ESA Science & Technology - Cluster detects invisible escaping ions

By applying a new analytical method to a unique set of electric field data collected by instruments onboard the Cluster mission, it has been possible to quantify the amount of hydrogen naturally escaping each year from the Earth's atmosphere. This hydrogen outflow has been shown to be of the order of thousands of tons. The escaping hydrogen has previously been invisible to classical particle detectors on satellites due to its very low energy. For further details see Engwall et al., 2009.

This graphic illustrates the larger region of the magnetosphere (green band) which was studied by Engwall et al., using Cluster data. Previous studies of outflows from the polar ionosphere have covered a much smaller volume (yellow band).