A Sunlight Shifted Asteroid Might Hit the Earth in 2068 with a 1200 Megaton Impact

Dave Tholen and collaborators have detected light from the sun is moving the 300 meter near-Earth asteroid Apophis by 170 meters per year. This acceleration means that Apophis might hit the earth in 2068.

Detailed analysis on the next close pass in 2029 will determine if Apophis is a risk.

The Sentry Risk Table estimates that Apophis would impact Earth with kinetic energy equivalent to 1,200 megatons of TNT.

The highest probability of impact is on April 12, 2068 and the odds of an impact on that date, as calculated by the JPL Sentry risk table using a March 2016 solution, are 1 in 150,000. The calculations are that it should miss the Earth by 150 million kilometers. The acceleration should only shift the asteroid by about 122 kilometers.

Assuming Apophis is a 370-meter-wide (1,210 ft) stony asteroid with a density of 3,000 kg/m3, then if it were to impact into sedimentary rock, Apophis would create a 5.1-kilometer (17,000 ft) impact crater.

A deep-water impact in the Atlantic or Pacific oceans would produce an incoherent short-range tsunami with a potential destructive radius (inundation height of about 2 meters) of roughly 1,000 kilometers (620 mi) for most of North America, Brazil and Africa, 3,000 km (1,900 mi) for Japan and 4,500 km (2,800 mi) for some areas in Hawaii.

SOURCES- Wikipedia, University of Hawaiʻi Institute for Astronomy, Sentry Risk Table, B612 Foundation
Written By Brian Wang, Nextbigfuture.com

45 thoughts on “A Sunlight Shifted Asteroid Might Hit the Earth in 2068 with a 1200 Megaton Impact”

  1. "Paint" implies pigment in solvent, which is a convenient way for us to apply pigments on Earth. But carrying solvent to an asteroid just to throw it away would be pretty darned expensive. (Setting aside that the solvent would vaporize between the nozzle and the rock, and the asteroid would just be sprayed with dry particles of paint.) That's why I suggested sputtering; You only need a few atoms thick of aluminum, and given months or years to do it in, the required power supply wouldn't be prohibitive.

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  2. Your tee-shirt analogy is particularly apt.  

    An important quantitative factor is figuring the face-surface area of the bolide, then using that area … how much mass is the cylinder of air 'impacted' by the passing bolide RELATIVE to the mass of the bolide itself.  

    Of course one can do the calculation in 'specific mass, relative' terms on just one m² of the thing.  

    D = 300 m, which is the transept distance
    1 m² specific face area; 

    1 m² of air pressure at 100,000 Pa or 10,000 kg/m² or 10 ton/m². 
    300 m × 1 m² = 300 m³ … × 3000 kg/m³ = 900,000 kg → 900 ton/m²
    … for the bolide. 

    Relative difference is 900:10 or 90× more mass than displaced air assuming no ablation. From there it is fairly straight forward to reason-out that the MV of the thing only loses about ¹⁄₉₀th incoming velocity to air. So it impacts Planet Dirt with an appreciable energy. (1 – ¹⁄₉₀)² = 97.8% of incoming kinetic energy.  

    For smaller objects (like the 17 m Chelyabinsk) the calcs have to be more energy than momentum based to be accurate. I've done those too … but the derivation doesn't as easily 'fit in the margin'. LOL.

    ⋅-=≡ GoatGuy ✓ ≡=-⋅

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  3. 1000ish Falcon Heavy launches to deploy a train on nukes to detonate on one side opposite the sun facing one. Maybe we can pack 10000 or more 1-5 Mt nukes in all the FHs, the world already hae most of what we need on the nuke end. Should be within our capabilities, FH can send 5 tons past Mars with reusable side boosters. Detonate them in a train a few minutes apart from one another a few kms from the asteroid surface. Thats about 100 gigatons of force. 5+ years warning, start intercept 3 years out. That should nudge do it. Likely about 1.5 trillion USD in cost over 3 years with current tech.

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  4. With a collision that big, I suspect that the energy shed to the atmosphere just adds to the total energy radiating out from the impact site, so it doesn't really matter whether those GJ were deposited into the air, hence into a streak of plasma, hence into a heat blast moving out from the plasma, or whether that same amount of energy is deposited into the ground, which vaporises, turns into plasma, and then turns into a fireball that radiates a heat blast out.

    Like if someone shoots you, it doesn't really matter if the energy is deposited directly into your skin, or into your t-shirt that then transmits it into your skin.

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  5. Yeah, but we won't have an exact course that is aimed directly at the centre of the Earth.
    It'll be a probability curve of likely trajectories, with Earth sitting at some point within the "possible" range.
    So if the centre of that probability curve is not centred on the Earth, there will be a direction that increases the probability of a hit, at least until you go over the middle of the curve and then start moving away.

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  6. '.. involving an absolute minimum of delta V'
    Just because it passes close to Earth doesn't mean you don't have to burn a lot of fuel to match velocities – and far more to put the rock in a useful orbit.

