Hitting a Bullet with a Bullet

[Just thinking]

Well, we did it (http://ukpress.google.com/article/ALeqM5iPNa4S_FTdq3tykhXlzLoy1DR70Q)!

In the first mission of its kind, the US Navy struck the satellite with its first attempt.

[JoeEllison]

Good thing it was moving in a completely predictable orbit and broadcasting a signal, just like "bullets" do.

[Rob Lister]

Well, we did it (http://ukpress.google.com/article/ALeqM5iPNa4S_FTdq3tykhXlzLoy1DR70Q)!

But Chinese officials said China was on alert for possible harmful fallout from the fuel tank and urged Washington to release data to allow the countries likely to be affected to take precautions.

I wonder what data they want.

[Rob Lister]

Good thing it was moving in a completely predictable orbit and broadcasting a signal, just like "bullets" do.

the sat wasn't broadcasting anything...nor responding to any command.

[Just thinking]

I wonder what data they want.

I know ... just what exactly were we keeping secret about this strike attempt from them?

[Just thinking]

Good thing it was moving in a completely predictable orbit and broadcasting a signal, just like "bullets" do.

It followed a ballistic trajectory ... just like bullets do. Oh, yes ... it also was completely dead --- hadn't worked since its launch. Ok ... I'll give you that it's a big bullet.

[Rob Lister]

I know ... just what exactly were we keeping secret about this strike attempt from them?

I'm only guessing, but probably our telemetry feeds, such as...

"The high-definition imagery that we have indicates that we hit the spacecraft right in the area of the tank."

and everything else they can get. I'm sure if I were them i'd love to know exactly how clear a view we had. Additionally, I suppose they would grudgingly accept the schematics for the working end of the sat.

[Rob Lister]

It followed a ballistic trajectory ... just like bullets do. Oh, yes ... it also was completely dead --- hadn't worked since its launch. Ok ... I'll give you that it's a big bullet.

with the other bullet being very, very smart.

[Just thinking]

I'm only guessing, but probably our telemetry feeds, such as...

But if they knew what were were up to, what the satellite's orbit was, where the debris field would be, what the chances are of any fallout harming anyone, then they pretty much knew just about everything. As did the rest of the world. Yes, they might have liked our telemetry feeds, but that isn't necessary information (I believe) for them to know regarding all the above. I think we've been more than above board in all this as this topic seems to already be lending itself to the CTer's.

and everything else they can get. I'm sure if I were them i'd love to know exactly how clear a view we had. Additionally, I suppose they would grudgingly accept the schematics for the working end of the sat.

Well, that certainly has nothing to do with out attempt at shooting it down; they have no more right to that than if the satellite were still in orbit and functioning properly.

[Rob Lister]

But if they knew what were were up to, what the satellite's orbit was, where the debris field would be, what the chances are of any fallout harming anyone, then they pretty much knew just about everything. As did the rest of the world. Yes, they might have liked our telemetry feeds, but that isn't necessary information (I believe) for them to know regarding all the above. I think we've been more than above board in all this as this topic seems to already be lending itself to the CTer's.



Well, that certainly has nothing to do with out attempt at shooting it down; they have no more right to that than if the satellite were still in orbit and functioning properly.

Yea, but it doesn't hurt to ask, right?

[Just thinking]

Yea, but it doesn't hurt to ask, right?

:D

[JoeEllison]

It followed a ballistic trajectory ... just like bullets do. Oh, yes ... it also was completely dead --- hadn't worked since its launch. Ok ... I'll give you that it's a big bullet.

Gotcha... so it was an quiet object in a completely predictable orbit, with no sort of way for it to dodge or change speeds. So, we did something that's really nothing.

[Just thinking]

Gotcha... so it was an quiet object in a completely predictable orbit, with no sort of way for it to dodge or change speeds. So, we did something that's really nothing.

No .... it's obvious you don't get it.

[JoeEllison]

No .... it's obvious you don't get it.

So why don't you explain it? You used the language of the "Star Wars" missile defense, in a case that is completely irrelevant to "hitting a bullet with a bullet."

[Rob Lister]

Gotcha... so it was an quiet object in a completely predictable orbit, with no sort of way for it to dodge or change speeds. So, we did something that's really nothing.

For extremely large values of 'nothing', yea. We've had the capability to do 'stuff like this' for a good while now...just never the desire or need to do this specifically.

