Frankly speaking, exploration is not adding stardust for me. I lost more explorers (one time they are priced around 300 SD, recent yamato module hit the ship price hard.) then the stardust I found through the exploration.
If I remove the one planet that I found through exploration, I am net negative .

Finding the planet is luck but I think finding stardust should not be luck. You can come up with calculation how the 70K SD can be distributed to all exploration ranging from 10SD to 100 SD.