The earth system is considered a closed system. A closed system is one that allows energy but not mass to pass across the system boundary. The boundary of the earth system is the outer edge of the atmosphere. But where is the outer edge of the atmosphere?
Scientists at the University of Calagary have apparently identified what they believe is the ‘edge of space’ or the boundary of the earth system. Using the Supra-Thermal Ion Imager launched aboard the JOULE-II rocket in 2007 by NASA, they are able to track the transition of the gentle winds of the upper atmosphere and the high velocity flows of charged particles in space. David Knudsen, associate professor in the Department of Physics and Astronomy at the University of Calgary points out that this project ‘allows us to calculate energy flows into the Earth’s atmosphere that ultimately may be able to help us understand the interaction between space and our environment.’
For more see “Scientists pinpoint the ‘edge of space‘” at EurekAlert