Risky asteroid 2009 WM1(Nov 2009)

[MeteorWayne]

Re: Risky asteroid 2009 WM1

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.

The primary reference for the Palermo Technical Scale is a scientific paper entitled "Quantifying the risk posed by potential Earth impacts" by Chesley et al. (Icarus 159, 423-432 (2002)).

Quantifying the risk posed by potential Earth impacts
Steven R. Chesley (JPL), Paul W. Chodas (JPL), Andrea Milani (Univ. Pisa), Giovanni B. Valsecchi (IASF-CNR) and Donald K. Yeomans (JPL)
Icarus 159, 423-432 (2002)


ABSTRACT
Predictions of future potential Earth impacts by Near-Earth Objects (NEOs) have become commonplace in recent years, and the rate of these detections is likely to accelerate as asteroid survey efforts continue to mature. In order to conveniently compare and categorize the numerous potential impact solutions being discovered we propose a new hazard scale that will describe the risk posed by a particular potential impact in both absolute and relative terms. To this end we measure each event in two ways, first without any consideration of the event's time proximity or its significance relative to the so-called background threat, and then in the context of the expected risk from other objects over the intervening years until the impact. This approach is designed principally to facilitate communication among astronomers, and it is not intended for public communication of impact risks. The scale characterizes impacts across all impact energies, probabilities and dates, and it is useful, in particular, when dealing with those cases which fall below the threshold of public interest. The scale also reflects the urgency of the situation in a natural way, and thus can guide specialists in assessing the computational and observational effort appropriate for a given situation. In this paper we describe the metrics introduced, and we give numerous examples of their application. This enables us to establish in rough terms the levels at which events become interesting to various parties.

 

[R1]

Re: Risky asteroid 2009 WM1

Had they not discovered Apophis to this day, Apophis would still be part of their so-called background risk ?

 

[MeteorWayne]

Re: Risky asteroid 2009 WM1

I can't say I'm sure how to reply to that. I think I may have the whole Palermo Scale paper on my hard drive somewhere. I'll try and find it tomorrow. A bit too busy today as I am preparing a presentaton on my anuual meteor observations for the NJAA tonight.

 

[bigbadbenny]

Re: Risky asteroid 2009 WM1

Never the less, i'm still polishing my Louisville Slugger! LOL I've always wanted to say that!

 

[rocketmonkey]

Re: Risky asteroid 2009 WM1

MeteorWayne,

Why do you always end your posts like that?

 

[spacechronicles]

Re: Risky asteroid 2009 WM1

I wonder what we could do if a rock of such size is discovered in so little time in advance to be a threat to the earth. Is something the Nasa or another space agency could do in order to protect us? Is there's something prepared to counteratack these dangers? Would be very happy to know about that!

 

[Shpaget]

Re: Risky asteroid 2009 WM1

MeteorWayne,

Why do you always end your posts like that?

It's a signature. He doesn't type it each time he posts.
You can set up your sig here.

bigbadbenny, are you planning on clubbing the asteroid?

 

[robnissen]

Re: Risky asteroid 2009 WM1

What is background risk? Risk of other well known asteroids in the solar system ? Or is it the risk
of that which is unknown ?

I probably shouldn't answer this becuase I am certainly not an expert on this, but I will give you what I believe is the background risk. I'm sure if I'm wrong, MW or others will correct me. I believe the background risk is the risk of the unknown and includes the cumulative risk of unknown large and small objects and their potential for harm. For example, the odds are very low that there is a 1 km object out there that is within earth's orbit and has always been on the sun side of earth when it might have been observed (if it hit the earth the effects would be devastating). But while low, that risk is not zero -- that would be part of the background risk. In addition, the odds are much higher that there are numerous small objects say around 50 meters which might hit the earth. But generally such an object would not cause much devastation, but it is certainly possible that such an object might hit Times Square on New Year's eve, killing thousands. Adding up all the potential posssibilities, which admittedly is at best an educated guess, gives you the background risk.

 

[silylene]

2009 WR52

Now 4 days of data and the cumulative impact odds of 2009 WR52 have increased to 1 / 9090 (JPL Sentry). Many virtual impacts still. Low risk score due to the small size, but the impact odds are relatively high as these things go.

LOL, small size! That's an understatement It's amazing the thing was even detected!

BTW, Close approach (0.0086 AU, 3.3 x LD) was on Nov 17, and was not discovered until 6 days later; not surprising for such a small object.

 

[R1]

Re: Risky asteroid 2009 WM1

The ratings are not intended for the public, I understand. Maybe it's merely to facilitate a
charting of the unknown which rates NEOs in the predetermined scale.


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One thing I'm confused about now is the odds of an impact.

Let's say that there's a 250 meter NEO approaching, and it has impact odds of 1 in 8000.

