May 07 – Launch of SAS C (Explorer 53)

Wow. I just looked on my WordPress page and saw that the latest entry under “recently published” is dated Sept 13th 2017. I never realised I could be quite as lazy as this. It’s time for an update.

Today in 1902 asteroid 485 Genua was discovered at Heidelberg Observatory by Italian astronomer Luigi Carnera (1875-1962). Genua is a main belt asteroid of about 64km diameter, and is one of 16 discovered by Carnera, all of which happened in the years 1901 and 1902, while he was under the spell of legendary asteroid hunter Max Wolf. Carnera himself had to wait until 1995 before having anasteroid named in his honour (number 39653).


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)
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)
Crew of Endeavour mission STS-49 (image credit: NASA)

Last updated: May 08, 2019.