Van Tassel began conducting weekly meditation sessions at the Rock, during which he claimed to be able to communicate telepathically with aliens, conveying their messages through his vocal cords.
One night, he said he was awakened by a being from Venus who took him aboard a spaceship and gave him a formula to build an anti-gravity time machine that could inhibit aging.
He founded the Academy of Cosmic Intelligence, which at one time maintained a list of some 17,000 space creatures who had interacted with humans, and began holding annual spaceship conventions at the Rock.
The Times reported on one such meeting in 1955:
“join in [Van Tassel] Serving as sponsors are many men and women who have written or will soon write books about spacecraft. They pretty much all have some dire warnings for Earthlings, but also give us a little bit of hope if we wake up and listen to what the friendly space creatures are telling us to do.
“…a man walking around with a Geiger counter said that even the air around the boulder was filled with cosmic rays from the remnant cloud of the atomic explosion in Nevada, or the backwash from the spacecraft. Either way, everyone is looking The spaceship comes to land.
In later years, the convention featured speakers, skydivers and stuntmen performing acrobatics on rope ladders beneath airplanes, according to the Times.