Twenty years ago today — June 1, 1990 — the US-UK-German Roentgen Satellite (ROSAT) launched from Cape Canaveral on a Delta II.
(X-ray image of Comet Hyakutake, taken by ROSAT’s High Resolution Imager. NASA image.)
True to its namesake, ROSAT was an X-ray observatory, designed to last 18 months and to conduct both a full survey of the sky and detailed observations of points of interest. The mission far exceeded expectations, as the spacecraft operated into 1999. ROSAT not only discovered X-ray emissions from comets, as seen in the image above, but specifically observed emissions from the impact of Comet Shoemaker-Levy on Jupiter.
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