Plus, we can do more betterestly than that, using different technology. And in the very near future, much more betterestlyer!

I know you don't like it...but it's true! :)

Besides, if you think it is so easy, then you give it a try.

[Diogenes]

http://ap.google.com/article/ALeqM5h7aoM2ii3QVBCAV8m2HtJSuPxPNwD8UUTLKG0

"we are prepared to share whatever appropriately we can."
Translation:

" We'll share what we damn well please; up to and including jack ....."

[Just thinking]

So why don't you explain it? You used the language of the "Star Wars" missile defense, in a case that is completely irrelevant to "hitting a bullet with a bullet."

No ... that wasn't the point at all. But in a final attempt at explaining it, I will offer this. Not too long ago I argued with other members on this forum (hey, it might have even been you --- but I'm not going to dig it up) my pro-position of the US advancing its capability at shooting down incoming threats from low orbit. In other words, a missile defense. I was hit with lengthy explanations of how it would be prohibitively expensive and the chances of it working would be the equivalent of hitting a bullet with a bullet. (Of course, I know of no law of physics that prevents a bullet from hitting a bullet, but that's how it was presented in their arguments.) So now it looks like we've actually done something quite extraordinary --- and along the lines of what I argued in favor of the US pursuing. Now ... that's all there is to it. Obviously, you wish to play this down ... fine. I don't. I think it's important as I'm sure many other do too. I'm also very proud to be a citizen of the nation that has the human resources, technology and will to accomplish such a task. I am also very pleased to see that there can be uses for such technology to a peaceful end --- one that not only benefits us, but the rest of the world as well.

[JoeEllison]

No ... that wasn't the point at all. But in a final attempt at explaining it, I will offer this. Not too long ago I argued with other members on this forum (hey, it might have even been you --- but I'm not going to dig it up) my pro-position of the US advancing its capability at shooting down incoming threats from low orbit. In other words, a missile defense. I was hit with lengthy explanations of how it would be prohibitively expensive and the chances of it working would be the equivalent of hitting a bullet with a bullet. (Of course, I know of no law of physics that prevents a bullet from hitting a bullet, but that's how it was presented in their arguments.) So now it looks like we've actually done something quite extraordinary --- and along the lines of what I argued in favor of the US pursuing. Now ... that's all there is to it. Obviously, you wish to play this down ... fine. I don't. I think it's important as I'm sure many other do too. I'm also very proud to be a citizen of the nation that has the human resources and will to accomplish such a task.

In other words, I get it completely, I characterized your position correctly, and I just don't agree with you.

[Rob Lister]

In other words, I get it completely, I characterized your position correctly, and I just don't agree with you.

poor joe.

[Just thinking]

I know you don't like it ...

Duh ... ya think so?

;)

[George]

How do you 'De orbit' a satellite by smashing it to tiny bits?
I know bugger all about orbital mechanics, but surely if you have a satellite following a certain trajectory then it will follow that same trajectory, in bits or not.

[Rob Lister]

How do you 'De orbit' a satellite by smashing it to tiny bits?
I know bugger all about orbital mechanics, but surely if you have a satellite following a certain trajectory then it will follow that same trajectory, in bits or not.

When you 'blow it to bits' some of the bits will slow (actually most since it was a head-on shot) and the orbit will decay much quicker. Some of the bits will speed up and take a bit longer to decay, but unless you impart escape velocity on them, they too will decay, but I suppose it could take a bit longer, depending on how much energy you impart. It will all be down within a couple of weeks, regardless (or so NASA sez).

[mhaze]

No ... that wasn't the point at all. But in a final attempt at explaining it, I will offer this. Not too long ago I argued with other members on this forum (hey, it might have even been you --- but I'm not going to dig it up) my pro-position of the US advancing its capability at shooting down incoming threats from low orbit. In other words, a missile defense. I was hit with lengthy explanations of how it would be prohibitively expensive and the chances of it working would be the equivalent of hitting a bullet with a bullet. (Of course, I know of no law of physics that prevents a bullet from hitting a bullet, but that's how it was presented in their arguments.) So now it looks like we've actually done something quite extraordinary --- and along the lines of what I argued in favor of the US pursuing. Now ... that's all there is to it. Obviously, you wish to play this down ... fine. I don't. I think it's important as I'm sure many other do too. I'm also very proud to be a citizen of the nation that has the human resources, technology and will to accomplish such a task. I am also very pleased to see that there can be uses for such technology to a peaceful end --- one that not only benefits us, but the rest of the world as well.

