Monday, February 26, 2007

Bowling for Planets! (Part 2) or "Strikes, Spares and (near) Misses"

The more I look into this the worse the scenario looks. Who knows, by then we would have colonized the Moon and Mars....right?

You know, there is an ancient Chinese proverb which is considered a curse: May you live in interesting times" ...No doubt, those living in the next 40 years will experience that many times over!

New Analysis Identify a Small Possibility that Asteroid 1999 AN10 Could Collide with Earth in 2044 or 2046

New orbital analysis for the kilometer-sized asteroid 1999 AN10 have revealed a remote chance that this object might collide with the Earth in the year 2044 or 2046. Although this asteroid will be monitored in the future, it is not thought to be a serious hazard to Earth at this time. Researchers Andrea Milani, Steven Chesley and Giovanni Valsecchi in Italy, as well the undersigned at JPL, have identified these new impacting possibilities by using new observational data, and by projecting the asteroid's motion somewhat farther into the future than before. New measurements of 1999 AN10, made over the last week and a half by amateur astronomer Frank Zoltowksi in Australia, have allowed astronomers to make significantly more precise orbital calculations, and the revised predictions indicate that the asteroid could approach the Earth particularly closely on August 7, 2027. The orbital motions of the Earth and the asteroid do not permit a collision in 2027, but the close approach will certainly change the asteroid's orbital path. During the past week, researchers have focused on the range of possible paths the asteroid could follow after 2027.

The accompanying diagram shows the uncertainty in the predicted close approach in 2027. The asteroid must pass through the plane of the diagram somewhere within an extremely skinny uncertainty ellipse, which appears simply as a line segment. New measurements taken over the weekend have moved the center of the ellipse (the most likely point of passage) out to a distance of about 200,000 km from the Earth, significantly farther than last week's estimate. The predicted point of passage may continue to bounce around within the ellipse as new data are added, but it cannot decrease below a minimum of about 37,000 km from the Earth's center.

During the 2027 close approach, Earth's gravity will change the asteroid's orbit by an amount which depends on the precise location of the point of passage through the uncertainty ellipse. In particular, a range of post-2027 orbital periods are possible: a passage on the left side of the Earth in this diagram will decrease the orbital period; a passage on the right side will increase the period. If the asteroid passes through certain narrow "keyholes" in the uncertainty ellipse, its changed orbit will bring it back for another Earth close approach in a later year. The 2039 impacting scenario identified by Milani et al. last month actually required passage through two keyholes, one in the 2027 ellipse, and one in the 2034 ellipse, which explains why it was so unlikely (about one chance in a billion using last month's orbital estimate). This week's new observations have now moved the uncertainty ellipse completely off the 2034 keyhole, which indicates that this impacting scenario is no longer possible.

The newly identified impacting possibilities for August 6, 2044 and August 7, 2046 each require passage through only a single keyhole in the 2027 ellipse, and the probabilities of impact for these cases are correspondingly larger, on the order of one chance in 500,000 for 2044, and one chance in five million for 2046. These odds of collision are larger than those for any other object, but they are still less than one hundredth the chance of an undiscovered asteroid of equivalent size striking the Earth sometime before 2044.

In summary, asteroid 1999 AN10 does not pose a serious impact hazard at this time, but observers should continue to monitor its motion over the next few decades, and the chance of impact should be carefully reassessed whenever new data become available.

Paul W. Chodas
Research Scientist
Near Earth Object Program Office
Jet Propulsion Laboratory
May 26, 1999


Sunday, February 25, 2007

Are you Making Plans for August 2027?

According to scientists there is an excellent chance (astronomically speaking, of course!) that we might have a close encounter with a meteor a kilometer-wide that could strike a bulls-eye right here on Terra-Ferma!

That's right, boys, girls (...and sailors), in as little as 20 years we might have our proverbial "Evolutionary PlayStation" reset and have to start over, although that is more likely to happen a few years later in 2039 the results will no doubt be "a smashing success" for the astrophysicists that predicted the event.
Although new evidence released this week predict that the new close encounter date is August 13th 2027 (Yes, that happens to be a Friday too!) Most recent predictions have lowered the odds to 1:45,000 (that's NOT good!)

The Continuing Story Of Asteroid 1999 AN10

New observations are now available for asteroid 1999 AN10, which is gradually moving away from the glare of the Sun. The new data allow a considerably improved orbit to be calculated for this potentially hazardous object, and the revised predictions indicate that this kilometer-size asteroid could pass particularly close to the Earth on August 7, 2027. The passage in 2027 could be as close as 37,000 km from the Earth's center (just 19,000 miles above the Earth's surface), but no closer. The miss distance is still very uncertain, and the asteroid could easily pass well outside the Moon's orbit. The probability of a collision in 2027 is essentially zero.

The accompanying diagram shows the uncertainty in the predicted close approach in 2027. The asteroid must pass through the plane of the diagram somewhere within an extremely elongated uncertainty ellipse, which appears simply as a line segment. (To be precise, the ellipse as drawn is a three-sigma linear confidence boundary.) The center of the ellipse is indicated by the plus sign, which is located at a nominal distance of 58,000 km from the center of the Earth. The minimum distance between the ellipse and the Earth center is 37,000 km.

here is still a very remote possibility that asteroid 1999 AN10 could pass by Earth in 2027 in such a way as to return in the year 2039 on an impacting trajectory. First identified by researchers Andrea Milani, Steven R. Chesley and Giovanni B. Valsecchi, this scenario is still exceedingly unlikely, but the probability of collision in 2039 has now increased to about 1 chance in 10 million. The post-2027 (Monte Carlo) analysis of this object's motion will continue.

Paul W. Chodas
Research Scientist
Near Earth Object Program Office
Jet Propulsion Laboratory
May 18, 1999

...Hey, if you don't believe me, look it up for yourself!

Friday, February 16, 2007

You know someone forgot it!

You know, some things are best remembered, while other things are not. But one thing that everyone seemed to forget was that 25 years ago on January 30th 1982 the last vessel to bear the name BOSTON was commissioned.

That's right folks, we missed a chance at a mini-reunion on the silver anniversary of the commissioning! Perhaps we can have a party in Buffalo April 19th to celebrate the 27th anniversary of the launching!

...Geez, I remember that day like it was yesterday, heading down the ways backwards while standing topside!
THAT was FUN!!!

Thursday, February 08, 2007

Dive! Dive! Dive! As seen from the periscope

Okay, here's something the cruiser never wanted to do!