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Earth’s Close Encounter With Large Asteroid On July 3, 2006

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Astronomers anticipate the approach of a prominent-sized asteroid as it passes Earth just beyond the orbit of the moon.

Discovered by Lincoln Laboratory Near Earth Asteroid Research (LINEAR) on December 10, 2004, Asteroid 2004 XP14, is due to come uncomfortably close to Earth during the early hours of Monday, July 3, 2006.

The LINEAR project, funded by the United States Air Force and NASA, uses technology that was developed to monitor satellites orbiting the Earth, in an attempt to locate and record potential cosmic threats to our planet.  To date, the LINEAR project has confirmed 1622 Near Earth Objects (NEOs), which also includes comets with a close approach orbit to the Earth.  The greatest current potential impact risk, at an estimated diameter of 300 metres, is asteroid 99942 Apophis (2004 MN4) when it approaches Earth in April of 2036.  The probability of 99942 Apophis impacting the Earth is 0.0026% or 1 in 38,000.

Believed to be 600 metres or more in diameter, Asteroid 2004 XP14 was originally thought to be an impact threat, but further studies of its orbit later revealed the big rock is not an immediate danger to the Earth.  Classed as a PHA (Potentially Hazardous Asteroid), 2004 XP14 is one of 796 within this classification, which is defined as an asteroid with a Minimum Orbit Intersection Distance (MOID) with the Earth of 0.05 AU or less, and an absolute magnitude of 22.0 or brighter.

The asteroid will pass just beyond the orbit of the moon at 1.1 LD (lunar distance from Earth) and is expected to reach an absolute magnitude of 12, so amateur and professional astronomers will be readying their telescopes in order to catch a glimpse of the fly-by.  It will be traveling at a relative velocity of 17.41 kilometres per second.

Asteroid 1999 AN10At a distance of 1.7 LD, the most recent close approach by an NEO was only a few days ago on June 28th 2006, by 2006 MB14, but at an estimated diameter of 24-53 metres, it was a mere pebble compared to 2004 XP14.  NEOs at such distances are somewhat rare.  The next known asteroid expected to pass at a comparable distance of 1.4 LD, is 2005 YU55 in November of 2011; and then another, 1999 AN10, in August of 2027 at a distance of 1.0 LD.  NASA reports that asteroid 1999 AN10 is at least 1 kilometre in diameter, and with the projected distance of this asteroid relative to the moon, we can certainly anticipate apocalyptic stories to accompany its approach.

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About PoizonMyst

  • sr

    Maybe if were lucky, it will hit ted kennedy house.

  • Warren

    I can’t imagine anything worse except nuclear war if that thing hit our world!!! Are people so uneducated to not realize that these things have hit Earth thousands of times in the past and WILL hit Earth again!!! We need to tell our governments to DO SOMETHING!!!!

  • wolfe

    ^^ Chill..

  • Ruvy in Jerusalem


    What is the government going to do? If they try to nuke an incming asteroid, they’ll create MORE asteroids.

    Repeat after me…

    When de univoise toins its back you, you hafta toin your back on de univoise!

    Hakuna Matata!

    Maybe there are times, you just have to pray to G-d that we are all worthy of being spared such a disaster – and then behave in such a way as to convince Him.

  • In reality there is a great deal we can do to protect our planet from future impacts by large asteroids or comets. However, all of the best protective measures involve having an active human presence in space.

    The key to preventing this type of disaster is early detection. Our chances of early detection will be much better if we have a detection system that is no longer limited to our own planet.

    Right now we have detected only a fraction of the objects that could potentially smash into our world, because there is only so much we can see when all our telescopes are stuck here.

  • Dark

    can we hack it ? 😀

  • There is not human power to stop this type of disaster. We can not turn the earth in another direction as a car nor send a missile. If is going to happen, is going to happen… Good luck!!!

  • The gov in my opinion is doing all he can… for the moment they only count the asteroids 😀 😀 😀 😀 😀

  • John Roush

    My personal theory (and I have yet to hear of it in any scientific journal or article) of how to best avoid a catastrophic collision with a NEO is to send a spacecraft to the object and have it drill into its interior to anchor itself to the object and then deploy a huge parachute that can be adjusted to the varing solar wind intensities so that a somewhat controlled force can be applied to it to slow it down and alter its timing of intersection with earth’s solar orbit. The ideal goal of such alteration of its trajectory would probably be to stear the object into the sun, itself, where it could have a chance of totally being destroyed and permanently ending its threat to humankind. I hope a good scientist reads this and analyzes its feasability.

  • Humans do in fact have the power to stop such disasters, provided we know about them early enough.

    When a large object is only a few days away from striking our planet, by then it is far too late for us to stop it. This much is true.

    If our warning comes a few months or a couple of years before the impact, this also is probably too late to help us.

    However, it’s a different story if we can track the orbits of such objects well enough to know when one might hit us several years from now, and even better if we can see their orbits several decades ahead. It would take only a very small change in such an object’s orbit to make it miss our planet completely. This tiny deflection is well within the capabilities of our current technology.

