 Why was the Stortulian so determined to make it to Earth?
The aliens came in every shape and form, in all colors and textures—and all of them eager for a Corrigan contract. Before then, anyone could visit Earth. After the gate clanged down, a non-terrestrial could only get onto Sol III as a specimen in a scientific collection—in short, as an exhibit in a zoo. At the same time, we had turned away a dozen ursinoids, fifty of the reptilian natives of Ghryne, seven Sirian spiders, and no less than nineteen chlorine-breathing Procyonites wearing gas masks. There's no such place as Wazzenazz XIII and there's only one human race in the Galaxy—on Earth.
 He wanted to find and bring back his wife.
 He wanted to seek revenge on his wife.  He was desperate for money.  He wanted to find and bring back his wife.  He was fearful of his future with the other Stortulians.