back to article Confirmed: Asteroid shoved by Earth crash probe DART

NASA's DART spacecraft successfully smashed into asteroid Dimorphos with enough impact to alter the rock's orbit, scientists confirmed on Tuesday. Dimorphos, described as a moonlet, orbits larger asteroid Didymos more than 11 million kilometres (6.8 million miles) away from Earth. Before DART struck Dimorphos on September 26, …

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    1. Jason Bloomberg Silver badge

      Job well done but "You were only meant to blow the bloody doors off" does come to mind.

  2. Winkypop Silver badge

    Great job NASA

    But there goes their No Claim Bonus!

    1. Benegesserict Cumbersomberbatch Silver badge

      Re: Great job NASA

      Not at fault - some idiot in a red Tesla swerved right in front of them.

  3. Threlkeld

    Follower pics?

    There was a following probe that was supposed to photograph the impact, but I have not seen any images from that. Did it fail to work? Or was it photobombed by a LGM?

    1. DJO Silver badge

      Re: Follower pics?

      The Italian cube sat was just behind it and got some pictures of the impact but the follow up ESA mission to image the crash site has not even been launched yet.

      1. FrogsAndChips Silver badge

        Re: Follower pics?

        I'm curious about what the followup mission is expected to find that they haven't already obtained from the existing pics and orbit observations?

        1. DJO Silver badge

          Re: Follower pics?

          "By gathering data close-up, Hera will help turn DART’s grand scale impact experiment into a well-understood and repeatable deflection technique."

    2. imanidiot Silver badge

      Re: Follower pics?

      You're thinking of LICIAcube. The first pictures have been downloaded but it's a slow process and only a few of them have been released at this time

      ( Due to the small size of the cubesat and the distance involved, downlink speeds are very low and it'll take a few more weeks to get all the data back.

    3. Eclectic Man Silver badge

      Re: Follower pics?

      NASA's APOD recently showed a video:

      "Explanation: What happens if you crash a spaceship into an asteroid? In the case of NASA's DART spaceship and the small asteroid Dimorphos, as happened last week, you get quite a plume. The goal of the planned impact was planetary protection -- to show that the path of an asteroid can be slightly altered, so that, if done right, a big space rock will miss the Earth. The high brightness of the plume, though, was unexpected by many, and what it means remains a topic of research. One possibility is that 170-meter wide Dimorphos is primarily a rubble pile asteroid and the collision dispersed some of the rubble in the pile. The featured time-lapse video covers about 20 minutes and was taken from the Les Makes Observatory on France's Reunion Island, off the southeast coast of southern Africa. One of many Earth-based observatories following the impact, the initial dot is primarily Dimorphos's larger companion: asteroid Didymos. Most recently, images show that the Didymos - Dimorphos system has developed comet-like tails."

  4. Sgt_Oddball

    Smashing success then?

    You could even say they've made an important impact on the field, let's just hope it's no one hit wonder....

    I'll see myself out, mines the one with the Prof. Brian Cox book in the pocket.

    1. b0llchit Silver badge

      Re: Smashing success then?

      Unfortunately, the asteroid remains rock solid and is still cemented to its big parent rock. Maybe they simply paved the way for a rocky planet to be hit. Death by one big rock or gazillions of pebbles. Medusa is calling.

  5. Pomgolian

    Has anybody thought..

    What the effect was going to be on the larger Didymos asteroid? Surely there is some effect now that Dimophos has less mass? Gravity or something? Is it now on a collision course? All this just as Bruce Willis hangs up his hat. We're doomed, I tell ye, doomed!

    1. This post has been deleted by its author

      1. Pomgolian

        Re: Has anybody thought..

        "I think. I am neither a mathematician, nor an astrophysicist."

        But every second counts! 18 seconds at the speed of light is 3.348 million miles which is a lot more margin for error than I'm comfortable with. Then again at that speed it's all relative. I'm no physicist either, and certainly no Einstein.

