NASA Asteroid Deflection Test Imminent!

[Rogue 9]

T-3 minutes as of posting! https://www.nasa.gov/content/live-cover ... rt-mission

[Rogue 9]

Direct feed from the spacecraft.

[wautd]

Pretty freaking amazing. When will they know if the impact had any effect on the asteroid?

[LadyTevar]

Well, so far we see a very large debris trail.

Asteroid leaves 10K Trail

A new image shows that an asteroid which was deliberately struck by Nasa's Dart probe has left a trail of debris stretching thousands of kilometres.

A telescope in Chile captured the remarkable picture of a comet-like plume spreading behind the giant rock.

The probe was crashed last week to test whether asteroids that might threaten Earth can be nudged out of the way.

Scientists are working to establish whether the test was a success, and the asteroid's trajectory altered.

The extraordinary image was taken two days after the collision by astronomers in Chile, who were able to capture the vast trail using the Southern Astrophysical Research Telescope (Soar).

It stretches for more than 10,000km (6,200 miles), and is expected to get even longer until it disperses completely, and looks like other space dust floating around.

(see link for rest of article)

[Rogue 9]

NASA reports the test was successful. Breaking from NPR

NASA says its asteroid defense test was a success
October 11, 20223:35 PM ET
James Doubek

NASA says its mission to knock an asteroid off course — a test of planetary defense — succeeded beyond its expectations.

The Double Asteroid Redirection Test (DART) slammed a spacecraft into one asteroid to see if it could change its orbit around another asteroid.

It did.

About 7 million miles away from Earth, the asteroid Dimorphos is in orbit around a larger asteroid called Didymos. It usually takes 11 hours 55 minutes for Dimorphos to make a complete orbit.

After the DART spacecraft made impact two weeks ago, that orbit has shortened to 11 hours, 23 minutes: a 32-minute change.

"This is a watershed moment for defense," said NASA Administrator Bill Nelson. "This mission shows that NASA is trying to be ready for whatever the universe throws at us."

The two asteroids pose no threat to Earth, but the test is proof of concept that if another asteroid does appear headed in Earth's direction, scientists have a way of pushing it off course.

"For the first time ever, humanity has changed the orbit of a planetary body," said Lori Glaze, director of the Planetary Science Division at NASA.

This is a breaking news story and will be updated.

[Solauren]

Does anyone know if there was a goal to accomplish? I mean, a target orbital change?

While the test was a success, I'd like to know by how much.

If they were aiming for 10 minutes, and they achieved 32, that's a massive overachivment.
If they were aiming for 30 minutes, that's still great,
and if they were aiming for 45, at least we hit the asteroid and achieve 2/3 of the desired change (and they know they need to up the mass and velocity for the next test)

[bilateralrope]

Wired article

The team would have considered a 10-minute difference a success, said NASA chief Bill Nelson. But DART actually shortened the asteroid’s orbit by a whopping 32 minutes.

[Broomstick]

Beautiful proof-of-concept.

[Bedlam]

Yes and No. It depends on what the objective was, if it was to just hit a rock and move it as much as we can then it worked, if it was to alter the orbit by a specific amount then it failed. If they really planned for 10 minute change and managed 32 then that means that there are some major factors which we're not aware of which resulted in 3x the change expected. So we know we have the technology to alter a rocks orbit but not the knowhow to alter it by the amount we want which might be important in future.

[Broomstick]

The primary goal, as I understood it, was to see if we could change the orbit/trajectory at all. That the change was different than predicted is not the problem as we already knew we didn't know a lot about doing it. Yes, accurate change is important for the ultimate goal, but not a requirement of this particular mission. Analysis of this mission will, hopefully, give us the information needed to be more accurate in the future.

[Solauren]

With 10 minutes vs 32 minutes, it's possible the target asteroid did not have as much mass and calculated.

Personally, when it comes to planetary defense, I'd rather they overcalculated what was needed to knock an asteroid away from us. (So long as that didn't make the problem worse)

[Isolder74]

Sadly the conspiracy nuts are going ballistic.

I say to heck with them. NASA doesn't care about them and we can see that doing what they are suppose to do is all we want NASA to do anyway. Seeing it work as advertised is great and all we need.

I'm waiting on the SLS launch now.

[Rogue 9]

Yes and No. It depends on what the objective was, if it was to just hit a rock and move it as much as we can then it worked, if it was to alter the orbit by a specific amount then it failed. If they really planned for 10 minute change and managed 32 then that means that there are some major factors which we're not aware of which resulted in 3x the change expected. So we know we have the technology to alter a rocks orbit but not the knowhow to alter it by the amount we want which might be important in future.

If there's an asteroid on a collision course with Earth, I would like them to be able to move it as far off that course as possible, thanks.

[Bedlam]

If there's an asteroid on a collision course with Earth, I would like them to be able to move it as far off that course as possible, thanks.

Sometimes it might not work quite that way you could end up disrupting an orbit so that something which would have hit in 5 years is changed into something which will hit in 6 months or alter the angle it's going to hit at to make things worse. The ability to predict and plan a change to orbit wold be much more useful.

