Merged Apophis Topics

[bpiscean]

UK space scientists and engineers have designed a mission to investigate a potentially hazardous asteroid. <br /><br />The 300m-wide (980ft) rock, known as Apophis, will fly past Earth in April 2029 at a distance that is closer than many communications satellites. <br />

 

[robnissen]

The problem is not 2029, that pass is well-known. The potential problem is the next pass -- IIRC 2037. There is a small but real possibility that during the 2029 pass, the gravity of the earth could change the path of the asteroid, such that the asteroid hits the earth on its next pass.

 

[lukman]

Ok, so, the average speed of asteroid is 25km/sec. It is 22 years away from here, so it is about 17billion km from here. How one precisely calculate movement of a 300m diameter asteroid at that distance? for comparison, Pluto with diameter of 2300km farthest distance is around 7.5billion km from the sun. <div class="Discussion_UserSignature"> </div>

 

[MeteorWayne]

You've got it wrong. It's much closer than that.<br /><br />In fact it is in an eccentric orbit with a 323 day period, and a semimajor axis just inside the earth's, so it passes by the earth every 7 years or so. It orbits the sun just slightly faster than the earth's ~ 29.8 km/sec<br /><br />It has been very well observed, so it's position and motion are quite well known<br /><br />Analysis based on 2 radar delay, 5 Doppler, and<br />731 optical observations spanning 884.52 days<br />(2004-Mar-15.10789 to 2006-Aug-16.626954)<br /><br />After than, then it's just a matter of doing the math.<br /><br />Since all inputs into the calculations are not perfect, there is some inevitable error, which is why the uncertainty exists.<br /><br />MW <br /><br />Edited to correct closest approach to earth period. <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>

 

[robnissen]

<font color="yellow"> Since all inputs into the calculations are not perfect, there is some inevitable error, which is why the uncertainty exists. </font><br /><br />Yes, but hitting earth is outside the margin of error of all predicted paths. Therefore, it won't hit earth in 2029. The margin of error for the next pass, however, does include potential paths that could hit earth. It all depends on which path within the margin of error, the asteroid takes in 2029 and how the earth's gravity affects that path.

 

[MeteorWayne]

Just as a curiousity, we had a recent close approach of a very tiny asteroid/meteoroid on September 5th.<br /><br />Object 2007 RS1 passed by earth at 1/5th the distance to the moon!<br /><br />Of course, it's estimated size is only 1.7 to 3.8 meters, but still I find it encouraging we found such an object.<br /><br />The next upcoming "fairly close" approach is 2007 RJ1, a 25 to 56 meter sized object passing about 2.5 lunar distances away on September 16th.<br /><br />MW <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>

 

[adrenalynn]

These darned things are all like apparent mag 20something, up to 16 something tops. You'd think if they were going to "moon us", they'd at least have the decency to do it where we backyard types could see 'em... <div class="Discussion_UserSignature"> <p>.</p><p><font size="3">bipartisan</font>  (<span style="color:blue" class="pointer"><span class="pron"><font face="Lucida Sans Unicode" size="2">bī-pär'tĭ-zən, -sən</font></span></span>) [Adj.]  Maintaining the ability to blame republications when your stimulus plan proves to be a devastating failure.</p><p><strong><font color="#ff0000"><font color="#ff0000">IMPE</font><font color="#c0c0c0">ACH</font> <font color="#0000ff"><font color="#c0c0c0">O</font>BAMA</font>!</font></strong></p> </div>

 

[lukman]

You are right <img src="/images/icons/laugh.gif" /> but it is still brave to give the exact year 2029, maybe should just be range like around 2025-2030 <img src="/images/icons/laugh.gif" /> <div class="Discussion_UserSignature"> </div>

 

[MeteorWayne]

