NRL SSULI Data (IMAGE) Naval Research Laboratory Caption This is a first light limb scan from the SSULI 002 instrument on DMSP F18. The x-axis represents wavelength, the y-axis is altitude and the color represents accumulated counts in one second. Credit Naval Research Laboratory Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.