Paintballs To Deflect The Next Meteor

No I did not read the article yet.

It is too easy to undertstand:

Paint it red and you can see it coming. Red will make everyone go away since it is a warning sign!

The red paint rocket missle will find and destroy it.

No I do not think that paint will help heating the asteroid up and destroy it before it hits Earth. Still I have not read the article.

I think that size will be the downfall of this time critical mission. Too Large --> still BANG.

As said before let Engineers do it not scientists! (maybe work together if need to)

Going to read the article now!

Aha Ok. Why not then let Bruce install a little rocket on the side and steer it away. Surly and truly?

Could the deflection also mean hitting the Gobi desert or New York??

Yeah, if we can find the asteroid early enough that sunlight can be used to deflect it, then we might as well use a small ion engine running slowly and steadily to do an even better, more carefully controlled job of nudging it away.

It might not be easy developing a paint-ball ball of paint that will work in the vacuum of space over the extremes of temperatures it would see, constantly exposed to UV...and assuming the paint would stick properly. The development costs would probably be more than the cost of deploying the NEXT ion rocket that has already been built and tested.

Just remember: David killed Goliath with a sling-shot and a stone (and Goliath's sword to decapitate the giant). The point is that with some spider web tech (strong fibers that can withstand exposure to space environment), and a small rocket engine having a slowly building thrust, it should be not all that difficult to nudge even a giant. The trick will be either encompassing the giant in the web, or alternatively firing a sticky web that latches onto any sized object. Ion engine can be used after the chemical rocket plays out.

A larger question (that has been blogged about on here before) is: Who exactly pays for all of this?

There is one thing never mentioned in these asteroid adjustment stories that has always bothered me. My concerns are similar to Usbport.

To be able to move an impactor asteroid trajectory far enough out of our gravity well to not impact somewhere on the planet will require knowing the trajectory of a relatively small mass far away from our planet. All of the discussions focus on the idea that the sooner and farther away we can measure this trajectory the less force over a longer time is required to successfully change the trajectory. What's rarely if ever mentioned of this problem is that with more distance in space and time to the asteroid also comes more uncertainty in the trajectory.

One thing we can and should be doing right now is *locating* these asteroids. The WISE probe was a good start, but its liquid helium cryostats held too little for the long-duration missions expected of deep-space probes. (The liquid helium is used to chill the probes' IR sensors to where they can detect the faint IR signatures of these bits of space rock, many of which are dark-to-nearly-coal-black at visible wavelengths, making them nearly impossible to see except at close (too-close) range.

These asteroid/comet hunter-probes need to be dispersed throughout the Solar System, not just in Earth or Lunar orbit (WISE was stationed at the Lagrangian point beyond the far side of the Moon.) Limiting our search to what we can see from Earth orbit is playing Russian Roulette in that it reduces our chances of detection to what can be seen at the last possible minute - and from the one place early detection matters most: Home.

We need to know where these objects are and if/when they pose a threat *years* in advance. A deep IR probe every once in awhile just ain't gonna cut it. Had WISE still been operational it would have detected *both* objects which made last week's news.

If we can spend trillions on a conflict of dubious value in the Middle East, just ten percent of that would buy us five hundred to thousand (or more) asteroid hunters. On the flip-side, one good impact by a trillion-ton asteroid anywhere on Earth would make a permanent end of ALL conflicts on this planet so..uh..never mind. Earth could use a break, and maybe even evolve species more deserving of the wonderful home it has been given.

I wonder what sort of radar or microwave cross-section (per meter diameter) these asteroids, meteors, etc. have, and if it should be possible to detect them using coherent radiation in the RF or microwave range of the spectrum, and if so, could Doppler shifting be sufficient to determine trajectory? Or are we already doing this?

With a complicated system containing many bodies, could the perturbation of the orbit of one near-earth object affect a whole cluster of others? It would seem that mostly, the larger objects (planets, moons, the sun) would a much more dominant contribution to object trajectory than anything else, again, it is all a matter of range, and total mass pulling on the object.

James asks "I wonder what sort of radar or microwave cross-section (per meter diameter) these asteroids, meteors, etc. have, ..."

The radar cross-section of these objects varies widely and is a function of their size, surface roughness and composition, to name a few. Being metallic, iron-nickle objects are of course far more reflective at microwave wavelengths than their stony counterparts, as you might expect. Stony objects tend to reflect little microwave energy, but how much is actually reflected (versus absorbed or transmitted) varies with surface roughness, angle of incidence, composition and wavelength.

"... and if it should be possible to detect them using coherent radiation in the RF or microwave range of the spectrum, and if so, could Doppler shifting be sufficient to determine trajectory? Or are we already doing this?"

This collage of 72 individual radar-generated images of asteroid 2012 DA14 was created using data from NASA's 230-foot (70-meter) Deep Space Network antenna at Goldstone, Calif. The data were collected on the night of Feb. 15 to 16, 2013, after the asteroid had made its closest approach to Earth and was exiting the Earth-moon system. During the observations, the space rock's distance to Earth increased from 74,000 to 195,000 miles (120,000 to 314,000 kilometers).

^{Image credit: NASA/JPL-Caltech}

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We are indeed! Doppler alone won't tell us everything, nor need it; fortunately we can also ascertain the object's range and angular velocity (and acceleration, and more) from the same signal. Doppler shift tells us the object's apparent velocity toward or away from the transmitter, of course, the delay the range and the object's angular motion with respect to the "fixed" stars, the average signal strength it's approximate physical size, and the first and second derivatives of each what to expect in the immediate (and longer) future. All of them taken together tell us a great deal about the object's trajectory to within some margin error, depending on distance and angle of approach. Using widely separated transmitters can reduce this error significantly, and quickly too.

Our best bet is to combine techniques: microwave, deep-IR and visible, mainly, and maybe even gamma- and X-rays (interestingly, the Moon is brighter at gamma wavelengths than the Sun, thanks to the constant rain of energetic particles which strike the lunar surface). Possibly these objects (some of them, anyway) may be quite bright at gamma wavelengths, depending on where they've been and how long they stayed. Some objects - comets - are bright in X-rays, and asteroids aren't the only objects which could devastate Earth, not by a long shot.

A direct comet strike could sterilize the planet completely and we need to be forewarned about newcomers (most of them are; many comets do not follow periodic orbits and are first-timers about which we initially know nothing). Fortunately for us comets fluoresce brightly in X-ray and ultraviolet light as they approach the inner reaches of the Solar System, making them easy to spot.

Comet Lulin (click on image for Wiki page)

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James asks "With a complicated system containing many bodies, could the perturbation of the orbit of one near-earth object affect a whole cluster of others? ..."

Saturn's rings are a prime example of this.

Hope you found this useful.

-e