I didn't have the time or the inclination to read all of the Challengers series at this point, so I thought it might be entertaining to jump ahead five years and check the changes.
Challengers of the Unknown #31 contains a retelling of the Challengers' origin with new details. We learn that before the fateful flight, Rocky had defended his wrestling championship despite an attempt by the mob to influence the bout.
More unbelievably, Prof Haley was reintroduced as a rich delinquent. Uh, how did he get the nickname "Prof" then? He reforms after helping rescue an ancient statue from the deeps via his skin-diving ability.
Red Ryan, who had originally been introduced as a circus daredevil (only to have Kirby ignore that aspect of him), was now reincarnated as a mountain climber, and electronics expert. He builds a radio tower on a mountain with the money of a rich patron to educate the poor people of a valley in South America. However, it turns out that the patron really intended to use the tower to transmit propaganda and become a local dictator, fortunately prevented by Red.
Ace Morgan was a pilot who had contracted to carry high explosives for miners in his plane, but was forced to toss them out when they broke loose. He manages to hit the mountain in a place that reveals a vein of ore, so the miners are happy.
However, as the four men fly in Ace's plane, they feel like failures for one reason or another, especially when the plane conks out and they must crash land in a forest. Given a second chance, they feel like they are living on borrowed time, and resolve to do something more with this second chance at life.
This origin retelling is contained within a larger story where a mysterious stranger claims to have rescued the Challengers from their plane. Thus they were not really saved by "fate" as they had long believed. Their rescuer, a Mr Clayton, presents evidence. He is in a jam and needs the Challengers to help him reassemble an ancient statue. It turns out the statue's actually a giant robot that has two arms missing which when assembled will give him incredible power. But the Challengers eventually realize Mr Clayton did not really save them and defeat his robot.
Comments: Interesting but uneven origin retelling by DC.
Challengers of the Unknown #32 contains two stories. The first one features Volcano Man, who had previously appeared in Challengers #27. In the second story we learn that the Challs had picked up an alien pet whom they called Cosmo. He seems to have almost unlimited mental powers, so much so that he dwarfs the rest of the team. Looking back I see that Cosmo first appeared in Challengers #18, and had made a couple intermediate appearances. In this story, they discover his original alien owner, who is happy to let them keep the pet since it is proving of so much use. Perhaps typically for DC, this ended up being the last time Cosmo appeared in the Silver Age Challengers; probably for the reason noted above; he was just too powerful and made it too easy for them to get out of tight scrapes.
My previous article on the Challengers is here.