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  7. With roughly 1 trillion in USD cost for launch vehicles at current tech, we can hit it 3-5 years out with our current nuke stockpile at a total of 50+ gigatons of force for roughly 1T in cost (That is 500 to 1000 Mt, St Helens eruptions of force), I think that would nudge it enough. At 100 million per launch for 5 tons to Mars, 700-1000 Falcon Heavy launches packed with nukes should do it. Detonate in succession a few miles and minutes apart to one side of it in a train of nukes. Sort of a nuclear pulse engine.

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  8. Then… thinking further, with a kind of inevitability that is neither satisfying nor exciting, one can abstract that to a few thousand kg of water; like aluminum, it can be 'exploded' with spark. Very high accelerations.  And it potentially can be maintained as a liquid.  

    Or alcohols. Somewhat polar and conductive.  Sparks and capacitors would work.  

    Or crygens.  
    Or mercury. 
    Or a whole host of benign and stable things like propane.  

    Sign…
    There are very few new ideas that are good ideas. 
    ⋅-=≡ GoatGuy ✓ ≡=-⋅

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  9. Hmmm… 

    Another almost-no-parts-moving gambit would be to include several tons of aluminum wire and a few hundred kg of hermetically sealed ultracaps. charge up the caps, discharge thru wire. It explodes (literally).  While half of the stuff ends up going back at ya, the rest heads out at speeds of potentially thousands of meters per second. F = ma, so … = Δ /Δ .  

    Actually, ironically, it is the 'half' that comes back at yah that in turn imparts a wee bit of N⋅s of momentum change to the big rock. 

    Its kind of fun to try with aluminum foil.  Pound a couple of nails in a pine wood board, and hook in a standard lamp cord to them; suspend a strip of aluminum foil a couple of centimeters wide around the top of the nails.  

    Plug it in and be prepared for a festive pop!

    Oddly as a kid, I did this dozens of times and never blew any my parent's 19th century wiring fuses.  Old screw-in things.  

    Shocking! LOL.

    I also did this with the same apparatus, but with a well charged 33,000 µF, 200 volt bank of capacitors, DC charged.  

    450+ joules, at 165 V charge.

    Now THAT was a bang. In a vacuum, I'm sure my bedroom plasma gun was winging along at many kilometers per second. Having next-to-no mass, the air stopped the itsy bits fast, turn all into a deafening POP  

    Unlike carrying TNT or something like that, it is not 'armed' until the capacitors are charged.  So, pretty benign to shoot at the rock. 

    ⋅-⋅-⋅ Just saying, ⋅-⋅-⋅
    ⋅-=≡ GoatGuy ✓ ≡=-⋅

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  10. Agree, 99942 Apophis is not so much a threat, as an opportunity. It's a prototype asteroid habitat, involving an absolute minimum of delta V.
    However, other than PV, waste heat radiators, chemical refineries, and storage, it's inside should be developed rather than it's outside. Anything that is sensitive to ionizing radiation, high, or low temperatures, and is not explosive, or toxic would be better inside. There is plenty of matter(shielding) to make long term stays in space radiologically feasible. There is also plenty of room for a centrifuge for sleeping, however much additional time it takes to make zero gravity endurable for long stays.
    The asteroid is believed to be a LL Chondrite containing around 20% iron, which is probably good for a first go. Enough Iron, and Nickle for steel, with plenty of silicon, and phosphorous for PV, and oxygen for breathing, and reaction mass.
    Eventually, once larger asteroids are in use as habitat, it would make a good cycler station for Earth-Mars transit.

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  11. Lantz would be enthusiastic about that; "Slingers" were to be a common propulsion technique in O'Neill's proposal.

    My thought was that aluminum foil has no moving parts that need to keep working for years on end.

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  12. Or,maybe solar cells, motors and 'slings'?  

    Creepy crawlers rummage around at glacial speeds, picking up 'stuff' to deliver to the slinger.  Solar cells provide plenty of energy.  It mightn't seem like much, but chucking a few kilograms an hour, continuously, at a few hundred meters per second can over time deliver a lot of newton-seconds to a wandering asteroid.  

    Let's see.  U = Δ = 1 kg × 100 m/s = 100 N⋅s, per hour. 

    300 m diameter = 150 m radius
    V = ⁴⁄₃ π ³
    V = 14,000,000 m³.

    Density = 3000 kg/m³
    Mass = 42 billion kg. 

    The Δ per day is thus 2400 N⋅s ÷ 40,000,000,000 = 5.7×10⁻⁸ m/s, which is 0.005 m/day, per day of acceleration. 202 days of acceleration buys you 1 m per day of Δ

    Given a 10 year window of 'moving the rock', doing this for merely 7 years can move the stone some 6,500,000 m or 6500 kilometers from its nominal track.  

    Motors, solar cells, and creepy crawlers.

    ⋅-⋅-⋅ Just saying, ⋅-⋅-⋅
    ⋅-=≡ GoatGuy ✓ ≡=-⋅

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  13. Aluminum foil. This calls for a load of aluminum foil. Change the albedo, change the path.

    Though maybe aluminizing it by sputtering would be easier.

