May 7th 1975 saw the launch, from the San Marco offshore platform in Kenya, via a Scout launch vehicle, of SAS-C, also known as SAS-3 or Explorer 53. The primary mission of this small astronomical satellite was to measure various X-ray sources, using four experiments. The Extra-Galactic Experiment (EGE) was used to pinpoint very weak X-ray sources beyond the Milky Way; the Galactic Monitor Experiment (GME) measured variations in intensity of sources whose position had been determined using EGE; the Scorpio Monitor Experiment (SME) was pointed specifically at the strongest known source of X-rays in the known universe (Scorpius X-1), and the Galactic Absorption Experiment (GAE) measured the density of interstellar matter using variations in the X-ray background.
SAS C (image credit: NASA)
Today also marks the launch the shuttle Endeavour on mission STS-49 to retrieve and relaunch the intelsat 603 satellite. The mission was a success, and included the first ever 3-astronaut EVA (spacewalk).
Crew of Endeavour mission STS-49 (image credit: NASA)
