Asteroid to buzz Earth this week

Four years ago, a house-sized asteroid tore through the atmosphere over Chelyabinsk, Russia, and exploded.  Shock waves shattered windows and knocked down onlookers as fragments of the disintegrating space rock peppered the Ural countryside.

This week an asteroid about the same size is approaching Earth. It will not hit our planet, but it’s coming very close. On Oct. 12, 2017, the speeding space rock, named “2012 TC4,” will skim just above the zone of Earth’s geosynchronous communications satellites and briefly become a target for amateur telescopes.

2012 TC4 measures somewhere between 10 m and 30 m wide, and on Oct. 12th it will pass 27029 miles (43,500 km) above our planet’s surface, about 1/8th the distance to the Moon. The flyby is so close, Earth’s gravity will significantly alter the asteroid’s trajectory before it exits the Earth-Moon system.

Above: An artist’s concept of the 2012 TC4 near-Earth flyby

“We know the orbit of 2012 TC4 well enough to be absolutely certain that it won’t hit Earth,” says Paul Chodas, manager of the Center for Near-Earth Object Studies (CNEOS) at JPL,”but we haven’t established its exact path just yet.”

To get a better handle on the asteroid’s orbit (and possible future encounters), an international network of telescopes will monitor 2012 TC4 as it goes by. Pinging the asteroid with its Goldstone radar, NASA hopes to learn much about the space rock’s physical properties. The space agency will even exercise some aspects of its planetary defense systems.

This asteroid is too small to see with the naked eye. However, skilled amateur astronomers using 8+ inch telescopes will be able to observe it. At peak brightness, 2012 TC4 will shine like a 13th magnitude star as it zips through the constellations Capricornus and Sagittarius, according to AstroBob, who has detailed observing tips.

Source: NASA’s


75 thoughts on “Asteroid to buzz Earth this week


    NASA unveils plan to test asteroid defense technique

    (CNN)”Humanity could face one less doomsday scenario if NASA has its way.

    On Friday, the space agency announced plans to redirect the course of a small asteroid approaching Earth, as part of the Double Asteroid Redirection Test (DART), according to a NASA press release.

    The release notes that asteroids hit Earth nearly every day, but most are small enough to burn up in the atmosphere.

    But the DART project — a joint effort between NASA and the John Hopkins Applied Physics Laboratory in Maryland — is for the asteroids that are too big to break up — those that could have severe consequences for the Earth if they hit.

    “DART would be NASA’s first mission to demonstrate what’s known as the kinetic impactor technique — striking the asteroid to shift its orbit — to defend against a potential future asteroid impact,” said Lindley Johnson, NASA’s planetary defense officer in Washington, in the press release.

    The target of the test is an asteroid system called Didymos, the release said. Didymos — Greek for “twin” — is a binary asteroid system, made up of one asteroid, Didymos A, and a smaller one, Didymos B, which orbits its larger neighbor.

    In October 2022, as Didymos makes an approach near Earth, NASA will launch a refrigerator-sized spacecraft towards the asteroids, aimed at Didymos B, the release said. When the DART spacecraft and the asteroid collide, the spacecraft will be traveling at a staggering 3.7 miles per second.

    The kinetic impact technique works by changing the speed of a threatening asteroid by a small fraction of its total velocity,” the release says, “but by doing it well before the predicted impact so that this small nudge will add up over time to a big shift of the asteroid’s path away from Earth.”

    end excerpt

    I guess 2022 is better than nothing. I hope nothing big comes along before then.

    • There would appear to be a not insignificant risk that the impact will cause one or both asteroids to partially or totally disintegrate and the resulting pieces could be on a collision course for the surface of the Earth. The only sensible way to avoid this will of course be to fake the entire thing (if it’s not fake already), generate huge amounts of publicity, achieve a 100% success, pat yourselves on the back and garner increased funding. Fakery will require modest CGI, it’s only rocks, give it to the noobs.

