How would you better engineer this instead for it to actually last 55 million years?
Edit: For the defeatists, I meant if you had access to all the Earth's resources and the full effort of mankind.
Edit: For the defeatists, I meant if you had access to all the Earth's resources and the full effort of mankind.
Sphere should be mosty empty so that it has lower density than sand - it will float on it no matter how the dunes change.
Add small electric engines that rotate against the sphere in 2 axis, that will move the sphere back to its desired geographic position slowly.
You can pretty much seal up everything else (encased in a solid glass cube, e.g.). You may want an inert out-gassing source internally, but that would probably only last a few millennia.
Lead-acids would be garbage after 5 years, unless they were way oversized. After about 20 years, failure would be inevitable.
Ultracapacitors would probably last north of 50 years.
Whatever you encase the PV within needs to allow sunlight through. Diamond would probably not work for this. Silicon itself is freakin' hard (about 9 on the Mohs scale) so it would outperform even quartz in terms of abrasion resistance, and you could put its contacts on the back to keep them from eroding away. Silicon needs a different layer on the front to couple its high index of refraction to the incident light, and I'm not aware of any superior optically clear materials that could accomplish this.
Am not a speaker expert, but I'd be surprised if they didn't fail before the rest of the system. Apple's iPhone speakers will warble themselves dry after they're immersed in water, so I'm wondering if constant Toto will keep the sand out of the speakers.
An ultrasonic-interference sound generator based on piezoelectric elements might outperform a conventional speaker setup. Tinny > Short-lived.
The mechanical transducers in the loudspeakers are the big weak point though. Suspensions, foam mountings, the voice coil magnets themselves, the cone; all subject to stress. Under ideal conditions, hundreds of thousands of hours of use. A desert is far from ideal - fine dust and temperature extremes - though far from disastrous too (a damp salty cave by a tropical ocean). Hundreds of thousands of hours gets you a decade and a half of play. So only 54,999,985 years to engineer for.
Alternative speaker tech (piezo speakers maybe?) could last longer. But it's limited! Fine moving parts are anathema to this kind of longevity experiment.
EDIT: Actually I'd encase the electronics in a giant diamond; glass would get scoured rough by the sand pretty quickly, to the detriment of the PVs.
They are finally starting to build the thing, pretty exciting for someone one who has followed the project for 10+ years:
10,000 years might be the 1st baby step to building something to last 55 million, but that number is so large I would say it is effectively impossible.
That or robots...