“Something Unknown Is at Work” Behind NASA’s DART Planetary Defense Mission—and Astronomers Are Worried

The Debrief ^ | July 10, 2025 | Ryan Whalen·

[BenLurkin]

NASA’s DART asteroid redirection mission may have inadvertently made future asteroid deflections much more challenging after its test sent boulders hurtling through space on unexpected trajectories.

In September 2022, the DART mission successfully altered the orbit of asteroid moon Dimorphos. Unfortunately, the smaller space rocks that were dislodged when the kinetic impactor struck the natural satellite achieved three times the momentum of the spacecraft that created them.

The University of Maryland-led team (UMD) behind the new research paper on DART’s repercussions cautions that results demonstrate planetary defense may be considerably more complex than previously suspected, with the potential for many unintended consequences.

...

The researchers’ data came from an Italian cubesat named LICIACube, which was sent to follow up on the DART mission, as Earth-based observations would be inadequate for deriving precise measurements from the aftermath. In the LICIACube images, the team identified 104 boulders moving at speeds of up to 116 miles per hour and tracked their trajectories in three dimensions. These newly independent space rocks range in diameter from 0.2 to 3.6 meters.

Based on the craft’s impact, the team believes that its solar panels broke up larger boulders on Dimorphos’ surface before the main body hit. That first part of the impact most likely created the largest debris cluster, which holds roughly 70% of the known objects. This cluster raced away from the asteroid at high velocity.

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TOPICS: Astronomy
KEYWORDS: 2022; 202209; asteroid; dart; deflection; nasa; planetarydefence

[Lurker]

“the smaller space rocks that were dislodged when the kinetic impactor struck the natural satellite achieved three times the momentum of the spacecraft that created them.”

Isaac Newton would have something to say about that.

L

[BenLurkin]

I’m still baffled how light has momentum when it doesn’t have mass.

[Big Red Badger]

Hammer Time.

[WKUHilltopper]

Satan is working on them to develop something to deflect wormwood. He knows it’s coming.

[reed13k]

Momentum requires knowing the mass of an object.

Since they can’t weigh what they are looking at then they are making assumptions that the interior of the rocks are homogenous with what they see on the surface of the rocks (most likely using spectroscopy).

So their calculations could be off significantly.

Interesting result nonetheless.

[maro]

You are applying Newtonian concepts to a non Newtonian realm.

[silverleaf]

And the eulogy for mankind was two words…

“ unintended consequences”

[GingisK]

...a non Newtonian realm...

How so?

[BenLurkin]

Or possibly it was just one....

“Oops”

[GingisK]

Maybe the the object was made of something like Styrofoam or popcorn.

[dangus]

No, DART didn’t make them more difficult; it only demonstrated why they are more difficult. At least for those who don’t watch Morgan Freeman-Tea Leoni science fiction movies.

[HombreSecreto]

He may try to stop it but it’s still coming.

[Big Red Badger]

Impenetrable Mystery

[ConservativeMind]

There may be stored energy in some space rocks we don’t yet understand.

[dangus]

I’m confused by this. First, the problem seems to be that the asteroid they struck was a conglomerate rock. We know that such rocks form the earliest seeds of planets, but we also know that larger asteroids come from a destroyed planet and tend to have a more consistent material, so this looks like mere bad luck.

Second, the mission was successful. Meteors that size might make a cool bang in the skies, but won’t be deadly.

Third, 116 MPH is incredibly slow, still. Or did they means MPS?

[Paul R.]

Good God, what a bunch of knee-knocking fear-mongering. Some of the ejecta picked up a microscopic amount of speed compared to what the asteroid would have should it impact Earth. The biggest chunk was under 4 meters diameter, and the odds it is on the same course as the original asteroid, or any eventual Earth-intercept course, are negligible. (Just the fact it picked up speed means that when it gets to Earth’s orbit, Earth isn’t likely going to be “there” yet.) (Surely we are hitting the dang asteroid over one week “out”.)

And, IF by incredible tiny odds some 3 or 4 meter boulder does get sent off with a new vector that means an eventual Earth impact, such an object impacting or air-bursting would create minimal damage compared to the asteroid. (I’m not saying “no damage”, but it’s so much less than the damage the asteroid itself would cause as to be negligible in consideration of whether to smack the asteroid or not.)

The only worry is that a big boulder or protrusion on the surface of the target might mess up the deflection of the asteroid. (Another very small chance.)

It’d be nice if someone who actually knows a little about physics, orbital mechanics, etc., would write these articles.

[rigelkentaurus]

From Perplexity:

The maximum size of a body that is not a threat to the ground (i.e., will almost always burn up or explode harmlessly high in the atmosphere) is typically under 20 meters in diameter for stony asteroids. Iron meteors can reach the ground at smaller sizes due to their greater strength and density

[Oscar in Batangas]

It’s not nice to FA with Mother Nature.
You may FO she can unleash some unfortunate responses.

Some questions might be better answered if we let artificial intelligence computers take a crack at the problem first.

[maro]

To paraphrase something I saw on Reddit, photons are not little bullets. Nor are atoms little solar systems. The rules that apply at that scale are completely different.