        1. This post has been deleted by its author

        2. imanidiot Silver badge

          Re: Has anybody thought..

          If we ever encounter space rocks moving at relativistic speeds we'd certainly have a lot of problems (or never have problems again probably). At those speeds even a tiny bit of rock can be a planet killer.

          1. Jonathan Richards 1
            Thumb Up

            Look on the bright side...

            ...if a space rock ever comes at us at near-light speed, then we literally won't see it coming.

      2. imanidiot Silver badge

        Re: Has anybody thought..

        It's not even an 18 second change on the orbit of 770 days I think as most of the velocity change of dimorphos is it's orbital velocity around the parent body, for the total system I think that only equates to a small change in angular velocity so likely it'll only change the rotational speed or wobble of Didymos. It's orbital period is probably less affected.

      3. brainwrong

        Re: Has anybody thought..

        Err, no.

        The change is referring to the orbital period of the Didymos / Dimorphos system. They both orbit a common centre of mass with the same orbital period, which just reduced by 32 minutes.

        The orbital velocity of Didymos (relative to their common centre of mass) will have changed by 1/104 of that of the change of orbital velocity of Dimorphos, because it's more massive and closer to the system's common centre of mass.

        I'd be interested to know what the change of the orbit of the Didymos / Dimorphos system around the Sun is, but that wasn't the objective of the mission and will take a much longer observation time.

        According to wikipedia, the two bodies were tidally locked. I imagine that lock has been broken (somewhat), and the eccentricity of their orbit also changed. This is surely worth investigating up close for an extended period of time, to learn something about how binary asteroid systems, and contact binaries, come to be.

  6. ThatOne Silver badge

    Now if we only had a reliable means of spotting them early enough...

    > Warning time is really key here in order to enable this sort of asteroid deflection

    Great, but given our currently rather limited means of detection, we can only hope detecting any potential hazard early enough (years!) to do something about it. Detection needs to get an upgrade if we don't want to go the way of the dinosaurs.

    Figuratively speaking, yes, I know about "Kentucky Fried Dinosaurs"™.

    1. Swarthy

      Re: Now if we only had a reliable means of spotting them early enough...

      Even acknowledging the existence of "Kentucky Fried Dinosaurs"™, I would argue that "going the way of the dinosaurs" is still a fate to be avoided.

      Imagine either the corvids getting their own back, or the cephalopods filling the gap and having "Kentucky Fried Primate" on the menu.

  7. Anonymous Coward
    Anonymous Coward

    Not the first time

    > First time humanity has successfully shifted the orbit of an astronomical object

    Not quite. Any time a spacecraft has availed of a gravity assist slingshot around another planet, that body has slowed down in accordance with Newton's Third Law. Although to paraphrase Arthur C. Clarke, it'll be a long time before humanity has instruments sensitive enough to measure such a change.

    1. Eclectic Man Silver badge

      Re: Not the first time

      Also "Deep Impact", the NASA mission to study the internals of Comet Tempel 1:

      "The primary mission of NASA's Deep Impact was to probe beneath the surface of a comet. The spacecraft delivered a special impactor into the path of Tempel 1 to reveal never-before-seen materials and provide clues about the internal composition and structure of a comet."

  8. PerlyKing

    BBC coverage

    I loved this part of the BBC's coverage:

    It saw the refrigerator-sized Nasa satellite drive straight into Dimorphos at 22,000km/h (14,000mph), destroying itself in the process.

    Emphasis added. See icon for details.

    1. LateAgain

      Re: BBC coverage

      Bloody Big Comet?

  9. Neil Barnes Silver badge

    Bruce Willis

    Did he sell his image rights to NASA for future missions? Enquiring minds want to know!

  10. heyrick Silver badge

    How big a rock is a kamikaze probe able to move?

    For the ones we ought to be worried about, would it not be a better test to land on the thing, spin around, then fire up the thruster to push it out of the way?

