The Feasibility of Missile Launch Detection Through Clouds Using the 589 . 6 nm Na Emission

Spectral measurements of various solidand liquid-propellent rocket plumes have shown the presence of strong emissions from sodium (589.6 nm) and potassium (766.5 nm). Theoretical calculations indicate that emissions near 589.6 nm should be efficiently transmitted through the atmosphere and clouds and thus should be easily detectable by a downward-looking sensor positioned above the clouds. To test this concept, a visible radiometric sensor with an interference filter (and later with an atomic line resonance filter) was developed and flown on an aircraft platform. A simple groundbased Na emission source was fabricated using several low-pressure sodium discharge lamps. A number of nighttime measurement flights were conducted for several different cloud types and conditions. Data collected during these nighttime flights are presented and discussed. These initial measurements have confirmed that a simulated rocket emission source at 589.6 nm is detectable through clouds. Additional measurements covering a wider range of cloud conditions and types and during daylight conditions are planned for the near future. Form SF298 Citation Data Report Date ("DD MON YYYY") 00001999 Report Type N/A Dates Covered (from... to) ("DD MON YYYY") Title and Subtitle The Feasibility of Missile Launch Detection Through Clouds Using the 589.6 nm Na Emission Contract or Grant Number Program Element Number Authors Project Number