[The_Saint]

I suspect a large part of the uncertainty around this from NASA, from the simple success criteria to the fact there is a substantial difference between expectation and reality is down simply to this being the first ever such attempt.

Leading up to it all the NASA write up was that it was simply a test case to take a conceptual idea and see how reality matched up. They have the known data points of the probes mass, velocity and potentially the impact angle. They have the result of the orbital change. Now they can see if working backwards from the last gives them very different details of the asteroid mass/composition or if that still potentially lines up. (It's entirely plausible that the achieved outcome was within expectation and that they just set a low bar to cover against any unknown issues)

[Formless]

If there's an asteroid on a collision course with Earth, I would like them to be able to move it as far off that course as possible, thanks.

Sometimes it might not work quite that way you could end up disrupting an orbit so that something which would have hit in 5 years is changed into something which will hit in 6 months or alter the angle it's going to hit at to make things worse. The ability to predict and plan a change to orbit wold be much more useful.

The change in orbit was a mere 4%, which means that if you wanted to deflect an asteroid with these figures you would need a lead time of 30 years. While that's fine for deflecting asteroids specifically, as we can track most of them, the bigger danger is arguably from long period comets like Shoemaker-Levy and extrasolar objects like Omuamua which can suddenly be detected mere months before they cross Earth's orbit. In those cases, a bigger push means the difference between the object missing the Earth, and sending a comet that would have hit New York into London instead. Arguably a success that went over the expectation was better than going under it.

[bilateralrope]

With 10 minutes vs 32 minutes, it's possible the target asteroid did not have as much mass and calculated.

Personally, when it comes to planetary defense, I'd rather they overcalculated what was needed to knock an asteroid away from us. (So long as that didn't make the problem worse)

Deflecting an asteroid so far that you knock is so far out of the window where it will hit Earth that it lands in a second window seems really unlikely. Finding one where the asteroid hits sooner than the unaltered orbit would be even less likely. Even if NASA doesn't pick a direction to minimise that risk.

[Solauren]

It seems like the thing to do (with current technology) would be to hit a threatening asteroid with something to knock it off course enough to buy us the time to deal with it in a more permanent manner (orbital adjustment, sending it into the sun or a gas giant, or may knocking it into high orbit for mining...).

i.e
Deflection 1 - Okay, we knocked it off course so instead of hitting in 6 months, we now have 5 years
Deflection 2 - 6 months later - Okay, we now have 30 years
Deflection 3 - 18 months later - And now it's no longer a problem.

[EnterpriseSovereign]

I sometimes wonder if there's a minimum size an asteroid has to be before it becomes dangerous enough to warrant action since there's an awful lot of smaller asteroids in near Earth orbit.

[bilateralrope]

I sometimes wonder if there's a minimum size an asteroid has to be before it becomes dangerous enough to warrant action since there's an awful lot of smaller asteroids in near Earth orbit.

There has to be. At the small end, we are talking rocks that punch a hole through a roof if they even make it through the atmosphere. Way too small to worry about even if they could be detected.

As for what the threshold is, I don't know how you'd calculate that. Probably something comparing the cost of fixing the damage it would cause if it hit to the cost of the rocket(s) to deflect it.

[Solauren]

Off hand, it would be somewhere above 'If it hit 1 person, it could kill them' and below 'level a city block'

[bilateralrope]

What worries me about a 'level a city block' asteroid is politicians deciding that the people of whatever country* it's going to hit aren't worth saving. Well, not unless their government pays.

*How well can NASA predict where the impact will be ?

[Broomstick]

As that Siberian meteor showed a few years back, just having a substantial-sized one pass overhead can cause some damage on the ground. I don't doubt there are some people who'd happily let others get space-rocked, but thinking they can allow that without side effects displays an ignorance of physics.

[Formless]

The Chelyabinsk meteor would have done a lot more damage if it had come in at a steeper angle. That wasn't a street leveler, it released several megatons of energy into the atmosphere. It was a city leveler. And it was just the size of a small apartment building.

Dimorphos on the other hand is about the size of the largest pyramid at Giza (prior to impact-- we don't know exactly how much mass it lost as ejecta). Its an even bigger city leveler, possibly able to cause a small Tunguska event. We don't track many asteroids of this size...

[Dondor]

Yes and No. It depends on what the objective was, if it was to just hit a rock and move it as much as we can then it worked, if it was to alter the orbit by a specific amount then it failed. If they really planned for 10 minute change and managed 32 then that means that there are some major factors which we're not aware of which resulted in 3x the change expected. So we know we have the technology to alter a rocks orbit but not the knowhow to alter it by the amount we want which might be important in future.

If there's an asteroid on a collision course with Earth, I would like them to be able to move it as far off that course as possible, thanks.

Not one asteroid will never fall on Earth to kill all life on the planet. These are just our fears. This is far from reality. But politicians and scientists can speculate about that.

Let's just relax and go drink beer or play computer games.