Design and scientific return of a miniaturized particle telescope onboard the Colorado Student Space Weather Experiment (CSSWE) CubeSat

The Relativistic Electron and Proton Telescope Integrated Little Experiment (REPTile) is a loaded-disc collimated solid-state particle telescope designed, built, tested, and operated by a team of students at the University of Colorado. It was launched onboard the Colorado Student Space Weather Experiment (CSSWE), a 3U CubeSat, from Vandenberg Air Force Base on September 13th, 2012, as part of NASA´s Educational Launch of Nanosatellites (ELaNa) program. REPTile takes measurements of energetic particles in the near-Earth environment. These measurements, by themselves and in conjunction with larger missions, are critical to understand, model, and predict hazardous space weather effects. However, miniaturizing a power- and mass-hungry particle telescope to return clean measurements from a CubeSat platform is extremely challenging. To overcome these challenges, REPTile underwent a rigorous design and testing phase. This paper highlights some of the design and testing which validates the data as a valuable contribution to the study of space weather. CSSWE uses a keep-it-simple design approach to minimize risks associated with low budget and student built missions. A coherent testing plan confirmed that the spacecraft would remain healthy and take reliable measurements in orbit. This paper also highlights the system-level design and testing that verified spacecraft performance pre and post launch. Despite the risks inherent CubeSat missions, REPTile to date has returned over 300 days of valuable science data, more than tripling its nominal mission lifetime of 90 days. Initial in-flight instrument results are presented, including engineering hurdles encountered in receiving and processing the data. Also, the preliminary scientific contributions of the mission are covered in this paper to demonstrate the capabilities of a low-budget CubeSat mission. As an affordable, robust, and simple instrument and mission design, CSSWE demonstrates that small satellites are a reliable p- atform to deliver quality science.