In short: Beacon unlikely to survie on the surface, but the structure of underground tunnels could be visible via seismic measurements, or a gradient of rare elements. For example, tunnels could be put in such order that they form something like diffraction grid for typical seismic waves and this unusual deflection of the waves will be visible for the future scientist. However, I think that creation of the beacon on the Moon surface is more feasible via ditching lines.
More detailed: We have 4 billions years old rock formations in Australia, and micrometer size fossils of early microorganisms survived for billions of years which imply possibility of sending data in the future. We could also predict which rock will likely not disappear in the next hundreds millions of years. So if we put an object deep into such rock, it will survive for very long time and could carry information onto the future.
There is also a data preservation project in a salt mine in Austria, but they are going to send data 1 million years in future only using printing on ceramic plates, and many small maps printed on ceramic coins as beacons. https://en.wikipedia.org/wiki/Memory_of_Mankind
The main problem of leaving long-term data storages on Earth is beacons, not data. However, I found a possible solution: use large underground storages of radioactive materials as possible storage locations and beacons. The reasons:
1) The are already in the rock which is proved to survive for long-term, like Scandinavian crystal shield.
2) They are deep undersurface, so surface scratching by future ice ages etc will not affect them.
3) Such storage is a large structure of artificial form, which could be found via some advance seismic measurements.
4) Radiological waste storage consists of the system of horizontal tunnels which could be planned as a drawing, so its plan could be part of the message, like a spiral, which centered in the place of location of the main message, or even as a diffraction grid or a hologram, which change direction of the seismic waves in a very peculiar way. However, the Finish project is already built, so using tunnels for drawing is not possible here.
5) The whole project could have negative cost, as radiological waste storages have bad PR and large sunk cost, so using them for ensuring human survival could be done as part of their PR project. It will cost only small fraction of the radiological storage which costs 3 bn.
In short: Beacon unlikely to survie on the surface, but the structure of underground tunnels could be visible via seismic measurements, or a gradient of rare elements. For example, tunnels could be put in such order that they form something like diffraction grid for typical seismic waves and this unusual deflection of the waves will be visible for the future scientist. However, I think that creation of the beacon on the Moon surface is more feasible via ditching lines.
More detailed: We have 4 billions years old rock formations in Australia, and micrometer size fossils of early microorganisms survived for billions of years which imply possibility of sending data in the future. We could also predict which rock will likely not disappear in the next hundreds millions of years. So if we put an object deep into such rock, it will survive for very long time and could carry information onto the future.
There is also a data preservation project in a salt mine in Austria, but they are going to send data 1 million years in future only using printing on ceramic plates, and many small maps printed on ceramic coins as beacons. https://en.wikipedia.org/wiki/Memory_of_Mankind
The main problem of leaving long-term data storages on Earth is beacons, not data. However, I found a possible solution: use large underground storages of radioactive materials as possible storage locations and beacons. The reasons:
1) The are already in the rock which is proved to survive for long-term, like Scandinavian crystal shield.
2) They are deep undersurface, so surface scratching by future ice ages etc will not affect them.
3) Such storage is a large structure of artificial form, which could be found via some advance seismic measurements.
4) Radiological waste storage consists of the system of horizontal tunnels which could be planned as a drawing, so its plan could be part of the message, like a spiral, which centered in the place of location of the main message, or even as a diffraction grid or a hologram, which change direction of the seismic waves in a very peculiar way. However, the Finish project is already built, so using tunnels for drawing is not possible here.
5) The whole project could have negative cost, as radiological waste storages have bad PR and large sunk cost, so using them for ensuring human survival could be done as part of their PR project. It will cost only small fraction of the radiological storage which costs 3 bn.