Scientists overjoyed after DART smashes into asteroid Dimorphos, contact lost

A spacecraft smashed head-on into a 170-metre-wide asteroid named Dimorphos on Monday in a first-of-its-kind experiment demonstrating how we could one day potentially divert a hazardous object on a collision course with Earth. The Double Asteroid Redirection Test (DART) spacecraft, with a mass of 570 kilograms before impact, …

[SammyB]

If it actually did alter its path, one has to then wonder if that new path might somehow alter the path of another object which then might alter another object which somewhere down the line would cause a major impact with Earth. Sometimes, leaving things alone, is the smart move.

[sarusa]

There's no altered path - they hit a 'moon'

This binary 'system' of asteroids was chosen particularly because that's not an issue. Who knows what will happen in billions of years (butterfly effect) but for now it's just as likely to make it more likely to not hit Earth as to make it hit Earth (effectively zero for both).

First, Didymos and Dimorphos are on a 2.1 year orbit around the sun with minimal interactions. They come nowhere near Earth (10.6M km at the closest).

The second key here is that Dimorphos orbits Didymos with a period of about 12 hours. What they did is hit Dimorphos head on with the force of about 3-4 kilotons of TNT. This will make Dimorphos slow down slightly so it takes a few more minutes to orbit, which will cause it to orbit slightly closer to Didymos (by the rules of orbital dynamics, slower = closer). That's it! The total mass of the two is unchanged except for the negligible size of the DART probe, which may be made up for by the ejecta. Didymos will continue to orbit the sun just as before.

Understanding this is crucial to why they chose this pair as posing no danger.

[KittenHuffer]

Re: There's no altered path - they hit a 'moon'

One slight correction, I agree that slowing Dimorphos will causing it to drop into a closer (lower energy) orbit. But in dropping to a closer orbit it will then take a few minutes less to complete an orbit rather than a few minutes more.

[Lars]

Re: There's no altered path - they hit a 'moon'

It's worth pointing out that they chose a binary system because it's so much easier to calculate the effect of the impact as there is something to compare to, before and after sort of.

[DS999]

Yeah I'm sure no one checked that. They should have asked you first, because you are clearly a bigger expert than NASA!

[Anonymous Coward]

In theory yes as as gravitational forces or space curve interconnect all masses. Kind of butterfliy effect but that could also be true to minimal variances. but what I ma not sold off is really their test actually be valid to claim planetary to defense system as they pompously claimed today. First they stated that they shortened the orbit duration by 30 minutes when they expected only 10 minutes. But shorthern by what by putting the astroid in lower orbit due to the impact or actually by transfering a Kinect energy to the object in its curr not orbital trajectory? How also this even is analog to defending athis planet for a big asteroid coming directly to earth may because every 100 million years from outside of solar system or even from the two asteroid belts in the solar system? I guess this another project to funnel tax money to NASA.

[Mooseman]

" I guess this another project to funnel tax money to NASA."

Well, no. I'm not sure why americans complain about funding NASA when your obsession with the military means you funnel trillions to the armed forced every year.

What they have attempted and proved is that yes, we can alter the orbit and trajectory of an asteroid, so that if we manage to detect a threat in time we can potentially shift it so that it is unlikely to hit the planet. Personally, I think that's a better use for tax money than yet another nuke.

[Winkypop]

Take only photos, leave only footprints

!!!BLAM!!!

sorry

[ChoHag]

Re: Take only photos, leave only footprints

Big foot.

[John Brown (no body)]

Re: Take only photos, leave only footprints

...and burn marks from landing rockets. And left over tools, instruments etc. And remote science experiments. Bits of the lander not need for the ascent. A golf ball or two. That's just on the Moon. On Mars there are the remains of parachutes, inflated bouncy balls, crashed skycranes and dead or soon to be dead rovers, some with nuclear power plants in them.

Of course, on an entire large Moon or planet, it's a tiny amount of "rubbish" we've littered the places with, but it's lot more than just "foot prints"

[Atomic Duetto]

Should have flung a sheep

Little disappointed at the lack of standardised units Reg’o (Aussie, Aussie, Aussie)

Seems the little bugger was only travelling at 0.2135% of the maximum velocity of a sheep in a vacuum.

https://www.youtube.com/watch?v=5k3UPct2cqI

[TRT]

Re: Should have flung a sheep

Is there a maximum velocity for a sheep in a vacuum? Other than c, that is?

[Anonymous Tribble]

Re: Should have flung a sheep

Shirley you can't have a sheep in a vacuum. There should be at least one Baa of pressure.

[Michael Wojcik]

Re: Should have flung a sheep

I know I can't. It gets stuck in the hose.

[Danny 2]

170!

