Ultraviolet photodesorption as a driver of water migration on the lunar surface

► We obtained water desorption cross-section for 193 nm photons on amorphous carbon. ► We obtained cross-section for desorption of water on lunar soil 65901 by 4 keV He+ ions. ► Estimated lifetime for desorption at the subsolar point is ∼14 h for average solar activity. ► Photodesorption is two orders of magnitude more efficient than sputtering for desorbing water.