> Something changed recently, making the US "first to file". Did that totally eliminate the concept of prior art?

No, it just removes the question of when an invention happened. Under first to invent, if two similar patents are filed, there is some effort required to determine which was invented first, and gets priority. Under first to file, it's much simpler to determine.

Prior art is still a reason to deny a patent, and patent examiners are still likely to miss it.

Then what exactly does first to file even mean? If you and I both invent something, but I invent it a month after you do and file for a patent first, would it be granted since I'm the first to file, or could you invalidate the claim by showing that there was prior art - specifically, your prior invention of the same thing?

It depends. If I invented it, and kept it to myself, and don't get around to filing a patent until after you; first to file means you get the patent. I may have rights to continue to use the invention as a prior user, but I'm not familiar with the details there.

If I published it before you filed though, that's prior art. Again, I'm not super familiar with details here of if it had to be published for some time or just the day before is fine.

> the Viking lander in 1976

I love this as prior art. The Viking lander was definitely "a mobile device", was wireless and transferred images. I think the only question might be if the "filtering" involved qualifies.

I wonder when we started sending digital images from space. Apollo did not use them but sent analog signals. But I think Voyager used digital images.

Commercial digital TV was first introduced in the US in 1994, also predating this patent. That's fairly well known and widespread, also all of the TVs all of us own and which are part of FCC standards violate this patent.