Deflecting Asteroids with Paint

schnippy writes: "Researchers at the University of Arizona have calculated that small earth-crossing asteroids can be deflected by "coating them with a layer of white paint or dust." This finding won't be of much help against the larger doomsday asteroids (like the recently discovered 1950 DA) but it will help deflate military proposals to use nuclear weapons to deflect potentially hazardous asteroids."

Comments

Chaos Intervenes

[Perdo]

If predicting the trajectory of an asteroid's orbit is so heavily dependent on surface reflectivity, how do we know the change we make will not bring it closer to earth and not farther away? I liken it to our ability to change the weather, but not predict the weather.

I would prefer to make the trajectory change closer to the impact event so that we could more accurately predict the results.

Re:Chaos Intervenes

[Perdo]

1) the mass of the object is know

The mass of an asteroid is not known. 433 Eros, which we know better than any other asteroid, still has an unknown mass for purposes of calculating it's orbit 800 years into the future. Being off by even a few grams results in being off by thousands of miles in final trajectory. It's apparent mass is between 6.69 and 7.2 x 10^15 kg enough to put our calculations off by entire solar units, after 800 years have passed. There is also the problem of asteroids constantly shedding and gaining mass due to collisions, dust deposition and even the solar wind itself depositing dust or blowing deposited dust away.

2) the sice of the surface is known

"Sice" is an Ceske (Check) word that I assume means reflectivity. Consider this: look at a common crystal. Notice that it's reflectivity is determined by it's orientation to the veiwer. The moon always presents the same face to earth, but the sun "gets to see" all sides of the moon. If we base our calculations of an objects reflectivity on observations from earth, or a spacecraft orbiting the asteroid, we cannot make accurate calculations of the objects reflectivity because only one set of data really matters, the reflectivity of the object from the sun's point of view, which may also be variable.

3) the orbit(distance) is known

The orbit can be guessed. We can know with relative certainty where an object was. We can know fairly accurately where it will be in 20 years. We can wildly speculate where it will be in 800 years. Consider the cesium beam atomic clock. It is accurate to 1 x 10^-17 seconds. Such a clock would be off by as much as a thousandth of a second in 800 years. Given that deviation, Calculations of an orbit could be off by several kilometers just on un-guessable timing errors alone. Unfortunately, there is a mathematically unsolvable problem too: The Three-Body Problem, well explained here. Unfortunately, we are faced with a 32 body problem, just counting the sun, planets and major moons. It doesn't even end there. The mass of any body is not consistent across it's surface. For instance, there are places on the earth that "pull" harder than others. This is well mapped on earth, and there are satellite launches planned or in orbit to more closely map this phenomenon, but we have just barely scratched the surface as far as research into, for instance, Jupiter's Local gravitational variations, which have a much greater impact on solar orbit calculations than any body in the solar system.

4) the intensity of sunlight is known

The intensity of sunlight is unknown. The sunspot activity cycle causes the solar wind to change in intensity. Additionally, it warms and cools cyclically. I've heard on a ten thousand or so year cycle, but I cannot remember the source. The sun is also very gradually warming due to the natural life cycle of stars. The planet's magnetic field's slow and accelerate the solar wind and create airfoil shaped shadows in their wakes, through which asteroids must pass. The Planet's magnetic fields also have a quite variable affect on the solar wind, as watching an aurora will show you.

I'll leave you with this:

You can watch a wave sweep the beach and know that the beach will likely have the same shape after its passing but to predict with certainty where a particular grain of sand will go is not within our abilities and never can be.

There are many waves, and even they affect the orbits of asteroids, as the friction of tides moved the moon out to it's current orbit, and slowed the earth to it's present length of day.

Care to guess the coefficient of friction of metallic-hydrogen against it's unknown but assumed "rocky" core? Tidal forces within Jupiter will have to be factored in too.

Just to many variables.

Asteroids, I used to play that game...

