Having been taken captive by the Army Eyes, you wake up and find yourselves prisoners aboard the Gaira Satellite in outerspace. For the crime of trying to destroy Mother Brain, you have been sentenced to death. You have been stripped of your possessions, and you are bound by plasma rings, making combat impossible. You are, however, free to move about the satellite, and explore. You will encounter security robots in the process, but they do very little damage, and are easy to run away from.
You begin in the lower left corner of the satellite. As you walk, you will see red tiles which cause a small amount of damage to your entire party whenever your party lead sets foot on them. Your goal is to make it to the control panel of the satellite on the far right. Oddly enough, there is very little security considering you are prisoners.
Once you investigate the panel, an interesting sequence of events will begin. You will discover why no one else is aboard the satellite with you: it has been programmed to crash into the planet Palm (or Palma as it was called in the original Phantasy Star.) When all hope seems lost, and it appears you are fated for destruction, the screen blacks out.
You have the same dream that you had at the beginning of the game. Upon awakening, you are greeted by a space pirate named Tyler. Lucky for you, he happened to be in the vicinity of space when Gaira began to hurtle toward Palm, and he was able to rescue you and nurse you back to health aboard his ship. The consequence of Gaira's collision with Palm results in the complete destruction of the planet. Tyler took to space due to his disdain for life under Mother Brain, but he transports you back to Paseo in order to support your effort.
Back home, visit the Central Tower again. This time, a new option is available: Roof. Select it, and you will discover that there is one last spacecraft on Mota. It's pre-programmed to fly back and forth between Mota and Dezo, so anyone can make use of it. When you have sufficient supplies (particularly a good amount of Trimates), choose to use the spacecraft and fly to Dezo.