CNN — A 2,000-pound European satellite is expected to re-enter Earth's atmosphere within hours, its controllers announced Sunday as the craft circled gradually downward.
The Gravity Field and Steady-State Ocean Circulation Explorer -- a European Space Agency satellite known shorthand as GOCE -- had fallen to an altitude of about 126 kilometers (80 miles) by Sunday evening, the ESA reported. It's now expected to plunge into the atmosphere and break up sometime between 5:30 and 7:30 p.m. ET, the ESA said.
"The most probable impact ground swath largely runs over ocean and polar regions," the space agency noted on its website. "With a very high probability, a re-entry over Europe can be excluded."
GOCE's orbit can be tracked via an ESA website.
The 5-meter (16-foot) satellite was launched in 2009 to map variations in the Earth's gravity in 3-D, provide ocean circulation patterns and make other measurements. Powered by solar panels and not-your-average lithium-ion battery, it lasted more than three times its expected lifespan before running out of juice on October 21.
In March 2011, the ESA added another role -- as the "first seismometer in orbit" -- when GOCE detected sound waves from the massive earthquake that struck Japan.