  One of the objectives of the NASA LWS Institute on Nowcasting of Atmospheric
Drag for LEO Spacecraft was to investigate whether and how to increase the
accuracy of atmospheric drag models by improving the quality of the solar
forcing inputs, namely Extreme Ultraviolet (EUV) irradiance information. In
this focused review, we examine the status of and issues with EUV measurements
and proxies, discuss recent promising developments, and suggest a number of
ways to improve the reliability, availability, and forecast accuracy of EUV
measurements in the next solar cycle.
