INCOMING!, Detection and observation of Earth-approaching asteroids. |
INCOMING!, Detection and observation of Earth-approaching asteroids. |
Oct 20 2013, 09:38 PM
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#301
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Senior Member Group: Members Posts: 1627 Joined: 5-March 05 From: Boulder, CO Member No.: 184 |
I think I've seen this pattern before where the probability goes up to a peak, then goes down to zero. We'll see if this plays out and what the peak is.
-------------------- Steve [ my home page and planetary maps page ]
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Oct 20 2013, 10:27 PM
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#302
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Member Group: Members Posts: 593 Joined: 20-April 05 Member No.: 279 |
As long as the moving probability peak itself peaks before 2032, we'll be fine!
This time. Andy |
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Oct 21 2013, 12:58 AM
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#303
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Merciless Robot Group: Admin Posts: 8783 Joined: 8-December 05 From: Los Angeles Member No.: 602 |
Yeah. I'm definitely not gonna buy my Wile E. Coyote little 1890s parasol just yet...
-------------------- A few will take this knowledge and use this power of a dream realized as a force for change, an impetus for further discovery to make less ancient dreams real.
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Oct 21 2013, 02:31 AM
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#304
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Senior Member Group: Members Posts: 2081 Joined: 13-February 10 From: Ontario Member No.: 5221 |
Yep, here's a picture from Wikipedia's Apophis page showing what's (hopefully) going on: http://en.wikipedia.org/wiki/File:Apophis_ellipse.svg
We're not in the bulls-eye I trust.... |
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Oct 21 2013, 10:43 AM
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#305
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Senior Member Group: Members Posts: 2492 Joined: 15-January 05 From: center Italy Member No.: 150 |
I think I've seen this pattern before where the probability goes up to a peak, then goes down to zero. We'll see if this plays out and what the peak is. Indeed, I recall that, 9 years ago, Apophis chances for 2029 impact rised to a scaring 2.7% in few hours before to drop to "0" thanks to recovery of older observations... in this case, we probably should go back to images collected to last 2013 TV135 close approach, dated 1990... UPDATE: now probability is decreasing in both sources (1:19000 for JPL and 1:8400 for NEODys) -------------------- I always think before posting! - Marco -
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Oct 22 2013, 04:14 PM
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#306
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Senior Member Group: Members Posts: 2346 Joined: 7-December 12 Member No.: 6780 |
What you never wanted to know: How to calculate impact probabilities. May be with the exception of the first few pages .
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Oct 22 2013, 05:04 PM
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#307
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Senior Member Group: Members Posts: 2492 Joined: 15-January 05 From: center Italy Member No.: 150 |
Thanks Gerald, very interesting article!
PS: meanwhile, impact chances are going to "stabilize" around 1:16000 (JPL) and 1:8000 (NEODys) -------------------- I always think before posting! - Marco -
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Oct 23 2013, 04:24 PM
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#308
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Member Group: Members Posts: 723 Joined: 13-June 04 Member No.: 82 |
Current estimated odds:
NEODyS 1:5076 on 220 optical observations NASA/JPL 1:10000 on 220 optical observations The probability of impact is still increasing (although it is still quite low). Both calculations indicate a closest approach of 65% of the Earth's radius ( ), but I assume with a much larger error ellipse. |
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Oct 23 2013, 06:32 PM
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#309
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Senior Member Group: Members Posts: 2346 Joined: 7-December 12 Member No.: 6780 |
... a closest approach of 65% of the Earth's radius ... ... to the geocenter, means the LOV intersects with Earth, with a 66%-error below 0.1 Earth radii. Excerpt of the NASA/JPL legend: QUOTE Distance The minimum distance on the target plane (scaled b-plane) from the LOV to the geocenter ... So it looks to me like a matter of timing. The amount of the sigma value is again below 1, that's a bit surprising after it had been above 1. Edit: Timing uncertainty (1 sigma) adds up to about 24.6 days, at the moment, from now to end of august, 2032 (18.8 years). Calculated from orbital data: 24.6 days = 18.8 years * 5 days uncertainty / 3.82 years |
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Oct 24 2013, 08:29 PM
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#310
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Member Group: Members Posts: 723 Joined: 13-June 04 Member No.: 82 |
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Oct 25 2013, 01:27 PM
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#311
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Senior Member Group: Members Posts: 2346 Joined: 7-December 12 Member No.: 6780 |
Based on 304 optical observations (of 307) NEODyS calculates the risk to about 11% of the background risk.