      Fait vos jeux.

    • NASA is taking a cautious step with this program. The kinetic energy from the impact is small compared to Didymos B and is expected to only nudge it slightly in its orbit about its bigger “twin”. The risk of fragmenting the asteroid and causing more problems is insignificant.

      • If you look at the speed of the asteroid, the speed of the supposedly intersecting lump of craft and the size of the object the “hit” window is going to be measured in something like 1/4 of a femto second, and the angular accuracy is going to need to be around 3 quadrillionths of a degree, and its all in 3d.

        I am calling fake right now. There is no positional measuring system using stars (no GPS up there guys) for the intercept craft, no radar monitoring system for the rock and no burn control system for propulsion that has anything like the right order of magnitude of control necessary for this. It is WAAAAY beyond the realms of our physical/engineering abilities, pure and utter science fiction.

        I look forward to hearing your challenges.

        BTW the first person who suggests that we can have all the super computing power and radar here on Earth and then send instructions to the craft wins my Wobel Prize. Any volunteers?

      • At the end, the craft will be guided by on board radar.
        As to the difficulty involved, we’ve (meaning humans) have already impacted a comet.

      • Dear Reverend,
        True GPS doesn’t work in orbit. Of course it didn’t work before it existed either. Yet, seafarers seemed to be able navigate across vast distances without it. They relied on things like….stars.
        Well, you should be pleased to know that for celestial navigation they still rely on the stars. In that link I attached, there are some images of the vehicle NASA is sending to hit the asteroid. You’ll notice that there is this item located on the top called a “Star Tracker”. It’s a modern-day camera linked to a computerized map of the stars. It observes the relative positions of the stars and triangulates the location of the satellite.
        Burn control?, of course we do. Those systems are used on EVERY space propulsion system. All of these things you assert don’t exist I use extensively.
        Per your assertions every space mission is a sham. So, are all the images of celestial objects also forgeries?

      • @Bryan A

        Call it “Epi”

        You spotted NASA’s in joke. Here’s the clip that explains it (right at the end).

      • The binary set of asteroids do have an Earth crossing component of their orbit. The perihelion (closest approach to the sun) is .03 AU (4.5xE6 km) closer to the sun than Earth’s aphelion (farthest from sun). This means that eventually the orbits could intersect as long as the orbital planes (inclination to the ecliptic) also align. The whole thing could go wildly wrong, but the likelihood of missing the whole thing is far greater than a catastrophic impact the could nudge this thing into earth’s orbit in say a million years.

  2. I still think the 1972 Great Fireball was the best. And since it passed through a cumulous cloud, it could only have been some 10,000 to 20,000 ft up. I did not hear much about the shockwave from this one, which should have been very noticeable.

    • That video is cropped from the one linked below which shows it passing behind the cloud. I think your video cut it to look as if it had gone thru the cloud and caused that horizontal slit in the cloud on exit. The slit is always there, well before the meteor passes it in the video.

      If it got to cloud height it would definitely burn up or explode, being at 14.7km/sec and it would therefore not exit the atmosphere. So there was no sudden explosion, just a continuous ablation at circa 50-85km. i.e. from 80, down to 50 and then back up to 80.

      This might sound like skimming or bouncing but in fact it’s just a mathematical artefact of the asteroid’s (meteor’s) hyperbolic path being fatter than the curvature of the Earth.

      These rocks (if 10 or 20 metres diameter or more) just grind through the atmosphere relentlessly at these speeds and heights. Chelyabinsk lost only 0.55km/sec over a 13-second run from 95km altitude to 27km altitude, much deeper into the dense atmosphere than the 1972 fireball. It started at 19.15km/sec and was at 18.6km/sec after 13 secs just before main explosion.