I'm impressed by the aim and I had a 170 finish at darts when I was 12. If you don't know darts that is like a hole in one in golf, or England beating Germany in football.

[tiggity]

Re: 170!

Best checkout I had against me was a 3 bull 150 from John Lowe. This was in an exhibition match where he was only scoring on bull / inner bull (with exception of one non bull dart allowed to count in scoring to allow setting up score to allow a finish). Us general public allowed to score on any number obv.

This was when he was one of the top handful of players in the world - just so impressive seeing 3 darts squeezed in the bull & room for more (especially as he used quite chunky darts) -but visually it was great. Something you would be unlikely to see in a "real" match due to high deflection / bounce out risk. I have had many higher out shots against me (and made higher outs, sadly my max a 164, numbers never dropped for a 170 attempt when I used to play, though did some in practice) - .

It was a pressure shot for him, us amateurs were allowed to go first and I was averaging in the 80s and so got a chance at a high 3 dart out (but missed the "out shot" at double 18).

Seeing the effortless skills close up made me realise I would never be more than an OK amateur player (though I think "real" match pressure affected him a fair bit as his exhibition play quality was notably better than any tournament play I ever saw from him)

[A.P. Veening]

Re: 170!

Something you would be unlikely to see in a "real" match due to high deflection / bounce out risk.

Michael van Gerwen has done it a couple of times (on TV) in his prime, just to make a statement.

[The Oncoming Scorn]

Re: 170!

I had the pleasure of seeing (& drinking in his pub a few times) Andrew Fordham play for his pubs team in my local bar in Kent, when he was up for his throw, he used his opponents darts as a handicap.

[Lordrobot]

There goes the prime directive... Murica Successfully Saves the world AGAIN with a bomb

Something there is that doesn't love a bomb. Aside from the Murican Celebrations, this bloody asteroid didn't move a millimetre, do the math. Not that, that matters. Awards and prizes will still be given out, the Space Farce will be declared a fundable success. The story will grow over time as to how Murica saved Europe once again. Of course, Europeans will be allowed to participate in future experiments, through their generous contributions.

Why not celebrate with a big Bill "Deliverance Kid" Nelson smile, as blowing up celestial objects, or attempting to do so, is not only acceptable but will save mankind from the next earth extinction... Isn't the solar system lucky today....? Man and his bombs will be around for another 450 million years... I hope all you European junior scientists know which nation buttered your bloody bread today.

[Anonymous Coward]

Re: There goes the prime directive... Murica Successfully Saves the world AGAIN with a bomb

Keep taking the dried frog pills.

[Martin Summers]

Re: There goes the prime directive... Murica Successfully Saves the world AGAIN with a bomb

"Keep taking the dried frog pills"

I've a feeling they're not actually working...

[Mooseman]

Re: There goes the prime directive... Murica Successfully Saves the world AGAIN with a bomb

"asteroid didn't move a millimetre, do the math"

Maths.

It did move, it's been pushed into a slightly lower orbit. The whole point of the mission was not to blow up the asteroid but to test whether an impact by a comparatively tiny object could A) be accurately targeted across millions of miles, and B) whether it could actually have an effect.

I'd suggest a little reading up on the topic before ranting about...whatever you were ranting about.

[Primus Secundus Tertius]

Re: There goes the prime directive... Murica Successfully Saves the world AGAIN with a bomb

A body 170 metres diameter has a volume 2.6 million cubic metres. If the density is 2.5 tonnes/cubic meter, that is a mass of 6.4 million tonnes. The impact vehicle weighed 0.57 tonnes, travelling at 6,400 metres/sec.

If that momentum is transferred to the asteroid, that change in velocity is about 0.57 millimetres/sec. On a one year journey that would amount to 18km. Not very helpful if you want to swerve past a target (Earth) of diameter 12,600 km.

[Headley_Grange]

Re: There goes the prime directive... Murica Successfully Saves the world AGAIN with a bomb

"..that change in velocity is about 0.57 millimetres/sec.."

Pedantically, that's a change in speed. Velocity is a vector and it's the change in direction that is more important. If you hit something that's a long way off and change its direction by only a few millirads it could be the difference between hitting or missing earth.

[David Nash]

Re: There goes the prime directive... Murica Successfully Saves the world AGAIN with a bomb

Speed is a component of velocity, so the velocity did change, right?

[Michael Wojcik]

Re: There goes the prime directive... Murica Successfully Saves the world AGAIN with a bomb

The downvotes here seem a bit harsh.

Speed is the magnitude¹ of velocity, so, yes, a change in speed is a change in velocity. But OP wrote "that change in velocity is about 0.57 millimetres/sec", which is under-specified. The correction from "velocity" to "speed" was warranted – as was the correction regarding the possible utility of a small change in velocity.

¹Some might quibble with your use of "component", if it's taken in the technical sense. And this is a technical discussion.

