Detection of cold gas releases in space via low-energy neutral atom imaging

Low energy neutral atoms (LENAs) are produced in space plasmas by charge exchange between the ambient magnetospheric plasma ions and cold neutral atoms. Under normal conditions these cold neutrals come from the terrestrial geocorona, a shroud of few-eV hydrogen atoms surrounding the Earth. As a consequence of this charge exchange, it has become possible to remotely image many regions of the magnetosphere for the first time utilizing recently developed LENA imaging technology. In addition to the natural hydrogen geocorona, conventional explosions and maneuvering thruster firings can also introduce large amounts of cold gas into the space environment. In this paper we examine whether such potentially clandestine activities could also be remotely observed for the first time via LENA imaging. First, we examine the fluxes of LENAs produced in the space environment from a conventional explosion. Then we review the present state of the art in the emerging field of LENA detection and imaging. We conclude that the sensitivities for present LENA imager designs may be just adequate for detecting some mad-made releases. With additional improvements in LENA detection capabilities, this technique could become an important new method for monitoring for conventional explosions, as well as other man-made neutral releases, in the space environment.