September 23

In the last week of September 2022 — September 23–27, 2022 — Russian authorities and their proxies staged plebiscites in parts of Donetsk, Luhansk, Kherson and Zaporizhzhia oblasts that they then used to declare those territories annexed by the Russian Federation on September 30, 2022. Held under military occupation, without independent observers and amid mass displacement and active combat, the votes were widely condemned as illegitimate by the United Nations and most countries. The declarations deepened international isolation of Russia and reshaped the next phase of the war in Ukraine. Read more

The Mars Climate Orbiter launched from Cape Canaveral on December 11, 1998, bound to study Martian weather and serve as a communications relay. On September 23, 1999, during the planned Mars orbit insertion maneuver, the spacecraft failed to reestablish contact and was lost. An investigation found the proximate cause to be a units conversion error—thruster performance data supplied in pound‑force seconds were treated as if they were newton‑seconds—compounded by inadequate interface verification and systems‑engineering oversight. The loss reshaped NASA procedures for software verification, contractor interfaces, and unit standardization. Read more