If it's chemical propulsion, you're dead when you get there. If there's no refuelling (and you need refuelling) with some other travel mechanism, you can't get

If it's chemical propulsion, you're dead when you get there. If there's no refuelling (and you need refuelling) with some other travel mechanism, you can't get back. So we have an "or" assumption, not "and", with an additional and assumption about refuelling. That's how I read it.