2010 KQ – a very small, very close asteroid

Small asteroids buzz past the Earth every day. The great majority of them pass by sight unseen. One little asteroid, now named 2010 KQ, was picked up by the Catalina Sky Survey on the night of May 16. The fact that this object is small and passing close to Earth is not unusual. Rather it’s orbit is the interesting thing about  this object.  2010 KQ has an orbit that is very Earth-like as the diagram and table below shows.

Orbit of 2010 KQ and the inner planets. Created with C2A. Credit: Carl Hergenrother.
Orbital Parameters:
Perihelion distance = 1.016 AU
Aphelion distance = 1.032 AU
Semi-major axis = 1.024 AU
Inclination = 0.07°
Period = 1.04 years

Currently the official orbit sources give 2010 KQ an absolute magnitude (H) of 28.3 which corresponds to a diameter of 3-8 meters. This H value makes a few assumptions. My independent analysis of it brightness suggests it might be smaller and fainter with an H value of 29.9. This results in smaller diameters of 2-6 meters. Either way this is a small asteroid and only a handful of smaller ones have been detected. I will be able to better define these values as more observations are made.

The very Earth-like orbit creates very slow, long Earth fly-bys. Close approach happened yesterday (May 21) at a distance of 0.0033 AU (~490,000 km or 290,000 miles). That’s just a little further than the Moon.

Small objects on similar orbits have been found in the past. Only one of these objects turned out to be a natural asteroid. All of the others were man-made space hardware. Just like on Earth where it is hard to travel anywhere without running across man-made structures or garbage, space is also littered with working and non-working satellites, rocket bodies, and assorted nuts and bolts.

Bill Gray does an excellent job of monitoring these sorts of objects and determining whether they are natural or man-made. He studies the motion of the objects along their orbits. Man-made objects are light and have a large surface area to mass ratio. This allows the solar wind and other non-gravitational forces to change the motion of the objects. Within a week or so, he should have enough data to declare the object an asteroid or just space junk. He has set up a site where you can follow the current orbit of KQ and his current thoughts on its nature.

The last time KQ was in the vicinity of Earth was back in August 1990. Prior to that it passed Earth in 1975. Perhaps it is a piece of an interplanetary or high-Earth orbit spacecraft mission launched during those times (though the 1990 date already looks unlikely).


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