I've read about Bitcoin core being powered in space inside a satellite and streaming down the bitcoin blockchain back down to earth. What has been discussed so far and timeline for this to go live for Blockstream?
Blockstream launched a satellite service. It did not launch a satellite.
Bitcoin blocks are being broadcast by Blockstream, by contracting with several existing several satellite systems. These satellites are primarily designed for broadcasting TV signals, and thus don't run their own full nodes; the broadcast is dependent on ground stations that uplink the data.
The data is freely available from (nearly) every place on earth (excluding oceans and polar regions). You do need your own satellite dish and some other hardware, but the system is designed to keep the costs as low as possible.
For more information, see https://blockstream.com/satellite/