Is it possible that the planet was actually Jupiter? In that case, the story may be Isaac Asimov's Victory Unintentional.
To what extent do the characteristics of both descriptions (question and Wikipedia article) match?
"three robots": ZZ One, ZZ Two, and ZZ Three,
"spaceship designed for them": "spacecraft ... does not need to ...
I'm suprsed that the question was migrated. The use of "half + adjective" is common enough:
"He was half-dead with exhaustion".
"She was half-aware of a conversation taking place in the adjoining room".
"I was half-convinced by the ridiculous argument."
The meaning of "half" is not literal but more "...
Windows and doors are often used as symbols, representing transition, or access to something, especially without fully immersing in it. Consider:
when one door closes, another opens
I shut the door on that possibility
the eyes are the window to the soul
for a brief window anything seemed possible
The passage seems to me to say that being surrounded by ...