Get out the way! The European GOCE (Gravity field and steady-state Ocean Circulation Explorer) satellite ran out of fuel in October and it’s on the way down. Scientists at European Space Debris Office expect it to plunge through the atmosphere between 12:30 p.m. and 6 p.m. this afternoon.
Since most of the Earth’s surface is ocean, that’s where GOCE’s likely to fall … but you never know. This isn’t a controlled re-entry, so there’s a small chance it could land in your backyard. A very small chance. If it does burn up over inhabited land it will be a spectacular sight even in the daytime.
Most of the 2,000-pound satellite will burn up harmlessly, but Heiner Klinkrad, head of the Space Debris Office, estimates that about 20 percent or 440 pounds (220 kg) of debris in the form of dozens of fragments will survive the plunge and reach the ground along a sizable re-entry swath.
Spread out this way, the chances of a particular piece of machinery coming down on your head is exceedingly small. But if that does happen, you’ve got options. According to a 1972 U.N. agreement called the Convention on International Liability for Damage Caused by Space Objects, you’re fully covered by the European Space Agency in case of damage to life or property.
GOCE’s currently about 90 miles up and losing 0.6 miles of altitude for every orbit it makes from friction with the atmosphere. It was launched in March 2009 on a mission to precisely map Earth’s gravity field and ocean currents and create a high-resolution map of the boundary between Earth’s crust and mantle (dense rock layer directly beneath the crust that’s some 1,800 miles thick.)
Primer on GOCE’s mission
One of the coolest things it did was create a detailed map of the “geoid” or virtual map showing the strength of gravity across the planet. Mountain ranges, composed of dense rock, have a stronger gravitational pull on the spacecraft compared to ocean waters. Every minute variation in gravity altered GOCE’s orbit a little bit here and a little bit there. Combined with data from its internal gravity-measuring gradiometers, the probe compiled the information to create a map showing a very lumpy Earth.
Mapping the geoid helps scientists better understand sea level changes and global ocean circulation which are in turn affected by climate change.
I’ll report back later today when GOCE bites the dust. In the meantime click HERE to track it live from your phone or computer.
Please note that it sometimes takes a minute for GOCE to show up on the tracking map.
** UPDATE 8:15 p.m. CST: According to the BBC News, GOCE has re-entered Earth’s atmosphere. It was last sighted at 4:52 p.m. CST passing just 75 miles (121 km) over Antarctica. Any debris that survived the fiery dive would have fallen anywhere from Eastern Asia across the Pacific to Antarctica. We can all breathe now!
More information can be found on Visual SAT-Flare Tracker 3D as well as on Daniel Souka’s blog. Souka is Senior Editor for Spacecraft Operations at ESOC, ESA’s European Space Operations Center in Darmstadt, Germany.