Understanding the ionosphere and thermosphere

In this talk we discuss the most important questions in understanding the ionosphere/thermosphere and how they can be addressed with small satellites. The ionosphere is created by the solar radiation and the precipitation of energetic magnetospheric electrons and ions and by the ionization of meteoritic material. This last component has not attracted much attention lately but it plays a significant role, through the creation of the sporadic E-region, in limiting the performance of some of technological systems. The ionosphere is also driven from below by the creation of lower atmosphere tides and atmospheric gravity waves. We also note that transient phenomena, such as tropospheric storms and earthquakes and missile launches, produce an ionospheric signature. One particularly fascinating conjecture is that there may even be an ionospheric precursor signature that heralds earthquakes. There are still many mysteries to be addressed. Small satellites can address the ionospheric space weather by either providing a number of in situ measurements (we will briefly describe some new ideas); by imaging some of the drivers or the response (AGWs or the aurora); or by radio techniques. The key to understanding the global behavior of the ionosphere is to unravel the many different factors that influence its behavior – to achieve that goal we must make many, many observations. Only by achieving an international collaboration of many kinds of instruments (ground- and space-based) and models can we truly make progress.