>Based on the change in the binary orbit period^2 , we find an instantaneous reduction in Dimorphos’s along-track orbital velocity component of 2.70 ± 0.10 mm s^–1

I should have read the article more closely. I thought they meant the angle changed when what really happened is the speed reduction increased the orbital period by 33 minutes.

After giving some consideration as to why they'd write it like that, it makes sense. Changing the orbital period by an amount of time may be enough for another orbiting body to get out of the way.

My bias got in the way of this one, thanks for the correction.

I wonder what the cutoff is for the size of an asteroid that would spur this kind of mission

The shape of orbits are not measured in minutes, there are multiple variables.

It's 30 minutes difference in the orbit around Didymos, an orbital motion with a tiny orbital velocity (~18 cm/s). The impact changed the velocity by around 1 cm/s. Over 2 years and for a free-flying asteroid that accumulates to 600 km in the best case. We would need a larger impactor (or many) for this scenario.

No, we're talking the orbital period in time. Actual minutes of time.

Well if its orbit takes 1 year to complete then it equates to changing the orbital speed/period around the sun by 0.0057%

I have no problem with public funding for this type of experiment. But, isn’t it obvious that detonating a nuke at the right spot on the asteroid is the way to really make sure you are changing the trajectory?

If you want to split hairs, it's impossible to prove a theory. But this mission did verify the theory. Another test can further verify the theory or break it. We won't know for sure until we do another test.

In other words, yes, more tests are needed to get a better idea.

These are arc minutes. There are 360° in a circle, 60 minutes in a degree, and 60 seconds in a minute.

On earth, an arc minute along a great circle is equal to a nautical mile. The conversion to any unit of length depends on the radius of the rotation. If the orbit is elliptical, the equation gets more complicated.

EDIT: I was totally incorrect about what they were talking about. See daughter post for details.

Two different budgets, but go off I guess.🙄

>So you say we survived 5, but a sixth is just crazy?

We (humans) weren't around for those 5 mass extinctions. The 6th mass extinction will very likely take us with it. The entire planetary ecosystem changes during/ after a mass extinction event.

>That being said, how is allowing people to die today of today's problems with these misspent funds going to save those same people in the future...

You've never heard of spinoff technology? People have said the exact same thing you have about space exploration since the start. The technologies developed for the space industry has been applied to other industries which includes the medical field. Tomorrow's medical problems are solved with today's space challenges.

Also, the technologies developed from space programs go on to be used in society. It could be a mundane as velcro or as advanced as medical imaging technology.

That is an enormous effect. Dimorphis was 560 feet in diameter. It was about the size and mass of the great Pyramid at Giza. If it hit the earth, it would completely destroy everything within a 10 mile radius and creat earth quakes that would be felt up to 1000 miles away. It would be worse if it hit water as the tsunami effect would flood nearly 70% of the globes ocean coast lines, killing an untold number.

If we can redirect something that size, then it should scale upwards from there. Just need to detect it early enough

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Only if it is a big enough impact. Otherwise it will create lots and lots of other problems for everyone still alive.

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This would be ridiculously hard to weaponize. You have to find an asteroid that was already coming extremely close to earth to be able to adjust its course enough to hit the earth, and then it wouldn't be possible to know where it would hit. And it would probably cost more than just dropping a bomb exactly on target by a factor of 10.

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>So the best case scenario is that we have the data available to make a correction to the orbit of such an object if we need to.

Wow, best case you can imagine is super limited. I thought for sure you'd go into astroid wrangling for convenience of mining. Nope, you're happy with, probably not going to need it, but if we spend an unbelievably higher amount of money then we might just maybe not kill ourselves unintentionally simultaneously ignoring petty issues on the big blue marble.

I'm just more confident that this technology will be used specifically to aim astroids at Earth. How do I know? Humans always say, "but this time it will be different." Sure resting on the fact that it's a technical difference in weapons, major advances that could change human civilization always, 100% of the time, get weaponized.

This is no different.

So you say we survived 5, but a sixth is just crazy?

I think an asteroid is a natural course of nature and no amount of human involvement will overcome anything nature has to throw at us.

That being said, how is allowing people to die today of today's problems with these misspent funds going to save those same people in the future should an extremely unlikely event like an asteroid that we happen to detect in time to divert?

It's not quite so simple, Dimorphos turned out to have a lot of loose rubble, so the impact created a lot of ejecta going the opposite direction of the site of impact, which means you get a greater pushing effect.

Imagine tossing a sticky ball at metal cube in space.

The ball will stick to the cube and they'll float away at a slower velocity than what the ball originally had

If you toss a rubber bouncy ball of the same mass at the same velocity, it'll bounce away from the metal cube, and come flying back at you while the cube will float away faster than if you used the sticky ball

So it's orbital speed and orbit changed by how much? In relation to it's parent body?

All of this will come with further research

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Yes, that's why this mission was important. Let's say we see an asteroid this size a few orbits before it's going to collide with Earth. We could launch a mission similar to this DART impactor and change the asteroid's orbit by 30 minutes per orbit.

That may not seem like much, but if it's still 2 orbits before impact that's an hour difference. The asteroid now misses Earth by about 60,000 km.