[DJO]

Re: There goes the prime directive... Murica Successfully Saves the world AGAIN with a bomb

Every 7 minutes the Earth moves by one diameter, you don't need slow a rock down (or speed one up) by much to turn a direct hit into a near miss.

[GloriousVictoryForThePeople]

Re: There goes the prime directive... Murica Successfully Saves the world AGAIN with a bomb

Assuming your figures (18km/yr) are correct, then:

To miss a 12600 diameter object you have to move 6300km / 18km/yr = 350 x 570kg=200,00kg

SpaceX Starship is ~100T dry mass and 100+T payload = 200,000kg

Coincidence??

[John Brown (no body)]

Re: There goes the prime directive... Murica Successfully Saves the world AGAIN with a bomb

"Not very helpful if you want to swerve past a target (Earth) of diameter 12,600 km."

You do know this was only a proof of concept, don't you? Or do you think airliners are not possible because the Wright brothers barely managed to fly 100' on their first attempt?

[David Nash]

Re: There goes the prime directive... Murica Successfully Saves the world AGAIN with a bomb

Who said anything about a bomb?

[Andrew Newstead]

Re: There goes the prime directive... Murica Successfully Saves the world AGAIN with a bomb

Hmm, I don’t think you’ve actually looked into this. The plan is to observe the movement of the asteroid after the impact has taken place with an object of precisely known mass and velocity. Observations will be done using telescopes and radar. There is an expected result but we don’t know if “real life” matches the prediction, hence doing the experiment.

[An_Old_Dog]

Megalomaniac Plan

When I was six, my father explained the duality of light to me. That night I took a flashlight out into our back yard and gleefully shot it at the Moon. Since light was, in some sense, particles, I was pushing the Moon out of its orbit! (Though by just a picoscopic amount.) Muu-ha-ha-ha-ha-haaaah!

[Spherical Cow]

Re: Megalomaniac Plan

The Moon is gradually getting further away from Earth... omg your torch trick worked!

[Headley_Grange]

Re: Megalomaniac Plan

Was it in 1999?

[The Oncoming Scorn]

Re: Megalomaniac Plan

Well they did use nukes twice.

[stiine]

I'm disappointed

You should have included the last image, or should I say partial last image taken by the probe, which was the top 10% of a frame with the rest being just noise.

I'm also waiting for the JPL scientist to update his plastic model to include the impact crater....GO JPL ! ! ! ! !

[Richard 12]

Re: I'm disappointed

Not noise.

Just <carrier lost>

[MrBanana]

NASA insurance hike

Well that's going to clobber their No Claims Discount.

[Twanky]

Re: NASA insurance hike

Nah, it was 'protected NCD'. Only one smash = No immediate increase in fee. If they keep doing it though... or if it ever gets out that they crashed it deliberately... Eh? Wassat? Oh!

Nice shootin' though.

[Anonymous Coward]

Re: NASA insurance hike

NCD only protects the percentage discount on your policy. It doesn't prevent them putting up the basic premium you pay on next renewal because of the claim.

As I found out when I queried why a minor scrape in a supermarket carpark increased the total amount that I paid for the next renewal by a considerable amount (the people I hit, rather than wanting me to pay for the repair directly got in touch with a claims management company, meaning that the overall claim was significantly more than the couple of hundred quid it would have taken to buff out the scratch in the top coat , and then repaint. It really was a very minor touch).

The lady on the phone at the insurance company was actually quite open to the fact that it is a common mis-understanding of what NCD actually is. I guess she had to explain this to a lot of people.

[David Hicklin]

Re: NASA insurance hike

"NCD only protects the percentage discount on your policy."

Fully agree, had a friend who was stung by this. He was quite upset!

[John Brown (no body)]

Re: NASA insurance hike

Yes, it's something that really ought to be spelled out more clearly to drivers. They might drive more carefully!

[ThatOne]

Time

> The DART craft was launched from Earth on November 24, 2021

Let's hope any incoming danger gives us a fair warning, ideally a decade before the impact...

_{To get over the "no, it's not my turn" phase, build the rocket et impacter, launch it, wait for it to get there...}

[John Brown (no body)]

Re: Time

Yeah, there does seem to have been a number of near misses that we learned about days or weeks before nearest approach.

[Neil Barnes]

It needs a big wide sound...

Yes, ground. That's it!

I wonder if it will be friends with me?

[FrogsAndChips]

Re: It needs a big wide sound...

Damn, you beat me to it! Though what I had in mind was a bowl of petunias thinking "On no, not again!"

[brainwrong]

RIP Clangers

We can only hope the Iron Chicken survived the calamity.

[Pat Harkin]

I have a bad feeling about this.

Did we learn NOTHING from Captain Scarlet?