Irritated at TV "Science"

vbimport

#1

Sitting at home watching the History channel’s “The Universe”
they are talking about deflecting potentially dangerout asteroids with some rinky dink method of a “Gravity Tractor” which I will admit in theory will work…

But in practice anything that must run for a LONG, LONG TIME reliably will eventually fail.

I believe Nuclear warheads are the better method, and do not feed me that dung about “blowing the asteroid to pieces”

Nuclear warheads triggered in vacuum release ALL their energy in the electromagnetic spectrum the “blast effects” that happen in atmosphere
are that energy acting upon air.

So if you set ogg a megaton range thermonuclear device a hundred meters or so from a threatening asteroid there is a bright flash and one side of the asteroid is suddenly incandescently hot.
This is certain to have a pronounced “propulsive effect”

Now if you are intelligent you want to increase the inclination of the asteroids orbit relative to the plane of the ecliptic, where it is many orders of magnitude less likely to interact with another celestial body.

Changing it’s orbit about the sun doesn’t make the danger go away it just changes it “tipping” the orbit so that it spends most of it’s orbit time out of the plane… and you don’t need to worry about that one any more.

Another thing that could be done is a scheme I have never heard any scientist mention… a method of permanantly eliminating the asteroid from concern, a method employed by nature.

Change it’s orbit just enough to insert it into a trajectory that causes
it to collide with the moon.

The Moon gets an new crater we have one less earth crossing asteroid to worry about and we get to record the event.

What woud be even better? But admittedly harder to manage?

Insert into an accessable earth orbit and start mining the sucker.

AD


#2

[QUOTE=AllanDeGroot;2647937]

But in practice anything that must run for a LONG, LONG TIME reliably will eventually fail.[/quote] Voyager 1 seems to disagree.

I believe Nuclear warheads are the better method, and do not feed me that dung about "blowing the asteroid to pieces"
I rather kill asteroids with them, than our current planet.

Insert into an accessable earth orbit and start mining the sucker.
I wonder what the working shifts would be. :slight_smile:


#3

My wife and I recently also watched the first four seasons of “The Universe”. Our favourite here was Alex Filippenko by the way :wink:

I guess many smart people have already thought about what can be done and they’re just presenting their proposals on that series. (Actually the series is NASA advertising that you have to pay for)

While I think that a lot of what they present is very theoretical - most of the things probably won’t be possible - it’s still interesting to watch everything. What is giving me a good feeling is that although a lot of things can - and eventually will - happen to our earth, chances are extremely low that anything of this happens while I’m still alive.


#4

Unless the Earth is threatened soon by an asteroid it won’t be a worry for mankind.
The over population bomb is what will kill the Earth . Unless we nuke ourselves to oblivian first .
But the plot always makes a good movie if it is done well. I’ve watched Armegedon several times.


#5

[QUOTE=cholla;2648039]Unless the Earth is threatened soon by an asteroid it won’t be a worry for mankind.
The over population bomb is what will kill the Earth . Unless we nuke ourselves to oblivian first .
But the plot always makes a good movie if it is done well. I’ve watched Armegedon several times.[/QUOTE]

The Movie Armageddon had one thing going for it… Liv Tyler

It was downhill from there.

NO concept of orbital mechanics by either the writers or director.
And drilling INTO the asteroid and setting the bomb off inside it
will only turn a “Cannonball” into “grapeshot”, that makes the
scientist’s worst case scenario certain.

The “Gravity tractor” requires a man made machine to “hover” near the asteroid and power just enough so the mutual attraction will “pull” the space rock in the desired direction.

it will take YEARS for any meaningful deflection to occour.
That’s after the “Tractor” flies to a rendevous with the rock and achieves near perfect station keeping, then it must main that precise balancing act for likely a decade or more to achieve the necissary deflection of it’s orbital track…

to be bothered undertaking the years of planning for such a mission, the years to fly the space craft to the proper point in space
THEN actually perform the deflection suggests that you KNOW the particular spacerock constitutes a threat AND that everyone agrees that it must be deflected.

