Plot summary

As the Dhar's Jupiter 4 is mid-launch, Maureen radios Victor, urgently warning him that the ship has too little fuel to escape the planet's atmosphere and will crash. John infiltrates the Jupiter 4, and activates the emergency shut down. He gathers all survivors to explain the planet's situation. One ship can be launched using Maureen's plan to incorporate NASA's early mission protocols. The Jupiter 4 will be stripped of excess weight and systems, and the launch controlled from the ground, though once aloft needs a pilot. As everyone prepares the ship, Smith offers to help Will back on the Jupiter 2. Later, Judy tells Maureen the truth about 'Dr. Smith'. Returning to Jupiter 2, Maureen tricks Smith and confines her to a storeroom. Smith recounts partial truths and claims she is really Jessica Harris, a physicist. She implies she may have sabotaged Jupiter 4. When reviewing pilots, John's skills are found to be near perfect, but during the prep-test, John repeatedly fails on the procedure. The Resolute sends a message that due to Hawking radiation, they must leave the solar system within 24 hours. Don reluctantly agrees to help pilot the ship. With his assistance, the prep-tests are successful. In holding, Smith tricks Will into releasing her. Later, as John and Don launch in Jupiter 4, Smith escapes leaving Will bound, and knocks out Maureen before she can give John the course change information. Their ship explodes, and John and Don are presumed dead.