We’re all aware of the growing accumulation of space debris orbiting our planet, but some of these debris objects are coming back to haunt Earth in a rather unusual way. The European Space Agency (ESA) recently discovered that what was previously classified as near Earth object (NEO) 2013 QW1 is actually manmade.
“It was a bit of a challenge, because the object was moving fast with respect to a typical suspected NEO,” said Dr Davide Perna of the Observatoire de Paris, Meudon.
“But despite the difficulties, observations were made with an instrument called DOLORES, for ‘Device Optimized for the LOw RESolution’, which allowed us to obtain the object’s spectrum.”
The result was a spectrum that does not resemble any asteroid. Instead, it bore strong similarities with the spectra of previously observed space junk such as discarded rocket stages, abandoned boosters or defunct satellites.
This is not the first time an artificial object took on a peculiar orbit. The third stage of Apollo 12 took an interesting journey when it failed to crash into the lunar surface as intended. In 2002 it was identified as asteroid J002E3. Later study discovered that the object’s spectral signature matched the white paint used on Apollo rockets. J002E3’s orbit was quite unusual, spending some time in the Sun-Earth first Lagrange point before swooping close enough to Earth to endanger operational satellites. J002E3 is off roaming the solar system now, but may return to Earth orbit in the 2040’s.
Nor is J002E3 the only such object. 6Q0B44E was first thought to be a meteor when it was spotted in 2006; it’s now considered artificial but its originating spacecraft is not known. In the opposite situation, 2006 RH120, discovered shortly after 6Q0B44E, was first thought to be manmade because it exhibited reflectance similar to the aforementioned Apollo booster paint. It turned out to be a small asteroid now out orbiting the Sun, although some think it stills owes its existence to human activity as ejected lunar rock from one of the Apollo impacts.
Clearly, it can be challenging to identify just what it whizzing around up there. Fortunately, we don’t frequently have the problem that cropped up in 2007 when a Catalina Sky Survey astronomer mistakenly labelled the Rosetta spacecraft as asteroid 2007 VN84 making a scarily-close approach at 5,700 km. Rosetta survived its Earth flyby without interference and is now en route to its 2014 rendezvous with comet 67P/Churyumov–Gerasimenko.
At the end of the day, these small episodes of confusion are just one more reason to keep our eyes (or telescopes) trained on the skies. With all the asteroids, boosters, and satellites rocketing around up there, you never know what might happen.
Image caption: The motion of J002E3, showing how the object was captured into its current chaotic orbit around the Earth. The Sun is to the left in these animations. Animations created by Paul Chodas and Ron Baalke. Credits: NASA