Development of a 12m coilable boom for the Arcus MIDEX mission.

Arcus is an innovative MIDEX-class X-ray spectroscopy mission with 12 m focal length grazing incidence optics. The instrument has a 10.8 m long by O1.85 m, 4-longeron coilable boom with an enclosing sock. The boom, designed and built by Northrop Grumman, is included to enable launch in a fairing that is shorter than the operational length of the instrument. This paper outlines the process to select the boom type, design it to meet Arcus requirements, construct a flight-like engineering model, and test it to the expected environments. The team demonstrated that the 4-sided Arcus coilable boom offers a stiff, thermally stable platform that is precisely and repeatably deployable with a high packing density (compact stowage). This low-cost and low-risk solution permits the Arcus orbital X-ray observatory to use a focal length that greatly exceeds the limitations of the launch vehicle fairings. We offer comparisons to other boom designs, outline the design of this boom, its predecessors, the design of the sock, its deployment performance, and the results of its environmental testing.