As a teenager, Meinel assisted her father in making the first time-lapse photography of solar prominence eruptions, using a movie camera and a quartz-polarising monochromator attached to the 6-inch Alvan Clark refracting telescope at their home.

[3][4][5] As her mother's health declined Meinel increasingly assisted her father's research on the telescope at home and at the observatory.

[6] While at Pasadena Junior College Marjorie met and began dating fellow pupil Aden Meinel, urging him to study astronomy.

[8] For her masters research at Claremont Colleges she used the family telescope in 1943–1944 to study the variable red giant RT Cygni.

[17] While raising their children she was not employed, but remained scientifically active, collaborating in Aden's research, attending conferences, and editing their work.

[22][23] In 1972, Meinel returned to academic employment, working as a research associate at the University of Arizona Optical Sciences Centre, which Aden had founded in 1964.

[15] They were skeptical of the existing focus on small scale solutions, instead arguing for large-scale applications of solar technology by industry and government.

[25] One idea they developed and promoted was the construction of a 5000-square mile farm of parabolic solar collectors in the deserts of Arizona and New Mexico to heat water to produce 1000-gigawatts of electricity using steam turbines.

[34] Their work at JPL focused on telescope design, including optical systems, the TAU mission, the Large Deployable Reflector project, and applications of interferometry.

[3][13] Meinel was cited on Aden's Frederic Ives Medal (1980) and his George W. Goddard Award in Space and Airborne Optics (1984).