      PS, Anthony, TC4 passes 35,000km below the geostationary ring (which sits in the equatorial plane) at close approach. That is, 35,000km below the equatorial plane in the equatorial reference frame. It’s certainly not just above the orbit of the satellites and therefore sitting in the equatorial plane at close approach. I know you will have got your info from “experts” at ESA or NASA, but these people just slavishly follow their orbital sims and readouts without actually visualising how these rocks come in. They certainly have no interest in educating us on these finer points, hence this lax statement. What they actually mean is the closest radius at which TC4 passes will be just a little larger in magnitude than the orbital radius of geostationary satellites. However, that larger radius extends out at -45° Declination i.e. directly above Tasmania. It can’t occupy that position and be in the equatorial plane at the same time. It’s nowhere near the satellites (in comparative terms) at close approach.

      ESA fell fell for its own erroneous info in this regard by saying that since TC4 would be just above the geostationary ring at close approach, it would be amenable to radar observation. This implies that Arecibo and Goldstone radio scopes can see TC4 at close approach over Tasmania. They will be almost on the opposite side of the Earth at close approach. Indeed their obs schedules both show a big gap in the hours of the actual close approach. They’ll be observing TC4 when it’s around double its CA distance and more i.e. when it’s approaching the Earth and receding from it along on a path which is indeed somewhat close to the Equatorial. TC4 is close to that plane (a few 10’s of thousands of km) but it still skims under the Earth as it passes. When close in, it’s underneath us for the crucial few hours of close approach.

      • The Arecibo facility isn’t seeing anything just now. It suffered damage in the hurricane, and repairing it is a rather lower priority than food, shelter and medical care. There was talk, earlier this year,of shutting it down completely and the NSF was exploring the cheapest method of doing so.

        Folks that work there are worried the government could use the cost of repairing it as an excuse to close it.

        The ability to use active radar on space rocks is just too precious to squander.

      • Nice data. It always pays to remember all Earth based facilities are on a rotating rock. “Obs schedule” – VERY IMPORTANT. This point will be relevant in lots of stuff we do in space.

      • And here’s NASA saying TC4 is doing the exact opposite of what ESA is saying: passing under Antarctica, which is wrong as well:

        The lowest latitude TC4 passes over during the pass is -46° which happens 20 minutes before close approach. Close approach is at -45°.

        In other words, ESA and NASA between them, have managed to place the close approach of TC4 at both 0° and 90° declination while the actual close approach declination sits exactly between the two: -45°

        FYI the latitude TC4 passes over is an exact read-across to its declination on the celestial sphere in the equatorial reference frame. So a 45° south latitude ground track point, over Tasmania, for TC4 has a declination of -45° in the equatorial reference frame (ie looking up at TC4 against the celestial sphere).

        Here’s the link to NASA Horizons for the ephemeris just for sake of transparency (you have to do the inputs yourself, given below).

        Ephemeris Type: OBSERVER
        Target Body: 2012TC4
        Observer Location: 500
        Time Span: Start = 2017-10-12 Stop = 2017-10-13, Step 1 m
        Table Settings: Don’t touch this
        Display/Output: Don’t touch this

        500 is the code for the Earth’s geocentre
        Step 1 m is how it will look on the refreshed page. It means 1 minute intervals and you have to click that along with the dates.

        (Horizons is my go-to place to avoid the dreadful fake news associated with all asteroid passes).

      • The asteroid/Earth video in the above comment is actually a link to a written article 🙄. And “90°” should read “-90°” i.e. over Antarctica

      • Thanks Scute, I have not been on Horizons for a while. It would be interesting to grab the data of the trajectory today and then compare to what they say on the day and what is measured, to get an idea of how stable and accurate the previsions are.

    • Now think of a 10 km wide asteroid coming in at 14.7 km/sec.

      From the time it hits the top of the atmosphere and begins to show up until it hits the ground – 7 seconds later

      When it touches the surface, the top of the asteroid is still above the clouds in this frame.

      From the time it touches the ground until the top above the clouds is fully into the ground – 0.75 seconds.

