Stopping Killer Asteroids 627
Drog writes "Earth has had a few near misses with asteroids recently (although "near hits" would be more accurate). It's just a matter of time, though, before we detect one with our name on it. In this New York Times article, experts discuss the various ways that we might go about saving our planet. Remarkably, nuclear detonations are not a good option, as they would break the asteroid into many pieces and merely increase our odds of being hit. And a detonation some distance away may simply be absorbed by the asteroid with virtually no effect. Instead, say scientists who study asteroid hazards, a gentle sustained push is what's needed (slow and steady wins the race). Some of the approaches have been discussed in science fiction for years--a mass driver, an electromagnetic machine which hurls dirt from the surface, an orbiting parabolic mirror to heat up the surface and create a plume of vaporized material. All of these methods require one thing, however. Time. At least several decades warning."
Earth has made it this long w/out our intervention (Score:3, Interesting)
But then again; don't we have a few major telescopes in orbit; and thousands more both professional and personal (like mine) on the surface? Shouldn't we be able to note anything on an obvious trajectory here and consider our options at that point? Maybe not; I have no experience in that sort of 'ballistics' thinking and perhaps there are far too many objects in our sky to track any that might cause us serious damage.
Uh - what about the southern hemisphere? (Score:5, Interesting)
On another note, who wants to bet that in the event we had, say, 50 years warning, the politicians would be utterly unwilling to do anything about it for at least 48 years?
Re:More pieces is bad...why? (Score:2, Interesting)
Jon
Does anyone actually know what a nuke would do? (Score:5, Interesting)
Re:Small fragments better than one large (Score:1, Interesting)
If an un-fragmented asteroid can hit us with 100 MegaTonnes of force...the fragments will still total up to 100 MT.
Even if you pulverize it into dust... the 100MT may just get deposited into the atmosphere instead of on the ground
If the sky above you heats up 1,000 degrees you are still as dead as if the meteorite hit you on the ground and heats up (explodes) the ground 10,000 degrees
Thomas Dzubin
Making Comparisons (Score:5, Interesting)
It all depends on the situation. If something the size of the moon were to suddenly aim itself at the earth, no amount of nukes would help. But a 1km piece of rock travelling at 25km/sec (which would probably poke a nice hole in the Earth's crust and kill us all) could be blown into 1000 pieces, 10% of which would hit the earth and take out a city block if it hit a city, I'll still vote for the nukes.
Then again, maybe it's like choosing between being shot with a big rifle or a shotgun. There's only one way to know for sure...and I'll take a pass, thank you very much.
Re:Almost but not quite (Score:3, Interesting)
I've always wondered something about this line of reasoning. Everytime I see an argument against the nuclear option, there seems to be an assumption of using only one device. I wonder if it wouldn't be possible to use several devices to disperse an asteroid around our planet? For example, the first device is launched, then after a bit of a lag, say a few days, a second is launched, wash, rinse, repeate.
My thought is that we could start by fragmenting the object. Then, using a string of devices, both slow and deflect the resultant cloud of matter. In the article they stated that using a nuclear blast near an object, but not on it, to try and push the object off course would probably fail, since the object would absorb the energy. But would this hold true if the object was fragmented? Each piece would be eaiser to move, and most likely, the "cloud", if you will, would have more surface area to be hit by the blast, assuming the same distance from the center of the explosion, more energy would be transfered to the "cloud" than would have been to the object.
Ideally, if you have a year or so of warning, and you launch with a 1 day delay between devices, you could probably put 100 or so devices on the object before it reached the Earth. and basically set up a poor man's orion drive for the object, or resultant "cloud". What are the possible failings of this idea?
Solution Already Exists: Nuclear Rocket (Score:5, Interesting)
Keep in mind that even if the asteroid was only a month away from impact and it was heading our way at 7 miles per second, that means that the asteroid would be 18.1 Millions miles away, which means that the angle of its trajectory would only have to be diverted by less than 1/1000th of a degree. A moderately size nuclear rocket could easily divert an asteroid of 1-2 miles in diameter in plenty of time to divert the disaster.
