Background on the Ørsted Experiment

Ørsted was launched on February 23rd 1999 aboard the same rocket as SUNSAT, and was managed by the Danmarks Meteorologiske Institut. The Danish PI of the occultation experiment was Per Høeg. Ørsted carried a Turbo-Rogue GPS receiver built at the Jet Propulsion Laboratory in California and paid for by NASA. The purpose was to accurately determine the position of the satellite. This instrument was used periodically to track radio-occultations.

The receiver prototype was a model identical to the one aboard SUNSAT. Data coverage however was continuous in for orbit purposes, which enabled a precise orbit determination as it is required for occultations. As a result some hundred occultations were succesfully retrieved during the life of the experiment. One of the 2 GPS frequencies was measured with a very low SNR, which motivated a study on the capabilities of doing single frequency occultation retrievals.