My grandma had a stash of books for the grand kids and one used to constantly play on my mind. This was 30 years ago.
There was a guy in a little spaceship (possibly lost) .. Suddenly he is going past this massive green spaceship that is about 1000 times bigger than his. It looks ancient and relic-y. It's completely dead silent. It kinda made you feel a bit spooked. He goes onto it to investigate it. I can't recall what happened next, but I think maybe they killed themselves off.
It is a picture book but may have some words and it is very 60's/70's style.
To make it worse it may have even been a mini story in a kinda bunch of short drawn stories.