Mark is unquestionably the most prolific composer for the medium, and the GEODESIUM name has become synonymous with planetarium music. Since 1975, he has recorded and produced soundtracks for more than 50 planetarium shows, with presentations at more than 800 planetaria in the U. S. and 47 other countries. Mark has also performed live in concerts at major planetarium facilities in the U.S. and Great Britain. GEODESIUM albums are popular items in planetarium gift shops.

Mark uses electronic keyboards, samplers and synthesizers to create his unique brand of planetarium space music. From verdant planetscapes to flights of fantasy through deep space, the music portrays magnificent visions of the universe. Relaxing yet provocative, GEODESIUM stylings embody "traditional" space music — that ethereal, beautifully floating music that characterizes the genre — as well as more dynamic and rhythmic sonic odysseys that transcend their "new age" and e-music heritage. Mark infuses all his music with rich textures that are the signature of the Geodesium sound.