The Start-Planet Activity Research CubeSat (SPARCS) is a NASA-funded mission led by Arizona State University, devoted to characterizing the UV emission of low-mass stars. During its nominal one-year mission, SPARCS will observe close to 20 low-mass stars, with the goal of understanding their short and long-term UV variability. SPARCS will be ready for launch in 2025. SPARCS’ payload is a 9-cm telescope paired with two delta-doped charge-coupled devices (CCDs). The data calibration converts the raw instrument counts into an average flux within the two ultraviolet bands (153 - 171 nm, 258 - 308 nm). While the system is only weakly sensitive in the infrared, the target stars are very bright at long wavelengths. This requires careful correction of the data for out-of-band emission. The system is being fully characterized on the ground to provide supporting calibration data. The calibration uses observations of very stable white dwarfs to achieve the 10% photometric accuracy requirement in both bands.
We discuss the final assembly, integration, and testing of the Star-Planet Activity Research CubeSat. SPARCS is a 6U CubeSat mission designed to monitor the dual-channel, far-UV (153-176 nm) and near-UV (258-308 nm) photometric activity of nearby low mass stars to advance our understanding of their evolution, activity, and the habitability of surrounding exoplanets. This paper details the assembly of the SPARCS instrument and the testing process to characterize and validate the performance of the payload prior to spacecraft integration. To test SPARCS, we have established a customized CubeSat AIT laboratory and thermal vacuum chamber at ASU equipped to handle CubeSats requiring meticulous contamination control for work in the FUV. After a brief overview of these facilities and the testing plan, we will detail the methods and data used to verify the performance of SPARCS and generate calibration products to reduce raw flight data to high-quality science products. The result will be the delivery of the first highly sensitive FUV astrophysics CubeSat which will inform exoplanet environments and future observations of these systems by facilities like the Habitable Worlds Observatory.
The Star-Planet Activity Research CubeSat (SPARCS) is 6U CubeSat whose mission will be to observe low-mass stars in two ultraviolet (UV) bands. SPARCS will provide time-dependent spectral slope, intensity, and evolution of stellar radiation with the goal of understanding the short- and long-term variability of these targets.
Here we summarize the performance of SPARCam, the science camera for SPARCS. SPARCam is a two-detector camera system allowing independent commanding of two delta-doped, UV CCD47-20 detectors, separately optimized for the SPARCS near UV (NUV) and far UV (FUV) bands. The manuscript includes an overview of the UV detectors optimization and performance as well as a brief description of the camera electronics.
SPARCam was developed by the Jet Propulsion Laboratory and delivered to Arizona State University in October 2023.
The star-planet activity research CubeSat (SPARCS) is a small space telescope tasked with monitoring sunspots and flares of M-type stars in near ultra-violet (NUV) and far-ultraviolet (FUV) wavelengths. The SPARCS instrument is approaching its critical design review (CDR), and the team is moving forward with assembly integration and test (AI&T) plans for the payload and spacecraft. This paper focuses on the SPARCS thermal vacuum (TVAC) testing facility and thermal testing plan for the payload. The SPARCS TVAC testing chamber has been developed at Arizona State University (ASU) to provide a clean and relevant thermal environment for testing CubeSats and their payloads. The chamber can perform long-duration bakeouts at +80°C for cleaning and monitoring volatile and condensable contaminants with a thermal quartz crystal microbalance (TQCM) and a residual gas analyzer (RGA). These capabilities allow the SPARCS team to control and monitor the cleanliness of the test environment. An FUV monochromator is mounted to the side of the chamber, providing a calibrated light source to test and calibrate the payload. The SPARCS payload will be the first instrument tested in this chamber and demonstrate the capabilities of the SPARCS TVAC Test Facility. The team will verify the payload’s thermal capabilities, such as heating critical surfaces to expel contaminants and cooling the detectors for imaging. The thermal test plan details thermal cycling, hot/cold dwells, thermal balance, and instrument operations through the test. The SPARCS payload TVAC test aims to verify various performance requirements before integration with the spacecraft.
The Star-planet activity research CubeSat (SPARCS) is a 6U CubeSat mission focused on dual channel, SPARCS farUV (153-171 nm) and near-UV (260-300 nm), photometric monitoring of nearby M-stars. These data will advance our understanding of the typical day-to-day UV environments around M stars and how these conditions evolve over the stars’ multibillion-year lifespans; critical factors that constrain the potential habitability of planets orbiting M stars, informing the search for life in the galaxy. This paper lays out the detailed plan for the SPARCS science payload assembly, integration, and testing (AIT), including the optical calibration and performance measurement methods for the science telescope, thermal vacuum bakeouts for part cleaning, ongoing contamination monitoring methods, and spectral performance measurements of the assembled payload camera. We will provide updates on AIT proceedings at ASU and the SPARCS thermal vacuum chamber (TVAC) test facility built for UV CubeSat missions at Arizona State University’s School of Earth and space exploration.
The Star-Planet Activity Research CubeSat (SPARCS) is a 6U CubeSat under construction that is devoted to the photometric monitoring of M stars in the far-UV (FUV) and near-UV (NUV), to measure the time-dependent spectral slope, intensity and evolution of low-mass star high-energy radiation. We report on the progress made in the assembly, integration and test of the instrument payload at Arizona State University using a custom TVAC chamber and optical stimulus that provides calibration light sources and the custom contamination control environment that the FUV demands. The payload consists of a custom 90mm clear aperture telescope developed by Hexagon/Sigma Space, combined with a dichroic plate to separate the FUV and NUV beams developed by Teledyne Acton and Materion, married with twin focal plane array cameras separately optimized for their bandpasses as developed by JPL.
KEYWORDS: Ultraviolet radiation, Stars, Atmospheric modeling, Space operations, Space telescopes, Planets, Telescopes, Sensors, Exoplanets, Control systems
Roughly 40 billion M dwarfs in our galaxy host at least one small planet in the habitable zone (HZ). The stellar ultraviolet (UV) radiation from M dwarfs is strong and highly variable, and impacts planetary atmospheric loss, composition and habitability. These effects are amplified by the extreme proximity of their HZs (0.1–0.4 AU). Knowing the UV environments of M dwarf planets will be crucial to understanding their atmospheric composition and a key parameter in discriminating between biological and abiotic sources for observed biosignatures. The Star-Planet Activity Research CubeSat (SPARCS) will be a 6U CubeSat devoted to photometric monitoring of M stars in the far-UV and near-UV, measuring the time-dependent spectral slope, intensity and evolution of low-mass star high-energy radiation.
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