Ralph invented a time machine for the Guardian Warriors to use. When the Guardian Warriors came to visit Ralph, he explained the time machine to them. The Guardian Warriors realized that they could use the time machine to go back in time. They selected January 28, 1986. The Guardian Warriors went back in time to January 28, 1986 and arrived at Cape Canaveral, Florida. The Guardian Warriors saw the space shuttle Challenger on the launch pad. They took pictures of the Challenger. It was a cold January morning. The Guardian Warriors were in the stands with the families of the 7 astronauts. The Challenger's launch was delayed twice because of ice. The third time, Kennedy Space Center told Mission Control "We're a go for launch!" The Challenger lifted off. Everything looked good. Then, 73 seconds into launch, Commander Scobee said "Go with throttle up!" The Challenger blew up because of a defective O-ring, killing all 7 astronauts, including the first civilian teacher in space, Christa McAuliffe. Everyone was shocked and very sad.