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More results from DART impact of Dimorphos

Didymos and Dimorphos as seen from Earth
Click for movie.

At a science conference this week scientists provided an update on the changes that occurred to the asteroid Dimorphos after it was impacted by the DART spacecraft in September, shortening its orbit around the larger asteroid Didymos by 33 minutes.

The image to the right is a screen capture from a short movie made from 30 images taken by the Magdalena Ridge Observatory in New Mexico, and part of a new image release of the asteroid pair.

It shows the motion of the Didymos system across the sky over the course of roughly 80 minutes, and features a long, linear tail stretching to the right from the asteroid system to the edge of the frame. The animation is roughly 32,000 kilometers across the field of view at the distance of Didymos.

According to the scientists, the impact displaced more than two million pounds of material from Dimorphos.

Observations before and after impact, reveal that Dimorphos and its larger parent asteroid, Didymos, have similar makeup and are composed of the same material – material that has been linked to ordinary chondrites, similar to the most common type of meteorite to impact the Earth. These measurements also took advantage of the ejecta from Dimorphos, which dominated the reflected light from the system in the days after impact. Even now, telescope images of the Didymos system show how solar radiation pressure has stretched the ejecta stream into a comet-like tail tens of thousands of miles in length.

Putting those pieces together, and assuming that Didymos and Dimorphos have the same densities, the team calculates that the momentum transferred when DART hit Dimorphos was roughly 3.6 times greater than if the asteroid had simply absorbed the spacecraft and produced no ejecta at all – indicating the ejecta contributed to moving the asteroid more than the spacecraft did.

This information is teaching us a great deal about these two particular asteroids, which could be used if for some reason their totally safe orbit got changed and they were going to impact Earth. However, NASA’s repeated effort to make believe this info would be useful for deflecting other asteroids is somewhat absurd. It is helpful, but each asteroid is unique. The data from DART is mostly helping astronomers get a better understanding of the geology of these specific asteroids, which will widen their understanding of asteroids in general. Planetary defense is really a very minor aspect of this work.

Conscious Choice cover

Now available in hardback and paperback as well as ebook!


From the press release: In this ground-breaking new history of early America, historian Robert Zimmerman not only exposes the lie behind The New York Times 1619 Project that falsely claims slavery is central to the history of the United States, he also provides profound lessons about the nature of human societies, lessons important for Americans today as well as for all future settlers on Mars and elsewhere in space.

Conscious Choice: The origins of slavery in America and why it matters today and for our future in outer space, is a riveting page-turning story that documents how slavery slowly became pervasive in the southern British colonies of North America, colonies founded by a people and culture that not only did not allow slavery but in every way were hostile to the practice.  
Conscious Choice does more however. In telling the tragic history of the Virginia colony and the rise of slavery there, Zimmerman lays out the proper path for creating healthy societies in places like the Moon and Mars.


“Zimmerman’s ground-breaking history provides every future generation the basic framework for establishing new societies on other worlds. We would be wise to heed what he says.” —Robert Zubrin, founder of founder of the Mars Society.


All editions are available at Amazon, Barnes & Noble, and all book vendors, with the ebook priced at $5.99 before discount. The ebook can also be purchased direct from my ebook publisher, ebookit, in which case you don't support the big tech companies and I get a bigger cut much sooner.


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  • john hare

    The information on this concept for changing asteroid orbits is quite useful. One of the possibilities for diverting a dangerous asteroid is to nudge another smaller asteroid into a collision course. The data from this mission suggests that impact may be more effective than previously thought. A kiloton impact at 10 km/sec could change the course of a gigaton monster by far more than previously thought. I called it Dinokiller eight ball in a blog post some years back.

  • Edward

    John hare wrote: “The data from this mission suggests that impact may be more effective than previously thought.

    Robert’s point is that “ each asteroid is unique.” If NASA had targeted the larger parent asteroid, Didymos, the results may have been different. If the larger astroid has less loose rock and other material, then the amplification factor most certainly would have been less. DART only gives us one data point, and its meaning needs much analysis to understand how this data point relates to any future data points that we may gather.

    Essentially, this was low-hanging fruit. It was easy to reach, and being a double asteroid it is easy to manipulate and relatively quick to analyze the changes. Larger asteroids may not be as easy to collect this kind of data, and the data points gained from those experiments may take much longer to understand.

    A possible followup mission could be to use a more massive probe on the same body, Dimorphos, to see how the differences in “bullets” affects the results. Starship comes to mind as a possible future bullet, being somewhere around 20 times more massive.

    Fortunately, we do not know of any asteroids that are a real danger to us in the next few decades, so we have some time to gather more data before we are likely to have to use it in practice.

  • Edward: Though no impact mission is planned to this asteroid binary, a mission, Hera, to fly in formation with both to gather data on the consequences of the impact is scheduled for rendezvous with the asteroids in 2026. See:

  • Edward

    From the abstract:

    The main goals of Hera are the detailed characterization of the physical properties of Didymos and Dimorphos and of the crater made by the DART mission, as well as measurement of the momentum transfer efficiency resulting from DART’s impact. The data from the Hera spacecraft and its two CubeSats will also provide significant insights into asteroid science and the evolutionary history of our solar system. … Hera will thus provide a crucial element in the global effort to avert future asteroid impacts at the same time as providing world-leading science.

    It looks like they will get some good geology from both asteroids.

    Wouldn’t it be something if there were a second impactor experiment while Hera was still operational?

    No wonder this sounds familiar. You mentioned the Hera mission a couple of months ago:

  • Jeff Wright

    I’m not sure a nickel-iron slug would have been affected much.

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