By the time all this is done the resulting crater from the thing impacting
has had several years to cool…

Frankly I doubt NASA can plan a trip to the bathroom to pee in less than six months.

and the European space agency is no better.

As for “Hollywood” they have never made a scientifically accurate special effect of what a major space impact would look like…


#6

IMO, the best way to avoid a collision with an asteroid is determined by its size and its flight path. This might dictate slowing or increasing the object’s speed instead of focusing on changing its flight path. If the object is fairly massive then a gravity tractor is much less effective. If it is a smaller object then it might be very effective.

One of the most important characteristics to determine is the rotational nature of the object and its density. The beauty of a gravity tractor is the rotation is irrelevant to its function. A nuclear blast should consider rotation and object shape to be most effective. No matter what the solution is, the key is to identify the threat as early as possible so there is the maximum amount of time available to effect a solution. If we know early enough then we might even have the luxury of trying multiple methods to change its trajectory.

Depending on object size I think nuclear propulsion engine(s) placed on the object might be the best solution. They would need to have the ability to turn themselves on and off at the right frequency to be the most effective. They could use steam from a water payload to provide the propulsion. This technology is already tried and true and used in ships, submarines etc. Depending on the object material the propulsion material (i.e. water) might be on the object already.

For any scenario of an asteroid collision, I think the first step would be a recon mission to ascertain its size, makeup, precise trajectory and rotation. Knowing these properties would likely be critical to develop and effective solution.


#7

I always wonder about the massive explosions you always see both in science programmes and sci-fi films.

When a planet or a star explodes for example a flat planar ring of material is always shown as being ejected from the equator of the object.

Would this actually happen in real life or have they just copied the effect experienced when a nuclear device explodes against the surface of the Earth?

[B]Wombler[/B]


#8

I don’t know about exploding planets but a gamma ray burst leaves the star at its poles and is very focused. If we were ever in the path of one then all life on Earth is probably toast. Even if the star was on the other side of the Milky Way Galaxy. If the burst is large enough then one from a nearby galaxy could do the same. The other bad thing is that there would be no advance warning of a gamma ray burst since it travels the speed of light. Here is an artist rendering of one if the gamma rays were in out visual spectrum.

A supernova can have some interesting explosion configurations. Here is one taken by the Hubble Space Telescope:


#9

I guess I’m one of those people that can ignor the science & just enjoy the movie.
Unless it is so bad as to insult anyone & maybe not then if there is enough comedy in it.


#10

[QUOTE=UTR;2648265]IMO, the best way to avoid a collision with an asteroid is determined by its size and its flight path. This might dictate slowing or increasing the object’s speed instead of focusing on changing its flight path. If the object is fairly massive then a gravity tractor is much less effective. If it is a smaller object then it might be very effective.
[/QUOTE]

Slowing or speeding the object will by definition change it’s flight path

Slowing will make it fall to a lower/faster orbit closer to the sun
Speeding it will push it to a higher orbit farther from the sun

The issue with doing either is that it keeps the object in the plane of the ecliptic (the orbital plane of the solar system) where it can still potentially
interact with another astronomical body and have it’s orbital path altered again…

Pushing it up or down and giving it an orbital inclination relative to the solar system can place it in a path where it can potentially never again
interact gravitationally with another body, so it will tend to STAY in the “Safe Place” where you put it.

Leaving it in the plane of the ecliptic does not eliminate the risk of future orbital path changes due to perturbations, unless you degrade the orbit so far as to put it on an intentional collision course with another planetary body or attempt to plunge it into the sun (it would likely melt and vaporise before it got there)

[QUOTE=UTR;2648265]
One of the most important characteristics to determine is the rotational nature of the object and its density. The beauty of a gravity tractor is the rotation is irrelevant to its function. A nuclear blast should consider rotation and object shape to be most effective. No matter what the solution is, the key is to identify the threat as early as possible so there is the maximum amount of time available to effect a solution. If we know early enough then we might even have the luxury of trying multiple methods to change its trajectory.
[/QUOTE]

Ideally you’d want to detonate the nuclear weapon, in this case “nuclear propulsion charge” as near to the axis of rotation as possible.

