From Development Through Re-Entry: CTIM Operational Lessons Learned and Successes

The University of Colorado’s Laboratory for Atmospheric and Space Physics’ (CU-LASP) Compact Total Irradiance Monitor (CTIM) SmallSat mission was a 6U CubeSat designed full-cycle and in-house between 2018-2022 and flew for 1.5 years after launch until re-entry, overshooting the 1-year mission lifetime goal. CTIM\u27s primary mission was to measure the total irradiance of the Sun, with ancillary measurements of the night-side Earth IR radiance, while demonstrating new technological capabilities of silicon-substrate room temperature vertically aligned carbon nanotube (VACNT) bolometers. The instrument was based on the Total Irradiance Monitor design that flew on SORCE (2003), TCTE (2013), and TSIS (2017). CTIM successfully continued the 40-year, uninterrupted measurements of total solar irradiance (TSI) with 0.017% measurement uncertainty. CTIM also hosted the first LASP-built spacecraft bus using the LASP Common Code flight software suite. Upon launch, commissioning was fast and efficient despite not having a GPS unit onboard to assist with spacecraft identification and ground station pass planning. All subsystems performed nominally throughout the mission with a few small hiccups requiring operational workarounds. Thanks to the establishment of automated ground station interfacing, command-and-control, and data processing and ingest, CTIM was able to perform at near-maximum efficiency using reduced staffing during the two months prior to re-entry. Future LASP SmallSat missions utilizing the CTIM bus and FSW designs will benefit from the CTIM lessons learned assessment. The most impactful lesson learned came from a series of undervoltage events seen early in flight due to a lack of power analysis and planning tool bugs. The half-duplexity of the UHF antenna, flash corruptions, and interface lockups created operational challenges as well. LASP demonstrated a highly successful in-house bus while CTIM successfully continued the TSI Climate Data Record. The lessons learned will pave the way for more low-cost missions to continue these important measurements into the future

Two Generations of CubeSat Missions (CSSWE and CIRBE) to Take on the Challenges of Measuring Relativistic Electrons in the Earth’s Magnetosphere

The Colorado Student Space Weather Experiment (CSSWE) CubeSat, carrying the Relativistic Electron and Proton Telescope integrated little experiment (REPTile) to measure 0.5 to \u3e3.8 MeV electrons and 8-40 MeV protons, operated for over two years, 2012-2014, in low Earth orbit (LEO). There have been 25 peer-reviewed publications, including two in Nature, and five Ph.D. dissertations associated with CSSWE. Another 3U CubeSat mission: Colorado Inner Radiation Belt Electron Experiment (CIRBE), has been under development to address an unresolved science question: Where is the break point in terms of electron energy below which electrons can be transported into the inner belt from the outer belt but above which they cannot? This requires clean measurements of energetic electrons with fine energy resolution in an environment where all instruments are subject to the unforgiving penetration from highly energetic protons (tens of MeV to GeV). An advanced version of REPTile has been designed and built, REPTile-2. It has been integrated into the CIRBE bus, which has active attitude control, deployable solar panels, and a S-band radio, provided by Blue Canyon Technologies. CIRBE advances our science capabilities and has significantly improved performance vs. CSSWE and is ready to be launched into a LEO in early 2023