Or in theory, indefinitely, https://news.ycombinator.com/item?id=16527007 https://news.ycombinator.com/item?id=16527007 ("First firing of air-breathing electri

Or in theory, indefinitely, https://news.ycombinator.com/item?id=16527007 https://news.ycombinator.com/item?id=16527007 ("First firing of air-breathing electric thruster (esa.int)" (2018))