PBS | 9:00 pm

Marking the end of the Cassini-Huygens mission after 20 years, the new episode "Death Dive to Saturn" features many of the images captured by the spacecraft as it has orbited that planet — and also has taken a number of risky dives toward it, any of which could mean its destruction if it impacted against Saturn’s rings at a high rate of speed. The vessel’s last dive, performed the week before this telecast airs, can be seen via the series’ social media.