The first appearance of Miss Pickerell, her famous and quirky major character, was in the short story "Swept her into Space", published in Liberty during 1950.

MacGregor's goal was to provide fantasy literature with correct (for the time) scientific facts that would appeal to children.

After MacGregor's death in 1954, McGraw-Hill searched unsuccessfully for someone to continue the series until 1964, when they selected Dora Pantell, a social worker, and a writer of publicity and educational curricula.

Miss Lavinia Pickerell is an unlikely heroine: prim, spinsterly, angular and stiff, wearing old‑fashioned clothes and an outlandish hat, and devoted to her pet cat, she nevertheless manages to inadvertently stow away on a rocket to Mars in her first adventure.

But only one other author has written in the Miss Pickerell "universe" for publication,[3] Dora Pantell, who was also responsible for bringing other Ellen MacGregor-conceived projects to completion.

Later writers who indicated that Miss Pickerell had been either an influence or a favorite include such authors as Harry Turtledove,[4] Susan Page Davis,[5][6] and Sam Riddleburger.

Some of the topics she addressed were weightlessness in space travel, atomic energy and carbon-14 dating, nuclear-powered submarines and the continental shelf, the "bends" affecting divers who surface too rapidly, and many others.

Ellen MacGregor managed very skillfully to incorporate a good deal of information that a child reader could absorb almost without realizing it.

A clear picture in bald outline, rather than a mass of confusing and discouraging detail, is most apt to appeal to and instruct that active age group.