Mae and Clinton's teenage mentor from the future, Selectra Volt, can only give them vague hints about what will occur. Their time travel takes them to visit space historian Steven Dick, ancient Chinese admiral Zheng He, Isaac Newton, Wernher von Braun, astronaut Sunita Williams, space sickness scholar Suzanne Nooij, and astronaut and asteroid scholar Ed Lu. When they learn that the malicious Dr. Gravitium is hunting asteroids, they have to come up with a plan and visit the space station to try and stop him before he destroys one, or maybe two, worlds.