Basically at one of the asteroid’s “poles”

[QUOTE=UTR;2648265]
Depending on object size I think nuclear propulsion engine(s) placed on the object might be the best solution. They would need to have the ability to turn themselves on and off at the right frequency to be the most effective. They could use steam from a water payload to provide the propulsion. This technology is already tried and true and used in ships, submarines etc. Depending on the object material the propulsion material (i.e. water) might be on the object already.
[/QUOTE]

A nuclear bomb detinated CLOSE to an asteroid IS a “propulsion device”

But it does not require landing on the asteroid it’s only got to function correctly ONCE and for about 9 nanoseconds to do it’s job

[QUOTE=UTR;2648265]
For any scenario of an asteroid collision, I think the first step would be a recon mission to ascertain its size, makeup, precise trajectory and rotation. Knowing these properties would likely be critical to develop and effective solution. [/QUOTE]

Instrumentation of asteriods, radio transponders to accurately track their orbital path to a far more precise degree is logistically no less difficult as visiting each one that is known to be a potential threat with a single 5-10megaton device exploded next to one of it’s poles and increasing it’s orbital inclination and shoving it out of any potential interaction with any planetary body.

The object of “moving” something as heavy as an asteroid is to move it as little as possible while decreasing it’s threat as much as possible.

“out of the plane of the ecliptic” is the best way of accomplishing this.

The other thing to be remembers is the farther it is from a potential impact the less vector needs to be applied to accomplish the desired effect, so moving it decades or years in advance is better than months.

If only for the fact that if the brutal but effective method I’m on favor of fails you have a long of time to try again… and again… as often as necissary to achieve the desired result.

Instead of one large nuclear device a series of them arriving a day or more apart

Look up the original concept of an “Orion spacecraft”, this is the vary basic “bomb and iron plate” concept, in vacuum the bomb turns a thin layer of the plate into incandescently hot gas that through simple neutonian physics drives the plate away from the detonation.

[QUOTE=Wombler;2648422]I always wonder about the massive explosions you always see both in science programmes and sci-fi films.

When a planet or a star explodes for example a flat planar ring of material is always shown as being ejected from the equator of the object.

Would this actually happen in real life or have they just copied the effect experienced when a nuclear device explodes against the surface of the Earth?

[B]Wombler[/B][/QUOTE]

Hollywood is always enamored of the “it looks really Kewl” special effects or
the “Tennis ball covered with burning tar” meteor…

Anyone who has ever seen a real meteor knows what it looks like, a bright white point of burning light…

a 200foot wide nickel-iron meteor like that which created “Meteor crater” near Winslow Arizona,
if you were close enough to that impact to see the initial fire trail you were vaporized by the
impact blast. Anything far enough away to have survived would have seen something indistinguishable
from a nuclear test.

as for “Space explosions” in most cases of you are close enough to be worried about shock waves
there was probably enough for the first burst of X-ray and gamma radiation to have turned you off
like god cut the puppet strings long before the fast neutrons arrived.

And those neutrons would be flying through a diffuse, ionized gas cloud that used to be you,
because the bulk of the x-rays turned you into incandescent gas.

It’s kinda like a physics trivia question if the sun suddenly changed color (or went black) while
you were watching what would the visual effect be like?

And the answer is kinda weird until you think it through…

The disc would NOT turn a different color all at once, it would change color in the center
of the disc and the color change would rapidly expand to the edge taking just over two seconds.

Now think about WHY…

the Edge of the solar disc is just over 2 light seconds further away from your eye than
the center of the solar disc… Of course if the sun did suddenly change color (or go completely black)
even if you were watching intently you wouldn’t know about it until eight minutes after it happened.

Because the earth’s nominal distance of 93million miles from the sun is also about eight light minutes away.


#11

[QUOTE=UTR;2648442]If we were ever in the path of one then all life on Earth is probably toast. Even if the star was on the other side of the Milky Way Galaxy[/QUOTE]
In the German Wikipedia I read that there’s only a risk, if the GRB is closer than 3,000 lightyears.

The earth already has been hit by Gamma Ray Bursts - fortunately they were all million or even billions of lightyears away from here.