hello! i have a suggestion to the second cover.
First, great work! The covers are really fine in my board. i love them.

i think the three main characters of this tv show are kirk, spock and bones...
Perhaps the second cover, shall show mr spock not uhura.

or you can find a way to show the other 4 characters on the covers too...
scotti, checkov, zulu and uhura with the three main characters combined?

ok... i like the covers
thanks for this great work.