    If we are prudent enough to invest in the early detection systems, and we get enough advance warning, we could easily prevent potential impacts that would become unstoppable later on.

  • John, various types of solar sail techniques have been discussed many times as possible methods for asteroid deflection.

    Steering an asteroid into the sun would be a terribly wasteful act, however. There are far better uses for any such object once it has been brought under human control.

    Scientific study of such an object can give us insights into the early history of our solar system. Many asteroids are rich sources of precious metals such as iron and iridium that could be used to develop space infrastructure, and others are rich in even more precious metals such as platinum.

    Letting such a thing crash into the sun is almost as crazy as letting it smash into the earth.

  • Ruvy in Jerusalem

    Victor, John,

    You both express great ideas. Do you think your country has enough money to pull them off, not to mention the moxie?

  • Ruvy, if an object is detected early enough, deflecting it away from our planet would not be much more difficult than landing a spacecraft on Mars.

    Granted, we’ve had plenty of trouble with our Mars missions, so we shouldn’t depend on any one spacecraft to handle the impact deflection mission if it becomes necessary.

    However, we certainly have enough money to do it several times over. All we lack right now is the political will to prepare our defenses. That part could change rapidly if astronomers confirm a specific impact event well enough to set a particular date for the disaster.

  • sr

    We have a better chance of getting hit with blue ice then any asteroid. NUKE THE UNBORN GAY ASTEROIDS.

  • With Bush diverting funds for science and astronomy projects to the war and his moon/mars mission, there’s not much chance of us detecting anything on in time.

    Also many asteroids are not solid rock but a cluster of smaller ones brought together by gravity. Pushing against one would be more likely to break it apart than to dislodge it from its course.

    The only reliable method is the one in front of our faces, the moon’s gravity diverting it off course, but only if it’s in the right position to do so. You only have to look at our lunar friend to see how many times that’s happened already.

    Of course there’s always that silly garbage bag commercial…

  • There you have it, ladies and gents. If an asteroid hits us, it’s Bush’s fault.

    If something does come our way, just find the world’s best Atari player and those asteroids will be history.

  • Every president since the Apollo moon landings has done stupid things to reduce the agency’s effectiveness, so I don’t accept any effort to lay all the blame for its current troubles on Bush.

    As for the asteroid types that might be easily broken apart, all the more reason to achieve early detection so we can minimize the force applied to any object we need to deflect.

    Of course no human technology is going to reach 100% effectiveness, just as the lunar deflection effect has not provided our world 100% protection from impacts. However, we might feel rather foolish if it turns out we all get killed by an object that was indeed one of the types we could have easily deflected.

  • sr

    Hello Jet, hope all is well for you. Comment #15 you mentioned lunar friend. Did you mean looney friend with many hits to the head from blue ice and asteroids? Was married to this very large women and she had many assdroids. She married later to a bigfoot if I recall. Have a great 4th dude and drink much rum for me. sr

  • In the last six years we could’ve made huge strides in this area and to childishly say that since other presidents didn’t-that gives Bush an excuse not to either, is the ultimate in irresponsibility.

    During past presidencies this problem wasn’t as well known, researched or urgent as it has been in the last six years.

    If we were hit by one that wasn’t detected, you damn well better believe I’ll lay the blame squarely on Bush. The billions we’ve spent and thousands of lives we’ve wasted on his useless war could’ve been better spent on cures for world diseases or science.

    At the end of his USELESS war, the middle east will be NO BETTER OFF than it was before we invaded Iraq and you know it!

  • Ruvy in Jerusalem

    Good to see you back in action, Jet. Kept this short chapter length comment just for you, guy…

    Hope the eyes are not bothering you too much…

    I knew somebody would drag Bush into this discussion somehow. Maybe what you Americans need for the Fourth is a “burning Bush.” Then you can “turn in to see this less than great sight.”

  • “Kept this short chapter length comment just for you” IT-it’s the big one ‘lizabeth-I’m comin’ for ya honey!!!

  • Wow. I’m guilty of the ultimate in irresponsibility? Quick work for a Monday morning, I guess. Welcome back, Jet.

    However, please note that I did not entirely absolve Bush of any responsibility for the sad state of affairs over at NASA. Of course he could have provided much better leadership than he has. It just doesn’t make any sense to lay all the blame on him, because the American people have spent decades letting every single president get away with neglecting or outright damaging the capabilities of NASA.

    Ultimately, we the people are the ones responsible because we have failed to make official mismanagement of NASA have any real political consequences for our elected representatives.

  • Oh that clears it up… thanks

  • Get a load of Jet “Waah, My Opinion Is As Valid As Yours” in Columbus, in Comment 19, invalidating anyone who disagrees with him on a subject completely unrelated to the topic at hand.

