Development of a thermal vacuum chamber, performance tests plan, and contamination control procedures for the Star-Planet Activity Research CubeSat (SPARCS)

The Star-Planet Activity Research CubeSat (SPARCS) is positioned to revolutionize our understanding of M-dwarf star evolution, activity, variability, and the habitability of surrounding exoplanets. SPARCS will be the first mission to observe M stars for long periods of time simultaneously using a dual channel FUV (153 – 171 nm) and NUV (260 - 300 nm) imaging system. Anticipated to launch in 2023, SPARCS will provide key UV context to future observations by TESS and JWST, and the spaceflight application of advanced new detector technologies will pave the way for their implementation into future missions like LUVOIR and HabEx. To realize the scientific potential of SPARCS against the challenges of the ultraviolet spectrum, we are developing the specialized facilities, procedures, and tests necessary to assemble, integrate, and test the SPARCS science payload and spacecraft. A thorough testing campaign will verify the performance of individual payload components and obtain calibration baselines from the fully assembled science instrument that are vital to the data reduction process and in-flight contamination monitoring. SPARCS requires extensive contamination control to maintain its sensitivity in the FUV and NUV, which means all of AIT must occur in controlled and precisely monitored environments. This work will result in: (1) The delivery of the assembled and tested SPARCS spacecraft for launch in 2023. (2) A comprehensive performance validation and calibration baseline for SPARCS including a measurement of system throughput to for every wavelength across the SPARCS bandpasses, maps of NUV and FUV sensitivity across the payload field of view, and a full set of calibration products like flatfield images and dark current measurements for data reduction and comparison with calibration products acquired in orbit to monitor spacecraft conditions. (3) The establishment of a fully operational CubeSat AIT laboratory at ASU equipped to handle CubeSats up to 6U in size requiring meticulous contamination control up to the levels required for working in the FUV. This paper presents the work completed so far on the development and early operation of assembly, integration, and testing facilities for SPARCS. A custom thermal vacuum (TVAC) chamber facility was created and one of Arizona State University’s cleanroom environments was retrofitted to accommodate a 6U ultraviolet CubeSat requiring strict contamination control. We will describe the TVAC facility design and early testing, the cleanroom operation and contamination monitoring, and the development of an optical system and procedures to characterize the optical performance.