Stephen Hawking’s Favorite Places, a three-part TV series that debuted in January, has been made available to watch online for free in honor of Hawking’s life, according to tech and science video streaming site CuriosityStream. The renowned astrophysicist passed away today in Cambridge, England. He was 76.

The final episode, which had still not been released, was also published today for free.

In the show, Hawking takes trips to the sun and planets in our solar system and beyond via a digital spaceship called the S.S. Hawking. In the first episode, Hawking ponders how AI could impact a civilization — not on Earth, but on an alien planet whose inhabitants appear to have left or gone extinct.

Hawking’s predictions on the TV show were hardly his first about artificial intelligence.

At the Web Summit tech conference held in Lisbon, Portugal last fall, Hawking expressed uncertainty about what AI will mean for humankind. According to reporting by CNBC, Hawking said AI could be the “worst event in the history of our civilization” but added that he didn’t know yet whether AI will bring about great advances in the fight against poverty and disease or whether intelligent machines will be trained to oppress humans with things like autonomous weapons.

Hawking had predicted for years that AI could kill us all. In 2014, he told the BBC that “the development of full artificial intelligence could spell the end of the human race.” Despite a reputation as an AI doomsayer, Hawking didn’t see himself that way.

“I am an optimist, and I believe that we can create AI for the good of the world. That it can work in harmony with us. We simply need to be aware of the dangers, identify them, employ the best possible practice and management, and prepare for its consequences well in advance,” Hawking said.

Discovery Channel and CuriosityStream founder John Hendricks said Hawking’s life and work urged humanity to reach for distant worlds.

“Although Stephen Hawking demonstrated a remarkable optimism about our capacity to understand the universe, he also cautioned us about the fragility of our human condition, as we currently remain bound to a small planet subject to meteor strikes and other natural and manmade catastrophes,” Hendricks said in a statement shared with VentureBeat. “In the end, he urged us all to get on with the quest to explore and populate worlds beyond our origin. He will always remain a towering figure in the history of human thought and inspiration.”

Ahead of its debut last fall, the show won an Emmy for Outstanding Graphic Design and Art Direction.