The ISIS Story - Science Return from Rescuing, Archiving and Analyzing a Unique Dataset

The Alouette and ISIS topside sounder satellites recorded a great wealth of information about the topside ionosphere during their long periods of operation (from 1962 to 1990). Even though more than 700 publications resulted from this project, only a small percentage of the dataset was analyzed during the mission life time. The soundings were stored on more than 100,000 seven-track analog telemetry tapes. In the mid-nineties space limitations and storage costs threatened an imminent loss of these tapes. Only a last minute intervention spear-headed by NASA’s Ionosphere, Thermosphere, Mesosphere (ITM) Data Evaluation Panel saved a significant portion of these tapes and with funding from the AISRP program these data were first digitized and then converted into electron density profiles. This data restoration effort more than tripled the Alouette/ISIS topside sounder data base and has led to significant improvements of models for the topside ionosphere, e.g., about a factor of 2 improvement in the case of the IRI-2007 topside electron density profile. We will present a brief history of this successful data restoration effort and will highlight the science dividends this investment has produced. The homepage for the ISIS project is at http://nssdc.gsfc.nasa.gov/space/isis/isis-status.html.