Planet P [planetp.cc] - Liberation Through Technology.
Our reason for existence (Score:2, Interesting)
Bacteria (Score:2, Interesting)
Why a "sustained gentle push" probably wont help. (Score:2, Interesting)
KISS (Score:3, Interesting)
Those who claim that the smaller pieces will be just as destructive as the whole are stopping the scenario short. You don't just shoot and hit with one or more at the same time. Over some amount of time you continously hit it with nukes, breaking the smaller pieces into still smaller until the pieces are either too small to do massive damage or blow out of our path.
In my opinion, all of these exotic solutions are a waste of time and money. Hell, at this point even the nuke solution isn't very feasible and considering the chances of being hit not a very good way to spend money.
Re:Does anyone actually know what a nuke would do? (Score:1, Interesting)
Astrophysists probably know what will happen, and I'm sure they have done some computer sims of the explosions.
A different idea (Score:3, Interesting)
Re:nukes ARE best. (Score:3, Interesting)
It's also obvious that you've never seen the video of the exploding whale [google.com].
Here's a hint... if you start off with an 8 ton whale, and you blow it up, you end up with 8 tons of whale parts! Asteroids also follow this simple rule.
The Yarkovsky effect (Score:3, Interesting)
How this small net force affects the asteroid's orbit depends on the orientation and direction of the asteroid's spin axis. From this month's Astronomy magazine: [astronomy.com] If the spin goes one way, Yarkovsky thrust adds to the orbital speed and the asteroid moves outward, away from the sun. If the asteroid rotates the other way, Yarkovsky thrust slows the asteroid's orbital velocity, and it draws closer to the sun.
"Painting" the asteroid with a material to alter its absorption and re-radiation of solar energy is very likely to be the most cost-effective method for altering an asteroid's orbit. It may even be the most practical method, assuming that we have enough time to allow the small change in thrust to alter the orbit enough to cause a miss.
There is an asteroid that is a very likely candidate for this treatment. 1950 DA was discovered and lost over 50 years ago, but was recovered on Dec 31, 2000, and was recognized as the long lost asteroid soon afterwards. With a 50-year basline to work with, its orbit was found to be in 11 to 5 resonance with Earth, which has the effect of making predictions reliable out to several hundred years. In the year 2641, the resonance will begin to decompose, sending the asteroid into a more chaotic phase of its orbital evolution. But the reliability holds long enough for scientists to recognize that there is a 1 in 300 chance of 1950 DA striking the Earth in the year 2880. This is the highest chance of collision ever estimated for any asteroid, and due to the resonance effects, it is considered very reliable.
So sometime during the next 900 years or so, we will probably have to decide that an attempt to alter its orbit is necessary. The sooner we act, the more likely we will succeed. 1950 DA is about 1.1 km in diameter, which would directly destroy an area the size of Wisconsin upon impact, and cause widespread devastation over a continent-wide area. But as little as a few tons of white chalk spread over one hemisphere could alter the Yarkovsky effect enough to change its orbit sufficiently over the next few centuries to complete avert any chance of impact.
idiot, yourself (Score:3, Interesting)
I still argue that one or two a-bombs launched from a remote location with limited tonnage directed towards some properly sized space-rocks is a very acceptable risk if we are to assess technology that could potentially save the entire planet. There isn't much chance that the bombs would go off accidentally while in the atmosphere, and there isn't much chance we will experience an extintion level event.
The devil is in the details. There isn't much radioactive material in a modern a-bomb - a few kg IIRC. Even less if it's an H-bomb. That is the reason why a nuclear meltdown at a nuclear reactor is such a major disaster - since there potentially is more radioactive material to be dispersed at such a site than there is inside of a bomb.
Re:Almost but not quite (Score:3, Interesting)
I agree, this could be a problem. Though you will have a vague idea of where the bits are going to go. You would be able to expect that they would all follow the trajectory of the original object, though modified slightly due to the explosion.
The object of the follow-up devices wouldn't be to hit pieces individually, but mearly to explode near the remaining pieces and push them into a safer trajectory. As such, I think you could simply explode them at a "best guess" location, maybe also have a bit of fuel on them for manuvering to make last minute corrections.