Well not in this case. We know exactly the day in 2029 (April 13th) when it will pass the earth.<br /><br />That's actually fixed by that being the place where Apophis crosses the earths plane in the solar system at 1 AU distance. That can only happen on April 13th, and 2029 will be when earth and Apophis will be at that point.<br /><br />What we don't precisely know is exactly where and exactly when (to the second) it will pass that point.<br /><br />All of that goes in to how it is deflected by the earth's gravity then.<br />That precise deflection will determine if we will get whacked 7 or 8 years later.<br />(Late morning UT for an April 13 2036 impact, early afternoon UT for an April 13 2037 impact)<br /><br />We will likely get more refinements in early 2013 when Apophis passes just outside of the earths orbit (within 0.1 AU) and should be close enough for radar and visual imaging. That will geatly increase the accuracy of it's obit. <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>

 

[lukman]

<blockquote><font class="small">In reply to:</font><hr /><p> What we don't precisely know is exactly where and exactly when (to the second) it will pass that point <p><hr /></p></p></blockquote><br /><br />Just forecasting rain, one may know when to rain (roughly) but where is the first drop of the rain will fall, it is difficult. At April 13th 2029, the asteroid will just pass the earth without any impact is possible right? or is it 100% colission? <div class="Discussion_UserSignature"> </div>

 

[MeteorWayne]

There is a zero chance of collision on April 13 2029. (Unless new data in 2013 changes that)<br /><br />It's 2036 and 2037 where the odds are not zero. <br /><br />From NEODyS<br /><br />"Near-Earth Asteroid (99942) Apophis [2004 MN4]: current status <br /><br />The asteroid (99942) Apophis (previously designated as 2004 MN4) will have a very close approach to Earth in 2029. The observations collected in the months of December 2004 and January 2005 by professional and amateur astronomers have provided enough information to exclude the possibility of an impact in 2029. At the end of January 2005, radar observations performed at Arecibo have led to a substantial improvement of the orbit"<br /><br />Hmmm, I ought to copy that over to the Arecibo being decomissioned thread.... <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]

We need to dig up the two old threads on this asteroid. All the information is in there. <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>

 

[alokmohan]

And place in archives.

 

[astroguard]

RobNissen is right, the threat will not be in 2029, but in 2036, when there is an estimated one-in-45,000 probability of impact with an energy of 400 megatons TNT.<br />99942 Apophis (2004 MN4) Impact Risk

 

[lukman]

400 Megatons impact on earth surface? you got to be kidding right? <div class="Discussion_UserSignature"> </div>

 

[schmack]

lukman, there is enough information in this thread to complete this http://www.lpl.arizona.edu/impacteffects/ form and get a good idea of what to expect come "doomsday apophis" <div class="Discussion_UserSignature"> <p><font size="4" color="#ff0000"><font size="2">Assumption is the mother of all stuff ups</font> </font></p><p><font size="4" color="#ff0000">Gimme some Schmack Schmack!</font></p> </div>

 

[rfoshaug]

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.<br /><br />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.<br /><br />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.<br /><br />But maybe an impact would be worse "per megaton" than a nuclear explosion? <div class="Discussion_UserSignature"> <p><font color="#ff9900">----------------------------------</font></p><p><font color="#ff9900">My minds have many opinions</font></p> </div>

 

[rfoshaug]

BTW, the energy in the earthquake that created the Tsunami in the Indian Ocean on December 26, 2004, has been estimated at between 250 and 800 megatons, at least according to Wikipedia.<br /><br />Surely a very bad day for the region, but not the end of the world. <div class="Discussion_UserSignature"> <p><font color="#ff9900">----------------------------------</font></p><p><font color="#ff9900">My minds have many opinions</font></p> </div>

 

[tdamskov]

You're quite right that 400 megatons is relatively small for an asteroid impact. The tsunami created by the quake in 2004 was the result of a very specific way of energy release (a vertical and horizontal slip of several meters along a line hundreds of km long) at an unfortunate depth just below the ocean floor. Many quakes deliver the same energy without much consequence; it all depends on the depth and location. An asteroid impact would have to deliver far more energy to cause a similar tsunami to the one in 2004.<br /><br />Yes, an impact would probably be worse per megaton than a nuclear explosion if it hit the wrong location. Depends on how you measure bad <img src="/images/icons/smile.gif" />

 

[lukman]

Tsar Bomba was detonated miles above earth surface, at it was equivalent to 1% sun output, so 400megatons almost 10% sun output. On the ground, it will be bad. <div class="Discussion_UserSignature"> </div>

 

[robnissen]

Since we know the exact time of a potential 2036 impact, within a few minutes at most, and we know the exact track, there has already been an estimate of where it would hit. IIRC, the estimate was in the North Pacific, but I may be completely wrong in my recollection.

