Merged Apophis Topics

[MeteorWayne]

In fact there are close encounters (relatively close) with another asteroid or two that could affect it's trajectory.<br /><br />The paper listed above is interesting (but brain hurting) reading.<br /><br />Without observations from Arecibo in 2013, it would be too dangerous to attempt to do anything to try and deflect Apophis, or it could make things worse. <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[silylene old]

<p>Apparently the calculation on 2004MN4 Apophis don't include enough critical factors to understand the odds at predicting a collision in 2036.&nbsp; Namely, the trajectory calculation have not taken into account the earth's deviation from sphericity, nor have they taken into account the rotational rate of Apophis.</p><p>Also note how important Arecibo is to understanding the risk from this close-approach asteroid.</p><p>&nbsp;</p><div id="artHead" class="floatleft"><h2 class="inline">Killer asteroid predictions 'off by millions of miles'</h2><ul class="notlist straptext"><li>15 July 2008 </li><li>From New Scientist Print Edition. <font color="#000000">Subscribe</font> and get 4 free issues. </li><li>David Shiga </li></ul></div><div id="artToolsTop" class="floatright"><div class="artTools">http://space.newscientist.com/article/mg19926643.500 </div></div><div id="artBody"><p>YOU'D think that by now we'd have a firm grip on the trajectory of the solar system's most worrisome chunk of rock. In fact we have only a hazy understanding of how likely the asteroid Apophis is to strike Earth. What's more, budget cuts may shut down the telescope that could clarify the situation.</p><p>Since Apophis was discovered in 2004, asteroid-watchers have known that it has a slim chance of hitting Earth in 2036. At 270 metres wide, it is too small to rival the object that wiped out the dinosaurs, but it could cause devastating tsunamis were it to hit the ocean. Worrying as this is, we have been able to take comfort in the computed probability of impact, which is just 1 in 45,000.</p><p>Now it seems the true risk is unclear, thanks to minute effects that the calculations didn't take into account. "You really can't estimate the probability because it's driven by these unknown physical parameters," says Jon Giorgini of the Near-Earth Object Program at NASA's Jet Propulsion Laboratory in Pasadena, California.</p><p>Whether Apophis ends up on a collision course with Earth depends on what happens during a close encounter between Apophis and our planet in 2029. During this swingby, the Earth's gravity could alter the asteroid's path enough to put it on a collision course with us when its orbit brings it back in 2036.</p><div class="artquote">&ldquo;Whether Apophis ends up on a collision course with Earth depends on a close encounter between them in 2029&rdquo;</div><p>One problem, says Giorgini, is that our calculations do not include effects arising from the fact that Earth is not a perfect sphere. This slightly alters its gravitational field and could make a difference to the asteroid's path when it swings close to Earth.</p><p>Yet the most powerful steer could come from the way the sunlit asteroid radiates heat, says Giorgini. Radiation gives rise to a small thrust, and since warmer areas of the asteroid radiate more than cooler ones, there is a net force on the asteroid. This phenomenon - the Yarkovsky effect - means our calculations of Apophis's path could be out by millions of kilometres, according to Giorgini, who will present his results at the Asteroid, Comets, and Meteors conference in Baltimore, Maryland, on 17 July.</p><p>Unfortunately, we can include this effect only if we know how Apophis spins, which has so far been impossible to measure. <strong><font color="#ff0000">There will be a chance to do so with the 305-metre Arecibo radio telescope in Puerto Rico when Apophis comes within a few million kilometres of Earth in 2013.</font></strong> The observations made then may even lengthen the odds of an impact and show that the effects highlighted by Giorgini won't matter.</p><p>Yet the US National Science Foundation is considering cancelling the funding for Arecibo. Ironically, shutting down the telescope might require sending an expensive space mission to orbit the asteroid so it can be tracked. The US House of Representatives has directed NASA to plan such a mission, in a bill now awaiting Senate approval.</p><p>Alan Harris of the Space Science Institute in La Canada, California, says watching Apophis will reveal much about the limitations of our calculations of asteroid motion. He adds that the vast majority of asteroids that could present a risk to Earth have not been seen, and that one of these is much more likely to strike us before 2036.</p></div> <div class="Discussion_UserSignature"> <div class="Discussion_UserSignature" align="center"><em><font color="#0000ff">- - - - - - - - - - - - - - - - - - - - - -</font></em> </div><div class="Discussion_UserSignature" align="center"><font color="#0000ff"><em>I really, really, really miss the "first unread post" function.</em></font> </div> </div>