    1. imanidiot Silver badge

      The problem with that approach is that you need to bring along an enormous boatload of fuel to slow down and then move the object. Whereas due to the wonders of the Oberth effect it's possible to impart a lot more kinetic energy into your spacecraft for the fuel burned.

      There is also the problem that most of these space rocks aren't really hard rocks but more like giant gravel piles floating through space. There was even some worry that Dimorphos might have been too loosely bound for the impact to work and that the probe might just blow straight through. Certainly if you were to attempt a "land and push" approach you'd have to take into account that you need a lot of surface area to avoid the probe from burying itself deep into the surface potentially damaging itself in the process. Alternatively it's been proposed that doing so on purpose might allow the probe to fire a lot of surface material along with the exhaust gas of the thruster, increasing it's impulse and making it more effective, but if we're talking a (very near) earth impactor then this might just result in a long term hail of smaller rocks raining down into our planets atmosphere. Potentially (slightly) better than one huge big honking one, but certainly not going to be enjoyable.

      1. Eclectic Man Silver badge

        re: Rotation

        Another issue with 'land and push' is that all astronomical objects are spinning. The Earth rotates once every 23 hours and 56 minutes on an axis that wobbles slightly. Asteroids similarly can have quite complicated rotational motion. So co-ordinating the pushing with the rotation would be crucial and much more complicated than simply crashing.

        1. ThatOne Silver badge

          Re: re: Rotation

          Nonsense! You both forget movie physics basics: Spaceships don't need fuel (no fictional spaceship I've seen had enough fuel capacity to even fly from New York to Los Angeles), alien planets/asteroids/whatevers' surfaces are as hard as any studio floor can be, and all stellar bodies only move when it's convenient, the rest of the time they stay put, allowing for easy targeting and navigating.

          So, the dropping of a tiny cubesat with a huge nozzle extension (to look badass) which unfolds into a huge engine and pushes the asteroid out of our solar system is totally credible. I'm sure ACME Corporation sells some.

          1. Eclectic Man Silver badge

            Re: re: Rotation


            You're correct, movie physics 101: just point your spacecraft at the orbiting object you want to get to, and 'hit the go stud' and you'll get there. Because orbital mechanics is exactly like driving a car*.

            movie physics 102: All interstellar spaceships power life support systems for the the entire journey, even though the entire human population and living cargo is in deep hibernation**.

            movie physics 103: you get 'gravitational attraction' everywhere in your spaceship, despite actually having to use a centrifuge for the crew quarters and exercise area***

            Oh well, I'll just mumble to myself from now on.

            *SPOILER ALERT - 'Gravity' with George Clooney.

            **SPOILER ALERT - 'Passengers' with one of the Chris's (Pratt, Pine, Rock, they all look the same to me ;o) )

            ***SPOILER ALERT - '2001 - A Space Odyssey' (There is gravity in the pod bay when Dave and the other astronaut discuss de-commissioning HAL, but it cannot be part of the centrifuge system as it has external doors).

  11. Pirate Dave Silver badge

    "We conducted humanity's first planetary defense test,"

    Sounds like to opening line to a post-apocalyptic sci-fi movie...

  12. KBeee

    DARTs and Pool?

    I recall an episode of Red Dwarf where Lister had to simulate the angles needed to deflect an object from a collision by getting drunk and playing pool.

    Are all earth saving tactics going to be based on Pub games?

    1. Pomgolian

      Re: DARTs and Pool?

      It's as good a plan as any - have a nice cold pint, and wait for this all to blow over.

    2. John Miles

      Re: DARTs and Pool?

      That's the one with Talkie Toaster - the episode is White Hole (wiki link)

      1. Jimmy2Cows Silver badge

        Re: White hole

        What is it?

        1. DJO Silver badge

          Re: White hole

          I've never seen one before -- no one has -- but I'm guessing it's a white hole.

  13. anonymous boring coward Silver badge

    The inhabitants of Didymos are really angry now.

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