The Carruthers Geocorona Observatory at the Earth-Sun Lagrange Point 1

The Carruthers Geocorona Observatory is a SmallSat mission to Lagrange Point 1 (L1), where it will use an advanced ultraviolet imager to monitor Earth’s exosphere — the outermost layer of the atmosphere — and the exosphere’s response to solar-driven space weather. Carruthers is poised to become the first SmallSat to operate at L1 and the first to deliver continuous exospheric observations from this vantage point.

Earth's geocorona is a cloud of neutral hydrogen that extends from the ionosphere out to the orbit of the Moon and possibly beyond. It is created from the breakdown of water and methane to hydrogen atoms in the upper atmosphere by ultraviolet light from the Sun. This hydrogen is observed in ultraviolet light (a wavelength called Lyman-alpha) from the subsequent excitation and de-excitation by the ultraviolet light.

Led by the University of Illinois Urbana-Champaign, the mission is scheduled to launch no earlier than 2025 as a rideshare component of NASA’s Interstellar Mapping and Acceleration Probe (IMAP) mission, which will explore the boundaries of the heliosphere, the bubble that is inflated by the solar wind and surrounds the Sun and planets. The Carruthers Geocorona Observatory is a vital addition to NASA’s fleet of heliophysics satellites. NASA Heliophysics Division missions study a vast, interconnected system from the Sun to the space surrounding Earth and other planets to the farthest limits of the Sun’s constantly flowing streams of solar wind.

See science.NASA.gov