Does that mean that if we find 8000 of these ( and even if they're not found ! ),
each with the same odds of 1 in 8,000 , the earth
better brace for impact as one of these will indeed collide with the earth ?

 

[MeteorWayne]

Re: Risky asteroid 2009 WM1

No it means 1 of every 8000 possible orbits for this object (that fit the observations) intersect the earth.

 

[MeteorWayne]

Re: Risky asteroid 2009 WM1

{sound of taps playing softly in the distance}

The brief meteoric career of 2009 WM1 is just about over. Now 75 observations over 12 days.
JPL Sentry ahs only one low risk event listed, PS -3.53 in 2032. NEODyS has two lower risk events wth PS lower than -4 in 2067 and 2079.

It was fun while it lasted.

Hopefully, those who followed the thread have a better understanding of how an increasing number of observations and longer observational arc almost always eliminate any substantial impact risk for asteroids.

 

[Astro_Robert]

Re: Risky asteroid 2009 WM1

Someone asked about surveys to detect these smaller bodies prior to potential impacts. There is one just entering pre-operational phase, and others on the books.

Pan-starrs - is a 1.3meter optical scope in Hawaii currently completing checkout and initiating data collection. It has a large field of view for a large scope, and is connected with a 1.4 Giga-pixel camera (currently the world's largest). Ultimately the full Pan-starrs system will/should comprise 4 identical telescopes mounted together that can use different filters on the same patch of sky. I believe this is part of the Congressionally mandated Skyguard survey to detect Earth threatening objects down to 140meters. It has a rather complete homepage if you are interested.
http://pan-starrs.ifa.hawaii.edu/public/

Large Synoptic Survey Telescope is on the drawing board, and would have even greater field of view.

 

[Solifugae]

Re: Risky asteroid 2009 WM1

Goodbye, 2009 WM1. So near, yet so far in the sky. It was not meant to be.

 

[MeteorWayne]

Re: Risky asteroid 2009 WM1

So now we're back to the old top 6 until the next new object comes along:

Object 101955 (1999RQ36) PS-1.12 with 8 impacts beginning in2169
2007 VK184 (a lost asteroid) PS -1.82 with 4 beginning in 2048 (The only Torino Scale 1 object)
153814 (2001 WN5) PS -2.13; 1 potential impact in 2133
99942 Apophis (2004 MN4) PS -2.97; 6 beginning in 2036
1999 WR12 PS -2.99; 121 beginning in 2054
1979 XB PS -3.05; 2 beginning in 2056

 

[MeteorWayne]

Re: Risky asteroid 2009 WM1

Astro_Robert,

Yes as PanSTARRS comes online, it should cause a big shakeup.

As each new systematic survey has come on line over the years the number of discoveries, as well as the depth (i.e. fainter/smaller objects) has increased. Prior to 1997 Spacewatch had most of the discoveries, from 1997-2004 it was Linear, and since then it's been the Cataline Survey with 3 scopes.

It should be interesting to see how the PanSTARRS addition affects the discovery stats, and how many objects show up on the risk list, if the number doesn't break the system

Discovery Stats here:

http://neo.jpl.nasa.gov/stats/

 

[TheMeal]

Re: Risky asteroid 2009 WM1

Hopefully, those who followed the thread have a better understanding of how an increasing number of observations and longer observational arc almost always eliminate any substantial impact risk for asteroids.

Only lurked the thread since the 25th, but appreciated all the effort that went into it, including the historical comparison to other recent asteroids of (temporary) interest. Thanks, folks, for doing what you do and sharing with the rest of us interested parties.

 

[MeteorWayne]

Re: Risky asteroid 2009 WM1

I'm glad you found it interesting. Believe me, it has been as educational for those doing the writing as for those doing the reading!

MW

 

[silylene]

Re: Risky asteroid 2009 WM1

Well 2009 WM1 comes to a safe close.

Fun and games aren't over, let's still watch 2009 WR52 . It has a 1/9000 chance of colliding. Very tiny, would be 'only' a Tunguska size impact. But it is so small, it will be hard to collect enough data to get a good observational arc before it gets too dim to observe. If 2009 WR52 continues to have high odds next observation, I'll start a new thread. The PS and TS scores will never be high unless the collision odds get high, since the object is tiny.

 

[TheMeal]

Re: Risky asteroid 2009 WM1

Astro_Robert,

Yes as PanSTARRS comes online, it should cause a big shakeup.

As each new systematic survey has come on line over the years the number of discoveries, as well as the depth (i.e. fainter/smaller objects) has increased. Prior to 1997 Spacewatch had most of the discoveries, from 1997-2004 it was Linear, and since then it's been the Cataline Survey with 3 scopes.

