After nearly 31 years in space studying the protective magnetic bubble known as the magnetosphere that surrounds Earth, NASA’s Geotail mission has come to an end. The second Geotail data logger, which collects data on the structure and dynamics of our planet’s magnetosphere, malfunctioned on June 28, 2022. The spacecraft’s first data logger failed 10 years ago, in 2012. Attempts were then made to remotely repair the failed data logger, and on November 28, 2022, the joint mission with the Japan Space Agency (JAXA) came to an end. NASA announced the end of the mission in a statement on January 18.

Don Fairfield, an honorary space scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, was the first project scientist for NASA’s Geotail and worked on the mission until his retirement in 2008.

“Geotail was a very productive satellite and was the first joint mission between NASA and JAXA,” Fairfield said in a statement. “The mission made significant contributions to our understanding of how the solar wind interacts with Earth’s magnetic field to create magnetic storms and auroras.”

Since its launch on July 24, 1992, Geotail’s extended orbit has taken it 120,000 miles from Earth, allowing the spacecraft to enter and exit the magnetosphere and gather information about the physics within it. This horse of data has been the basis of thousands of scientific studies.

The magnetosphere is vital to life on Earth because it traps potentially harmful charged particles from the solar wind in field lines, forcing them to travel around Earth and back into space. These particles carry so much energy that, if not blocked by the magnetic field, they can rob the planet’s atmosphere and cause it to lose its water content to space as steam.

Many scientists believe Mars is a barren, arid planet that can no longer support life because it lost its magnetic field about 4 billion years ago, causing it to lose most of its water.

In addition to allowing researchers to study how charged particles and energy from the Sun reach Earth’s magnetosphere, the geotail also revealed the rate at which charged particles from the solar wind enter this magnetic field. Geotail was also responsible for determining the location in the magnetosphere where magnetic reconnection occurred. This is important because this phenomenon is responsible for the transfer of energy and matter from the Sun to Earth and helps create auroras, which are beautiful displays of light seen in the sky.

The spacecraft was able to study the Moon away from Earth and successfully identify elements such as oxygen, silicon, sodium and aluminum in the lunar atmosphere. During its three decades of operation, the Geotail mission has also assisted other NASA space projects by providing data on distant regions of the magnetosphere that helps paint a picture of how events in one region of the magnetic bubble affect the physics of another region.

The Geotail has gone far beyond its expected lifetime in space. The first mission was supposed to last only 4 years, but was later extended several times. While Geotail’s data-gathering mission is over, the science its operations inspire, and thus its legacy, is not yet over. Teams of scientists will continue to examine data the ship has collected since 1992.