We are truly spreading the worst of humanity into the cosmos. Good job it's only us that appear able to witness it.
Defraying costs by using ads is a strawman. If you can't afford to do something, maybe don't do it. If you really, really want to do it, maybe ask yourself if the world genuinely needs what you're doing. If it does, find a way. If the only way you can do it is by selling advertising, you've taken as mis-step.
That's an extreme position to take that rests on the claim that sponsorship/advertising is objectively bad.
Media & journalism have been underpinned by advertising for over a century. Tons of educational and informative services are available to the public for free because of advertising. Sponsorship has built art galleries, hospital wings, research centers, etc.
In this case, there's a relatively innocuous logo on a robotic lander that is 230k miles away on a desolate rock. It's not like this is a billboard in a nature preserve.
Whether advertising is objectively bad isn't necessarily the debate, but at some point it can cross a line. That line might be different for everyone, but most people will have it. You yourself give an example of something you suggest might be unaccaptable to some:
> billboard in a nature preserve
Where's the line? Why shouldn't we put billboards in nature preserves?
