A few more details here, but definitely read through the known issues if you decide to hop in:

We are intending to leave this build up for up to 24 hours but could come down sooner if blocking issues occur.
This test will have each Stanton shard split into many authoritative zones. We are planning to start the test out at 1 DGS with 100 players as a baseline and increase this to add more DGS with 500 and then as high as 1000 players

Edit: An easy way to download this is to rename your “LIVE” folder to “TECH-PREVIEW”.

Edit2: If they make it to 1000 players, this will be handled by 6 dedicated game servers (DGS) being meshed together into a shard.

The 500 player count will be achieved with 3 DGS

Global Chat will work, but will only show players in your DGS and not everyone in the shard: https://robertsspaceindustries.com/spectrum/community/SC/lobby/38230/message/55594666