The "Atlantic Research Corp." had the US military code of AR. One of the four divisions of this company, Propulsion, was dedicated to manufacturing small solid-fuel rockets and gas generators. These are engines for auxiliary use of element separation.

-Also the “boosters” of the Arcas, Terrier, Tomahawk missiles, etc.

-From appendix 10: A list of rocket engines to be used in the main text:
-Marc-13-A1
-Marc-14-A1
-Marc-14-B1
-Marc-2-B1
-Marc-2-C2
-Marc-42-A1
-Marc-60A
-Mk-30
-SR-45
-SR-49
-SR-61
-Arcon
-Arcon booster