 

[silylene old]

<p>ps.&nbsp; I hate this old original thread title.&nbsp; The danger is in 2036, not 2029.</p> <div class="Discussion_UserSignature"> <div class="Discussion_UserSignature" align="center"><em><font color="#0000ff">- - - - - - - - - - - - - - - - - - - - - -</font></em> </div><div class="Discussion_UserSignature" align="center"><font color="#0000ff"><em>I really, really, really miss the "first unread post" function.</em></font> </div> </div>

 

[MeteorWayne]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>ps.&nbsp; I hate this old original thread title.&nbsp; The danger is in 2036, not 2029. <br />Posted by silylene</DIV><br /><br />I don't suppose the Mods have the power to edit a thread title...</p><p>Naahhhh, it's pluck after all.</p><p>Question: Can Moderators edit thread titles?</p><p>Answer: That feature is not available on Pluck system.</p><p>sigh...</p><p>&nbsp;</p><p>Perhaps the solution is to start a "Save Arecibo" thread? Are you up for it?</p> <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[DrRocket]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>But "only" 400 megatons? That is not enough for global "doomsday"/extinction type scenarios. Probably not even regional devastation unless it hit in water and created a tsunami. It would be extremely bad for the city or area that was hit (and could create a huge tsunami), so I'm not saying that it's not a serious threat, but it's not a real "end of the world" doomsday rock then. For some perspective on this, in October 30, 1961, the Soviet Union tested the "Tsar Bomba", a fusion bomb with a yield of 50 megtons. But maybe an impact would be worse "per megaton" than a nuclear explosion? <br />Posted by rfoshaug</DIV></p><p>400 megatons, with no nuclear fallout might not be as bad as you think.&nbsp; The 2004 Indian Ocean earthquake that created the tsunami was close to 1000 megatons.</p><p><br />http://www.projectrho.com/rocket/rocket3x.html#boom</p> <div class="Discussion_UserSignature"> </div>

 

[MeteorWayne]

Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>400 megatons, with no nuclear fallout might not be as bad as you think.&nbsp; The 2004 Indian Ocean earthquake that created the tsunami was close to 1000 megatons.http://www.projectrho.com/rocket/rocket3x.html#boom <br />Posted by DrRocket</DIV><br /><br />Yeah, it only killed a quarter million people....chump change..... <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[DrRocket]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Yeah, it only killed a quarter million people....chump change..... <br />Posted by MeteorWayne</DIV></p><p>Not chump change.&nbsp; But not global total annihilation either.</p> <div class="Discussion_UserSignature"> </div>

 

[MeteorWayne]

Re: Apophis risk. New trajectory analysis based on Arecibo data

News on Apophis...a lesser threat:

http://www.space.com/scienceastronomy/0 ... azard.html

"The large asteroid Apophis poses less of a threat of walloping the Earth in the year 2036 than previously thought, new research finds.


The Apophis asteroid, discovered in 2004, is larger than two football fields in size and has captured the space rock limelight in recent years because of its potential to hit Earth in the relatively near future.


The asteroid would not cause a global catastrophe, but could likely spawn significant regional devastation if it were ever to strike the planet, scientists have said.


Now, new data from observations made with the University of Hawaii's 88-inch telescope near the summit of Mauna Kea have allowed astronomers to recalculate the space rock's orbital path. Fortunately for us, the new path indicates that the asteroid is less likely to smack Earth.

