Leaked Planetary Defense Papers Suggest U.S. Secretly Watched 3I/ATLAS for 20 Years

A deep image of interstellar Comet 3I/ATLAS captured by the Gemini Multi-Object Spectrograph (GMOS) on Gemini South at Cerro Pachón in Chile, one half of the International Gemini Observatory, partly funded by the U.S. National Science Foundation (NSF) and operated by NSF NOIRLab. The image shows the comet’s broad coma — a cloud of gas and dust that forms around the comet’s icy nucleus as it gets closer to the Sun — and a tail spanning about 1/120th of a degree in the sky (where one degree is about the width of a pinky finger on an outstretched arm) and pointing away from the Sun. 3I/ATLAS is only the third confirmed interstellar visitor to our Solar System.The exposures tracked the comet as it traveled across the sky, and the final image is composed to freeze the stars in place during the observation. Two small colored trails from unrelated asteroids with a different motion from that of the comet can also be seen.These observations of Comet 3I/ATLAS were conducted during a Shadow the Scientists program hosted by NSF NOIRLab. A full recording of the session can be found here. (Credit: Wikimedia Commons)

Leaked documents and images suggest the United States has been quietly tracking interstellar comet 3I/ATLAS for more than 20 years, using an advanced planetary defence system never revealed to the public.

The documents, obtained by a Medium writer, reference a programme called CASSANDRA, first outlined in a 2005 academic paper, along with associated surveillance networks including ORACLE VI, ARGUS-VIS, and UMBRA-3/C. Observers and amateur astronomers have noted unusual geometric patterns and structured emissions from 3I/ATLAS inconsistent with natural cometary behaviour.