(The current value of -0.95 on the Palermo scale (PS) means 10-0.95 = 0.112 of the background risk.) |
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Oct 25 2013, 04:11 PM
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#312
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Senior Member Group: Members Posts: 2492 Joined: 15-January 05 From: center Italy Member No.: 150 |
(The current value of -0.95 on the Palermo scale (PS) means 10-0.95 = 0.112 of the background risk.) I would like to add that background probability refers to the 19 years time frame from now to the potential impact; in other words, until 2032, we should have 0.09% chance that an asteroid with same impact energy potential will actually hit the Earth; now, if we divide the estimated 2013 TV135 impact probability by this number, we obtain the "relative risk" factor discussed by Gerald (I know, it's a bit complicated... this is the reason why they created also a "Torino scale" for large audience!). PS: meanwhile, the JPL impact probability has halved to 1:21000 and the asteroid isn't the highest in the Palermo scale anymore! -------------------- I always think before posting! - Marco -
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Oct 25 2013, 08:01 PM
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#313
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Junior Member Group: Members Posts: 59 Joined: 4-July 08 Member No.: 4251 |
Hello all -
As I'm sure many of you all know, back in April 2013 the third annual Planetary Defense Conference was held in Flagstaff AZ. After the conference ended I watched ALL the session videos (some 20 hours) that they'd put up on Livestream. The presentations were fantastic! I'll link to them here: All 15 videos: http://www.livestream.com/pdc2013/folder Example direct link to an individual video: http://www.livestream.com/pdc2013/video?cl...21-384cb8db9ac1 Also, some public events occurred as part of the conference: http://www.youtube.com/results?search_quer...ense+conference Three weeks ago, NASA held a multi-day "Asteroid Initiative Workshop". The sessions from the first day appeared on Youtube: http://www.youtube.com/watch?v=UJRJyljzwTA http://www.youtube.com/watch?v=INBt1iLJk_Q http://www.youtube.com/watch?v=tGhXcGztpI8 * http://www.youtube.com/watch?v=Xoqesv4Cm68 * my personal favorite presentation is in this one, at the 27m30s point So, my question is this ... The four Youtube links immediately above are just from the FIRST DAY of the conference. Nothing further has been posted. Where is the rest of the workshop? It was supposed to last 3-4 days. As I was collecting links together for purposes of this post, I went to the NASA AIW website: http://www.nasa.gov/content/asteroid-initi...thesis-workshop ... and found that the workshop actually had to shut down after the first day due to ... the federal government shutdown! Riiiight, of course, the first day was on Sept 30th, just before the shutdown. The workshop has now been rescheduled for Nov 20-22. I came in here to ask if anyone knew about the remaining session videos, and in the process of writing this I've answered my own question. So, I'll let this post stand as a recommendation. If you are really interested in this topic, then watch the above videos! The first set of videos in particular, from PDC 2013, represent an EXCELLENT overview of asteroid science and technology, from detection to characterization to mitigation. |
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Oct 27 2013, 04:49 PM
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#314
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Senior Member Group: Members Posts: 2492 Joined: 15-January 05 From: center Italy Member No.: 150 |
Going back a moment to 2013 TV135, I made a set of plots showing evolution of risk indicators and other useful reported figures, included 1-sigma uncertain of some orbital coefficients:
Last update: Oct,29 - 13.30 UT Edit: in the "Palermo scale" plot I added 2007 VK184 level (it's the other asteroid now classified 1 in the Torino scale) Note: on Oct,29 the Palermo classification from NEODys is back above -1 (impact probability 1:10600) -------------------- I always think before posting! - Marco -
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Oct 29 2013, 09:14 PM
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#315
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Member Group: Members Posts: 723 Joined: 13-June 04 Member No.: 82 |
Note: on Oct,29 the Palermo classification from NEODys is back above -1 (impact probability 1:10600) I was not expecting that. I had thought that the impact probability would continue to decline toward zero as the error ellipse shrinks. I assume that its calculated time of closest approach to the geocenter continues to approach the time that the Earth occupies that point in the geocenter. |
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