> Can’t we use some other medium with more space?

> The conditions in space prove hostile to many data mediums. Traditional CDs or DVDs would be destroyed in space, because they are composed of layers and would come undone. It’s different with a medium made of ceramics. Also, you have to consider the dimensions and weight of your medium. The ceramic disc is light enough and resilient.

I'm guessing microSD cards are not radiation hardened.