In 2016, the operators flying CryoSat at ESA’s European Space Operations Centre (ESOC), in Darmstadt, Germany, noticed that the spacecraft was using up its 37 kilograms of compressed nitrogen much faster than expected.

This meant that a fuel leak threatened to bring the mission to an end in 2025. Therefore, on 21 November, operators at ESOC initiated a swap to a back-up system, as CryoSat passed over Svalbard station on Spitzbergen Island and ESA’s Kiruna station in Sweden—thus saving the satellite for years to come.

CryoSat, ESA’s satellite dedicated to measuring the thickness of polar sea ice and monitoring changes in the ice sheets that blanket Greenland and Antarctica, was designed to last roughly 5 years, but it has now spent over 13 years in orbit, proving invaluable for humankind’s polar ice records.

As of November 2023, CryoSat has 13 kg of fuel left – 13 kg less fuel left than it should have based on the thruster use for orbit maintenance manoeuvres and attitude control— the swap carried out by ESOC operators had the potential to extend the life of the satellite by as much as 5 to 10 years. However, the back-up thrusters had never been used before and if something had damaged them during CryoSat’s 13 years in orbit, there was a possibility that the mission would come to a sudden end.

On 22 November, the flight control team at ESA conducted an ‘orbital control manoeuvre’, to test the two larger thrusters in the back-up system. Since no issues were found during or after the manoeuvre, CryoSat’s back-up thrusters are now officially commissioned, and the satellite is set to continue its scientific activities, possibly beyond the end of the decade.

CryoSat’s thirteen-year climate record of global ice and sea levels is unparalleled, including mission highlights like the first ever year-round map of Arctic Sea ice and our most accurate estimates yet for the ice volume lost by Earth’s glaciers and polar ice sheets.

These data are critical to inform climate reports and policy makers, and are also shaping the design of new ice-monitoring satellites, such as the Copernicus Polar Ice and Snow Topography Altimeter (CRISTAL) mission, due to launch in a few years.

CryoSat's data products cover not just sea ice and land ice, but also polar oceans, coastal oceans and inland waters— thus ESA's ice mission still has loads to give.

“We’re delighted that our ice mission will continue to extend its long-term record of global ice and sea levels, thanks to the hard work and skill of our colleagues at ESOC,” said CryoSat Mission Manager, Tommaso Parrinello. “There’s plenty more to come from CryoSat as we pave the way for future missions such as CRISTAL.”