Posted on 12/23/2004 8:24:16 PM PST by hole_n_one
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Thu Dec 23, 5:40 PM ET
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By JOHN ANTCZAK, Associated Press Writer
LOS ANGELES - There's a 1-in-300 chance that a recently discovered asteroid, believed to be about 1,300 feet long, could hit Earth in 2029, a NASA (news - web sites) scientist said Thursday, but he added that the perceived risk probably will be eliminated once astronomers get more detail about its orbit.
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There have been only a limited number of sightings of Asteroid 2004 MN4, which has been given an initial rating of 2 on the 10-point Torino Impact Hazard Scale used by astronomers to predict asteroid or comet impacts, said Donald Yeomans, manager of the Near Earth Object Program at NASA's Jet Propulsion Laboratory in Pasadena.
No previously observed asteroid has been graded higher than 1.
On Friday, April 13, 2029, "we can't yet rule out an Earth impact," Yeomans said. "But the impact probability, as we call it, is 300-to-1 against an impact."
The asteroid was discovered in June and rediscovered this month.
"This is not a problem for anyone and it shouldn't be a concern to anyone, but whenever we post one of these things and ... somebody gets ahold of it, it just gets crazy," he said.
"In the unlikely event that it did hit, it would be quite serious. We're talking either a tsunami if it hit in the ocean, which would be likely, or significant ground damage," Yeomans said.
Its estimated size has been inferred from its brightness, which assumes that its reflectivity is similar to other asteroids that have been observed. At about 1,320 feet in length, it would have about 1,600 megatons of energy, Yeomans said.
Asteroid 2004 MN4 takes less than a year to go all the way around the sun and on each orbit it passes by Earth's orbit twice, Yeomans said. It is also nearly on the same plane as Earth's orbit.
The asteroid will be visible for the next several months and the NEO program has alerted its network of ground-based observers to include 2004 MN4 in their searches.
Yeomans said there have now been about 40 observations, first from the observatory at Kitt Peak, near Tucson, Ariz., and this month from Australia and New Zealand.
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On the Net:
Near-Earth Object Program: http://neo.jpl.nasa.gov
Actually, if you go the NEO website, and look under http://neo.jpl.nasa.gov/risk/doc/sentry.html you'll see that they do.
Not only do they account for the gravity of all planets, they account for the radiation pressure (solar/thermal) and uncertainties in albedo. Apparently the greatest uncertainty in future position is due to the effect of integrated radiation pressure! (One of the proposed schemes for deflecting asteroids is to dust them with talcum powder and modify their albedo! Not as dramatic as a thermonuclear blast, so no Bruce Willis movie, but likely more effective.)
I found it interesting that they use a Monte Carlo technique to assess risk. (Two thumbs way up!) This is expensive and slow and explains why it takes so long to produce results, but it's undoubtedly the most reliable way of making these calculations. [Where I work, we do real time numerical integration to propagate partial low earth orbits. For partial orbits we just use a "J2" (ellipsoidal) Earth gravity model. We propagate uncertainty by propagating the covariance matrix. Not as accurate as their technique. Comparison to "ground truth" indicates that this technique is far more accurate than real time orbital elements. (I.e., uncertainty is due to measurement errors, not model errors.)]
If you go to http://neo.jpl.nasa.gov/cgi-bin/db?name=2004+MN4 they provide an "orbit simulation" model. (You can pan/zoom, propagate and rotate viewing angle. It's way-kewl.) However this applet only propagates a Kelperian orbit, so it's kind worthless for "risk assessment". At the greatest zoom, the orbit of the moon is less than a pixel. It is good for visualization, however.
I couldn't help noticing that this object's orbit shadow's Venus' orbit around Heliocentric longitude 320 degrees (where the Earth is in middle August). You'll see it if you look. It's current orbital period is approximately 41/59 of Venus. If it's orbit were not constantly perturbed by the Earth, I would bet that it would "quickly" (within a few million years) be locked in a 2/3 resonance with Venus. Every time it gets close to the Earth that celestial harmony gets disrupted.