  • sr

    Now Im confused. What does this subject have to do with Michael Jackson, pit bulls and Capt Morgan? From the village idiot. sr

  • Oh Matty don’t be so sweet, people will talk! It says if he hadn’t cut funds, we could more easily and quickly detect astroids (the subject of this piece) coming in soon enough to do something about it instead of blowing all that money into Haliburton’s pockets.

    You’re lovable when your huffy.

  • See, no, it doesn’t really say that.

  • Thanks Matt, you inspired my latest article and I dedicate it to you


  • of course, to deflect an object from it’s trajectory in space requires only the tiniest amont of Force applied to either change said objects speed or direction…

    so , if dealt with early enough, a spitball would be sufecient to change the course of yor theoretical asteroid enough for it to miss the earth entirely

    now, the closer said object gets, the more Force is required to alter said trajectory

    so, some decent shots with BB guns stationed on Phobos and Deimos should be good enough…

    just a Thought


  • I don’t hink I’ve ever tried to measure a tiny “amont”, is there a trick to catching one?

    Do you use a spitball for bait?

  • Can’t we just send Ben Affleck and Bruce Willis straight into the rock?

  • YOu know I heard rumors that they both had tiny amonts!

  • bah..i bring Science and get my chops busted fer spelling?


    but they do make great cheese steaks

    but i digress


  • If you elect me as your president, I will make it a bullet-point priority to fully fund the Ammo For Gonzo program, to keep America safe.

  • uh huh

  • Ah, we’re still here. Since Bush is obviously so connected to the asteroid, I’m confused as to why he didn’t have a press conference on how he saved the world from the evil terrorist Asteroid 2004 XP14. You would think that he would have learned at least one thing from the Clinton Administration: Take credit for things you didn’t do. His approval ratings might actually go above 50% then.

  • He probably had Laura stand out on the front lawn, frown up into the sky and scare it away

  • Last night, while walking with my family through a dark field on our way to a restaurant for dinner, I pointed to the sky and asked the kids if they could see the asteroid – like any space-nut would use such an event to trigger an astronomy lesson. 😉 Of course, I knew this particular asteroid was never going to be bright enough for us to see with the naked eye – but it was a good excuse, none-the-less.
    After some general discussion about when we could expect a possible collision, and what would become of the Earth and humanity should one of a reasonable size hit – the question was finally asked by my eldest: “Wouldn’t we have the technology by then(2036), to stop it from hitting the Earth?”
    I responded by informing her that “we very well could have that techonology working for us right now, but I doubt we would ever be told.”
    “Why not?” she asked.
    “Because the sort of technology that would be used to deflect or blow up an asteroid, could also be used in war,” I answered.

    The ideas presented here of ‘parachutes’ and ‘solar sails’ are certainly interesting. However given that it can take years to reach objects in space (and there is obviously thousands of NEOs out there), would we be able to implement such technology in a feasible amount of time? So the question of viability becomes apparent.

    Also, let us consider the results of NASAs “Deep Impact” mission last year, where a 372 kilogram impact probe was smashed into Comet 9P/Temple 1. The impact decreased the comet’s perihelion distance by 10 metres, compared to an alteration of 34 million kilometres when the comet passes Jupiter in 2024. This would suggest that in order to deflect or blow up a sizeable NEO, a considerable force from a reasonably large craft would be required.

  • Poison did you get a chance to observe Jupiter?
    Both red spots should be at their closest about not to a week from now?

  • PoizonMyst, if we knew for a fact that the 2036 close encounter was actually going to be an impact event, we would have plenty of time to implement a low-energy deflection plan.

    A change that makes an object’s orbit different by just 10 meters this year can by designed to have a cumulative effect over the next 30 years, with the total change to its orbit more than large enough to make sure the object will miss us by a large margin.

    This is why early detection is the key to any meaningful protection against impact events. Changing the orbit by 10 meters only one year before the impact doesn’t help us at all. Changing the orbit by 1 meter might be more than enough, if we can do it 20 or 30 years ahead of the impact date.

  • Victor makes the same Poit i did earlier…

    but let me add that changing the Vector of the orbit is not the only Answer…

    if done early enough, a change in Velocity can accomplish the same effect…as little as 1 foot per second speed up or slow down, if done in Time, can alter the dynamic enough to cause the Objects to completely miss each other as well


  • Well, if by “earlier” you mean after I made the same point, back in comments #5, #10, #13, and #17, then yes, I suppose I’m making the same point you did in comment #29, Gonzo.

    To most people the distinction between “vector” and “velocity” is not really important. The key point to remember is simple: the energy required to make either change is very small, and easily achievable with our present technology, if the change starts early enough.

    On that much we are completely agreed.

  • i did not mean “earlier than you” Victor…merely earlier in the Conversation…

    relax d00d….heh

    we are in complete Agreement, of course…physics applies and obeys no partisanship

    as for the differences betwixt vector and velocity, Victor… the variances vaccilate vividly, the veracity verified via the vernacular…

    but i digress…


  • Sorry if I over-reacted, Gonzo. Just tired of all the people claiming it would be “impossible” to alter the orbit of an asteroid if we find one headed in our direction. You’re certainly not part of that crowd, so I shouldn’t be taking out my frustrations on you.

