We're talking about space missions that cost a fraction of a billion dollars at the low end, and people have invested decades into just getting approvals and fu

We're talking about space missions that cost a fraction of a billion dollars at the low end, and people have invested decades into just getting approvals and funding. And then perhaps another ten years just to get the spacecraft where it needs to go. These are nation-level assets. You're going to protect them much more heavily & securely than a corporate website. You can't allow a hostile attacker in for even a fraction of a second, so guest access will be strongly vetted, and networks will be protected by physical isolation.