Harpswell geoscientist Bob Gastaldo conducts research in northwestern China. Gastaldo was a scientific script consultant for an upcoming episode of the long-running PBS program “Nova.” (Ziyue Ju photo)

An episode of this fall’s 50th season of the PBS science program “Nova” has a connection to Harpswell through its scientific script consultant, Bob Gastaldo.

The season includes a five-episode collaboration with the BBC titled “Ancient Earth,” which focuses on the planet’s geological past. The first four episodes will air in the U.S. in October.

Gastaldo, a professor emeritus of geology at Colby College in Waterville, consulted on an episode called “Inferno.” The episode recounts the “mother of mass extinctions” at the end of the Permian period, 252 million years ago.

“The event — now called ‘The Great Dying’ — came close to wiping out all life on the planet,” according to a description of the episode on the “Nova” website. “Follow scientists as they piece together geologic evidence from the deep past and clues from today’s ecosystems to discover how life made it through and evolved into the astonishing variety we see around us today.”

“Ancient Earth: Inferno” will premiere on PBS at 9 p.m. on Oct. 25.

Gastaldo has researched and published on this extinction event as recorded in the fossil record of the Karoo Desert, South Africa, for more than 20 years. He also has conducted and published on research in the Xinjiang autonomous region in northwestern China.

Gastaldo and his wife, Elvira, moved to the Charity Shores neighborhood on Great Island in August. Gastaldo invites viewers to contact him with questions about “Inferno” after it airs. He can be reached at 207-660-5508.