Dr Conway, Chief of the Council of Science, orders Lucky and Bigman to investigate the information leaks from Jupiter, where Sol scientists are trying to figure out a new form of Artificial Gravity that they call Agravity. Dozens of investigations have failed, but they didn't have the best councilman, Lucky Starr, there. Lucky wants to use a V-frog to gain an insight into the minds of the suspects. Director Donahue (project leader on Jupiter IX) agrees with the request and they're on their way.
Not long after they arrive, Lucky and Bigman get a "welcoming party" fromand company in the form of Artificial Gravity lessons. Despite the lopsided odds, the two prevail and impress the majority of the crew about their sincerity and interest only in investigating the possible Sirian information leaks. They show off their V-frog to the crowd (pets are popular on Jupiter IX) and then go to their room. Their neighbor, the blind Mr. Norrich (and his seeing-eye dog, Mutt), invites them over and explains how he's already heard about the fight. He predicts that the news will be all over the moon by tomorrow.
Back in their room, Lucky gets on the visiplate to arrange their next meeting with the project director while Bigman takes a shower. In those fifteen minutes, the V-frog is killed! At some point, the Sirian spy had seen them with their secret weapon and now they've gotten rid of Lucky's best investigative weapon. Not to worry, Lucky has already figured out a key clue about the spy; it's a robot! Unfortunately, that's the only lead he has now, and the next several days produce almost nothing useful, the Sirian robot is going to avoid detection!
Lucky Starr and the Moons of Jupiter provides examples of:
- Abomination Accusation Attack: After Bigman has accused and failed to prove that Mr Norrich is the robot spy several times, Lucky takes a turn doing the same thing (to throw his actual suspect off the mark).
- Bandage Wince: Lucky winces as Bigman, his sidekick, applies cold water to a ''bruise'’ after his adventures in a zero-gravity duel.
- Billed Above the Title:
- The 1974 New English Library cover credits Isaac Asimov above the title, using the same font size.
- The 1978 Fawcett Crest cover credits Isaac Asimov, writing as Creator/Paul French before listing the title. In this case, Dr Asimov's name is larger than the subtitle of and the Moons of Jupiter, but Lucky Starr is written much larger.
- The 1984 Del Rey cover plays around with the cover. At the top-right is their publisher's credit, then across the page is "Science Fiction Adventure". Below that is ISAAC ASIMOV writing as Paul French. Below that is the title, and below that and to the left is the tagline. All this in just the top half of the cover.
- Conviction by Contradiction: Bigman suspects blind Mr. Norrich of being a spy and not blind at all. His arguments are that the man is sitting with the lights on, and that he noticed when Bigman turned the lights off. However, the man provides perfectly good explanations; he realized Bigman turned off the lights because he heard him tiptoeing toward the wall and his guide dog going to sleep, and as for the lights... well, it doesn't matter to him, but it would probably matter to any friend who might come to visit.
- The Dog Was the Mastermind: Out of all the people on Jupiter-IX, Lucky couldn't really narrow down who might be the robotic spy sending information back to the government of Sirius. It isn’t until the last chapter that Lucky realizes the spy doesn't have to be a humanoid robot, it could be animal-shaped, too. Mutt, Mr Norrich's seeing-eye dog, is the robot spy.
- Heroic Dog: When Bigman falls into the ammonia river on Io, Mutt leaps in to rescue him.
- Logic Bomb: The robot spy used by the Sirians was equipped with an automatic self-destruct in case their cover is blown. So Lucky had to figure out a way to paralyze it using only the three Laws of Robotics. He and Bigman took the robot and another human out of the ship, and when Bigman attacked the other human, the robot ended up paralyzed from the conflict of two examples of the First Law; it couldn’t defend the human from harm without harming a human.
- Involuntary Suicide Mechanism: Lucky theorizes that any robot spy sent by Sirius would have been equipped with an explosive, and said explosive would probably be triggered by any obvious effort to uncover the robot's disguise.
- Phlebotinum-Proof Robot: The heroes come to investigate data leaks on a research facility, and bring along an animal capable of detecting and affecting emotions. A couple of days later, the animal is killed despite its abilities, and Starr realizes they must be dealing with a robotic infiltrator.
- Spy Bot: Lucky deduces that the government of Sirius has sent a robot to spy on their new Agravity spaceship technology. Because of the close observation present for everyone in the Jupiter-IX base, he also concludes that the robot must be disguised. The central conflict of the book is discovering who the Sirians sent as a spy.
- Tagline: "When the Sirians took Lucky's secret weapon, they gave him his biggest clue!" — 1984 Del Rey cover
- Video Phone: Lucky's ship, the Shooting Starr, is equipped with a visiplate that allows for two-way video communication.
- You Called Me "X"; It Must Be Serious: The first chapter lampshades Dr Conway's use of "David" when speaking to Lucky. Unlike in the first couple of books, his accidental use of Lucky's real first name is a sign that the current problem has him very stressed out.
- Zeerust: The Zeerust is pretty obvious when it comes to the computers that are available in the series. A specialized computer man has to prepare input in the form of paper tape in Moons of Jupiter.
