NASA’s Carruthers Geocorona Observatory to Study Earth’s Hydrogen Halo

NASA is set to launch the Carruthers Geocorona Observatory in September 2025. The observatory will study Earth’s thin hydrogen halo, also known as the geocorona. Partnering with NOAA, the mission will utilise ultraviolet imagers to capture light from hydrogen atoms in the outermost atmosphere. This will help protect satellites, support spacecraft missions, and investigate the loss of water on planets.

The geocorona extends 300 miles (480 km) above Earth. It potentially reaches halfway to the Moon and reflects faint ultraviolet light. It was first photographed during the Apollo 16 mission. The geocorona interacts with solar radiation and charged particles, impacting spacecraft. It reveals how Earth retains its atmosphere compared to other planets, such as Mars. This data also informs the search for habitable exoplanets.

Earth’s secret halo, revealed! 🌍✨

NASA’s soon-to-launch Carruthers Geocorona Observatory will capture the first movies of Earth’s geocorona, the faint halo of ultraviolet light given off by the exosphere, our planet’s outer atmosphere.

Within the first two hours of science… pic.twitter.com/FAO7suDRkd

— NASA Solar System (@NASASolarSystem) September 18, 2025

Named after astrophysicist George Carruthers, the 240-kilogram spacecraft carries two ultraviolet imagers. These include a wide-field camera for broad mapping and a near-field sensor for detailed analysis. Launching on a Falcon 9 with NASA’s IMAP and NOAA’s SWFO-L1, it will reach the Sun-Earth Lagrange Point 1, a million miles away. Following a four-month journey, a two-year science phase is scheduled to begin in 2026. It studies the effects of solar activity on the geocorona.

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The observatory’s data could enhance satellite durability and mission planning. This is crucial, given the presence of over 5,000 satellites in orbit (UCS, 2024). Understanding hydrogen escape enhances exoplanet research. It affects approximately 60% of NASA’s planetary studies (NASA, 2024). The mission thus strengthens Earth and space science.

NASA’s Carruthers Geocorona Observatory, launching in 2025, will unlock secrets of Earth’s hydrogen halo. Its findings could shape space exploration.