[X] My Assistant

[Bob Shaw]

I hate to point out a grim and downright unsettling aspect of extinctions, but by any reasonable use of the term we're currently slap bang in the middle of one of the worst multiple extinctions ever seen - and all (or at least mostly) down to the activities of our own species over the last few thousand years. All we need is a big impact, a super-volcano or whatever, and our degraded natural environment may go downhill even more rapidly.

Time for a lifeboat, methinks!

Bob Shaw

[Guest_PhilCo126_*]

Well the diameter of Apophis is 320 meter so it won't cause an Extinction Level Event but it's a great topic and for the amateur astronomers among us, just imagine the close passage of this rock near our Earth
Philip

[mike]

It could be that if a few more species become extinct, it will free up Earth's resources for all the remaining species such that they can survive more easily.

I don't see how it is that people can just 'know' that maybe a particular species was on its last legs anyway and it was just not good enough to persist as long as the others.

I do agree that as an intelligent species we shouldn't just dump untreated waste into groundwater and air, of course.. unless this waste somehow results in a species even better than ours, depending on how you measure 'better'ness of course, which seems to me is absolutely relative..

Personally, I will say that I don't like seeing people covered in sores and dying at the age of 7 from pollution. As far as species disappearing, eh, maybe they weren't that great in the first place.

[dvandorn]

...By the way, nuking asteroids, as it was proposed by some who have nukes but who rather don't know what to do with, is just sheer deliria: the asteroid would be broken apart, but all the pieces would continue on the same trajectory (this is basic celestial mechanics). So, in place of receiving a huge asteroid, we would receive several small ones, plus the radioactive wastes of the bomb.  It is not sure that it would be better.

Actually, as I've said before, if you could break a large (2-10km in largest extent) asteroid into millions and millions of chunks no bigger than your fist, the resulting meteor storm would cause *some* damage -- but it wouldn't be a major extinction event.

The key is that you would be increasing the surface area of the mass by more than a millionfold. The more surface area it presents to the atmosphere, the more of it is ablated away -- it's the only way you can get such a large mass to mostly burn up in the atmosphere.

Yes, it would have a definite impact, and you'd probably get a large numbr of car-sized chunks get through that would create pretty large craters. But overall, it would be far more survivable than an extermination-event-type impact, which would be the alternative.

-the other Doug

[mchan]

Actually, as I've said before, if you could break a large (2-10km in largest extent) asteroid into millions and millions of chunks no bigger than your fist, the resulting meteor storm would cause *some* damage -- but it wouldn't be a major extinction event.

The key is that you would be increasing the surface area of the mass by more than a millionfold.  The more surface area it presents to the atmosphere, the more of it is ablated away -- it's the only way you can get such a large mass to mostly burn up in the atmosphere.

Yes, it would have a definite impact, and you'd probably get a large numbr of car-sized chunks get through that would create pretty large craters.  But overall, it would be far more survivable than an extermination-event-type impact, which would be the alternative.

-the other Doug

The atmosphere would absorb the energy of collision with the same mass that would have hit the ground if it were in one piece. That would cause a different set of effects that threaten extinction.

[Guest_BruceMoomaw_*]

Yep -- remember that deafening series of "explosions" that the people of Texas heard as Columbia disintegrated overhead? Those weren't explosions -- they were multiple sonic booms, trememendously louder as a sum total than the usual boom which a Shuttle in one piece produced because large numbers of Shuttle pieces were plowing through the atmosphere simultaneously and being much more rapidly slowed down by their collision with it than a one-piece Shuttle is. All that kinetic energy still has to go SOMEWHERE.

Now, blowing an asteroid to smithereens might do some good IF it was otherwise going to crash into the ocean in one piece and produce a huge tsunami, whereas having multiple small fragments fall into the ocean in various places would produce a collection of lower-height tsunamis (some of which might even interfere with each other). But all this just proves again that knocking (or pushing) the damn thing off course in one piece is infinitely preferable to blowing it to bits.

[Guest_Richard Trigaux_*]

Actually that idea is not as silly at it sounds. The idea was to blow a nuclear charge some distance from the asteroid. The energy would vaporize a thin surface layer on the exposed side. The vaporized material would blow away at high speed  and the recoil would change the asteroid´s trajectory slightly.

Now the biggest problem in changing asteroid trajectories is probably that many (most?) asteroids are just rubble piles, very weakly bound by gravity. Most apparently less violent ways to move an asteroid would probably also break it up.

This is the beauty of the "gravity tug concept". Since it is based on gravity it affects all of the asteroid in the same way and there is no breakup. The downside is that it is quite slow.

