Per 2016 Facebook conversation with Bill Sienkiewicz:
"The original was 16x20 in (40x50 cm)on illustration board. I penciled, Klaus inked, Steve
Oliff colored it. But Marvel decided it needed more snap.So they asked Bob Larkin to add airbrush bits. Around MK's cape and the sparking terminals on the head, and on Marlene a bit, to unify it, and the moon. Basically anywhere you see airbrush is Bob.