[gnovos]

Why does everyone whine about nuking asteroids? Why NOT nuke them? Even the really big ones? Even the ones that people say are "the size of Texas"? And I don't mean the "try one nuke and give up" that they do in the movies right before sending the poorly trained oil rig workers. I mean rain down thousands, if not tens or hundreds of thousands, of 150 megaton nukes. Turn that whole nasty blob of metal and rock into white hot hell-fire plasma. Not only would it be fun and pretty, but we'd also get to empty out all the really nasty big mother nukes that have been sitting around and collecting dust forever.

Re:Asteroids, I used to play that game...

[Perdo]

Besides, a nuke would make an excellent paint spreader, or were they planning on sending the three stoodges up to paint a 15km asteroid.

Perhaps we could hit Saddam with a big paint grenade and he would have to take a knee and pretend he was dead when we hit him with a second shot.

"Ok, we've painted you, you have to put all your weapons of mass destruction behind your back!"

Re:Asteroids, I used to play that game...

[Perdo]

Texas is 801 miles across.

The moon is 1375 miles across.

um... ok...

Let's go ahead and nuke texas because all the nukes in the world aint gonna stop a a rock the size of it.

Re:Asteroids, I used to play that game...

[Perdo]

Let's see, we want to turn the entire thing into plasma, which I guess could arbitrarily be 10,000 degrees centigrade. Let's ssume it takes one calorie to raise 1 gram of stuff one degree celcious. Now we run our wizzard on a sphere the size of texas, with moon equvalent composition.

about 1.685 x 10^45 gram-calories needed

1 Kiloton TNT equals 1 x 10^12 gram-calories

Approximatly 1.68491109264290913984 x 10^32 Kilotons of TNT needed to convert our texas sized asteroid into 10,000 degree celcious plasma.

I'm going to step out on a limb and make the wild guess that we don't have 16,849,110,926,429,091,398,400,000,000 Megatons worth of nuclear devices.

In fact, It would take the sun 33 years to produce that much energy.

I think I miscarried a decimal somewhere but only being off by a magnitude of 10 is moot on the scales we are talking. suffice to say we could push it around, if we caught it early, but turning the entire thing into plasma is not an option.

Unless we used the mars' atmospheric lazing affect to concentrate a gamma ray lazer created by letting Phobos meet anti-Phobos...

The only question is, where do we get anti-Phobos from? heh..

Re:Asteroids, I used to play that game...

[Mr.Intel]

Put the abacus and crack pipe down. Step away from the crack pipe... You have *way* too much freaking time on your hands dude.

Re:Asteroids, I used to play that game...

[Mr.Intel]

The old, worn out simple-minded person's quip "too much time on your hands" doesn't get laughs anymore, dude.

Buahahaha! You are soooooo funny. At least that is what I was attempting to be. Apparently, at least two other people agreed. So try to take things a little less seriously, mkay? Life is a lot easier to live when you aren't calculating every freaking angle , speed, mass and light reflectivity quotient.

If you don't want to use your brain, then don't, but do NOT criticize others for doing so

Hey, I wasn't slamming him, just trying to let him know that it's not a big deal. So he knows how to do simple math. Who cares? I'm an electrical engineer so I am not a dim bulb when it comes to math and science and I *don't* worry about stuff like that. I have a life and would rather play with my kids than spend hours on that crap. If it was one post with some follow up I could understand. But OMFG! He posted three of those books! On slashdot! It's not like it's a dissertation or lab project that happened to coorelate or something *important*. As for being simple minded, look in a mirror sometime, 'dude'.

Re: Rate of change

[Raetsel]

Interesting choice...

1. A small rate of change over a very long time

   (OR)

2. A rapid change close to the point when change is needed

We see these types of things happen all the time -- notably on 'real life' cop shows. Either you steer early and avoid an obstacle, or you yank the wheel at the last second, lose traction, and skid into oblivion anyway.

I'll take the first choice, thanks. That way we can know earlier whether it's working or not, and take extra steps if necessary.

Re: Rate of change

[Perdo]

I fully agree, but since an asteroid's orbit cannot be accurately predicted to "earth hit or miss" accuracy greater than about 20 years in advance, that little nudge may be the nudge that causes the asteroid to hit instead of miss. Strapping one of these magnetic bubble solar sails would alter an asteroid's orbit so drasticly, even on late notice, and be steerable to boot, that they make painting the surface white pale by comparison (pardon the pun).