    We could get into a whole debate on the technicalities of the physics, but I don’t want to make the other readers’ eyes glaze over any more than they already have.

    Just remember: 186,000 miles per second. It’s more than a good idea. It’s the law!

  • the Law?

    somebody better start busting them damn tachyons then…

    but i digress…


  • Tachyons?? Has anybody ever actually observed those? I had the impression they were still just a hypothetical concept, much like “hyperspace” and other, similar ideas. Things that might be true, but remain unproven.

    Anyway, even if tachyons do exist, they are still subject to the law of 186,000 miles per second — but for them, that’s the minimum speed, not the maximum.

  • Victor, as I mentioned in the article … the whole point of the LINEAR project is prior detection of potential impact threats to our planet – the earlier the better.

    I don’t recall saying it would be impossible … but as I pointed out in comment #38, it takes a long time, and quite a lot of force, to have any affect at all on the orbit of such objects – so in each mission, we would want to get it right the first time. Perhaps 10 metres would be enough to make a difference … but if not, would we have the time or resources to make a second attempt.

    Also, we must consider that once we did make a difference to the trajectory of such an object, recalculation of it’s altered orbit would be required – something which requires more time to monitor accurately. Yes, 2004 XP14 was an impact threat – until further analysis of it’s orbit in space was conducted. I’m sure you will agree that calculating the orbit of an NEO, in relation to our own orbit, takes much more than just a couple of photographs. Again, several computations are required over time … afterall, space is BIG and these things could be going anywhere, in any direction.

    Anyhow, the following is an image and an animation which gives an idea of just how difficult such a job can be.

    Our Busy Solar System
    Animation of Asteroids Passing Near Earth

    Enjoy hunting for more space rocks dude, because there are many more to be found – and certainly plenty of impact threats to be diverted.

  • Connor

    The moon is our solar vacuum, and has kept earth from a variety of strikes over the epoch.

    Coupled with volcanic history and the pending potential of known volcanic history, I surmise that there just certain natural occurances which are out of our control.

    While one project may be centered at offsetting tragectory of cosmic threats, what project plans to diffuse the Yellowstone caldera, when it decides to blow again. A quick google on the subject will illustrate the futility of this discussion.

    The southern reaches of the San Andreas is ready to spring (again) and with the population growth which has occured over the last 300 years, it will have a catastrophic effect.

    To reiterate, there are a few things in our sphere of influence as human beings, which we just do not have control over. That should be obvious and as such, should be accepted as a matter of consequence.

  • kurt

    I think that if the astoeroid will hit it will probably destroy a whole country

  • duane

    The Earth’s moon is not a solar vacuum (#48). The Earth has been struck far more often than the Moon, simply because it has a larger cross-section. The moon, at a distance of 235,000 miles from Earth, has a diameter of about 2000 miles, while its orbit around the Earth tracks a path of about 1.5 million miles. The moon is a mere dot on the scale of the Earth-Moon orbital system. Its gravitational field is as likely to deflect objects toward the Earth as away from the Earth. It is nothing. The Sun is king. The orbits of comets and asteroids are determined by the Sun’s gravitational field, and the Earth and Moon occasionally manage to get in the way.

    The simplest solution to the asteroid impact problem is to simply vaporize them. Your 300 meter diameter asteroid would be turned to interplanetary plasma by a few megaton-class nukes. Some people would worry that you might split the rock into a few smaller, but still deadly, chunks. Nope. A few megatons (and why not make it 100 megatons just to be sure), and the ex-asteroid would join the solar wind and never know what hit it. We have the technology.

  • Ah it’s god’s will, I knew that’d come up sooner or later

  • the only problem i have with duane’s Answer is that anytime you place plutonium on top of a semi-controlled explosion(ie:rocket)…

    it makes me wanna go poopy in sheer Fear

    otherwise i’d say we shoudl go nuclear power for all electricity generation and store the waste on the moon for when we figure out what to do with it

    far easier is my answer of just smacking the rocks with some bb’s

    any math genious out there wanna break out the slide rule and tell me the effects on yer big space rock if you change it’s Vector by one tenth of oone degree and it’s Velocity by 1 inch per second when it’s an AU away from impact?

    i’ll bet ya a double mocha latte it means a clean miss by a wide margin…

    physics apply…and ballistics work really well in a vacuum

    but duane, as always , is exactly correct …the Sun IS king of the Gravity Well


  • sr

    Duane. Megaton-class nukes. You speak my language.

  • duane

    Gonzo, the glib answer is, of course, take yer pick — a big rock hitting the Pacific at about 100,000 mph, which would create a column of superheated water about a mile wide extending from the surface to the ocean floor, some serious water spoutage, a ground zero for tsunamis caused both by the disruption of the water column, followed rather quickly by a big thump on the Earth that would cause an earthquake like you can’t imagine, more tsunami action, blotting out the sun for a few weeks or so … or… some plutonium spillage. The nuke would not detonate, but it would poison the atmosphere, which could cause just enough panic for people to temporarily forget that there’s a big rock aimed at them. Glib. Sure. There are other ways. Nuking it is the simple way.

