Ice satellite detects powerful geomagnetic storm with precision

It seems improbable that a satellite designed to monitor polar ice sheets and floating sea ice could accurately measure a disturbance in Earth’s magnetic field. But that is just what ESA’s CryoSat mission did earlier this year. This is a story of unique innovation in satellite technology. At the end of last year, the CryoSat mission, which has been operating for almost 16 years, was given a remote upgrade of new software for its platform magnetometer. This instrument is installed on the satellite to ensure it orbits at the right altitude and directs its science instruments toward the right part of Earth’s surface. The platform magnetometer is therefore an operational instrument and was not designed to produce scientific data about Earth’s magnetic environment.

In fact, CryoSat is known primarily as an ice mission. It carries an advanced radar instrument that measures small changes on the surface of ice sheets and sea ice, down to an accuracy of a few millimeters. As part of ESA’s Earth Explorer family of satellites, it has produced scientific datasets that give us insights into Earth’s polar oceans, subglacial lakes, as well as ice sheets.

CryoSat’s upgraded role in magnetometry

The upgrade to its operational magnetometer means that CryoSat is now also able to measure changes in Earth’s magnetosphere with scientific precision, using data to calibrate its measurements from ESA’s dedicated magnetic field-observing Earth Explorer, Swarm. This newly acquired skill means there are now in effect two magnetometry missions in ESA’s Earth Explorer family. Swarm (and CryoSat) will be joined by another magnetic field-measuring Scout satellite, NanoMagSat, which is currently in development.

Swarm remains ESA’s primary mission dedicated to studying Earth’s magnetic field, while CryoSat maintains its key focus on measuring and monitoring changes to ice sheets and our polar oceans. The crucial thing to point out is that CryoSat’s platform magnetometer is being used innovatively to measure Earth’s stronger external magnetic field variations. It is providing excellent data compared to other platform magnetometers on other non-magnetic missions and the upgrade is helping the geomagnetic community by providing a complementary dataset.

Anja Stromme, ESA’s Mission Manager for Swarm, said, “This is a great accomplishment that significantly benefits the Swarm community.”

Real-world test during solar storm

At the beginning of this year, CryoSat was able to put its newfound skills to good use when a particularly strong X-class solar flare caused a geomagnetic storm in Earth’s atmosphere. The event began on 18 January and caused some of the most intense radiation storms on record—with people able to witness stunning aurora in much lower latitudes than usual, from Europe to Mexico. The cause was an eruption on the sun’s surface, which released high energy particles that reached Earth within 25 hours. Over a period of three days, CryoSat was able to contribute scientific data to measure the intensity of the geomagnetic storm. CryoSat’s data proved to be of high quality and complementary to data produced by Swarm.

A data analysis method, introduced in this study in Geophysical Research Letters, was used to create an animation showing the solar storm’s impact on Earth’s magnetic field during the solar storm.

How engineers repurposed CryoSat data

“This innovation is both unique and exciting,” said Tommaso Parrinello, ESA’s CryoSat Mission Manager, adding, “This is about leveraging data from an existing system that has been used for the past 16 years to actively control the satellite’s orientation in space.

“In essence, we use magnetometers to sense the Earth’s magnetosphere, which then sends signals to the onboard computer to adjust the satellite’s orientation, ensuring it achieves its mission objectives. The precision and low noise level of these measurements have led the scientific community to recognize their value as scientific data. Consequently, a new data packet is now generated by the onboard computer for scientific purposes.”

This new ability to create magnetometry datasets using acquisitions from CryoSat, complementing those from the Swarm mission, offers unique benefits at no additional cost. Tommaso noted, “There is lots of exciting science still to come as both missions fly on well beyond their design lifetimes.”