 

[adrenalynn]

Since we don't have a statistically significant calculation of the likelyhood of it hitting a keyhole (that doesn't change almost daily, and with numbers that don't agree with each other), it seems somewhat brash to decide the exact time and location of impact, doesn't it?<br /><br />Just in the past months, as memory serves, it's bounced around from something like 1:49000 and 1:10 of it nailing a keyhole... <div class="Discussion_UserSignature"> <p>.</p><p><font size="3">bipartisan</font>  (<span style="color:blue" class="pointer"><span class="pron"><font face="Lucida Sans Unicode" size="2">bī-pär'tĭ-zən, -sən</font></span></span>) [Adj.]  Maintaining the ability to blame republications when your stimulus plan proves to be a devastating failure.</p><p><strong><font color="#ff0000"><font color="#ff0000">IMPE</font><font color="#c0c0c0">ACH</font> <font color="#0000ff"><font color="#c0c0c0">O</font>BAMA</font>!</font></strong></p> </div>

 

[MeteorWayne]

As I said on page 1, in 2013 this asteroid comes close enough to earth that there should be considerable refinement of the orbit at that time.<br />I don't think there's been any significant change in predicted orbit over the last few months, since it is quite far away right now; hence no new data.<br /><br />Even if the position and velocity are know with absolute precision (which is impossible) in 2013 there will still be uncertainty due to the Yarkosky effect, and other unknowns.<br /><br />However, the potential impact times are reasonably precise, because that is the only time the orbits of the asteroid and the earth intersect. Any changes will be in velocity, which would have a small effect compared with the essential alignment of the orbits. That's why there are two potential returns after the keyhole a year apart (change in orbital velocity) but we still know it will happen (if it does) on April 13th. It's the only time it can happen.<br /><br /><br />MW<br /> <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]

New Arecibo Data

Meteor Wayne Edit: Based on some user suggestions and recent developments, I have brought together the remaining Apophis threads......


Apophis is making a close earth pass in 2029, and then another close pass in 2036 with a non-zero chance of collision. If it does hit, it will strike in the northern Pacific and create a tsunami which will kill hundreds of millions, destroy major cities, and cause a worldwide dust cloud and 'winter'.

An accurate determination of Apophis' trajectory is key to understanding in the unlikely case that affirmative intervention is required to save modern civilization.

Here are two recent papers (paper one is a condensed version of the 20 page long Icarus paper) on Apophis trajectory calculations.
one
two

(I am sure some of you will find the asteroid mass information of the 32 largest known asteroids in Table 7 in the Icarus paper useful.)

The authors of the Icarus paper considered so many factors and error sources in trajectory determination - it is a very fascinating read. There are so many factors that are poorly understood which have huge effects on the location of Apophis in 2036.

The report includes looking for encounters with other asteroids (e.g., Apophis comes close to 144898 2004 VD17 in 2034, which you may remember is another NEO non-zero collision hazard), how to best conduct pre-2029 observations (radar is vital), and, briefly, mitigation possibilities.

Here are some:
In reply to:Trajectory predictions for asteroids are normally based on a standard model of the solar system that includes the gravity of the Sun, Moon, other planets, and the three largest asteroids.

However, additional factors can influence the predicted motion in ways that depend on rarely known details, such as the spin of the asteroid, its mass, the way it reflects and absorbs sun-light, radiates heat, and the gravitati - - - - - - - - - - - - - - - - - - - - - - I really, really, really miss the "first unread post" function.

 

[publiusr]

A small object might always strike Apophis and change its orbit.