Complex sentence: Kubrick spent a great deal of time researching the film, paying particular attention to accuracy and detail in what the future may look like, and was given permission by NASA to observe the spacecraft being used in the Ranger 9 mission for accuracy.
Split into simpler sentences: Kubrick spent a great deal of time researching the film, paying particular attention to accuracy and detail in what the future may look like. He was granted permission by NASA to observe the spacecraft being used in the Ranger 9 mission for accuracy.