"Copenhagen Suborbitals is the world’s only manned, amateur space program."
The way this is phrased, it sounds like they've already achieved it, and I feel like that's a little bit intentional. They could have easily called it an "amateur manned space program", which would have lessened the ambiguity.
I'm pretty sure it is "big red bus"[0] and not "big, red bus" unless you're using the comma for emphasis? Either way, as you say, it can't be "red, big bus" nor can it be "red big bus" because these adjectives are cumulative, not coordinating.
I think that comma was correct. Try saying it (the whole sentence I mean, not just "big red bus". He wasn't an adjective phrase describing the bus but an example of a list of adjectives that could form an adjective phrase. You instinctively put pauses between "big" and "red" because you are talking about it as a list. When you are talking about lists you put commas between the elements, and when you take pauses you put commas. So there are at least two reasons why a comma belongs there even though when using adjectives naturally you don't put a comma.
Writing it that way makes it sound like they've already achieved the goal, that they're already putting humans into space.
Like, if just having it as a goal is sufficient, well heck, I could step onto my lawn tomorrow and declare my household a manned amateur space program.