There is a chance that it is in a long term 2/3 resonance with Venus and that the Earth's perturbations merely cause an oscillation around the equilibrium point. Of course, if the asteroid and Earth swap paint at some point in the future, you can cancel the dance, to mix a metaphor. It never gets to close enough to Venus to pose a collision threat.
Dang, the thing is back to zero.
http://neo.jpl.nasa.gov/risk/2004mn4.html
I got a feeling this guy's been around for a long-long time, like +100,000,000 years, that's he's fallen into a long term 2/3 resonance with Venus. (Who hasn't?) Superimposed on the long-term resonance is an aperiodic perturbation due to the the effect of the Earth. In fact, a gravitational encounter with Earth may have been what caused him to be captured by Venus. (Like I said, happens to all of us.)
Of course, I'm not 100 million years old, yet, but the older I get, the harder I have to fight my graviational encounter with Earth.
This is little more than a hunch on my part, but what do I know, I'm just a hopeless romantic.
Gotta keep watching though, it fell to zero once before. The "news" page on the NEO site has an article from the 27th stating that the risk had fallen to zero. Then the number rose again to "1".
http://neo.jpl.nasa.gov/risk/2004mn4.html
The one potential impactor that is known won't reach the rendezvous for about 880 years; they don't have that on the main page of close-call objects, keeping it on a page of its own.
http://neo.jpl.nasa.gov/1950da/
regarding Asteroid 1950 DA:
Asteroid Could Hit in 878 Years
Newsday ^ | 4/4/02 | Paul Recer
Posted on 04/04/2002 10:30:58 AM PST by areafiftyone
http://www.freerepublic.com/focus/f-news/659642/posts
Giant Asteroid May Strike Earth in 2880
The strike may generate tsunamis up to 122 meters high
Pravda ^ | 06/11/03 | Staff Writer
Posted on 06/16/2003 6:55:33 AM PDT by bedolido
http://www.freerepublic.com/focus/f-news/929818/posts
Massive Tsunami Sweeps Atlantic Coast In Asteroid Impact Scenario (Surf's Up)
UC Santa Cruz Press Release ^ | May 27, 2003 | UC Santa Cruz Press Release
Posted on 05/29/2003 9:57:14 AM PDT by Mike Darancette
http://www.freerepublic.com/focus/f-news/919723/posts
Worrying About The Next Big Splash
Casa Grande Dispatch ^ | 11 June 2003 | Alan Levine
Posted on 06/17/2003 8:01:59 AM PDT by Mike Darancette
http://www.freerepublic.com/focus/f-news/930513/posts
Of course, I'm sure those far-sighted ur-o-peens are already on the case, unlike that cowboy, Bush.
Heh... yeah... an MP from Wales was pushing some years back (post SL9, probably circa 1999) for UK funding an NEO search program; US grant-seekers, oops, I mean scientists, started seeking US funding in 1994, right on the heels of those shots from the Hubble showing the blackened impact site, which was bigger than the Earth. :')
Good news! 2004 MN4 is back up to "1" on the Torino scale.
http://neo.jpl.nasa.gov/risk/2004mn4.html
forgot to ping you, 2004 mn4's back to "1".
For all, here's another link:
NeoDYS
http://131.114.72.13/cgi-bin/neodys/neoibo?objects_list:0;main
The Torino number remains at 1, and the number of encounters has gone back up a little, to 16.
