W10
"That's coz it's not running W10"
Microsoft, which probably consisted of just Bill Gates and a couple of buddies at the time, if it even existed as a company at all in 1976 when the probes were being built, hadn't even yet considered ripping off the GUI from Apple, where Woz was still breathing solder fumes in a garage. And it would be some years yet before the Steves thought to steal it from Xerox, who had only just come up with it about 2-3 years prior. Ol' Bill was probably still working on Commodore BASIC for the first gen PET when the probes were being built..
I still envision an alternate history where X86 was only a bit player and we're all using Commodore-compatible instead of IBM-compatible machines.