In August of 1952, Van Tassel stated that aliens from Venus had landed near Giant Rock and invited him to enter their spacecraft. When word spread of his dramatic encounter, the first Space Convention was held at Giant Rock in the spring of 1953. In the years to come, thousands would attend these conventions, drawn to the rock, the desert, Van Tassel, and the promise of experiencing personal alien contact. In 1959, over 11,000 followers of the charismatic contactee came from all over the world to hear him channel messages from the Space Brothers and to take advantage of the opportunity to share stories of their own alien encounters with the media.
Van Tassel introduced the world to Ashtar, commandant of station Schare. "Schare" was one of several space stations in "Blaau," the fourth sector of "Bela," in which our solar system is moving. "Shan" was the name that Ashtar gave for Earth, and he said that the universe was ruled by the Council of Seven Lights, which had divided the Cosmos into seven sectors and systems. Ashtar proclaimed that the Space Intelligence's main purpose was to save humankind from itself. Once that great obstacle had been met, then the minor problem of how to deal with nuclear fission would right itself through the harmony that would then be extant on Earth.
Ashtar and his fellow Space Intelligences also gave Van Tassel instructions for the construction of the "Integratron," a four-story-high, 16-sided dome of wood and concrete, which was supposed to rejuvenate human cells by utilizing the natural energy found in the dry desert atmosphere of Giant Rock. Thousands of believers came to pass through the Integratron and to receive anti-aging electrostatic charges.
Van Tassel founded the Ministry of Universal Wisdom in 1953, basing its precepts on revelations from the Space Brothers. The ministry taught the universal law which operates on humankind in seven states: gender (male and female); the Creator as Cause; polarity of negative and positive; vibration; rhythm; relativity; and mentality.
Van Tassel maintained his headquarters at Giant Rock, California, for many years, making it a gathering place for both the curious and the true believers. He was the author of I Rode a Flying Saucer (1952) and The Council of Seven Lights (1958).

In the character of Roy Neary (Richard Dreyfus), Director Steven Spielberg's Close Encounters of the Third Kind expresses the dilemma faced by an ordinary man who experiences a close encounter with a UFO and is given a mental summons to meet with the aliens at a future time. The film explores the range of emotions and inner stresses faced by a UFO contactee, including the confusion of his family, the reluctance of the authorities to recognize his experience as genuine, and the obsession of the contactee to respond to the "invitation" that the aliens have somehow impressed in his psyche.
Forced by an inner compulsion to seek reunion with the aliens atop Devil's Tower, Wyoming, Neary must leave his confused wife (Teri Garr) and children behind as he continues his rendezvous with space intelligences. He is soon joined by an ally (Melinda Dillon), whose son was abducted from their farm home, who also is receiving telepathic messages about where he will be returned to her.
Spielberg claimed that he had adapted many actual stories of UFO contact for the screenplay, including accounts from the files of Dr. J. Allen Hynek, the astronomer who had been employed by the Air Force in their official research of the UFO mystery, Project Blue Book. Hynek was even given a cameo in the film, and he can be seen among the scientists gathered to welcome the aliens when the massive mother ship sets down on Devil's Tower.