    Your objection is precisely the same one that is given to the solution for nuclear waste — launch it into a Sun-bound orbit. Recycling on a solar system scale. Space elevator, anyone?

    The slide rule needs to be broken out not to find the new orbit if you were to impart a delta-vee to the asteroid, but to figure out how to impart the delta-vee in the first place. Josh (#9) presents the germ of a potentially workable solution. But instead of a parachute, embed rocket thrusters into the surface, and apply some retro rocket action. That’s a little beyond out current technological capability, but it might work in the future. I would have to look up the numbers for the thrust and delta t, but you could easily get the delta-vee for a given mass from those numbers, then find the new ellipse. Delta-vee = thrust x delta t/mass.

    All right. I looked up a few numbers. The Saturn 1 delivered a thrust of 890,000 Newtons for 150 seconds. If you burned one of these babies on the surface of a rock with 300 meter diameter, you could impart a tangential delta-vee of about 0.2 cm/sec, which amounts to a displacement of about 10 km if the impulse occurs at 1 AU (roughly). Not too impressive.

  • no Duane..i’m sorry if i was unclear…

    i’m talking just plain old impact from mass accelerators…

    a big bb gun..spitballs…or, as i said earlier…off the shelf Navy Phalanx…

    much simpler answer to just pop off a 1000 rounds, check the ballistic…rinse and repeat until vector/velocity is changed enough to miss impact

    much neater soloution than nukes…cheaper too!

    slow it down, speed it up, nudge it a little bit…doesn’t matter

    as you are much better Aware than i am, missing is MUCH easier than hitting when it comes to two moving objects in 3 dimensional space…change either course or speed of either object by a miniscule amount..and ya miss

    thas why i slipped in the 1 AU figure in the slide rule problem…plenty of wiggle room there

    so your .2 cm/sec is EVERY second multiplied by the objects original velocity…yes? now add the fraction of a degree angle for the nudge factor

    it only works over time due to it all adding up…a few hours late, or a fraction of a degree far enough out…and the earth is long gone by the time the rock gets there

    perhaps i’m missing somethign, but that is how i understand it according to god and Heinlein…


  • duane

    Gonzo: so your .2 cm/sec is EVERY second multiplied by the objects original velocity…yes?

    I assumed a speed of 100,000 mph at a distance from Earth of 1 AU, just for the sake of doing a back-of-the-envelope calculation. So, that’s about 3 million seconds (about a month) for the asteroid to cover the distance. If the impulse imparts a 0.2 cm/sec velocity perpendicular to its original velocity vector, then the total displacement is about 6 km. The displacement is proportional to the number of thrusters. 1000 thrusters gets you 6000 km, etc.

    The mass accelerator concept is interesting. Let’s work that out. I’ll just make up a few numbers for the sake of argument. Suppose you fire 1 kg chunks at 20 km/sec at a rock with diameter 150 meters moving at 100,000 mph when the distance is 1 AU from Earth. Each impact gives a change in momentum of 2 x 10E9 g cm/sec. If you want to shove the rock, say, 1 Earth diameter, then you need to change the transverse momentum by 2 x 10E16 g cm/sec. So you would need 10E7 impacts (if I did my cipherin correctly). Yow.

    Everything scales as you would expect. If the velocity is increased by 10, you need a factor 10 fewer impacts, If the mass of the projectiles is increased by 10, same thing. If you catch the asteroid at 10 AU instead of 1 AU, same thing. It still sounds like a stretch.

    This is all back of the envelope. There are other things to consider. If you start blowing chunks of the asteroid off, the mass will change, and it will need a new orbit consistent with its new angular momentum. So maybe explosive projectiles would help. You could pulverize the thing, and, as you say, most of the chunks would miss the Earth. If they’re small enough, they just burn up in the atmosphere if they happen to still want to impact the Earth.

    I don’t know. Sounds expensive. But I’ll be glad to chip in.

  • PoizonMyst, of course I agree on the difficulty of tracking Near Earth Objects. However, we make it far more difficult than it has to be when we limit ourselves to using telescopes and other instruments that are all based on or near the surface of the Earth.

    A thorough mapping of potential impact threats becomes a much more reasonable proposition if we select a more reasonable tool set. For example, a network of space based observatories strategically placed throughout the inner solar system would allow us to detect many, many objects we simply cannot see from Earth, due to interference from the sun. Telescopes like Hubble are not helpful for this specific case, because they also cannot look for objects that orbit close to the sun.

    Of course we will never reach a 100% guarantee of being able to detect and deflect all possible threats to human civilization, but that is no reason to give up in a fatalistic stupor, as Connor appears to recommend. A more intelligent response is to establish human populations on other worlds as soon as possible.

