at this point, zaphod leaves the task of getting to magrathea to the ship's computer eddie, and he, ford, and trillian depart to the ship's sauna. arthur finds eddie incapable of getting to magrathea without help. arthur initially tries to help by supplying the infinite improbability drive with a tea substitute from the ship's nutrimatic device to serve as a source of brownian motion, but this only causes arthur to temporarily take on the consciousness of ford, zaphod, and trillian in their respective pasts, and he must manipulate events such that items in these past periods are brought aboard the "heart of gold" in the present. through this, arthur gains enough parts as to replace the circuit board in the nutrimatic so that it can produce real tea. this tea is powerful enough to power the drive to get them to magrathea, but in orbit, the ship is attacked by two missiles from the surface. arthur employs the drive again to change the missiles into a sperm whale and a bowl of petunias, neutralizing the threat.