 

[MeteorWayne]

Just for reference, here's the JPL Sentry page on Apophis. I'm not sure, but I do not believe this includes the new telescopic observations, though I am not sure, since the article doesn't state when they were made. The latest observations included are from January 2008.

Apophis is the 4th highest risk asteroid on the JPL Sentry list.

http://neo.jpl.nasa.gov/risk/a99942.html

Here's the small body data base page with orbit diagram:

http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=99942;orb=1



Torino Scale (maximum) 0
Palermo Scale (maximum) -3.08
Palermo Scale (cumulative) -2.97
Impact Probability (cumulative) 7.4e-06
Number of Potential Impacts 6


Analysis based on 2 radar delay, 5 Doppler, and
633 optical observations spanning 1395.6 days
(2004-Mar-15.10789 to 2008-Jan-09.665088)

The 6 potential impacts are from 2036 to 2103 CE

Here's the statement from the NEODyS team:

The asteroid (99942) Apophis (previously designated as 2004 MN4) will have a very close approach to Earth in 2029. As a consequence of this, the orbital uncertainty will be increased by a factor about 40,000, and after that could have close approaches to the Earth in different years, including in particular 2036 and 2068. Recently submitted data from Mauna Kea and an in depth reanalysis of both observational biases and possible contribution from Yarkovsky effect, as presented by Chesley et al. at the DPS meeting taking place in October 2009 in Puerto Rico, suggest that collision with Earth in several different years, but especially in 2036 and 2068, cannot be excluded based on the best possible analysis of the available information. The NEODyS/CLOMON2 team, in collaboration with the JPL/SENTRY team and others, shall continue to process new data and to evaluate new models as they become available with the goal of keeping the information we provide on Apophis up to date.

The NEODyS/CLOMON2 team, October 7, 2009.

http://newton.dm.unipi.it/neodys/index.php?pc=4.1

 

[R1]

I wondered a long time ago if the moon could be at risk of colliding with Apophis.
I know that the moon is so far away , such as I've shown here:

But what I was wondering is actually at one or two points in the moon's orbit around earth,
for example A or B in the diagram below:

Viewed from the side, instead of an earth-polar view, it could be that the moon's orbit angle will enable
the moon to miss a collision, but the angle of the moon's orbit would have to be large enough,
or Apophis' path would need to be quite far from earth, or both:

The trouble I'm having is that I have not seen any mention of where the moon is expected to be when
Apophis approaches Earth next on Friday the 13th (part1) .



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(Actually, I could not even get the orbit diagram to play from the links above. Is there a jpg or youtube
diagram availabe somewhere?)

 

[MeteorWayne]

There is no risk of a lunar collision with either the 2029 or 2036 events, that possibility has been examined.

 

[R1]

Do some asteroids have magnetic properties ?

If we have not measured it yet, is it possible that Apophis does have magnetic properties ?

 

[MeteorWayne]

AFAIK, we've never been close enough with the right instuments to measure that (remember, we've only been close to a half dozen asteroids)

Certainly they would not have a dynamo creating a magnetic field, and anything other than an iron would probably not be able to susteain magnetism.

An interesting question, but I think we'll have to wait a few decades for firm answers.

 

[R1]

If it hits the north Pacific Ocean on friday the 13th [part 2], then that means that the time at the
eastern states of the U.S. will either be close to noon or close to midnight, correct ?

I also wonder, if it hits the north Pacific Ocean, it means that it will hit near the international date line,
or whatever it is called, right ? So, if this is true, are the countries on one side of the date line
actually saying right now that a possiblity exists that Apophis could strike the earth on thursday the 12th ?

What a strange landing site..

 

[R1]

Is there a time (a long time ago) when Apophis had another close approach to Earth?

 

[MeteorWayne]

Nothing anywhere near as close as the 2029/2036 pair. 2029 will be about 1/10 lunar distance (LD).

It came about 100 times further away (~ 10 x LD) in 1907,1949, and 1998 within the last century....I'm not sure if anyone has calculated distances further back in time.