This is called - “coordinator”. Because the middleman means that the data is coming through it, which is not the case.
The satellite is a part of the Storj network, it contains encrypted metadata of the customer. To get an access to the metadata you need to have an API key and the satellite URI. But only metadata is not enough, it would allow you only to get a list of nodes and the order of merging the pieces back to the segments and to the encrypted file (if the permissions integrated to an API key, which is macaroon too, are allowing to do so).
You also need an encryption key to be able to decrypt the file. And anyway, you always download your data from the nodes, and uploads your data to the nodes. Either directly using libuplink, or indirectly using the S3 Gateway (ours or yours). You updates your metadata on the satellite though (it should account how much data you are storing, how much data you downloaded, your bills and invoices, etc.).