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Wed Nov 24, 2021, 06:53 AM

NASA launches spacecraft to test asteroid defense concept

Source: AP

By JOHN ANTCZAK

LOS ANGELES (AP) — NASA launched a spacecraft Tuesday night on a mission to smash into an asteroid and test whether it would be possible to knock a speeding space rock off course if one were to threaten Earth.

The DART spacecraft, short for Double Asteroid Redirection Test, lifted off from Vandenberg Space Force Base atop a SpaceX Falcon 9 rocket in a $330 million project with echoes of the Bruce Willis movie “Armageddon.”

If all goes well, in September 2022 it will slam head-on into Dimorphos, an asteroid 525 feet (160 meters) across, at 15,000 mph (24,139 kph).

“This isn’t going to destroy the asteroid. It’s just going to give it a small nudge,” said mission official Nancy Chabot of Johns Hopkins Applied Physics Laboratory, which is managing the project.



The SpaceX Falcon 9 rocket launches with the Double Asteroid Redirection Test, or DART, spacecraft onboard, Tuesday, Nov. 23, 2021, Pacific time (Nov. 24 Eastern time) from Space Launch Complex 4E, at Vandenberg Space Force Base in Calif. NASA launched the spacecraft on a mission to smash into an asteroid and test whether it would be possible to knock a speeding space rock off course if one were to threaten Earth. (Bill Ingalls/NASA via AP)
The SpaceX Falcon 9 rocket launches with the Double Asteroid Redirection Test, or DART, spacecraft onboard, Tuesday, Nov. 23, 2021, Pacific time (Nov. 24 Eastern time) from Space Launch Complex 4E, at Vandenberg Space Force Base in Calif. NASA launched the spacecraft on a mission to smash into an asteroid and test whether it would be possible to knock a speeding space rock off course if one were to threaten Earth. (Bill Ingalls/NASA via AP)


Read more: https://apnews.com/article/space-launches-spacex-space-exploration-science-technology-1f351c9ce5890c275f1f9b2c884a0278

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Response to Omaha Steve (Original post)

Wed Nov 24, 2021, 07:04 AM

1. Sure they've considered this, but let's not "nudge" it the wrong direction ...

the best-laid plans, etc.

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Response to Auggie (Reply #1)

Wed Nov 24, 2021, 10:33 AM

10. The risk is minimal.

Even if it managed to knock it into a solar orbit with a periapsis below earth's orbit, it would most likely be on a slightly different orbital plane.

The good news is, if it does create an issue, we'll know we have the tech to ameliorate the issue!

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Response to Omaha Steve (Original post)

Wed Nov 24, 2021, 07:24 AM

2. The target is the smaller of two asteroids...

... which is orbiting the larger one like a mini-moon. The orbit can be observed and precisely determined from earth. So any change in the orbit caused by the impact can be observed and measured using earth based observations.

This is what makes this experiment practical. Otherwise, you would have to build two spacecraft, an impactor and an observatory. It would be very costly and difficult to build and deploy a sufficiently sophisticated observatory. This way we can observe from the comfort of home, for as long as we need to.

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Response to Omaha Steve (Original post)

Wed Nov 24, 2021, 08:55 AM

3. I wonder how they considered the speed and weight of the "projectile" satellite to be enough

to disrupt the orbital attractive force. How would you figure out the gravitational force of orbit at such a distance??? I love the analogy they use... "A object the size of a vending machine hitting an object the size of a football field"
https://sciencing.com/calculate-force-impact-7617983.html
m

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Response to mitch96 (Reply #3)

Wed Nov 24, 2021, 09:02 AM

5. It doesn't "disrupt the orbital attractive force"

The impact changes the momentum of the asteroid by some small amount, affecting its subsequent trajectory.

"How would you figure out the gravitational force... at such a distance?"

That's very easy - the formula has been known for centuries thanks to Newton. Multiply the masses of two interacting objects, divide by the square of the distance between them, and multiply by a scale factor that goes by the fancy name "universal gravitational constant."

It isn't really necessary to calculate the *force* of impact at all; what matters is something called the impulse, which is the change in momentum. It's just accounting:

Momentum before: momentum of asteroid + momentum of projectile

Momentum after: new momentum of asteroid (assuming projectile basically embeds itself in the asteroid

You then calculate the new trajectory post-impact based on gravity and the new momentum

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Response to caraher (Reply #5)

Wed Nov 24, 2021, 09:11 AM

7. Yes sir. Supercomputers make the calculation of Newton's laws of motion super easy now.

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Response to caraher (Reply #5)

Wed Nov 24, 2021, 09:14 AM

8. Ain't science grand!! nt

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Response to caraher (Reply #5)

Wed Nov 24, 2021, 09:53 AM

9. You raise exactly the point I was wondering;

Which is, why bother? Newton’s laws of motion have been around for centuries. They already know exactly what should happen.

I guess the real experiment is seeing if we can design a ship to hit a target so precisely at such high speeds.

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Response to robbob (Reply #9)

Wed Nov 24, 2021, 10:41 AM

11. I had similar questions

I'm guessing it's mainly about the development of the "deflector" - how to do it cheaply, reliably, effectively.

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Response to caraher (Reply #11)

Wed Nov 24, 2021, 12:16 PM

14. I think it's what they call "proof of concept"

As in “can we really hit a small fast moving object millions of miles away with self driving spaceship”? Im assuming the spaceship will be self driving so as to be capable of making small course corrections as it nears the target.

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Response to Omaha Steve (Original post)

Wed Nov 24, 2021, 08:57 AM

4. we try to safe humanity, russia attacks satellites, north korea attacks the oceans and who knows

what China is up to.

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Response to Omaha Steve (Original post)

Wed Nov 24, 2021, 09:08 AM

6. 🧐 Fascinating 🧐

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Response to Omaha Steve (Original post)

Wed Nov 24, 2021, 11:11 AM

12. Is Bruce Willis piloting the spacecraft?

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Response to Omaha Steve (Original post)

Wed Nov 24, 2021, 11:36 AM

13. If we put Steve Bannon on that rocket...

...the asteroid would jump out of the way on its own.

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