Presentation #116.01 in the session Solar X-ray and VUV Spectra: observation, modeling, and planetary atmospheric impacts — Poster Session.
The solar soft X-ray (SXR) radiation is highly variable with increases by more than a factor of 100 at some energies, even for moderate size flares. Those large changes have direct consequences in the heating of the thermosphere and increasing the ionosphere density. The Miniature X-ray Solar Spectrometer (MinXSS) CubeSat was developed to explore the solar irradiance energy distribution in the highly variable SXR range with new solar spectral measurements for the 0.5 to 15 keV range and to reveal its impact on Earth through modeling the effects in the ionosphere and thermosphere.
The MinXSS development and then flights also provided technology demonstration of the small solar SXR spectrometers and of new attitude and determination control systems (ADCS) developed by Blue Canyon Technologies (BCT). The MinXSS instrument has now had three small satellite flights using Amptek X123 spectrometers that included improvements for each new flight. The MinXSS-1 made solar SXR spectral observations from May 2016 to May 2017, and the MinXSS-2 made solar SXR spectral observations from December 2018 to January 2019. The MinXSS-3 is a flight of opportunity instrument aboard the international InspireSat-1 small satellite with a launch on February 14, 2022.
There are significant improvements for the MinXSS-3 with the novel addition of a dual-zone aperture for the X123 spectrometer to enhance the dynamic range for the higher energy range above 2 keV. The MinXSS-3 instrument is also known as the Dual-zone Aperture X-ray Solar Spectrometer (DAXSS). The improvement of the DAXSS response (effective area) as compared to the earlier MinXSS instruments is more than a factor of 600 higher for energies above 4 keV. Amptek also made significant improvements for its X123 Silicon Drift Detector (SDD) spectrometer to improve its noise performance and thus improve its energy resolution. The DAXSS X123 SDD has energy resolution of about 0.04 keV at 1 keV and thus easily resolve the Fe and Ni features at 0.81 keV and 0.91 keV, respectively. The DAXSS energy resolution is a factor of 2.9 times better than MinXSS-1 energy resolution. These measurement improvements of the solar SXR spectra allow for better scientific analyses, such as providing tighter constraints on the abundance of the hot coronal ions and their respective temperatures and emission measures, for addressing outstanding questions about coronal heating, flare energetics, and active region evolution. The new observations from DAXSS will be presented, including some highlights of the dozens of flares already observed in the first month of the InspireSat-1 mission.