Hi there! I am happy to write this new blog post. I did not write for a while. Actually, I am proudly Associate Editor of Astronomy & Astrophysics. I love this job, but this fills my week-ends, and during the week days I work as an Assistant Professor at the University of Franche-Comté, Besançon, France. So, this leaves me very few time for blogging. Anyway, I wanted to emphasize the loss of the radiotelescope of Arecibo.

The National Astronomy and Ionosphere Center was a 305 m-wide radiotelescope, which explored the sky since November 1963 from Arecibo, Puerto Rico. It was the largest filled-aperture radiotelescope in the world until 2016, when it was surpassed by the Chinese radiotelescope FAST. It was composed of a spherical reflector, i.e. a collecting dish, three radar transmitters, and a receiver on a platform suspended 150 m above the dish by 18 cables running from three reinforced concrete towers.
These cables suffered several damages, which led the decommissioning of the telescope in November 2020. It appeared that trying to repair it was too dangerous, because other cables could break at any time and damage the structure. This actually happened on Dec, 1st, triggering the fall of the receiver platform.

This is of course a great loss for observational astronomy. Shortly after its first light, Arecibo measured the spin rate of Mercury, giving evidence of its 3:2 spin-orbit resonance. So far, Mercury is the only known planetary object in this resonance, i.e. its rotation period (58 days) is exactly two-thirds of its revolution period (88 days).
Arecibo also discovered the first binary pulsar, in 1974, and permiited to image Near-Earth Asteroids. It also collected data for the SETI project (Search for ExtraTerrestrial Intelligence),
and was used to send a message to potential extraterrestrial civilizations in 1974.

You can try to save the radiotelescope anyway, in signing the petition. Beside this, interesting observations will be made by the Chinese radiotelescope FAST. So, we cannot say there is nothing, FAST is a wonderful instrument, but the National Astronomy and Ionosphere Center would have taken its share of the pressure for observing.

Merry Christmas.