      Bad day for you if you see this and bad day for you even it you don’t see it.

      Now make it one of the really big comets at 50 kms wide travelling at 50 kms/second.

      Bad day for all life on the planet including the bacteria living in the depths of the crust. Which means we have NOT been hit by one of these planet-killers in at least 3.8 billion years. Lucky planet.

  3. Ignored the fact we are regularly being shot at, Earthlings!
    We must focus our attention on the horrors of an atmospheric trace gas, the essential plant food CO2, increasing from 0.03 o/v to 0.04 o/v which might/maybe/possibly could cause catastrophic global warming!

    • If we Earthlings spent a healthy fraction of the money we waste on some climate science research, we really could have a reasonable chance at a planetary defence for smallish asteroids that may impact earth in the near future. And the spin off from that investment would catapult us into the future of asteroid capture and mining, space exploration and and ultimately perhaps protect us from that really big one some day. We really are sitting ducks, and I think these brushes and/or impacts are much more prevalent than we think. In the scheme of things, this issue far exceeds any threat from a slightly warmer planet supposedly caused solely by CO2.

  4. “We know the orbit of 2012 TC4 well enough to be absolutely certain that it won’t hit Earth,”

    At least on this pass…

  5. Breaking News:

    Small rock not visible to naked eye has trajectory altered by the mysterious force of gravity. WUWT contributors wonder what effect a continuous force field might have on a rather more massive ensemble of gases.

  6. Why the need for hardware in space? Surely NASA can simply adjust the position and velocity data, model gravity using advanced interpretations of physics, and use wishy thinking to project the nasty asteroid to follow another path. If all else fails they can form a 97% consensus. That’ll fix it!

    Maybe all the data fiddling and propaganda techniques will finally pay off.

    Oh wait. This is a real problem.

  7. I think a laser beam powered by a Solar Power Satellite (SPS) would be better. You don’t have to match orbits with the asteriod, just aim and fire.

    And when this device is not repelling asteriods, it can be used to accelerate small probes to all the planets and other bodies in the Solar System.

    My favorite design for an SPS would be a balloon-shape with solar panels covering the outside. You wouldn’t have to aim this design. Half of it would always be in sunlight. It would take about 40 pounds of Helium to inflate a one-mile-diameter balloon in orbit.

    • Surely you don’t intend to mount rigid solar panels onto an inflatable sphere? I get fidgets think about how to package or deploy even a smallish one (100m dia) let alone one a mile in diameter coated with panels. And, how you would account for thermal strains, or dynamic stability during maneuver(I assume you’ll want to aim the laser). What keeps it round after it gets machine-gunned by MMOD (micro-meteoric orbital debris)?
      Inflatable space structures are great things, but they are not mere balloons.
      You’re in my playground now… ;-)

      • MMOD is easily dealt with, just paint the outside with that special paint or clear varnish they use on the ISS. Its been up there years and if you look at outside video of the recent spacewalks or docking you can clearly see the logos and everything are 100% just fine, no evidence of pitting or abrasion at all. All still pristine, as indeed is all the hardware, no holes or pitting seen.

        I like your playground but I have bought my OWN bat and ball… ;-)

      • “Surely you don’t intend to mount rigid solar panels onto an inflatable sphere?”

        The original proposal was to use thin-film, flexible solar panels. Of course, back then, thin-film solar panels were just being developed, so it was more of a thought experiment than anything else.

        I presume we have made progress on thin-film solar panels since then, but I’m not sure they are yet suitable for this application.

        I just liked the simplicity of the design. Blow it up like a balloon, and no aiming necessary.

        With a suitable thin-film solar panel, at a reasonable cost, I think this would be a good idea. I don’t know how close we are to getting there, though, since I haven’t kept up with the progress in that area for quite a while.

  8. If NASA intends to hit it directly with an object, why not an explosive one that will send it into many small pieces?

    • Because an uncontrolled explosion will have unknown effects. This is just a test to see if we could even accomplish such a task, and how well we can do it. Baby steps. For the first test, it’s not always a good idea to send a bull into the china shop to see how well the displays are anchored.

