The Colorado Student Space Weather Experiment (CSSWE) was 3-unit (10x10x30 cm) CubeSat configuration nanosatellite mission designed and developed by students at CU-Boulder under the direction of faculty and staff. In January 2010, the CSSWE project was funded by the National Science Foundation (NSF) to address fundamental questions pertaining to the relationship between solar flares and energetic particles. These questions include the acceleration and loss mechanisms of outer radiation belt electrons. The goal of the CSSWE was to measure differential fluxes of relativistic electrons in the energy range of 0.5-2.9 MeV and protons in 10-40 MeV. The project was a collaborative effort between LASP and the Department of Aerospace Engineering Sciences (AES) at CU-Boulder, and included the participation of students, faculty, and professional engineers.
The CSSWE science goal was the study of the phenomenology and range of processes active on the sun and in the radiation belts. Coronal Mass Ejections (CMEs) are very large structures (billions of tons of particles) containing plasma and magnetic fields that are occasionally expelled from the sun into the heliosphere. This violent solar activity is the cause of major geomagnetic disturbances, reflected by space weather, during which the trapped radiation belt electrons have their largest variations. There is a strong correlation between CMEs and solar flares, but the correlation does not appear to be a causal one. Rather, solar flares and CMEs appear to be separate phenomena, both resulting from relatively rapid changes in the magnetic structure of the solar atmosphere.
Solar flares are very violent processes in the solar atmosphere that are associated with large energy releases. The strongest support for the onset of the impulsive phase is due to magnetic reconnection of existing or recently emerged magnetic flux loops. Reconnection accelerates particles, producing proton and electron beams that travel along flaring coronal loops.
Some of the high-energy solar particles, referred to as Solar Energetic Particles (SEPs), escape from the sun to produce solar energetic particle events. The CSSWE mission measured these SEPs with the Relativistic Electron and Proton Telescope integrated little experiment (REPTile) instrument.
SEP measurements are important for space weather applications because of their direct effects in Earth’s ionosphere and on man-made systems in space. SEPs and CME particles enhance the ionosphere, primarily at high latitudes. These ionospheric changes lead to a myriad of space weather consequences, such as degradation or even disruption of communications, degradation in the accuracy of highly relied upon Global Positioning System (GPS) measurements and surges in the power lines on the ground that could lead to widespread blackouts.
Earth’s radiation belts are usually divided into the inner belt, centered near 1.5 Earth radii from the center of the Earth when measured in the equatorial plane, and the outer radiation belt that is most intense between 4 and 5 Earth radii. These belts form a torus around the Earth, and many important orbits go through them, including those for GPS satellites (MEO) and spacecraft in Geosynchronous Earth Orbit and in highly inclined Lower Earth Orbit.
The science goals of the CSSWE mission were to study:
- How flare location, magnitude, and frequency relate to the timing, duration, and energy spectrum of SEPs reaching Earth
- How the energy spectrum of radiation belt electrons evolve and how this evolution relates to the acceleration mechanism
- CSSWE Principal Investigator, Xinlin Li, LASP Scientist and CU-Boulder AES Professor
- CSSWE Co-Principal Investigators Scott Palo, CU-Boulder AES Professor, and Shri Kanekal
- CSSWE chief technical mentor, Rick Kohnert, LASP Engineer
- AES provided the CubeSat laboratory, machine shop, and teaching faculty for the project
- LASP provided instrument testing facilities and equipment, as well as scientific and technical mentorship for the project
- More than 60 students from different majors including astronomy and planetary sciences, aerospace, mechanical, electrical, and computer engineering have helped to design the mission and build all of its subsystems
For more information about the CSSWE, see:
The CSSWE flight mission has been completed, however data analysis and modeling continue on a dataset that consists of 3.5 million points covering about two years, which is more than six times the nominal mission lifetime. The data is available through NASA’s CDAWeb archive by checking the “CubeSats” box.
REPTile (Relativistic Electron and Proton Telescope integrated little experiment)
The REPTile instrument provided the following functions:
- It measured the outer belt electrons, both trapped and precipitating to study how the low rate and energy spectrum of the Earth’s outer radiation belt electrons evolves
- It monitored the SEP protons associated with solar flares to study how flare location, magnitude, and frequency relate to the timing, duration, and energy spectrum of SEP protons that reach Earth
- It measured electrons in 3 differential and 1 integral energy channel. Protons were measured in 4 differential channels
REPTile was a small (6.05 cm in length and 6 cm in diameter), low-mass (~1 kg), and low-power (<1 W) particle detector capable of measuring relativistic outer radiation belt electrons in the energy range of 0.5 to > 3 MeV and solar energetic protons from 10-40 MeV.
The instrument was a scaled down version of the REPT instrument, which was built at LASP for the NASA Van Allen Probes mission (formerly the Radiation Belt Storm Probes mission) in the LWS (Living with a Star) program.
For more information about the Van Allen Probes mission, see:
Launch date: August 2012
Launch location: Vandenberg Air Force Base, California
Launch vehicle: Atlas V
Mission target: Low Earth orbit
Mission duration: Two years (nominal mission duration was four months)
Other organizations involved:
- California Polytechnic State University
- U.S. Navy Postgraduate School
- U.S. National Reconnaissance Office