My sister bought this for me at an auction for my birthday present. The miniature sheet and a set of stamps came together in one nice presentation package with the word Space on the front cover and a detailed explanation of Mars statistics. I was not sure which year this is as I don't collect Australian stamps either. When I heard the price, I thought she overpaid for it but then it was for charity, so I guess it is okay.
Anyway, I checked the stamps out. It was issued in 2000 but I am not sure what the occasion was. If there is anyone out there who can tell me more about these stamps, I would be most happy to hear from you.