Asteroid 153814 2001 WN5 observed again

[MeteorWayne]

The object with the highest event Palermo Scale rank has been observed again. (101955 1999 RQ36 has a higher cumulative risk of -1.12 for it's 8 impacts from 2169-2199, the highest event PS is -1.52)

PS is - 1.18 for a single potential impact in 2133. 1 in 10,000 chance of impact on June 28, 2133.

This is a 780 meter sized object.

It now has a 14.00 year observational arc!!!! From Feb 10 1996 to Feb 11 2010. (5115 days, with 119 observations)

http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=1 ... ;cad=1#cad

MW

 

[silylene]

Re: 153814 2001 WN5 observed again

WN5: Long time no see!

That is a pretty high risk for an object with such a long observational arc. I was rather surprised the Torino Scale is "N/A" for an object with a 1/10,000 chance and a high PS, and a long observational ARC. Is the Torino Scale "N/A" for everything over 100 years from today?

 

[MeteorWayne]

Re: 153814 2001 WN5 observed again

Yes, that correct. The Torino scale only covers a century into the future.

 

[SpaceTas]

Re: 153814 2001 WN5 observed again

The 1/10,000 risk is co-incidently the risk NASA uses as the threshold for mandating a controlled re-entry of a large satellite.
but here it is for a single fatality. eg Compton Gamma-Ray Observatory (see http://www.americanscientist.org/issues/pub/requiem-for-a-great-observatory)

 

[silylene]

Re: 153814 2001 WN5 observed again

Yes, but if satellite pieces crash down on earth (1/10,000 chance of striking anyone on earth), at most a handful of people would die. 1/10,000 chance of killing someone.

But if asteroid 2001 WN5 crashes down on earth (1/10,000 chance of striking our planet), perhaps hundreds of thousands of people might die. For sake of argument, assume 10,000 people die from the resultant tsunami. 1/1 chance of killing someone. Much worse odds!

 

[SpaceTas]

That was my sideways point! The consequences of an asteroid strike are so much higher. In this case the odds are already equivalent to what NASA has considered an unacceptable risk. I suppose more notice would be paid if the possible impact was to be sooner.

But I will have to argue with your use of probabilities.

Even the consequences are higher the chance of someone or anyone being killed by 153814 2001 WNS is still 1 in 10,000.
But the odds of a particular person being killed will scale with expected casualties.
eg. a satellite may only be able to kill one person so the odds of me (say) being hit 1 in 10,000 x ( population of Earth / 1 casualty me)

but if an asteroid can say wipe out the 1/2 population of earth then my (or yours or any particular person) odds are: 1 in 10,000 x 2

or if the it could kill everybody then my odds would revert to those of an impact ie. 1:10,000

 

[MeteorWayne]

There's an even higher risk of impact asteroid than this, 101955 1999 RQ36 . It has a 1 in 1410 chance of impact cumulatively among 8 virtual impactors between 2169 and 2199, with the highest of them (~ 1 in 3570) in 2182. It hasn't been observed since 2006.

Preprint Abstract: http://arxiv.org/abs/0901.3631

These two asteroids were selected for special examination beyond the 100 year time period that Sentry normally looks at due to the potentil for high risk.

 

[silylene]

New data in and analyzed, arc = 5122 days...
JPL Sentry PS = -1.30 cum, -1.30 max
Neodys PS = -1.18 cum, -1.18 max

 

[MeteorWayne]

Interesting. The difference between the two is the discarded obsevations. JPL Sentry has 121 obs, NEODys 125 (with 7 rejected, so I assume only 4 are rejected by Sentry) , with the same arc and the same last observation.

 

[silylene]

New Data, risk decreased substantially. The risk is almost at the threshhold for Torino Scale 1...but it is still PS = 0.

153814 2001 WN5 JPL Sentry 0513
risk year 2133 single encounter
probability = 1.3e-05 (1 in 77,000)
Palermo Scale = -2.07

JPL: "Analysis based on 124 observations spanning 5138.0 days (1996-Feb-10.39593 to 2010-Mar-06.399287)." Diameter approximately 0.770 km. from mean, weighted H=18.2.

 

[silylene]

Neodys maintains a higher risk factor:

153814 2001 WN5 NEODyS

2106-2133 6 encounters
probability = 3.01e-05 (1 in 33,000)
Palermo scale -1.72 (cum) -1.73 (max)

NEODyS: "Based on 128 optical observations (of which 7 are rejected as outliers) from 1996/02/10.397 to 2010/03/06.400."