Well said and thought out (ignore all them naysayers, they were naysaying all the time Apollo was launching). A small step to being able to hit and break up a space rock inbound...

no law of physics that prevents a bullet from hitting a bullet

Compression wave might well prevent that, or cause them to slip sideways past each other, unless the bullets were in chaotic tumbling mode, then all bets are off, but at the same time the likelihood of a hit went down. Well, that's atmospheric of course, here we are doing it up in a vacuum.

[George]

When you 'blow it to bits' some of the bits will slow (actually most since it was a head-on shot) and the orbit will decay much quicker. Some of the bits will speed up and take a bit longer to decay, but unless you impart escape velocity on them, they too will decay, but I suppose it could take a bit longer, depending on how much energy you impart. It will all be down within a couple of weeks, regardless (or so NASA sez).

Thanks for the explanation.
I had no idea those things were that accurate.

[X]

The pictures of the impact are lousy.
Next time, they should stick a camera on the missile's nose.

(p.s. Are they expecting it to break apart and completely burn up on re-entry?)

[Yalius]

When you 'blow it to bits' some of the bits will slow (actually most since it was a head-on shot) and the orbit will decay much quicker. Some of the bits will speed up and take a bit longer to decay, but unless you impart escape velocity on them, they too will decay, but I suppose it could take a bit longer, depending on how much energy you impart. It will all be down within a couple of weeks, regardless (or so NASA sez).

Also, it was already in the upper atmosphere; smaller pieces will have a greater surface area to mass ratio, thus the orbit will decay faster.

[Rob Lister]

;3459307']The pictures of the impact are lousy.
Next time, they should stick a camera on the missile's nose.

(p.s. Are they expecting it to break apart and completely burn up on re-entry?)

Where did you see the pictures? Love a link.

(p.s. if the pieces are small enough, that's what will happen. I suspect there are still some large enough chunks to make it all the way down, but not many)

[jsfisher]

I think it's important as I'm sure many other do too. I'm also very proud to be a citizen of the nation that has the human resources, technology and will to accomplish such a task. I am also very pleased to see that there can be uses for such technology to a peaceful end --- one that not only benefits us, but the rest of the world as well.


I'm with you on this one. Amazing stuff.

[shadron]

The main idea in the shot was not to deorbit the satellite, but rather to break the large tank and let the hydrazine out, so it didn't come down in an intact tank and poison an area roughly equivalent to two football fields side by side. Hydrazine is not something you want to play with, but it's not all that dangerous (1000 gallons wasn't going to contaminate a New York or Beijing). We had occasional, smaller leaks of it at the Titan/Atlas missile plant in Waterton, CO when I worked there, and they just evacuated the area for a quarter mile in every direction for a couple of hours.

Like anything else, when you break it into smaller pieces, there's more surface to heat up and vaporize, making the vaporization job more complete, so that's also a more minor goal. The downside is that the pieces could come down anywhere in the orbital track, so if there are still pieces dense enough to make it down, they could land almost anywhere.

And than, of course, more complete destruction means anything that does make it down will be less likely to have any secrets to give up.

[Walter Wayne]

Where did you see the pictures? Love a link.

(p.s. if the pieces are small enough, that's what will happen. I suspect there are still some large enough chunks to make it all the way down, but not many)
CNN had it.

http://www.cnn.com/video/#/video/tech/2008/02/21/pentagon.sat.shoot7a.cnn

Usual commercial at beginning.

[Cuddles]

When you 'blow it to bits' some of the bits will slow (actually most since it was a head-on shot) and the orbit will decay much quicker. Some of the bits will speed up and take a bit longer to decay, but unless you impart escape velocity on them, they too will decay, but I suppose it could take a bit longer, depending on how much energy you impart. It will all be down within a couple of weeks, regardless (or so NASA sez).

More to the point, it was coming down anyway. It wasn't destroyed in order to bring it out of orbit, it was destroyed so that when it did come down it would be in lots of little bits. Or just to prove that the US can do it too, depending on how you look at it.