  • Condor

    Duane, I am in error.

    After reading my post and yours, I stand corrected and recall the correct answer. Thanks for jogging my brain…

    It’s Jupiter which is the solar vacuum for earth.

  • Photo of the asteroid for your asteroid scrapbooks.

    At the distance of 269,000 miles from Earth, 2004 XP14 skims past…Scientists have stated that it would take mile-wide or larger asteroid to cause widespread devastation that could threaten civilization, this little guy was estimated at about a half-mile wide.

    Of course, trying to predict the outcome of such an encounter could be likened to a cosmic crapshoot. Estimations regarding the collisions of rocks this size into our Big Blue Marble are every 84,000 years. Any luck at all, we’ve got a couple of thousand to go…

  • sounds more like it to me, Duane…

    but there’s also the Velocity, not just Vector…

    heh..i palmed that ace

    add in the slight slowing down (or speeding up if ya hit it from behind) and ya get even more clearance…

    but thanks for the way Fun math lesson…always good to have a physicist around


  • Well, it’s too late to avoid boring readers who don’t care about technicalities of physics, so here goes.

    Talking of “vector” and “velocity,” along with the other details in the hypothetical discussion between Gonzo and Duane, may indicate a flawed model of the physics of asteroid deflection.

    The reality we are trying to model is objects moving in elliptical orbits, not the straight lines normally described with the term “vector.” It’s extremely difficult to change only the “vector” or only the “velocity” of any orbiting object. The vast majority of possible changes to its path will change both.

    When we think about the problem as if it involved two billiard balls on a pool table (the classic model environment for vectors and velocities), it might make the math easier but it can lead to errors in our thinking. One such error involves the matter of scale.

    Attempting to deflect an asteroid when it has only 1 AU left to travel before hitting our planet is far, far too late for low-energy deflection methods to work. Even 10 AU is an uncomfortably small distance on the scales we need to be thinking about here. 1 AU is basically the radius of the Earth’s orbit. In the thirty years between now and our 2036 close encounter with an asteroid, our planet will travel about 94 AU. (30 orbits around the sun x 3.14 x 1 AU = 94.2 AU).

    I don’t know the details of the asteroid’s orbit, but the total distance it will travel in that time is probably not vastly different from our 94 AU. This type of distance gives us the time to achieve a deflection at a much lower energy cost (much easier and less expensive than trying to hit the asteroid with millions of 1-kg slugs from a big Phalanx cannon).

    Those 94 AU will not be traveled in a straight line, of course. We’re talking about orbits constrained by the Sun’s gravity. If we choose our deflection method carefully, the Sun’s gravity will actually help us deflect the asteroid, but if we are not careful, solar gravity can make the job harder.

    If we want to make the task as manageable and as inexpensive as possible, early detection and a clear understanding of orbital mechanics both become necessities.

  • Nonsense Victor, I found your and Gonzos comments on my string to be a very good read-don’t shortchange yourself-I’m interested anyway. Maybe the ESA is reading too.

  • Victor sez…
    *If we want to make the task as manageable and as inexpensive as possible, early detection and a clear understanding of orbital mechanics both become necessities.*

    Quoted for Truth

    and the point of Impact usage for deflection affecting both vector and velocity was the point i was so pitifully trying to make…


  • Gianmarco Radice of Glasgow University has a few thoughts on how to avoid a collision with Apophis. “The deflection methods fall mainly in two categories, kinetic methods and low-thrust methods,”

    Dodging disaster

    Solar mirror
    This would reflect light from the sun on to the asteroid to boil parts away. The stream of gases would move the asteroid out of the way of the Earth.

    Covering the asteroid with paint or materials that either absorb or reflect light, heating or cooling bits and changing and way it moves.

    Collision course
    Smash a spacecraft into the asteroid to try to blow material away from the rock and change the asteroid’s orbit.

    Land a rocket on the asteroid and use it to propel the rock in a different direction. Chemicals on the asteroid could be used.

    “Kinetic methods are those which provide an instantaneous change of properties within the asteroid. Sending a nuclear warhead or some sort of exploding device against the asteroid (…) to create shock wave, for example. Low-thrust methods range from painting the surface of the asteroid with reflective or absorbing paint so that the properties of the surface are changed by attracting more or less light, thus heating or cooling the surface and changing the physical properties of the asteroid.”

    Whatever method is used, it would only change the path of the asteroid by minute amounts. “You can make very small adjustments to their orbits to create large changes in their orbits in the future,” said Prof McInnes.

    Preparing for a potential catastrophe is a valid concern.

    The exact methods used would have to vary depending on the type of asteroid being targeted. Some asteroids, known as rubble piles, are loose collections of rocks and ice. Slamming a rocket into these would be useless because the energy of the impact would just be absorbed, like the crumple zones in a car.

    In this case, one method might mean melting part of the surface of the asteroid by concentrated sunlight. A large solar sail or mirror could reflect sunlight on to the surface of the asteroid and burn part of it away. The jets of gas produced would create a small but constant thrust that could deviate the asteroid into a new orbit.

