Soft X-ray satellite missions and exospheric neutral density

Soft X-rays can be emitted when a highly charged solar wind ion and an exospheric hydrogen exchange an electron. Using the XMM-Newton soft X-ray observations and the OpenGGCM global MHD model, we inversely extract the exospheric hydrogen density near a subsolar location. The two case studies show 40 ~ 58 cm^-3 of neutral density at 10RE subsolar location. These density estimates are large enough to produce strong soft X-ray signals, a good sign for the upcoming missions, CuPID, LEXI, SMILE, and STORM.