"What did she do for the office?"
"What we all do there. Lots of filing, answering phones, meeting and greeting, taking notes. Basic office work. And even though it's not rocket science, she didn't do too well at it."
Wait a minute.... Not rocket science? This book is set in 1951, and I know rocket science has been around since then, but this idiom has always seemed fairly modern to me. So I did a bit of digging and it looks as if I was right.