question:  Why does Casey feels regret about choosing prison over the court’s option to be sent into Jupiter’s Great Red Spot to study its inhabitants?
context: It just ain't big enough for a gent of scope and talent; and the day the Solar System Customs caught me red-handed smuggling Kooleen crystals in from Mars, I knew I was in that corner, and sewed up tight. But—and this was the 'but' that was likely to deprive the System of my activities—even experimenting with them was illegal even if it needed to be done; also, I had promised not to rat on him before taking the job. So there I was, closeted with the ten members of the S.S. Customs Court, getting set to hear the gavel fall and the head man intone the sentence that would take me out of circulation for a long, long time. And instead, blast me, if they didn't foul me with this trip to good old Jupiter. Jupiter was a death sentence. "You've no doubt heard tales of the strange population of Jupiter," he said. How could any—" The senior judge rapped ferociously, and I skidded to a halt. We possess well-authenticated photographs of these inhabitants, and if you are prepared to visit them and in some way worm from them the secret of their anti-gravity field, the government stands ready to issue you a full pardon as well as a substantial monetary reward. Not when I already had more counts against me than a cur has fleas. Well, a cross between a scorpion and a grasshopper, to be accurate. After all, in the pen a man can eat and breathe, and a guard won't reach in and nip off an arm or leg while he's got his back turned. "I just made a pass at the Killicut Emeralds, that's all, and got nabbed." "What were you trying to do, start a feud between us and Mars?" Those emeralds were in the inner shrine of the super-sacred, super-secret temple of the cavern-dwelling tribe of Killicuts on Mars—the real aborigines.
output:  Terrified that being sent to Jupiter will kill him, Casey opts for a jail sell. When he’s told that Jupiter is not as dangerous as once thought, and that the mission could actually make him rich, Casey fears that he’s lost his daredevil edge.
options:  Terrified that being sent to Jupiter will kill him, Casey opts for a jail sell. When he’s told that Jupiter is filled with insect-like beings who share his enthusiasm for a reckless lifestyle, and that the mission could actually make him rich, Casey fears that he’s lost his dare devil edge.  Terrified that being sent to Jupiter will take too much energy on his part, Casey opts for a jail sell instead. When he’s told that Jupiter is filled with friendly life forms who love emerald and crystal as much as he does, and that the mission could actually prove his innocence, Casey fears that he’s lost his dare devil edge.  Casey is terrorized by his fellow prisoner, Pard Hoskins, which makes him regret not taking the chance to fly head first into Jupiter’s Great Red Spot. A true dare devil would have taken the challenge, after all.  Terrified that being sent to Jupiter will kill him, Casey opts for a jail sell. When he’s told that Jupiter is not as dangerous as once thought, and that the mission could actually make him rich, Casey fears that he’s lost his daredevil edge.