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A Rock Moves In Space
theBrownfury writes: "The BBC is reporting here that
a very large Earth collision course asteroid has been discovered. This asteroid, NT7,
was first observed on July 5th and current data suggests an impact date of
February 1st, 2019. NT7 is 2kms wide and on date of impact will be approaching
Earth at 28km/s. An asteroid of this size is large enough to cause continent
wide destruction. However astronomers are still cautious in reporting this
asteroid as the orbit of NT7 has not been fully verified. Current data on
NT7's orbit suggests it orbits the Sun every 837 days and travels in a tilted
orbit from about the distance of Mars to just within the Earth's orbit." The BBC article's headline (and accompanying illustration) are more alarming than the story itself seems to warrant: this asteroid has been given a 0.06 on the Palermo technical scale, which means it shouldn't bump getting run over by a llama off your list of worries.
The most important words in the article (well maybe they weren't actually there, but I paraphrase): More data needed. There is still a huge margin of error in the calculation of the asteroid's orbit. It just might hit Earth at this point.
2002 NT7 Impact Risk
It doesn't look so bad. -0.14 on the Palermo Scale (recently downgraded?).
It was first seen on the night of 5 July, picked up by the Linear Observatory's automated sky survey programme in New Mexico, in the southern US.
I work at Lincoln labs and acutally know the people running the LINEAR project (they are so proud that they are the best in the world, let me tell you). But for the rest of you, here is their website.
They find more than half of the new NEO (Near earth orbit) asteroids each year that are found. They have a telescope down in New Mexico and have the largest CCD (2560x1960 res) in the market. That's the thing that takes a digital image of the sky and compares it to past images to see if any "stars" have moved...i.e asteroid. The higher resolution you can get, the further out you can see. From their webpage, you can see they have found at least 951 NEO's. So there are a LOT of asteroids comming near us. But in space, near is still very far away. So unpack those bunkers and return to Real Life, we're still safe for a while. Also, the rate of finding new NEO's is decreasing, so that means that we've (humans) found most of the asteroids that can endanger us.
(most of that was taken from this post of mine from a while ago)
http://neo.jpl.nasa.gov/risk/doc/palermo.html
That should help a tiny bit
Visit www.seriouslythough.com
In case you're wondering what this means (and I was):
The Palermo Technical Impact Hazard Scale was developed to enable NEO specialists to categorize and prioritize potential impact risks spanning a wide range of impact dates, energies and probabilities. Actual scale values less than -2 reflect events for which there are no likely consequences, while Palermo Scale values between -2 and 0 indicate situations that merit careful monitoring. Potential impacts with positive Palermo Scale values will generally indicate situations that merit some level of concern.
The scale compares the likelihood of the detected potential impact with the average risk posed by objects of the same size or larger over the years until the date of the potential impact. This average risk from random impacts is known as the background risk. For convenience the scale is logarithmic, so, for examples, a Palermo Scale value of -2 indicates that the detected potential impact event is only 1% as likely as a random background event occurring in the intervening years, a value of zero indicates that the single event is just as threatening as the background hazard, and a value of +2 indicates an event that is 100 times more likely than a background impact by an object at least as large before the date of the potential impact in question.
Taken from NASA: http://neo.jpl.nasa.gov/risk/doc/palermo.html
"If at first you don't succeed, lower your standards."
So, the palermo value of 0.06 (p is just greater than one) means we are very, very slightly more likely to get hit by NT7 than we are to get hit by another astreroid of equal or greater size before 2019.
2002-NT7 was discovered 9-Jul-2002
There have been 102 observations (as of 8 hour ago) up thru 22-Jul-2002
Radar images show that the object is between 2 and 2.1km in size. The mass is about 1.1e13 Kg. This is somewhat light for an asteroid of this size. This suggests that it may belong to the "pile of compressed rock" set as opposed the more solid "iron chunk" types.
Impact speed is high, about 28.5 km/s. This speed is due to the nearly "head on" approaches for most of the close approaches.
There is too little data and some of the observations may suffer from systematic errors. So over the next week or two the odds of impacting will change.
Currently the odds of being hit by 2002-NT7 is about 1 in 100,000. The problem comes from how Earth deflects it during some of its close-by approaches.
The orbit of 2002-NT7 takes about 837 days. The path takes out as far as Mars and just inside Earth's orbit.
Close approach dates are:
The odds, given the current limited observations, of impacting us 2019 thru 2051 are slim. The real problems show up in the 2060 and every 7 years after that. Small changes due to the close passes in 2019 thru 2051 make it hard to pin down later on.
If this rock hits the earth then our way of life as we know it would surely end. Such an impact would be on par (but somewhat less) with the impact that ended the Dinosaurs 65 million years ago.
It is not known where on earth it might impact. Too early to tell. Not that is matters for a rock of this size ... anyway on early
will suffer sooner or slightly later.
Looking at the raw data: when one tosses out one set data (all from the same source) that seems to have a systematic error: then things get worse. That is, the limited data minus this one source suggests that the odds of being impacted on or after 2060 are much more likely. But again, more independent observations are needed before one can say all this with more certainty.
IMHO: 2002-NT7 does not have much of a chance to hit us before 2060. From 2060 on, things get really ugly.
Stay tuned ...
chongo (was here)
The KT event asteroid that hit 65 million years and formed the Chicxulub crater ago was almost certainly larger. Estimates of that impactor have ranged from 4km to 18km in diameter with more recent evidence suggesting that the smaller size estimates may be more accurate. Others prefer the larger sizes. Even if they are correct and the KT-impactor was on the larger end of the scale, an impact of a 2km asteroid is no trivial matter.
Assuming the same density, the ~2km 2002-NT7 has about 1/8th the mass of KT impactor. Perhaps 1/10th the mass if 2002-NT7 turns out to be a lower than average density asteroid.
When I said:
I should have said:
I want to repeat that the chance of impact prior to 2060, based on the current limited set of observations, is slim (1 in ~100,000 more).
The chance of an 2002-NT7 impact after 2060 is uncertain. It is hard to estimate the location of 2002-NT7 on/after 2060 in part because of the 4 prior close approaches and in part because positions become more uncertain as time goes on.
It is common to consider asteroid positions 100 years or more in the future to uncertain enough as to not be useful to estimate impact risk. This 100 year uncertainty limit gets shorter when one throws in 1 or more close approaches.
While 2002-NT7's orbit position will become better defined with additional data, the risk assessment of the 2060 pass (and beyond) will remain more uncertain for some time. Time (and more accurate observations) will tell how much the next generations will have to worry or not about 2002-NT7.
IMHO, there is nil chance of an impact by 2002-NT7 before 2060. The trend / perturbations on 2002-NT7 suggest that things could get ugly later on. Monitoring of 2002-NT7 over time, plus improved orbit models will tell how much future generations will need to worry about an impact >= 2060.
chongo (was here)
Near hit.
If you nearly miss something, you've come close to missing it, therefore, you've hit it.
If you nearly hit someone, you've come close to hitting it.
GAAH..
Thank you George Carlin, for making me notice that everytime someone says it.