An idea

I read somewhere that Mars might harbour life in a very far future when the sun become bigger during it exctinction phase.

Why nobody ever thought about sending a "time capsule" on Mars?
By time capsule, I mean a long lasting artifact that could explain that there was life on earth before.

Maybe, such an artifact exists on earth ... and it was sent by the ones who lived on Mars when there was life Mars?

Reminds me of a Novel from Philip K. Dick.