Frequent friend of the TMNT, Usagi Yojimbo has a cartoon in the works based off his space exploits. You may recall Usagi appeared in numerous iterations of the TMNT whether it was animated, action figure, or through the comic pages. A recent Reddit poster shared a link to a brief clip introducing space Usagi in a test pilot. What could have been! Check it out.
Further investigation led to the Usagi fansite that has a section dedicated to Space Usagi. According to the FAQ Space Usagi never got picked up due to a lack of toy company backing. Back in the 80’s and 90’s one of the biggest ways to get a cartoon made was to have a toy company backing them, makes sense when you look at the correlation between cartoons and related toy lines of the time.