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An image taken from a NASA DC-8 airplane shows the re-entry of Japan's Hayabusa spacecraft in 2010. WT1190F's re-entry will be less spectacular because it's due to occur at midday local time. (Credit: Jesse Carpenter / Greg Merkes / NASA Ames file)
An image taken from a NASA DC-8 airplane shows the re-entry of Japan’s Hayabusa spacecraft in 2010. WT1190F’s re-entry was far less spectacular because it occurred at midday local time amid cloudy weather. (Credit: Jesse Carpenter / Greg Merkes / NASA Ames file)

Was it a spent Apollo rocket stage from the ’60s? A scary space rock? Whatever it was, the mysterious object known as WT1190F zoomed in from deep space and went out in a largely unseen blaze of glory today.

The red arrow indicates WT1190F in this image taken by the University of Hawaii 2.2-meter telescope. (Credit: B. Bolin, R. Jedicke, M. Micheli)

Experts on orbital debris said WT1190F was probably a low-density object measuring just 6 feet (2 meters) long. Astronomers with the Catalina Sky Survey first observed the object in October. When they looked back at archived telescope data, they figured out that it had been tracing a highly eccentric orbit around Earth that swung out beyond the moon’s orbit.

Update: WT1190F caught on aerial video

The European Space Agency said the best match for an object with those characteristics was a “discarded rocket body.” Other observers suggested it could be debris cast off by a moon mission, perhaps going back to the Apollo era. No wonder the thing was nicknamed “WTF.”

WT1190F was unusual in that the course of its final, fiery plunge to Earth was extraordinarily well-known in advance. The experts said it was due to re-enter the atmosphere at 10:18 p.m. PT tonight (06:18 GMT Friday) at a velocity of 24,600 mph (11 kilometers per second).

Few if any pieces of the object were expected to survive the descent. If they did, they would have splashed into the Indian Ocean, about 60 miles (100 kilometers) off the southern coast of Sri Lanka. “Being local noon in the area, only the brightest part of the trajectory may become observable,” ESA’s Near-Earth Object Coordinating Center said in advance of the re-entry. “We would therefore expect observations to be possible from land only from the southern province of Sri Lanka.”

The initial reports on Twitter suggest that WT1190F was a no-show in Sri Lanka:

The people who had the best chance of spotting WT1190F on the way down were the researchers aboard a Gulfstream business jet that’s flying out of Abu Dhabi. Even if their observing campaign was a washout this time around, the exercise provided good practice for future aerial monitoring of incoming asteroids. Check for updates from the WTF-watchers on

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