A near-Earth object hurtled past us on Wednesday, just two days after its discovery was announced.
Orbital projections indicated that the object called 2010 AL30 flew by Earth at a distance of just 80,000 miles (130,000 kilometers). That's only one-third of the way from here to the moon.
If the object had been on a collision course with Earth, it wouldn't have done any damage anyway. But planetary scientists said the asteroid, or whatever it was, set a new standard: A 10-meter-wide (33-foot-wide) asteroid can be detected two days before it potentially hits Earth.
Expert astronomers could observe it shining with a brightness of a 14th-magnitude star (the approximate brightness of Pluto's weak glow as seen from Earth) as it dashed through the constellations of Orion, Taurus and Pisces. (Further details about the orbit of 2010 AL30 can be found on NASA's Solar System Dynamics Web site).
What makes this near-Earth object, or NEO, special is that it has an orbital period of almost exactly one year. This fact led some scientists to speculate that 2010 AL30 could be an artificial object and not an asteroid. After all, there's a lot of space junk up there. There's every possibility that it could be a spent rocket booster or some other chunk from a spacecraft.
But it could just be coincidence that the NEO has the same orbital period as Earth; it might just be another asteroid.
According to Alan W. Harris, senior research scientist at the Space Science Institute, apart from 2010 AL30's coincidental orbital period, there is nothing else to suggest it's anything other than a naturally occurring near-Earth asteroid.
"[2010 AL30 is] unlikely to be artificial, its orbit doesn't resemble any useful spacecraft trajectory, and its encounter velocity with the Earth is not unusually low," Harris said in a posting to The Minor Planet Mailing List. Harris also pointed out that 2010 AL30 has a "perfectly ordinary Earth-crossing orbit." In other words, it looks like any other near-Earth asteroid.
In a statement, NASA's Near-Earth Object Program Office said the object was most likely an asteroid because it had a steep, eccentric orbit that didn't match up with any recent rocket launches. However, European Space Agency mission analyst Michael Khan suggested the object might be the Fregat upper stage from the Soyuz vehicle that was used to launch ESA's Venus Express spacecraft in 2005.
"Probably 2010 AL30 is of natural origin. However, the possibility that it is man-made cannot be completely excluded," Khan said in an article on his blog. "If so, it might be the upper stage of a rocket used in an earlier planetary mission, possibly to Venus. The current orbit would have been acquired through a Venus swingby and other orbital perturbations."
The answer probably won't come until the results from NASA's Goldstone Solar System Radar carries out an analysis of 2010 AL30. The California-based radar dish is part of the Deep Space Network, and it provides some of the most detailed observations of NEOs.
In any case, the discovery of this 10-meter-wide object is testament to the increasing capabilities of the international community of asteroid hunters. Andrea Boattini of the Catalina Sky Survey made the interesting point that 2010 AL30 is a great example of how much of a warning we'd have for an object of this size that's headed for Earth. After all, the discovery was announced only on Monday.
It is worth noting that even if 2010 AL30 did hit Earth, it would most likely explode high in the atmosphere (with the energy of a small nuclear bomb), posing little danger to anyone on the ground. Impacts of this size happen every year.