Scified PSA: European Satellite Expected to Fall To Earth Anyday Now

Update!:

This morning, at about 1:00 am CET, ESA’s Gravity field and steady-state Ocean Circulation Explorer (GOCE) satellite reentered the atmosphere and burned up somewhere along its orbital path extending from Siberia, across the western Pacific Ocean, the eastern Indian Ocean, and to Antarctica. According to the space agency, it disintegrated in the upper atmosphere and though some debris may have reached the surface, no damage was reported.

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A European satellite that mapped Earth’s gravitational field in exquisite detail will be pulled down by gravity to its fiery destruction sometime in the next few days.

Where and when it will crash no one knows. It could be almost anywhere on the globe. About 25 to 45 fragments of the one-ton spacecraft are expected to survive all the way to the surface, with the largest perhaps weighing 200 pounds.

It is the latest in a parade of spacecraft falling from the sky in what are worryingly called “uncontrolled entries.”

About 100 tons of debris will fall from the sky this year alone. There are, however, no known instances in which anyone has been injured by space debris.

“It’s rather hard to predict where the spacecraft will re-enter and impact,” said Rune Floberghagen, the mission manager for the European Space Agency’s Gravity Field and Steady-State Ocean Circulation Explorer, or GOCE. “Concretely our best engineering prediction is now for a re-entry on Sunday, with a possibility for it slipping into early Monday.”

GOCE (pronounced GO-chay) ran out of propellant last month and has been dropping about 2.5 miles a day. As of Wednesday, it was still 113 miles up as it circled the Earth once every 88 minutes. Its orbit goes almost directly over the poles, and as the planet rotates, almost all places on Earth pass beneath it at some point.

Two years ago, NASA’s decommissioned Upper Atmosphere Research Satellite, tumbling out of control, worried people around the world until it splashed harmlessly in the Pacific. Later that year, the Russian spacecraft Phobos-Grunt launched into orbit, but then malfunctioned. Instead of heading toward Mars, it crashed back to Earth a couple of months later, again falling in the Pacific without incident.

The chances that a chunk of GOCE or any other space debris will injure anyone are tiny, but not zero. Dr. Floberghagen said the debris will endanger about 15 to 20 square yards of the Earth’s surface. “If you compare that to the surface of the planet, it’s a very small number,” he said.

An uncontrolled re-entry was always the planned fate for GOCE, which was launched in March 2009. Unlike most spacecraft, which use thrusters to adjust their orbits, it has a highly efficient propulsion system called an ion engine. Unlike thrusters, the engine can fire continuously to offset atmospheric drag.

That allowed GOCE, with its sleek, airplanelike shape, to maintain a low orbit, just 160 miles up and later 140 miles. From that perch, it made gravity measurements that were much more accurate and detailed than previous ones.

“We can actually map, see geology, in the gravity map,” Dr. Floberghagen said. “This is something that is quite unique, actually.”

Keep your EYES on the skies folks!

To read more, visit satellite-will-fall-to-earth-but-no-ones-sure-where

Props to:
KENNETH CHANG
Published: November 6, 2013

Resource:

@nytimesscience on Twitter.

New York Times