Also, this doesn't need to be an exact science really. if it misses us by 1000 miles, or a million miles it won't make a huge difference, as long as it misses.
Also, we could withstand the impact of a dozen or so Tunguska sized impacts, they would suck, no doubt, but if we could just get the vast majority of the mass of the object to miss us it would save lots of lives. Though I still would agree with the article, it would be nice, if we had enough warning, to use a non-nuclear approch. I'm thinking more of the short term warning.
This doesn't correspond to detonations on Earth (Score:3, Interesting)
The reason for this is when an nuclear device is detonated, the primary effect is a burst of Gamma radiation. Air absorbs the gamma, and re-radiates X-rays a little cooler until eventualy the radiation drops in color to infra-red. The distance from the center to when the black-body color temp drops to infra-red is called the fireball.
Dirt or astroid is much more opaque so the results are less. In space there is no air to speak of so what you'd have to do is detonate a ways off the surface so an area is irradiated with gamma, heats up and vaporizes a way giving a push from the mass of the vapors expelled by the astroid. This method might be best if the astroid is heading at us and has a high closing velocity, because time would be short.
If the astroid was coming from "behind" and closing slower, a reactor powering an engine place on the surface would be much more do able. It would be cool in such a case to place it in a parking orbit, hollow it out and make one whooper of a space-station out of it.
I've had a fantasy of catching an iron-nickle astroid, heating it up with a parabolic reflector and sunlight and inflating it like a glass-blower would.
Well put, but not everything you said works (Score:3, Interesting)
Well, no. We have only one planet, true, but a planet is a BIG place, it can take a *lot* of damage before it becomes uninhabitable by people. Even if a dinosaur-killer sized asteroid actually hit the planet and ruined the environment and sent us into a new and terrible ice age, we would still have huge amounts of water (later, water ice), oxygen, trace elements, metals, fissile materials (power source) available. In other words, even a post-apocalyptic Earth would have more resources and be more survivable than, say, a domed Mars colony with only very limited supplies of the above items - and it's also worth pointing out that building an airtight shelter than can filter the crap out of the surrounding air is a hell of a lot easier than building an airtight shelter than needs its own self-sufficient air supply, AND has to deal with radiation hazards from the thin Martian atmosphere (I'm assuming mars would be the first choice for a colony), AND deal with the fact that in the event of a breach, you won't have contaminants slowly leaking in - you'll have your air rushing out fast.
The Earth is vulnerable to an extent, yes. But it's so well-suited to human life that even a terrible cataclymic asteroid impact would leave it more habitable, and a better choice for the future residence of the human race, than anyplace else in the solar system.
"it is evident from the colonization of the Americas that people desire to go into the unknown, as refected in the popularity of Star Trek and other similar exploration entertainment"
Well, no. People did not colonize or even explore the Americas for the joy of it - they were looking for gold, or trade routs, or native to indoctrinate and/or enslave. Their mission wasn't "to boldly go where no man has gone before", it was "To boldly go, get rich (or at least get a better life, or religious freedom), and bring glory to the Crown and god". People do NOT abandon their homes for a whimsical love of the unknown, they leave because "the grass is greener...". And their ain't no freaking grass anywhere but Earth.
"it is not your place to belittle their opportunities. It may be your will to undermine the will of the continuation of the species through this means."
Excuse me? I didn't mean to belittle any "opportunities" - if the opportunity should someday arise, and people decide against all logic to colonize other worlds, good for them. I wish them nothing but good. I do, however, doubt very much that this will happen, for reasons already discussed.
"You have not demonstrated that colonization is any less viable than the multi-generational solutions proposed by the NY Times"
I'm sorry, I should have made the point more clear - but I DID mention that the nytimes ideas use technology we either have now, or could reasonably be expected to have fairly soon. Yes, these are multigenerational solutions, but the issue with colonization isn't time. It's social issues, and to a lesser extent, technology. Building a ship that can sustain life for hundreds or thousands of passengers for months would be *hard* - and please, do not talk to me about suspended animation until it actually exists.