click on images to enlarge
Astos was the Chief Medic on board the Tsuranga hospital ship.
When the Thirteenth Doctor woke from after being injured from a sonic mine explosion, he followed her across the ship as she tried to leave.
While inspecting a sudden sabotage on the ship, he was trapped in one of the Escape pods while looking for the creature that started the sabotage. The escape pod was then ejected and exploded soon after, killing Astos (The Tsuranga Conundrum)