In October 1989, Rockwell International (Space Systems Division) began a year-long contracted effort managed by Langley Research Center to perform an in-depth study of PLS design and operations with the HL-20 concept as a baseline for the study.
In October 1989, Rockwell International's Space Systems Division began a project at Langley Research Center to analyze the design and operation of PLS systems using the HL-20 concept as a starting point.