The most common and most likely answer to this crossword clue is the 16 letter word ROCKETÂ SCIENTIST
I've seen this crossword clue in The Guardian
R
O
C
K
E
T
Â
S
C
I
E
N
T
I
S
T
Buddy explains!

The straight part
We know that "One aims for space" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case one aims for space = rocket scientist.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.