US-German Earth gravity measuring satellites end mission

Facing a battery issue after more than 15 years in orbit, the US-German GRACE -- Gravity Recovery and Climate Experiment -- satellite mission has ended its science operations, NASA has said.

The twin GRACE-1 and GRACE-2 satellites made detailed measurements of Earth's gravity field, leading to discoveries about gravity and Earth's natural systems.

"During their mission, the twin GRACE satellites have provided unprecedented insights into how our planet is changing by tracking the continuous movement of liquid water, ice and the solid Earth," NASA said on Friday.

Following an age-related battery issue on GRACE-2 in September, it became apparent by mid-October that GRACE-2's remaining battery capacity would not be sufficient to operate its science instruments and telemetry transmitter.

Consequently, the decision was made to decommission the GRACE-2 satellite and end GRACE's science mission.

GRACE was launched in March 2002 to precisely map our planet's ever-changing gravity field.

It has revealed how water, ice and solid Earth mass move on or near Earth's surface due to Earth's changing seasons, weather and climate processes, earthquakes and even human activities, such as from the depletion of large aquifers.

It did this by sensing minute changes in the gravitational pull caused by local changes in Earth's mass, which are due mostly to changes in how water is constantly being redistributed around our planet.

"GRACE has provided paradigm-shifting insights into the interactions of our planet's ocean, atmosphere and solid Earth components," said principal investigator Byron Tapley of University of Texas at Austin.

"It has advanced our understanding of the contribution of polar ice melt to global sea level rise and the amount of atmospheric heat absorbed by the ocean. Recent applications include monitoring and managing global water resources used for consumption, agriculture and industry; and assessing flood and earthquake hazards," Tapley added.

GRACE established that measuring the redistribution of mass around Earth is an essential observation for understanding the Earth system.

"Users in more than 100 countries routinely download GRACE data for analyses," NASA said.

--IANS

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