Thanks for the email. I'd not noticed anything but April. Looks like there are three different years in which October encounters are projected. Wish now that I'd archived the page. Maybe Google or the Wayback Machine has older versions.
http://neo.jpl.nasa.gov/risk/2004mn4.html
couldn't get this one to do anything. Probably I have disabled Java in the browser.
http://neo.jpl.nasa.gov/cgi-bin/db_shm?des=2004%20MN4
Object range of possible size (m) Date Nominal Dist (km) Min possible distance (km) Max possible distance (km) 2000 EH26 138-314 2190-04-17 897600 2000 SG344 31-69 2069-05-02 1196800 23936000 2002 VX91 38-87 2133-11-02 1331421 2001 BA16 17-37 2191-01-16 1196800 2000 UK11 22-54 2153-11-04 792880 2002 AJ129 530-1200 2172-02-08 1376300 10247454 2001 FR85 29-51 2185-03-19 1196800 2003 YN107 12-27 2065-12-13 1421180 2002 FD6 95-210 2172-04-07 1496000 2002 CU11 508-940 2143-09-02 1077120 1998 KM3 302-680 2149-12-07 1496000 1998 KY26 27-33 2185-06-09 1496000 2001 AV43 27-63 2117-11-23 1300005 2002 AJ129 530-1200 2180-02-08 1346380 2002 GR 59-138 2102-03-22 1481040 2001 AV43 27-63 2029-11-23 1525898 10247453 2004 FU4 530-1200 2189-10-26 284240 2002 PN 29-66 2146-01-29 296203 2003 DW10 16-36 2050-03-02 299195 2004 FU4 530-1200 2122-10-26 762960 26135120 2004 MN4 330-740 2029-04-13 62831 34407 88263 2000 EH26 138-314 2106-04-21 1047200 149600 2393600 (2135) Aristaeus 670-1500 2240-04-02 1196782 224396 7046059 2004 FH 19-45 2070-01-11 373994 239356 3365952 2001 WN5 558-1260 2028-06-26 249828 245340 254316 2000 WO107 330-740 2140-12-01 273764 255812 291715 (85604) 1998 OX4 170-370 2148-01-22 296196 295937 296455 1999 AN10 736-1600 2027-08-07 388960 385968 1998 MZ 366-820 2116-11-26 429645 390450 803340 (7753) 1998 XB 508-1148 2311-12-04 404301 401242 407504 2001 GQ2 250-566 2100-04-27 558008 442816 689656 (2340) Hathor 384-860 2194-10-23 897600 448800 6732000 1998 SC15 348-780 2095-04-09 1196800 448800 3141600 2002 CU11 508-940 2080-08-31 628311 568471 688150 2003 YT1 1000-3000 2148-04-29 682166 589415 2377110 1999 RQ36 178-390 2060-09-22 718080 658240 777920 2003 SR84 25-60 2081-09-28 911051 703109 4241698 2002 LV 1000-3000 2076-08-04 1286541 733029 2468364 1999 VP11 530-1200 2086-10-22 897600 733040 1988 TA 186-410 2053-10-01 1346400 748000 6881600 2002 NN4 260-590 2130-06-07 1047185 762949 2932118 (54509) 2000 PH5 77-174 2104-01-02 787362 787335 787389 1999 FA 210-470 2143-03-07 1136960 807840 1899920 (4660) Nereus 614-1380 2166-02-11 942480 807840 7076080 1999 MN 130-300 2137-06-04 819796 812316 828772 (2340) Hathor 384-860 2086-10-22 861696 837760 911064 2000 LF3 126-288 2046-06-13 1047200 897600 4936800 (35396) 1997 XF11 1000-3000 2028-10-26 930349 929002 931695 1999 DB7 220-494 2048-02-28 976126 974106 978145 (2340) Hathor 384-860 2069-10-21 984368 982872 985864 2002 NY40 348-780 2038-02-11 1090119 1006015 1176736 1999 MN 130-300 2110-06-04 1018761 1011281 1027737 2001 AV43 27-63 2013-11-18 1117346 1019808 1209947 2000 YA 48-115 2011-12-26 1102552 1099560 1614184 2001 AD2 288-650 2133-04-05 1304493 1124975 1539362 1998 HH49 130-300 2023-10-17 1172864 1135464 1211760 2002 PN 29-66 2052-01-30 1331421 1166863 1481018 2004 BL86 420-940 2015-01-26 1346380 1196783 3156515 (4660) Nereus 614-1380 2060-02-14 1198296 1197698 1198894 2000 WO107 330-740 2093-11-30 1288037 1213238 1361134 2003 RM10 230-518 2141-09-04 1219222 1214585 1223860 2002 SY50 1000-2000 2071-10-30 1346380 1241662 1481019 2002 TZ66 18-40 2074-10-05 1510938 1301501 1735335 2001 BF10 81-182 2085-04-28 1458579 1316461 1585737 2002 NN4 260-590 2070-06-06 1522906 1326933 1738327 2003 RU11 20-50 2034-09-17 1455587 1421030 1492388 2000 LB16 420-940 2163-12-14 1585760 1470568 1736856 1999 JU3 316-710 2076-12-06 1561816 1557463 1565990
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2004 MN4
http://neo.jpl.nasa.gov/risk/2004mn4.html
Here are two more; the Near-Earth Objects (United Kingdom) website shows both as needing more observation, and the latter as having been "lost" after its 1997 discovery.
