To be clear, Didymos and Dimorphos do not pose a threat to Earth

They don't pose a threat yet. That may change after the impact.

You are assuming that the DART guidance system actually works correctly and actually gets to it's target.

Of course it's REAL target could be a nice shiny Russian or Chinese satellite currently minding it's own business...(or even eavesdropping on other businesses ;-) )

Had the Earth not been struck 50 million years ago we would probably never have evolved, back then we were just furry little balls crawling around on the surface trying to steal the dinosaurs eggs and without the impact we would never have been more than a meal. That asteroid impact lead to our evolution and lots of birds flying around so I think that it was very nice!

Yeah but the next impact will be a lot less nice for us.

Best we avoid that.

LOL Pascal, I don't disagree with you, certainly a huge impact could turn the world into a snowball again but a relatively small impact might fix our current climate change issues by causing a temperature drop for the next 100 years and could have the effect of making every nation start to work together to create a better and safer world for the entire human race, not just one country. The threat of an impact should be making us think that we are a world in space, not just a collection of idiots in one country that thinks that they are so much smarter than every other country (I see that criticism as applying to every country not one or another).

On the other hand, we haven't had a really bad volcanic eruption for thousands of years, one bad eruption might be worse than an average asteroid sized impact and there's a fair bit of evidence that climate change threatens a classic huge volcanic eruption.

"Had the Earth not been struck 50 million years ago we would probably never have evolved"

Well, you convinced me. Asteroid impacts can have horrible, unintended consequences. Best we be careful, then.

Shame to see those ageing Hollywood actors go but it’s not like there wasn’t a couple of documentaries that charted their future.

Well - Richard (Duvall) and Tommy (Lee Jones) didn't come back, but Clint did !

we could send Ben Affleck along, just for good measure. (And to prevent further encroachments of utter mediocrity on the Batman universe)

Affleck was actually quite good as Batman, it's the script that was awful. I'd quite happily see him in another film where they spend actual money on the plot and script rather than special effects.

Hilarious to think people really believe we can solve this "problem" with guns! (_if_ we detect it in time, and _if_ it is small enough, and _if_ it is still far enough away, and _if_ we can still see it . . . etc.)

Even funnier is people thinking we can "just" blow stuff like this up.

As usual you have forgotten the troll icon but I would be very interested in any valid researched reasons why this may not have an effect.

At least NASA are doing some research and I daresay have probably modeled some likely outcomes just to see if the DART mission could end in tears.

The extended longevity of so many of NASA's missions is not down to solely blind luck, they tend to think a bit before acting.

They are not blowing anything up. They are giving one rock (which is in orbit around another, larger rock) a tiny nudge to see how it is affected. *IF* it is affected, the small rock will stay in orbit around the larger one, but just be in a slightly different orbit.

From my (admittedly limited) reading, even the "nuke it" options are usually intended to slightly alter trajectories, rather than being about turning the target into an expanding cloud of space gravel.

Why wouldn't it work? F=ma and E=1/2*mv^2 tells us that it does. All other outside influences eliminated hitting something heavy with something much lighter moving at a high relative velocity will change the velocity vector of the heavy thing. What is being demonstrated here is just how efficient such a high velocity impact will be, and that the technology required to find such a target in the vast emptiness of space, rendezvous with it and precisely target the impact works. The math on WHY it works is simple. The technology to actually do so is far from trivial.

To those who reply without reading, I never said this wouldn't be successful. I am commenting on why they are doing it, and how pointless it is considering all the ifs (I only suggested a few obvious ones). Oh never mind . . .

Be interesting to see how solid a body it is, or if it's just a loosely bound bunch of gravel.

or if it's just a loosely bound bunch of gravel.

I get the impression that it may be merely a huge heap of low density pumice, given that the only small asteroids explored to date (Ryugu and Bennu) turned out to be loosely assembled rock piles. Even the boulders on Bennu's surface were light and fragile, judging by the way they were moved about by the low velocity impact and airblast of Osiris-Rex's sampling touch and go maneuver.

Its also noticeable that the only bigger asteroids visited so far (Eros, Vesta and Ceres) seemed to be rather more solid, with NEAR's landing on Eros showing what looks like a rather more compacted surface.

This all makes me wonder if DART may simply fly through the moonlet, with the shock of the collision turning the latter into a rapidly dispersing cloud of disintegrating pieces of low density pumice.

At least we won't have all that long to wait before we see what happens when DART scores 50.

Sample size of two is hardly conclusive (but it's certainly a strong option), and I'm pretty sure that DART itself will suffer badly - even hitting a reasonably sized cloud of dust at >6km/s will do that to... well anything really.

chain reaction with the obvious result, hopefully not in my lifetime ;)

As with most space related problems this could be solved far more elegantly by resurrecting Project Orion. Then you'd have some serious mass to use redirecting pesky asteroids.

It does make sense. A fraction of 1% change in speed/direction a few million km out can have a big effect by the time Earth orbit is reached - the difference between taking out the ISS and taking out New York.

But it will need preparation.

Presumably if DART proves the principle, it will be wise to shift some large masses into orbit on stand-by to be shoved in the right direction when needed?