June 30, 2023

The Dragon cargo spacecraft departing the International Space Station to end its CRS-28 mission (Image NASA TV)

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A little while ago, SpaceX’s Dragon spacecraft ended its CRS-28 (Cargo Resupply Service 28) mission for NASA splashing down smoothly off the Florida Coast. The Dragon left the International Space Station about 22 hours earlier. For SpaceX, this was the 8th mission of the 2nd contract with NASA to transport supplies to the Station with the new version of the Dragon cargo spacecraft.

Shortly after the splashdown, SpaceX’s recovery ship went to retrieve the Dragon to transport it to the coast. The cargo brought back to Earth will be delivered to NASA within a few hours. The Dragon spacecraft reached the International Space Station on June 6, 2023.

Diagram of Earth as a detection center for very low-frequency gravitational waves emitted by pairs of supermassive black holes (top) using pulsars (bottom) (Image courtesy EPTA)

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A series of articles published or being published in the journals “Astronomy and Astrophysics” and “The Astrophysical Journal Letters” reports various aspects of the detection of very low-frequency gravitational waves. Researchers from the European Pulsar Timing Array (EPTA), the Indian Pulsar Timing Array (InPta), the Parkes Pulsar Timing Array (PPTA), the Chinese Pulsar Timing Array (CPTA), and the North American Nanohertz Observatory for Gravitational Waves (NanoGrav) analyzed data collected over the course of more than 25 years using groups of pulsars to obtain a kind of detector of gravitational waves at the galactic level. This was possible by exploiting the extreme regularity of the signals emitted by pulsars to detect variations of less than a millionth of a second and their correlations to identify gravitational waves. This technique expands the gravitational-wave astronomy opened up by the LIGO and Virgo detectors since the announcement of the first detection in February 2016.