2004 VD17
http://neo.jpl.nasa.gov/risk/2004vd17.html
1997 XR2
http://neo.jpl.nasa.gov/risk/1997xr2.html
Biggest Threat So Far In Most Ways
Posted by Mark Eby on 12/24/2004 7:43:40 AM
http://www.habitablezone.com/space/messages/362407.html
"1997 XR2 is a practically permanent list member because it has not been tracked since 1997 after only 44 days of tracking. 2004 VD17's more specific Palermo scale ranking has been stable for several weeks after a similar period of observation with about 4 times as many individual observations and will probably take long term observation to eliminate from the list."
last few odds and ends:
Orbit for Hermes Dynamically Linked from 1937 to 2003
Steven R. Chesley
Paul W. Chodas
NASA's Near Earth Object Program Office
October 16, 2003
http://neo.jpl.nasa.gov/news/news140.html
"We now know that since it was last seen, Hermes has made eight close approaches to the Earth and Venus to within 0.06 AU, including an Earth approach to within about 1.6 lunar distances in 1942. The new orbit solution allows us to predict future close approaches with great accuracy; we can now predict that Hermes will not approach the Earth any closer than about 0.02 AU (8 lunar distances) within the next hundred years."
The Curious Tale of Asteroid Hermes
Author: Dr. Tony Phillips
http://science.nasa.gov/headlines/y2003/31oct_hermes.htm
"Hermes, it turns out, is a double asteroid--two space rocks orbiting one another, each about 400 meters across. No one knows how Hermes came to be this way. Margot and colleagues hope to learn more when the asteroid passes by on Nov. 4th as they continue their observations using both Arecibo and NASA's Goldstone radar."
still Torino 1; impact probability 3.7e-05; number of encounters from 2044 to 2103 is eleven.
http://neo.jpl.nasa.gov/risk/2004mn4.html
oldie topic:
Large Earth-Crossing Asteroid Found
News/Current Events News
Source: Astronomy.com
Published: 8/01 Author: Vanessa Thomas
Posted on 08/21/2001 14:42:10 PDT by Joe Hadenuf
http://www.freerepublic.com/forum/a3b82d5b20f51.htm
overall risk is 1:20000; closest approach, 1:26000. :') Here's a page from Italy:
http://131.114.72.13/cgi-bin/neodys/neoibo?riskpage:0;main
"More than 200 new observations of 2004 MN4 were obtained in the last 5 days. The discovery observations of June have been painfully remeasured, the impact monitoring computer programs have been run more than 30 times. Finally today some prediscovery observations from March 2004 were found and extracted from the archives of the Spacewatch survey. These allowed to extend significantly the observations time span, thus the confidence region for the orbital elements was sharply reduced and many impacts compatible with the previous data turned out to be incompatible with the extended observations.
"However, given the current knowledge of the orbit, we cannot yet exclude that there could be an impact at a later date, e.g., in 2044 and 2053. We have every expectation that further monitoring and further analysis on this object will entirely eliminate its potential hazard."
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