De acordo com a júnior novelisation do filme, o grande tubo é um tubo de escape . Luke acha que os sub-tubos menores estão lá para transportar resíduos soltos para longe do núcleo do reator:
Luke sailed into the exhaust pipe, a metal-lined tubular tunnel that twisted down and away from the reactor shaft. The pipe’s walls were smooth, sending Luke on an uncontrolled slide until he entered what seemed to be a dip in the pipe, and slowed to a stop. But before he could plan his next move, a trap-door dropped open beneath him, plunging him down another pipe.
Luke’s mind raced, trying to figure out where the second pipe would carry him. As the pipe twisted into an almost vertical slope, he guessed the pipes were designed to expel stray matter from the reactor shaft. He extended his limbs in an attempt to slow his descent, but the effort was too much for his drained, battered body. He continued to slide.
O novelisation oficial corrobora esta afirmação, descrevendo-os como um tubo de grande exaustão e um tubo de escape menor (mas sem entrar em mais detalhes):
The Dark Lord watched until he saw the youth’s body sucked into a large exhaust pipe in the side of the reactor shaft. When Luke vanished, Vader quickly turned and hurried off the platform.
Luke sped through the exhaust shaft trying to grab the sides to slow his fall. But the smooth, shiny sides of the pipe had no hand-holes or ridges for Luke to grasp.
...
Luke could no longer slow his inexorable slide out the exhaust pipe. He slid the final few centimeters and then dropped through the cloudy atmosphere, his body spinning and his arms flailing to grip on to something solid.
Isso é complementado por este slide oficial de storyboard, claramente identificado como INT. [por exemplo. Tiro interior] -EXHAUST PIPE
Ele também se casa-se bem com o script :
INTERIOR: REACTOR SHAFT
Suddenly Luke is sucked into an exhaust pipe in the side of the shaft. When Vader sees this, he turns and hurries off the platform.