I'm also very proud to be a citizen of the nation that has the human resources, technology and will to accomplish such a task.

China?

[Akhenaten]

{Polite snippy to get to the bit I want to respond to}

I'm also very proud to be a citizen of the nation that has the human resources, technology and will to accomplish such a task.

So you should, because it was awesome. Well done guys.

Sorry I don't have a political statement to make.

[baron]

I thought it was broken up to disperse the fuel, which was highly toxic (although I might be wrong).

And "bullet"? Both satellite and missile were going a hell of a lot faster than bullets!

[Rob Lister]

I thought it was broken up to disperse the fuel, which was highly toxic (although I might be wrong).

You thought right. The NASA folks said the intact hydrazine tank would survive re-entry and that was the only reason they were undertaking this project. I believe it.

And "bullet"? Both satellite and missile were going a hell of a lot faster than bullets!

Indeed.

[CriticalThanking]

My wow factor about this is not that we "hit a bullet with a bullet" but rather that "we didn't screw it up." This is not a knock against NASA or anyone else, but the tolerances are very tight. The basics of the technology have been around for a long time. But the slightest miscalculation means failure. What was it - the Mars lander that crashed due to simple human math error? Planes are amazing technology, which can crash when someone flips one wrong switch, or when you put in pounds of fuel instead of kg.

CT

[slyjoe]

It was the Mars Climater Orbiter that crashed due to one team using English units and the other team using metric units.

[Leicontis]

Hydrazine (N2H4, for the curious) is rather scary stuff. I used it in my undergraduate thesis as a reducing agent (a very strong reducing agent), and we kept it in its bottle, with three layers of chem film under the cap and at least 3-5 more layers on top of the cap, with the bottle in a resealable plastic bag and always kept under the fume hood, and only transferred the stuff by needle and syrnige. Its characteristics include:
-Highly active/reactive reducing agent (what we were using it for)
-Carcinogenic
-Highly volatile (thus the containment measures)
-Highly combustible (hence its use as rocket fuel)
-Risk of fuel-air explosion (due to the previous two)

The thought of that much hydrazine landing in a densely-populated area is scary indeed. Unless people were evacuated in time, landing in a city could lead to quite a few immediate deaths, as well as a great deal more down the road from cancer. All that, plus the fact that it could also contribute to fires/explosions...

[mhaze]

You thought right. The NASA folks said the intact hydrazine tank would survive re-entry and that was the only reason they were undertaking this project. I believe it.


No way!

Examples of intact propellant tanks making it down from orbit without a controlled re entry sequence and protection?

[slyjoe]

Delta II stage 2 propellant tank - 1997, see figure 7.

http://www.globalsecurity.org/space/library/report/enviro/reentrypaper.pdf

[shadron]

You thought right. The NASA folks said the intact hydrazine tank would survive re-entry and that was the only reason they were undertaking this project. I believe it.

What's all this about NASA? What did they provide in this, beyond, possibly, some expertise in the effects of hydrazine? Wasn't their satellite, wasn't their missile, wasn't their launch platform (either item).

[Tokenconservative]

Good thing it was moving in a completely predictable orbit and broadcasting a signal, just like "bullets" do.

Annnddddd....there it is!

Sheesh.

Tokie

[Dan O.]

If you think of this task in terms of launching a projectile from the ground and striking another moving object in orbit, it does seem quite impressive. On the other hand, the task is really only to place one object within an area of about 2 meters square* and wait for another object to hit it. Many of you could do that with your hand held GPS; the only obstacle being that the target location is in low orbit.

Off the shelf GPS units won't work at high elevations and high velocities only because they are intentionally disabled to prevent them from being used as missile guidance systems. But the system is just as accurate wether you are sitting still or moving at mach 10. Being above the atmosphere is a bonus because there is no atmospheric distortion.

ETA: * "I used to bullseye Womp Rats in my T-16 back home. They're not much bigger than two meters."

[quarky]

just curious:

was this satelite equipped with a remote means of releasing the fuel?
If so, did that safe guard fail?

If we had been able to empty the hydrazine remotely, would we have bothered to shoot it down?

I can see why this experiment is seen as provacative in other countries.

[Dan O.]

If they have an extra fuel dump system or a self destruct on the fuel tank it adds weight which increases the cost of the launch and there is the risk that it could trigger before launch or during assent which would pose even more of a danger.