07/02/06

A POTENTIALLY DANGEROUS ROCK

From the Director:

The primary objective of NASA's Spaceguard initiative is the identification of Near Earth Asteroids (NEAs) whose orbits may cross paths with Earth's own orbit at some time in the (hopefully very distant) future.  On the evening of June 18th, 2004, Francisquito Observatory played a key role in helping to better refine the orbit calculation of a recently discovered NEA/PHA (Potentially Hazardous Asteroid) designated 2004LV3.  As of this date, the asteroid was classified as a "Virtual Impactor", meaning that based on the position measurements made to date, there are a number of possible orbits in the future which may intersect with Earth's orbit.  And this is not a particularly small asteroid either; it is estimated to be between 500m and 1.2km in diameter, meaning that if it were to impact the Earth's surface, the resulting damage would be near-catastrophic, planet-wide.

Now, before we all run out and buy falling sky insurance, please bear in mind that along with these possible intersecting orbits which have been calculated, probabilities are assigned to them as well; presently the probabilities are small.  Since NEAs have been observed over the last 150 years or so, none have been found to have a high probability of Earth impact.  In virtually every case, a potentially dangerous asteroid has had its impact risk continuously downgraded as additional position measurements are made and its orbit is better understood.

NEA/PHA 2004LV3 was discovered on June 12th, 2004 and had been observed almost exclusively by large research telescopes since then.  There are a number of possible reasons for the relative lack of observations: it is quite faint (near magnitude 20); and at that time not far from sunrise, meaning that observatories in far northern latitudes may not have had enough dark time to observe it while it is high in the sky. This low frequency of observations was noted by Francisquito, and it was decided on the evening of June 18th to give it a try.  The sky on that night looked as though it would be a little steadier, darker and clearer than average for the time of year, though the likelihood of getting good images of this object was still considered to be fairly low.  Fortunately, the CCD imager was probably a little better-focused than average that evening as well.  When Francisquito's CCD frames were examined the following morning, 3 of the 5 frames showed the unmistakable path of 2004LV, and at magnitude 20, was very faint indeed.  Look at the image below to see if you can spot the asteroid.

 Image (magnified 2x) of NEA/PHA 2004LV3 taken at Francisquito Observatory on 2004.06.18.  Click here if you need a little help locating it.

As it turned out, Francisquito's measurements of 2004LV3 were the only ones made that evening, though it is an object of significant interest.  Hopefully the trend of decreasing impact risk with additional observational data will continue.  Check out the image below to see 2004LV3's orbital path (in blue) with respect to the inner planets in the Solar System, and 2004LV3's position when it was imaged at Francisquito.  Its distance from Earth that day was a comfortable 60 million kilometers.

Image generated with NASA/JPL's Orbit Diagram Tool (http://neo.jpl.nasa.gov/orbits/)