    • Good luck exploding something into something moving at 15 – 50 kms/second.

      Secondly, blowing it into smaller chucks between 10 metres to 1 km wide just means that every place on Earth gets hit by a regionally devastating asteroid. Bye.

      The only option is move its trajectory and keep it whole. If it is something moving at 15 kms/second, changing its trajectory takes an incredible amount of energy. As much as the energy as is caused when it would otherwise impact the Earth.

      Let’s say the Chicxulub dinosaur-killing asteroid. Energy require to move it – 2,600 Tsar Bombs (the 50 megaton biggest hydrogen bomb ever exploded on Earth). Now try and hit 2,600 Tsar Bombs at something moving at 15 kms/second. Take your time and make them count.

      • The only option is move its trajectory and keep it whole. If it is something moving at 15 kms/second, changing its trajectory takes an incredible amount of energy. As much as the energy as is caused when it would otherwise impact the Earth.

        Sorry Bill, your physics is not good.

        Firstly energy is not “caused” , maybe you meant released. That is the amount of energy needed to STOP it dead in its tracks not to deviate its path.

        You would presumably try to change the component of its velocity perpendicular to its trajectory ( directly heading towards the Earth ), not try to change its forward component.

        The only way its speed matters here is how hard you need to hit it to deflect it enough , early enough to change its path by an Earth radius and avoid a direct collision.

      • If it is something moving at 15 kms/second, changing its trajectory takes an incredible amount of energy. As much as the energy as is caused when it would otherwise impact the Earth.

        Nonsense. That much energy would only be required to impart delta-v of 15 km/s, and nowhere near that much delta-v would be needed to change the trajectory enough to miss the earth.

      • A lot depends on how large the chunks are and how wide the dispersal pattern.
        If the vast majority of the debris misses the earth, it’s a win.

      • This is elementary physics. The CG of the asteroid in question will continue to travel along the prescribed orbital path. If additional force alters this path then the CG will follow that path. I use the term CG because if the asteroid is fragmented the sum of all the momentum vectors will be the center of mass moving along the orbital trajectory. Some pieces will fly wildly apart yet the sum of the whole must continue along the path.
        As to how much energy is needed that all depends on how far away, how fast and how much do we need to deflect it?
        Cautionary point: if we fragment it we should assume that we will get hit with at least some of it. Anyone who has ever been in a snowball fight will know this. When you try to stop a snowball with a baseball bat where does the snow go?

        This is the big issue with every concept on comet/asteroid defense. Unless we know the varying density and structural make-up of these bodies, we cannot know what any impacts will do to them. Will they fragment, swallow and absorb the impactor. or will the impactor pass right through like a bullet through paper?
        The same applies to laser beams. Will the surface absorb the energy, heat up and spall, or do nothing?

    • I saw that movie, Bruce Willis did it. I think. I fell asleep before the end. And I had to go home and my friend didn’t keep the DVD. Did he do it in th eend?

      • Oh, c’mon. Bruce Willis has been in many good movies. Armageddon is not one of them, though. I blame Ben Affleck and the writters for the bad screenplay. J.J. Abrams was one of them, btw.

    • I think the film where they dug a hole in the asteroid and inserted the bomb is the closest to reality. If you explode a nuclear warhead in space, without the atmosphere to create a shock wave, maybe it would just melt the surface of the asteroid, which might move it some, unless there were also ice on it, that it could vaporize to create some more differential pressure to that could also move it some more in its trajectory. I haven’t thought this all out, but just exploding something next to it doesn’t seem like it would be the best idea to move it or break it up.

