Balloon Array for Radiation-belt Relativistic Electron Losses (BARREL, sometimes calledBalloon Array for RBSP Relativistic Electron Losses) was aNASA mission operated out ofDartmouth College that worked with theVan Allen Probes mission (formerly known as the Radiation Belt Storm Probes, or RBSP, mission).[1] The BARREL project launched a series ofhigh-altitude balloons during four science campaigns: January–February 2013 in Antarctica, December 2013–February 2014 in Antarctica, August 2015 in Sweden, and August 2016 in Sweden. Unlike the football-field-sized balloons typically launched at the Poles, these were each just 27 meters (90 ft) in diameter.[2]
The last balloon was launched August 30, 2016. During the BARREL program, a total of 45 balloon payloads were built, and eight test flights and 55 science flights were carried out.[3]
BARREL helped study theVan Allen radiation belts and why they wax and wane over time. Each BARREL balloon carried instruments to measure particles ejected from the belts which make it down to Earth's atmosphere.[2] By comparing such data to that of the Van Allen Probes, which orbit with the belts themselves, the two missions attempted to correlate observations in the radiation belts with the number of particles ejected.[4] This was done to help distinguish between various theories as to what causes electron loss in the belts.[5]
Theprincipal investigator wasRobyn Millan at Dartmouth College. Co-investigator institutions were theUniversity of Washington,U. C. Berkeley, andU. C. Santa Cruz. BARREL was part of NASA'sLiving With a Star program.[4] Support for the Antarctica balloon campaigns was provided by theNational Science Foundation,British Antarctic Survey, and theSouth African National Antarctic Programme.
