Is there any risk of contaminating Earth with something “not good” that normally would burn up when it entered our atmosphere
I guess 1 ton of rock isn't that much, but this is still a pretty surprising fact.
There's a lot of rock in space, and the Earth is a big target. Tons per day is not a lot when compared to the surface area available for it to land on.
The rocks that land can sometimes be cold enough that they build up frost on themselves, because they've retained their low temperature from space and started condensing moisture from the atmosphere.
Imagine the capsule crashes into a water source or breaks up in the near atmosphere. Even if there's 1/1B chances there's some deadly alien bacteria in there that will wipe out the Australian ecosystem as we know it, just taking the risk of complete media paranoia over a crash is quite something, even for the Australians.
You mean like Homo sapiens? :-)