unlike most space vehicles, it will be possible to test the aircraft proposed here in a conventional flight test environment.