 

[silylene]

Now, just a little less risky, Torino Scale 0

153814 2001 WN5 NEODyS

2106-2133 5 encounters
probability = 2.42e-05
Palermo scale -1.81 (cum) -1.82 (max)

NEODyS: "Based on 131 optical observations (of which 7 are rejected as outliers) from 1996/02/10.397 to 2010/03/18.455."

 

[Smersh]

Re: 153814 2001 WN5 observed again

The 1/10,000 risk is co-incidently the risk NASA uses as the threshold for mandating a controlled re-entry of a large satellite.
but here it is for a single fatality. eg Compton Gamma-Ray Observatory (see http://www.americanscientist.org/issues/pub/requiem-for-a-great-observatory)

Yes, but if satellite pieces crash down on earth (1/10,000 chance of striking anyone on earth), at most a handful of people would die. 1/10,000 chance of killing someone.

But if asteroid 2001 WN5 crashes down on earth (1/10,000 chance of striking our planet), perhaps hundreds of thousands of people might die. For sake of argument, assume 10,000 people die from the resultant tsunami. 1/1 chance of killing someone. Much worse odds!

Hmmm ... I thought the 1/10,000 odds (or 1/77,000 then 1/33,000 as in latest estimates) were of the object impacting with Earth, aren't they, regardless of how many fatalities an impact might cause? Are those odds in fact the chances of the object killing one person? (Which would surely shorten the odds referring to an impact alone,) or does it mean 1 in 10,000 chance of impact in the first place, then 1 in 10,000 chance of causing one fatality if it does hit?

 

[MeteorWayne]

The odds are for an earth impact

 

[Smersh]

Thanks Wayne - I thought that was the case but was getting confused when I read the other posts!

 

[silylene]

New data in, odds of impact greatly reduced. NeoDYS gives the new cumulative PS = -3.56 (5 solutions)

 

[jmdc619]

Ok so I don't know anything about space but my husband says an asteroid is going to end life as we know it. Is this the one or is there one coming sooner? You guys definately look like you know what you are talking about. Please don't make fun of me I'm just genuinely concerned about some articles I have seen on BBC.com and CNN.com.

 

[MeteorWayne]

Welcome to Space.com.

There is no known asteroid with more than a 1 in 77,000 chance of hitting earth in the next 40 years, and that is a newly discovered one (2010 JU39...see the thread I just started)

The highest risk asteroid is 101955 (1999 RQ36) with a 1 in 3750 chance of impact in the year 2182...that's 172 years from now.

There is always a risk from an undiscovered asteroid sneaking up and hitting us. But if what he's heard is that something is definately going to hit us, it is just plain wrong, and probably part of the 2012 hype.

There's a topic in the Unexplained forum about that.

Wayne

 

[Woggles]

Welcome jmdc619

I'm not an expert in this field. Many people here will give you correct information. I came across a web site that you may find interesting. It is a bit dated but still good info.

http://starchild.gsfc.nasa.gov/docs/Sta ... ion11.html

 

[MeteorWayne]

I need to correct myself. There is one "lost" asteroid, 2007 VK 184 which has a 1 in 3030 chance of impact in the year 2048 (June 3, to be precise). It's not very big (~130 meters dia.), big enough to cause major problems, though not big enough to "end life as we know it". Unfortunately, it has not been observed since January 2008, though if the orbit is correct, it could have been, though it would have been difficult. If the orbit is correct, we should recover it (be able to observe it again)in 2014 with excellent observing conditions, with 34 years to take action if needed.

Wayne

 

[MeteorWayne]

BTW, 2010 JU39 and 2007 VK 184 are both Torino Scale 1, which means:

"A routine discovery in which a pass near the Earth is predicted that poses no unusual level of danger. Current calculations show the chance of collision is extremely unlikely with no cause for public attention or public concern. New telescopic observations very likely will lead to re-assignment to Level 0. "

They are the only 2 Torino Scale 1 objects. All other known asteroids are TS 0.

Level 0 is:

"The likelihood of a collision is zero, or is so low as to be effectively zero. Also applies to small objects such as meteors and bodies that burn up in the atmosphere as well as infrequent meteorite falls that rarely cause damage. "

MW