After 30 years in orbit, missions for the joint NASA-JAXA Geotail spacecraft have ended after the spacecraft’s remaining data recorder failed. Since its launch on July 24, 1992, Geotail has been orbiting the Earth, collecting a vast array of data on the structure and dynamics of the magnetosphere, Earth’s protective magnetic bubble. Geotail was originally planned for a four-year period, but the mission was extended several times due to its high-quality data return, which contributed to more than a thousand scientific publications.
While one of the two Geotail data loggers failed in 2012, the other continued to operate until it detected an anomaly on June 28, 2022. After attempts to remotely repair the recorder failed, mission operations were terminated on November 28, 2022. The Geotail mission is a blue cylinder with a white top. On top of it is an orange flat circle with lines running through it. There are 6 long rods sticking out from around the spaceship. The Earth, Moon and Sun are in the background.
Concept art of the Geotail spacecraft
“Geotail was a very productive satellite, and it was the first joint NASA-JAXA mission,” said Don Fairfield, space scientist emeritus at NASA’s Goddard Space Flight Center in Greenbelt, Md., and NASA’s first project scientist for Geotail until his retirement in 2008. “The mission made significant contributions to our understanding of how the solar wind interacts with Earth’s magnetic field to produce magnetic storms and auroras.”
The extended-orbit Geotail flew through the invisible boundaries of the magnetosphere and collected data on the physical process that takes place there to help understand how the flow of energy and particles from the Sun reaches Earth. Geotail has made many scientific breakthroughs, including helping scientists understand how quickly material from the Sun passes into the magnetosphere, the physical processes occurring at the magnetosphere boundary, and identifying oxygen, silicon, sodium, and aluminum in the lunar atmosphere.
The mission also helped identify the site of a process called magnetic reconnection, which is the main conveyor of material and energy from the Sun into the magnetosphere and one of the instigators of the aurora borealis. This discovery paved the way for the Magnetospheric Multiscale, or MMS, mission, which launched in 2015.
Over the years, Geotail has worked with many other NASA space missions, including MMS, the Van Allen Probes, time histories of events, and macroscale interactions during the Substorms, Cluster, and Wind missions. With an orbit that occasionally came as close as 120,000 miles from Earth, Geotail helped provide complementary data from distant parts of the magnetosphere to give scientists a complete picture of how events observed in one area affect other areas.
Geotail also paired with ground-based observations to confirm the location and mechanisms of aurora production. Although Geotail is collecting new data, the scientific discoveries are not over. Scientists will continue to study the Geotail data in the coming years.