Mission to Byss (Rosh Penin)
The Initial Expedition to Byss was undertaken by the Jedi Rosh Penin in the year 14 ABY, acting on behalf of the New Jedi Order. Luke Skywalker tasked Rosh with the examination of the remnants of Byss, with the aim of ascertaining if the Disciples of Ragnos had been present.
The mission
Byss became Rosh's designated destination, but he failed to return or establish communication. Subsequently, after a period of time, Kyle Katarn resolved to search for him amidst the planetary debris, and later, alongside Jaden Korr to investigate given that Penin's assignment remained unresolved.
Aftermath
It was during this period that Rosh Penin succumbed to the influence of the dark side of the Force.