    More traditional solid asteroids have a range of options. “Another method is to place some sort of thrusting device on the surface of the asteroid,” said Dr Radice. “It can either have its own fuel source, for example a solar power generator, which will create a very low thrust but over a longer period of time. Or you would have some sort of motor that uses the chemicals inside the asteroids to generate the fuel to work.”
    Alternatively, a spaceship could be launched and hurled directly into the asteroid. The idea would not be to physically push the asteroid away but to use the collision to gouge out a hole in the rock. The ejection of material would then push the asteroid in a different direction.
    Meanwhile the European Space Agency (Esa) has already announced plans to conduct an experiment in deflecting asteroids away from the Earth.

    Esa’s Don Quijote mission will consist of two spacecraft: Hidalgo and Sancho. The former craft will smash into an asteroid named Apophis, which is expected to make its closest pass by the Earth in 2029, when it will be only 32,000km away.
    The Sancho spacecraft will watch the collision and record any shift in the asteroid’s trajectory. Esa plans to begin building Don Quijote in 2007, after a competition to select the best design from several European contenders.

  • duane

    Victor (#61): The reality we are trying to model is objects moving in elliptical orbits ….

    Yes, as already mentioned in #54.

    … not the straight lines normally described with the term “vector.”

    This is a misconception, Victor. Vectors (ha, vector, victor) apply perfectly well to curved trajectories. An asteroid has two vectors associated with its motion: (1) position (2) momentum. Each of those vectors has three components [(x,y,z) in Cartesian coordinates or (r, phi, z) in cylindrical coordinates, or (r, theta, phi) in spherical coordinates. At any moment, the asteroid’s trajectory is described by these six numbers.

    You might be trying to point out that the vectors are not constant. Right, of course they’re not. Like the position vector, the momentum vector changes in time. That makes it no less real nor any less useful. The momentum vector is related to the velocity vector in a simple way, p=mv (imagine arrows over the p and v). The velocity vector can be understood as an instantaneous direction and magnitude, where the magnitude is called “speed.” The term “velocity” implies its vector nature.

    My earlier posts (#54 and #56) were both done in the spirit of back of the envelope calculations. You seem to imply that I made an error. I’m more than happy to have errors pointed out to me, but I don’t think I made any. In that spirit, I simply calculated the aggregate deflection of an object given a momentum impulse. My calculations scale appropriately with all relevant parameters, including the distance at which the impulse is applied (impulse = force x time). So the “matter of scale” is embedded in my calculations, as I described in #56. I could calculate the ellipse resulting from such an impulse, but figured that might be a bit of overkill when we can get decent estimates to the answers in a much simpler way.

    it might make the math easier but it can lead to errors in our thinking.

    I tend to disagree with you. A useful skill is to be able to pick out what’s relevant to a problem and work out a quick estimate using simple considerations. Refined calculations become necessary only when one finds that the answer is “interesting,” i.e., when the answer is not very large or very small compared to the range over which the true answer “matters.” In this case, my estimates predict small deflections, but not ridiculously small, so that refined calculations would be needed. But the real answer would not be far off from my estimates. That’s the point. There are no errors in my thinking, which, admittedly, is a rare occurrence.

    If we want to make the task as manageable and as inexpensive as possible, early detection and a clear understanding of orbital mechanics both become necessities..

    Don’t worry about the latter issue. Orbital mechanics is definitely well understood.

    I’m sorry if I sound defensive, but I tend to bristle at the suggestion that I don’t know what a vector is. Plus I just got back from the dentist.

    I am enjoying the discussion. Carry on.

  • Duane’s math-fu is greater than mine

    /bows, hand over fist


  • Duane, I realize orbital mechanics is well understood — by physicists. Your understanding of the subject is not what I sought to correct, nor did I mean to imply you had made a mistake in your calculations. The mistake to which I refer was in the postulate you were given as a basis for the calculations, that is, a starting distance of only 1 AU between the threatening object and its point of impact with Earth.

    (In fact I think your calculations fit closely with what I’ve seen everywhere else I’ve read about this subject. If we want to deflect a potential impactor, cost-effectively and within the limits of our current technology, we’d better do it when the object still has much farther to travel than merely 1 AU.)

    You were also not the one I sought to correct in my statements about vectors. When Gonzo repeatedly drew a sharp distinction between “vector” and “velocity,” it seemed he was using a mental model in which one of those can be held constant while the other is changed. That may be true in the classic billiard-ball model, but is not the case with orbiting bodies, as you explained far better than I did.

    I appreciate your contributions to the discussion, and certainly did not mean to imply anything even remotely similar to “you don’t know what a vector is.” I think we both share the same goal, which is to help the interested general reader gain a better understanding of these concepts.

  • Joe

    Another asteroid is set to make an even closer pass within 20,000 miles from Earth on April 13th 2029.

