Allen Adam was the 1st Captain Atom.
Allen Adam was a physics prodigy at eight years old. He would later join the United States Air Force and rise to the rank of Captain as a test pilot. In the force he would be described as a career man, an expert in rocketry and missiles, a trained and decorated soldier, a chemist and ballistics genius, and that was before the accident that turned him into Captain Atom.
Allen was stationed at Cape Canaveral and was working on the experimental rocket Atlas when he dropped a screwdriver. This seemingly minor mistake caused him to not be able to leave the rocket in time and was launched into space, making him the first man in space. While in the nosecone of Atlas, Allen was subjected to terrific acceleration at 20,000 miles per hour and tremendous heat causing the vapor in his body to vanish.
Atlas also carried an atomic warhead that was to be detonated 300 miles above the earth. At the instant of fission Allen no longer flesh and blood but atomized at the atomic structure. The three minutes later after the explosion Allen reanimated back at base.
Unable to be near anyone due to the radiation. Allen built a special diulustel shielding suit that converted the escaping rays to another frequency in the light spectrum. Once safe Allen showed the top military brass his awesome new powers. It was then decided to keep these powers a military secret and give Allen the code name Captain Atom. This was made easier as a reported mistakenly reported Allen's death on-board Atlas.
Captain Atom was created by Joe Gill and artist Steve Ditko in Space Adventures #33 in March of 1960 from Charlton Comics. His first appearance was published in a series of short stories in the anthology series , titled "Space Adventures # 33-40 (March 1960-June 1961) and # 42 (October 1961). Eventually the series would be renamed Captain Atom and he would find himself facing odd villains and teaming up with other heroes, such as the famous Blue Beetle.
By 1967 Charlton's Captain Atom was canceled after issue # 89. He would later appear in 1982 in a series called Charlton Bullseye in which he wore his initial outfit. Before DC bought off the Charlton characters he last appeared in 1983 which teamed him up with most of the other symbolic Charlton heroes. These characters would be bought by DC Comics. Then in 1985, Captain Atom was revived as a DC character from Earth-4 in Crisis on Infinite Earths #6. During the story arc these characters would appear as people from Earth 4 of the multiverse whilst characters like Superman and Batman would derive from Earth 1.
The last time the Charlton Captain Atom would ever appear would be in DC Comics Presents: #90 being teamed up with Firestorm and Superman. After this event he was rebooted to fit the DC Universe. In 1987, Captain Atom's character history was retconned, like the rest of the DC Universe, and was updated in Captain Atom #1.