It should be interesting to see how the PanSTARRS addition affects the discovery stats, and how many objects show up on the risk list, if the number doesn't break the system

Discovery Stats here:

http://neo.jpl.nasa.gov/stats/

If I may be permitted to continue this digression...

Let me focus on large NEOs (defined to be >1km, I believe).

Looking at those discovery data, it would appear that with each new "era" there was not a jump in discoveries (which isn't all that surprising, previous eras were doing a bang-up job of discovering the big stuff). Allowing for a linear approximation of each era gives slopes of
[1995.5 - 1998.0] Spacewatch: +2.11 L-NEOs/half-year
[1998.5 - 2004.0] LINEAR: -0.42 L-NEOs/half-year
[2004.5 - 2009.5] Catalina: -1.40 L-NEOs/half-year

Additionally, in each of those eras, the max-min ranges did not overlap with an adjacent era:
Spacewatch: min: 2, max: 17
LINEAR: min: 27, max: 53
Catalina: min: 10, max: 26

Based on these items (and nothing else!) would it be fair to assume that during the PanSTARRS era there is not going to be a sizable number of L-NEOs discovered? Further, could we put an upper bound on that number of "outstanding" L-NEOs?

I then jumped over to the Harvard PHA list in an effort to determine the largest L-NEOs. From this list, I see the lowest magnitude object was 1990MU at H=+14.1 (which, depending on its albedo, is estimated to be somewhere from 3-9km in diameter). Now I understand normal distributions and their ability to predict maximum values, but based on the upper limit of undiscovered PHAs from the previous paragraph, and given this list of 1079 objects, could we say something about the probability of the largest object which is going to get close to Earth in the next 100 years being, say 5km in size?

Finally, back on the JPL site, I see a bit of discussion about the ramifications of size vs. impact consequences, and I am aware of the damage calculator used earlier in this thread (or maybe the 2009 KK thread, or both!). I also understand that it's a bit of a grey area as to what the damage would be like for an impact into one of our oceans vs. a land-strike, but I was wondering if there's an upper-size limit which is considered to be "game over," for mammalian life. I suppose a lot of it has to do with relative velocity of the impactor, as that term carries much of the energy content of the resulting kersplosion.

I'm not generally very fatalistic, but it's easy to lose motivation for accomplishing work deadlines when thinking in terms of NEOs. :mrgreen:

If my digression is unwelcome, please let me know, and I'll be more apt to bring things up in their own threads in the future.

 

[MeteorWayne]

Re: Risky asteroid 2009 WM1

Not a bad subject for discussion at all.

My expectations are that the PanSTARRS scopes will cause a modest increase in the 1km or greater class (since it will have the ability to regularly sample beyond the ecliptic where many previous searches have concentrated) and cause a huge increase in the number of small (< 1 km, but especially in the < 50 meter size range) asteroids detected.

As for this:

"Looking at those discovery data, it would appear that with each new "era" there was not a jump in discoveries (which isn't all that surprising, previous eras were doing a bang-up job of discovering the big stuff). Allowing for a linear approximation of each era gives slopes of
[1995.5 - 1998.0] Spacewatch: +2.11 L-NEOs/half-year
[1998.5 - 2004.0] LINEAR: -0.42 L-NEOs/half-year
[2004.5 - 2009.5] Catalina: -1.40 L-NEOs/half-year

Additionally, in each of those eras, the max-min ranges did not overlap with an adjacent era:
Spacewatch: min: 2, max: 17
LINEAR: min: 27, max: 53
Catalina: min: 10, max: 26"

I'm not sure exactly what any of these numbers mean. What slopes are you describing in the first part? What are your min/max values describing in the second part? Number of asteroids? Size? It's just not clear to me what you are trying to say here.

re the Harvard survey, what are "L-NEOs"? Large? Again, it's not clear.

 

[TheMeal]

Re: Risky asteroid 2009 WM1

All can be answered with but one image!

(Image blocked for me from work, but maybe not for you...)

 

[NEOMike]

Re: Risky asteroid 2009 WM1

It went from a 1 on the torino scale back down to zero.

 

[MeteorWayne]

Re: Risky asteroid 2009 WM1

Yes, 2 or 3 days ago, when the PS went below -2

BTW, no new observations reported today.

 

[Skeb]

Opportunity with asteroid 2009 WM1(Nov 2009)!!!

We have been reading a lot of information that a step to Mars and the Moon may be instead a trip for humans to visit an asteroid. Hmmm Seems like instead of a threat 2009 WM1 may actually be a big opportunity to accomplish that first step! It swings by close to home for first visits as well as it could be use for a hitch hiking ride to mars or beyond and back. Not to mention it stays just outside the orbit of Venus and within the orbit of Mars.
Sounds pretty neat to have just found an asteroid close at hand that would not only fit the bill for planned trips to asteroids but also make the trip a lot cheaper as it comes home about every year

Skeb