    Im sure the view will be great. 😀

  • duane

    OK, Victor, no problem then. Let’s move on. Or as Gonzo says, Excelsior?

    … but is not the case with orbiting bodies, as you explained far better than I did.

    Actually, I don’t think I explained that at all … but, OK.

    I think we both share the same goal, which is to help the interested general reader gain a better understanding of these concepts.

    Not me. I’m in it for myself. I enjoy the back and forth, which sometimes gives me the opportunity to attempt to discuss things that I’ve convinced myself I understand, only to find myself feeling ignorant once again when someone points out something I hadn’t thought of – like mass accelerators – or forcing me to think about the difference between billiard balls whacking into each other and a high-speed slug impacting an asteroid. So, for example, if Superman pushed on an asteroid in the direction opposite its motion, the speed would change, but its direction would also have to change in a way that would leave the orbit consistent with the asteroid’s new energy and angular momentum. You can’t change one without changing the other, a consequence of the conservation laws. Sound right to you?

  • heh…Kal-El would be better served pushing the asteroid from behind and adding to the momentum on a slightly different angle, would he not?

    those pesky conservation laws make it a bit easier to speed things up along a slightly different Path than to counter the momentum via direct opposition Force application

    think of it a sa cosmic masse’ shot…or am i missing something obvious?


  • duane

    One advantage to pushing on it from behind is that if you push it hard enough it will go onto a hyperbolic trajectory and never bother us again. Slowing it down forces it into a tighter ellipse, and we might have to deal with it again in the year 2525 — if man is still alive, if woman can survive, that is. But either way, you have to apply a force for a given time to change its kinetic energy. It takes more work to double its speed than to cut it in half.

  • ok..i follow ya there, but such a large change isn’t needed…even less if we “hit” it earlier and farther away from impact

    since both objects in question are moving…any change in any Variable will cause a miss

    i’m for the impact nudge to add acceleration and push up off the elliptic so as not to have to worry abotu it again…

    your mileage may vary


  • duane

    If you don’t like my nukular vaporization scheme, then I would opt for nudging the beast in such a way that it would eventually go into Earth orbit. Not for the resources (it’s not that big), but just so we could capture an excellent specimen and study it. Plant some retro rockets into its surface and you could steer it right into the space station’s orbit. And from Earth it would be quite the spectacle just after sunset.

  • now THAT is some bigtime ambition…

    wouldn’t lunar orbit be safer, and make for an even better view?

    but i get dibs on hollowing the bitch out and making condos…you get first choice, of course

    L5 4 lyfe!


  • duane

    Hollow it out and make it into a zero-g spherical trampoline park. Resort hotel on the surface, right next to my office, where I set the ticket prices and ponder my investment options. I’m thinking zero-g paintball a la Ender’s Game — every other Saturday — televised, of course. You could also spin the asteroid and make artificial negative gravity and walk around on the inside surface, but you go weightless at the poles. Think Olympics. I believe your buddy Heinlein had a few ideas, too.

  • oh yes…

    like a flying park, exoskeletal wing assemblages, he had worked out the mechanics for lunar gravity tho

    shoudl be even easier, but less excercise, inside an asteroid

    but i’m hip to it, sign me up for the first trip out, i’m betting ya can use a broken down old solder jockey somehow


  • Joey

    “OK, Victor, no problem then. Let’s move on. Or as Gonzo says, Excelsior?” Duane in #69.

    I’m off subject here, but allow me to explain.

    1. I read Duane’s comment to Victor.
    2. I think about moving on and the expressive Excelsior.
    3. Exclesior, means “higher” in Latin.
    4. I wiki for confirmation. It’s also the signoff of a Marvel Comic’s editor from the 60’s.
    5. I also notice it’s a Wodehouse short story.
    6. I click Wodehouse
    7. It’s a Wodehouse story on Golf.
    8. I Amazon Wodehouse Golf Stories.
    9. I read some comments
    10. I order a compilation of Wodehouse golf liturature.
    11. Wow.

    This has been a test… If had been an actual emergency you would have been instructed to tune to your local emergency radio station…..

  • Thanks for that interesting chain of events. Fascinatingly, no matter how odd the connections between the steps, the end result of the process is that Amazon makes money.

    Didn’t I read something somewhere about an Amazon exec getting interested in space launch tech? That would bring us full circle, I think.

  • Kat

    Hi:) the asteroid that is going to hit earth in 2036 is this the same sort of one that wiped out the dinosaurs? Well I think nasa will come up with a idea to get rid of the asteroid they have 29 years to think something plenty of time:) I am a belevier of god and the bible It has always said that god would destory this earth not man. this asteroid could be gods way of destorying the earth who knows, Revelation 20:9. I think we shouldnt be to afaid lets make the most of life now god bless:)

  • duane

    Kat, are you suggesting that God is blessing us by hurling a big rock at our planet? With blessings like that, who needs curses?

  • lalo

    will an asteroid hit earth eventually

  • billy

    Yes lalo an asteroid will hit earth again eventually. Question is, will we still be here by then…