Solar X-Ray Irradiance Variations: Instrument Design, CubeSat Mission Design, and Science Analysis of Solar Observations from Sounding Rocket and CubeSats

• Main Author: Schwab, Bennet David
• Format: Dissertation
• Language: English
• Published: ProQuest Dissertations & Theses 01.01.2022
• Subjects: Aerospace engineering; Physics
• ISBN: 9798845408068

Satellites obtain scientific data needed to answer some of the fundamental questions about our world and the universe in which we reside. The first Miniature X-ray Solar Spectrometer (MinXSS-1) CubeSat and its successors try to answer "can we better understand the evolution of the solar corona?" and "which heating mechanisms are dominant in making the solar corona more than 100 times hotter than the photosphere?". A scientific mission involves careful planning and rigorous testing. Improved testing methods, such as the Battery Automation Test System (BATS) described here, create more accurate and efficient battery performance testing techniques for the flight battery pack that was used in INSPIRESat-1 SmallSat and can benefit future missions. The MinXSS and INSPIRESat-1 missions capture solar spectra from orbit and observe the Sun on two key time scales important for the coronal evolution. The first is seconds to hours for solar flares and the second is days to years for active region evolution as related to the 27-day solar rotation and 11-year solar cycle. Three flares from the MinXSS-1 mission were analyzed using CHIANTI spectral models to fit the temperatures, emission measures, and relative elemental abundances of the solar corona plasma. It was found that the relative abundances of elements with a low First Ionization Potential (FIP) decrease during the beginning of the flare's gradual phase before relaxing following the flare peak, which supports the magnetic reconnection heating mechanism for the solar corona. The Dual Aperture X-ray Solar Spectrometer (DAXSS) instrument, which launched on a NASA sounding rocket in 2018, obtained the highest resolution to date for solar soft X-ray (SXR) spectra over a broad energy range. The novel design of the dual aperture and the instrument characterization techniques are discussed. Additionally, the quiescent solar spectra are analyzed and abundances of Mg, Si, and S were found to agree within 2% of the expected values, but the abundance of Fe was found to be 35 percent higher than expected in the quiescent sun's corona. This is an unexpected result that is discussed herein. DAXSS was put on orbit in the INSPIRESat-1 CubeSat on 2022 February 14, and its SXR spectral data will, going forward, provide further insight into the sources of coronal heating through modeling the changes of relative elemental abundances during developments of active regions and solar flaring events.