Same theory, more active approach and to paint it would still require a launch, intercept, and application of device, be it paint or a giant magnetic field. The best part is a system like this could be used to steer an earth crosser into earth orbit, providing plenty of zero G raw materials for future missions.

Re: One (slightly used) asteroid

[Raetsel]

• "...zero G raw materials for future missions."

Or... a counterweight for a space elevator!

I suppose the longer we wait, the more stuff we can take -- it'll take less fuel to get there. (Unless we're using antimatter propulsion in 850 years or so... then I guess it really wouldn't matter.)

Re: One (slightly used) asteroid

[Perdo]

God, I like how you think, even if we are on different sides of the T(H)GSB fence.

What he is talking about folks, is the bigger the counterweight, The bigger payload your space elevator could carry, without needing a thicker teather toward the top. Also it enables construction by lowering strings from orbit, because there is something nice sized in orbit to teather to. This is especially important for the first strand, that will be too weak initially to support any weight at all, and certainly not the weight of an entire other strand.

Armaggeddon 2

[Anonymous Coward]

So in Armaggeddon 2, instead of oil rig workers, they'll send... house painters?

whatcha gonna do

[DrSkwid]

when it comes round the next time and it's *already* white!

MS Paint to the rescue!

[10Ghz]

At last, Microsoft has software that's good for something!

Use a Laser

[AeiwiMaster]

Why not use a laser to heat
the surface of the asteroid,
This will create a hot plasma jet which
will alter the trajectory of the asteroid.

Re:Use a Laser

[Tablizer]

(* Why not use a laser to heat the surface of the asteroid, his will create a hot plasma jet which
will alter the trajectory of the asteroid. *)

The energy/force exerted it not likely to be any more than the power going to the laser itself. (You know, laws of conservation of mass/energy, etc.) Our lasers currently are way too weak for such.

We have a hard enough time using them to blow up missles, and those lasers can only peak for a few seconds before they melt.

deflecting 1950 DA

[Klox]

This finding won't be of much help against the larger doomsday asteroids (like the recently discovered 1950 DA)

Oink.NET and timothy obviously didn't read the article referenced by Slashdot yesterday (talking about 1950 DA). It explicitly states:

The good news is that the same effect might be harnessed someday to provide the gentlest of all methods of nudging this or any other asteroid aside if it does turn out to be on a collision course. Simply altering the surface albedo in places, for example by selectively dropping white chalk or black carbon powder to darken or lighten some regions, could be enough to do the trick. If so, it might be the first time in history that a whitewash was the real solution to a serious problem.

Maybe he's a busy guy, but I still think timothy should read the articles before he posts them (he posted both of these articles).

Re:They need to

[leucadiadude]

And change to a LOUDER exhaust system. Louder is always faster....

For more ideas check HERE!

Re:Jupiter�s local gravitational variations

[Perdo]

There are persistent and non-persistent variations in jupiters atmosphere. The great red spot, for instance, is a 12,000 km by 25,000 km by 8 km "tall" variation from the "surface" of Jupiter. 2.4 billion cubic kilometers of gas which is denser than the surrounding gasses forced upward by heat. This is an example of a continuously variable local gravity anomaly. We know that the red spot's composition and shape changes constantly and we cannot predict it's future. A recent collision with with a smaller white spot also drasticly changed it's color to a much lighter shade.

Jupiter also spins, so exibiting the same flattened sphere shape, and resulting reduced local gravity of the poles, that the earth has. To assume jupiter's metallic hydrogen core exibits no topographic variations is also unrealistic for purposes of calculating gravitational variations.

Additionally, imagine and iron bodied asteroid orienting itself to Jubiter's amazingly large magnetic field like and iron fileing would to a common magnet. This would change the meteorite's angle of incedence to the solar wind making it more or less "aerodynamic". We could change a meteors resistance to the solar wind by modifying it's reflectivity only to have our work undone because a previously stable meteor would begin to tumble, drasticly altering it's coefficient of drag.

Again, there are just too many variables.