The Cave Johhnson Period

Cave Johnson, founder and CEO.
In 1956, the Eisenhower administration signs a contract with Aperture to manufacture shower curtains to all branches of the US Military, except the Navy.
From 1957 to 1973, the company produces mostly shower curtains and enjoys a great deal of success, making Cave Johnson a billionaire. As far as 1973, Aperture also uses a bulletin board system.

During this point, early work on the Aperture Science Handheld Portal Device began; the early version, called the Aperture Science Portable Quantum Tunneling Device, proved to be too bulky for effective use, while poor surface conductors for the portals often caused mangling or death of the test subjects when they tried to use the portals.[source?] Repulsion Gel was first developed around this time as well for use as a diet aid. At first only the brightest and best of society were chosen for testing, but after being connected to a string of astronaut disappearances in 1968, Aperture Science focused on recruiting homeless people for testing, starting in 1976. Cave assumes that Black Mesa has been performing industrial espionage on the company's products, and blames them for Aperture's bankruptcy. (Propulsion Gel was released around this time too.)

In 1974, Cave Johnson is exposed to toxic Conversion Gel, made out of ground-up moon rocks.

In 1976, both of Cave Johnson's kidneys fail. Brain damaged, dying, and incapable of realizing time is not now flowing backwards (thus knowing his time will come soon), he lays out a three-tiered research and development program. The results, he says, will "guarantee the continued success of Aperture Science far into the fast-approaching distant past."