On this day: September 23

NASA Confirms Loss of Mars Climate Orbiter After Navigation Failure

NASA announced on September 23, 1999, that the Mars Climate Orbiter was lost during orbital insertion, likely due to a metric-imperial units navigation error that caused the spacecraft to enter Mars’ atmosphere at a destructive trajectory.

French police raid suspected cult compounds across the country

On 23 September 1995, French authorities carried out coordinated raids on multiple properties suspected of housing members of an alleged cult network, part of a wider post-1990s clampdown on sects and groups considered a public-order concern.

NASA Confirms Loss of Mars Probe After Failed 1999 Landing Attempt

NASA announced that its Mars probe failed to survive a scheduled landing on September 23, 1999, after communications were lost during final descent and recovery efforts were unsuccessful.

United States and Soviet Union Sign Limited Nuclear Test Ban Treaty

On September 23, 1963, the United States and the Soviet Union joined 100 other nations in signing the Limited (Partial) Test Ban Treaty, agreeing to prohibit nuclear tests in the atmosphere, outer space, and underwater while allowing underground tests.

EU member states approve major eastward enlargement

On 23 September 2002, European Union leaders voted to admit a large group of Central and Eastern European countries, marking a decisive step toward the EU's largest post‑Cold War enlargement and setting accession paths culminating in the 2004 expansion.