ASTRO refers to the robotic dog character named Astro from the animated TV series "The Jetsons". Astro is the loyal pet and companion of the Jetson family in the show, known for his ability to talk and perform various tasks.
Note: The provided meaning of the answer is for the latest New York Times crossword puzzle clue: Prefix with -naut. Explanations are generated by AI and may be inaccurate.