A team of more than 65 students designed, built and operated a small CubeSat satellite that helped researchers discover energetic electrons in the inner Van Allen radiation belt, believed to be created by cosmic rays bombarding Earth鈥檚 atmosphere. Image courtesy of LASP.
A 60-year-old mystery regarding the source of some energetic and potentially damaging particles in Earth鈥檚 radiation belts is now solved using data from a shoebox-sized satellite built and operated by CU Boulder students.
The results from the new study indicate energetic electrons in Earth鈥檚 inner radiation belt鈥攑rimarily near its inner edge鈥攁re created by cosmic rays born from explosions of supernovas, said the study鈥檚 lead author, Professor Xinlin Li of CU Boulder鈥檚 . Earth鈥檚 radiation belts, known as the Van Allen belts, are layers of energetic particles held in place by Earth鈥檚 magnetic field.
The team showed, during a process called 鈥渃osmic ray albedo neutron decay鈥� (CRAND), cosmic rays entering Earth鈥檚 atmosphere collide with neutral atoms, creating a 鈥渟plash,鈥� which produces charged particles, including electrons, that become trapped by Earth鈥檚 magnetic fields. The findings have implications for understanding and better forecasting the arrival of energetic electrons in near-Earth space, which can damage satellites and threaten the health of space-walking astronauts, said Li.
鈥淲e are reporting the first direct detection of these energetic electrons near the inner edge of Earth鈥檚 radiation belt,鈥� said Li, also a professor in CU Boulder鈥檚 aerospace engineering sciences department. 鈥淲e have finally solved a six-decade-long mystery.鈥�
- Student satellite data spurs major space discovery.
- 鈥淢issing鈥� energetic electrons discovered in inner Van Allen radiation belt.
- 65 students designed, built and controlled tiny CubeSat satellite from campus.
A paper on the subject was published in the Dec. 13 issue of Nature. The study was funded primarily by the National Science Foundation.
Soon after the discovery of the Van Allen radiation belts in 1958, both American and Russian scientists concluded CRAND was likely the source of high-energy protons trapped in Earth鈥檚 magnetic field. But over the intervening decades, no one successfully detected the corresponding electrons that should be produced during the neutron decay.
The CubeSat mission, called the Colorado Student Space Weather Experiment (CSSWE), houses a small, energetic particle telescope to measure the flux of solar energetic protons and Earth鈥檚 radiation belt electrons. Launched in 2012, CSSWE has involved more than 65 CU Boulder students and was operated for more than two years from a ground station they built on the roof of a LASP building on campus.
The instrument on CSSWE, called the Relativistic, Electron and Proton Telescope听integrated little experiment (REPTile), is a smaller version of REPT, twin instruments developed by a CU Boulder team led by LASP director and Nature paper co-author Daniel Baker that were launched on NASA鈥檚 2012 Van Allen Probes mission.
鈥淭his is really a beautiful result and a big insight derived from a remarkably inexpensive student satellite, illustrating that good things can come in small packages,鈥� said Baker. 鈥淚t鈥檚 a major discovery that has been there all along, a demonstration that Yogi Berra was correct when he remarked 鈥榊ou can observe a lot just by looking.鈥欌��
鈥淭hese results reveal, for the first time, how energetic charged particles in the near-Earth space environment are created,鈥� said听Irfan Azeem,听a program director in the NSF鈥檚 Division of Atmospheric and Geospace Sciences.
鈥淭he findings will significantly improve our understanding of the Earth-space environment,鈥� Azeem said.听鈥淚t鈥檚 exciting to see NSF-funded CubeSats built by undergraduate and graduate students at the center of a significant scientific discovery.鈥�
Other study co-authors include researcher Hong Zhao of LASP;听graduate student Kun Zhang of CU Boulder aerospace engineering sciences;听Richard Selesnick of the Air Force Research Laboratory at Kirtland Air Force Base in New Mexico;听Quintin Schiller of NASA鈥檚 Goddard Space Flight Center in Greenbelt, Maryland;听and Michael Temerin of the University of California, Berkeley.
CSSWE was designed and built by students under the direction of Li and aerospace engineering sciences Professor Scott Palo. More than 20 peer-reviewed scientific and engineering papers associated with CSSWE鈥攚hich ceased operations in late 2014鈥攈ave been produced thus far. CU Boulder graduate students continue to study the data.