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  14. I don't think there is a wrong direction… Earth might look big, but hitting something with it requires a fair amount of precision. If it would hit, pushing it in any direction will do the trick.

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  15. Yeah,Terra and terra are exact translations of Earth and earth.

    Terre in French
    Tierra in Spanish
    Terra in Portuguese and Italian

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  16. It's already being pushed around by sunlight, so simply changing the albedo should be enough. Providing you don't change it in the wrong direction!

    Only 300 m in diameter. So about 70 thousand square metres on one side. 70 tonnes of paint gets you a 1 mm thick layer. That, plus a robot with a spray gun and a drive to get you there is easy for a SpaceX Starship.

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  17. Radiation is the reason the simple Island 3 design is the way it is, the structure (glass and Al) requirement is the *same* as the radiation (mass) requirement, so 2-5 mile dia, a little large for first effort! At the other end, Al Globus has defined ELEO O'Neill designs that thus need no radiation shield. In between, you generally have slowly counter rotating shell, but whatever, it is made from lunar/asteroid material. "a hollow craft" was what Azimov had invented closest to O'Neill, but the point he made is that it is a totally different idea. And most asteroids would not hold up under air pressure, so you may as well just re process the stuff to be what you want. A highly counter intuitive but critical outlook. If you want to be *on* something, you must give a reason. Don't fall for gravity. Space is the Place.

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  18. perhaps. but the point is to 'repurpose' the mass into something rather than a 0.00001% (@10% extinction) threat- whether its a hollow craft in an adobe 'style' or similar or just feedstock for other things. It seems to me that O'Neill has not yet figured out radiation risk to be a viable relocation venue (unless you remove the windows).

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  19. If you use the material to make your own structure, usu a bubble sort of thing, you get far more 'sprawl' than 1/4 mile object surface. This is EXACTLY the topic that Azimov and O'Neill were on when Azimov used the term "planet chauvinism", the *gut* assumption that we should be *on* something.

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  20. I'll go with 'woke'. 'Proud Boy' began as a joke, and circumstances turned them into something more. Woke was supposed to be taken seriously from the beginning.

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  21. I recommend we excavate, utilize, inhabit, and develop this 'threat'; on its next pass circa 2029. What better way to say 'we win' than setting up a mine, Wendy's, nuclear 'nudge' thrusters and casino as we 'sprawl' over this rock. Not clear on what consumables, etc., are present on this stony 1/4-mile projectile. How could a Starship rendez-vous with such a trajectory and deploy agents of 'exploitation'?

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  22. "we will need a lot more infrastructure in space to deal with menaces like this one". To state the obvious, the ability to nudge a large asteroid away from a collision should also allow capturing smaller ones, to make the very infrastructure you mention.

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  23. Also… that illustration is SO BENIGN! The 'color' would be brilliant, blinding blue-white. Hotter black-body temperature than Sol. The ejecta-cone would rise well out of the atmosphere. Talk about a 'nuclear winter'. This'd be the real deal. GG

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  24. Dunno; maybe its relative velocity to Terra (AKA "Dirt" in Latin) is less than the surprise-surprise-surprise rock that caught Russia by surprise a few years back. You know, Chelyabinsk. 17 meter diameter, 500 kt of blast-and-light energy.  65 km up, or something like that.  Shards fell into a local (big) pond.  

    See, we know that E = ½mv² (the kinetic energy formula). IF the relative velocity is about the same, AND the relative density the same, then a 300 meter rock would be

    | k = (D₁ / D₀)³
    | k = (300 ÷ 17)³
    | k = 5,500× as big. 
    |
    | k × 500 kton = 5,500 × 500 = 2,750,000 kilotons or 2,750 megatons

    That's rather larger than the number estimated in this article. 
    Hmmm… velocity? density? fudge factor?  

    Whether the thing 'craters' in the ocean, the Antarctic, the middle of Africa or Russia or Canada … the 'hole' is almost always about 20 to 25× the diameter.  That'd be 6 to 7 km. It'd also 'dig down' to 15× its diameter before becoming subsonic … so, 4.5 km deep.  

    In the ocean that's a LOT of water displaced. Quite a mountain-load. Seismically, a M 9.3 if my calcs are right. So, a substantially larger tsunami than Sunda or Japan's recent one.  

    ⋅-⋅-⋅ Just saying, ⋅-⋅-⋅
    ⋅-=≡ GoatGuy ✓ ≡=-⋅

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  25. With that estimated date of arrival, a gentler approach might be better.

    First give more attention to the orbital calculations and be really sure it's a threat.

    If it is, then start planning and building gravity tractors or some laser pushers or a mix of them, something that gradually changes the orbit to make it safe.

    What matters, is that we get our act together and start taking asteroids seriously, and continue going to space in mass to prepare.

    Because we will need a lot more infrastructure in space to deal with menaces like this one.

    But specially, ignore the whining of the Luddites that want to forbid any human utilization of space, because it alters the sanctity of dead rocks with our filthy colonialism or some such.

    Article about the Luddites in question: https://www.nationalreview.com/2020/11/wokeists-assault-space-exploration/

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