    • Yes, but most of the reply discussion is ignorant of how to do it. It would not be an impact detonation. It would be at some distance suitable for accurate fuzing (timing). A nuclear detonation produces an immense quantity of X-rays. In the atmosphere, these X-rays are absorbed to form a ferociously hot plasma, which then begins to emit black-body radiation. In space, there is no absorption and the X-rays propagate without interference, to incide on any nearby body. The initial photons would have enough energy to ionize the surface of the body and form a plasma. The plasma would then absorb the remaining X-rays. Because this is all happening on a nanosecond time scale, the plasma is inertially confined and effectively is at constant volume, thus constant density. All the increasing temperature therefore produces increasing pressure–all across the exposed surfaces of the nearby body. This imparts impulse, which will change the momentum vector, and thus the trajectory.

      This is the famous “X-ray slap,” familiar to those working in military space studies. There is no way for it not to work. It is irritating to see discussion of airy-fairy gravitational “attractors” and suchlike as means to deflect asteroids, when the only practical method is available for the purpose. It would require alteration or abrogation of the Outer Space Treaty, but treaties are made to be broken, right? Divert the asteroid and spent a few decades whining and arguing in court afterward. Or not. Take your pick.

    • Most of these asteroids are spinning/rotating, so you can’t attach something to it with any accuracy. I’m not saying blow it to pieces. It depends on how far away the nuclear explosion is from the asteroid. Far enough and the asteroid will not blow apart but alter it’s course enough to avoid a collision with earth…

  9. “We know the orbit of 2012 TC4 well enough to be absolutely certain that it won’t hit Earth,” says Paul Chodas, manager of the Center for Near-Earth Object Studies (CNEOS) at JPL,”but we haven’t established its exact path just yet.”

    It’s refreshing to read a slice of real science for a change.

  10. Oh well, it was fun while it lasted—-for some folks, maybe. Science was never going to save us anyway. And faith? Why we’ve chewed it to bits, like a bulldog tearing a rag. Better out with a bang or a thump than a whimper. I always figured the end of humanity would be a SIW (Self Inflicted Wound – an acronym from the trenches in WWI) but it just might be a stray shot. After all, a lack of focused, personalized intention never lessened effect. Lt. Henry Shrapnel perceived that early on, circa 1784.

  11. A little poem for ‘2012 TC4’
    Big potato in the sky
    Can I poke you in the eye
    Big potato in the sky
    Will it hurt you will you cry
    Big potato in the sky
    Can you teach me how to fly

    • Asteroids – Have we had our chips?

      Big potato in the sky
      Is it time to say goodbye
      Big potato in the sky
      Is it true we gonna die
      Big potato in the sky
      I have a plan, it is quite sly
      Big potato in the sky
      My NASA friends have just used pi
      Big potato in the sky
      Your days are numbered so say I
      Big potato in the sky
      Push you away, that’s what we will try
      Big potato in the sky
      The plan is good, taxpayers will buy
      Big potato in the sky
      Equations all done, just don’t pry
      Big potato in the sky
      We have a plan, Elon’s the guy
      Big potato in the sky
      Can you teach me how to LIE

      • Is one of you Dr. Seuss,
        now tell the truth and don’t lie to me,
        right here on WUWT for everyone to see.

    • This unfortunate period in the history of mankind (belief in CAGW) will be remembered by future school children as the time of..


      Copywright- RevBaj2017

      I would expect it has been used before but cannot remember seeing it.

  12. Good job it isn’t climate scientists doing the calculations and making the near miss prediction, or I’d be digging a very deep hole in the garden and storing water and food.

  13. The fascinating extraterrestrial impact event over Chelyabinsk, Russia on 15 February 2013 was not captured on myriad cameras choreographed by prescient prize-winning scientists, august professors or Nobel laureates. Alas, even the boffins let the side down. No, the evidence was inadvertedly collected by a bunch of amateurs armed with dash-cams, doing something else entirely: simply going about their daily lives. The cognoscenti and paid help didn’t even see it coming because they were singularly focused on asteroid 2012 DA14. Are we bound for a repeat?

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