In cases where the warning time is short (say a few years or less) the "Nuclear recoil concept" may actually be the best bet. If the charge is exploded at some distance and a directed-energy design is used the "push" will be nearly parallell and approximately the same all over the asteroid so the breakup forces shouldn't be too bad.

It would of course be a good idea to try it out on some non-earth crossing asteroid first. 

tty

Perhaps the best way would be to lauch a mass of classical explosives toward the asteroid, explode this mass in dust and gasses just before the impact, so that the asteroid receives a shower of very tiny fragments repartited all along its exposed side. So we minimize the risk of breakup and give an accurate push (the kinetic energy of the mass gives the push, not the explosion) and we do not need to brake the vehicule before pushing. A shower of tiny fragments arriving at high speed would too create a massive evaporation of an icy asteroid, thus giving a much stronger push than just the kinetic energy of the impactor. Tis effect could be added if the fragments are some incendiary substance, but the strongest source of energy in any impactor (except a nuke) is alway its kinetic energy. Another advantage is that such a vehicule can be conceived quickly.

Otherwise the smart method is to land a thrusted equipped with sollar cells, ion engine and all, compensating the weakness of the push with its duration. But we don't know to do this right now, when the previous method we can.

[Guest_Richard Trigaux_*]

I hate to point out a grim and downright unsettling aspect of extinctions, but by any reasonable use of the term we're currently slap bang in the middle of one of the worst multiple extinctions ever seen - and all (or at least mostly) down to the activities of our own species over the last few thousand years. All we need is a big impact, a super-volcano or whatever, and our degraded natural environment may go downhill even more rapidly.

Time for a lifeboat, methinks!

Bob Shaw

Yes it is true that mankind activity resulted into many species disappearing, and many natural environment destroyed, and this is not just today, late prehistory men were already able to extinct species and destroy forests with flintstone axes. Today with technology we are just faster.

This is why I think that the survivability of any planetary civilization heavily relies on its "wisdom" about managing its natural environment, respecting it or at least exploiting it without degrading it each year more. This ecology wisdom is not unrelated with a more philosophical/spiritual wisdom, if we consider that in last analyse it is egocentricity of individuals which produces threatening pollutions, destructions, wars, etc. We can imagine authoritarian regimes willing to preserve environment, but they are subjects to revolutions which could result in a resurfacing of egocentric/predatory behaviours. So a freely accepted philosophical choice is an indispensible prerequisite, but it is still not enough: many countries (USSR) or philosophical movements tried to foster altruism (or at least enough citizen sense) but failed because they proposed no practical mean to really change our mind and become selfless. Only some buddhist or similar countries succeeded, because they proposed both the target (becoming non-selfish) the methods (spiritual works) and evidences of their success (successful communities based on some altruism) to convince selfish people, the whole set in a non-violent and non-authoritarian way. And it was not a 6 month plan, most usually it was rather 6 centuries to succeed. So the success of the human specy to survive relies on something like this, not on any technology or administration. Today we can begin to foster this awareness and encourage people who are able to help in this, in place of forming lobbies for burying our hands in the sand about climate change and the like.

We have not so much time: when climate temperature increases, there is more steam in the air, and steam is in turn a greenhouse gas. So greenhouse effect has a positive reaction onitself, in clear it can suddenly start to increase limitless: in some years we would have a temperature of 100°C or more on all the Earth. No doubt there would be some trouble with the stock exchange.

[JRehling]

Actually that idea is not as silly at it sounds. The idea was to blow a nuclear charge some distance from the asteroid. The energy would vaporize a thin surface layer on the exposed side. The vaporized material would blow away at high speed  and the recoil would change the asteroid´s trajectory slightly.

Now the biggest problem in changing asteroid trajectories is probably that many (most?) asteroids are just rubble piles, very weakly bound by gravity. Most apparently less violent ways to move an asteroid would probably also break it up.
tty

Two benefits of pushing the threatening object into an eventual collision with the Moon are that you could push quite gently, and not break it up into more threatening objects of smaller size. And, you would permanently eliminate the object totally. Pushing an object away from Earth on one encounter would likely mean we would see it again in the future. Considering the threat that such an object could pose to a terrestrial target, one has to smile at the thought of the counterthreat that our Moon poses to *it*.

An orchestrated program of pushing these things into the Moon would move us ever-closer to a future with no *potential* threats in orbits with eccentricity <0.9. Of course, Oort-cloud rejects would remain a smaller, but distinct, threat.

I think that the problem of negatively affecting the Moon compare rather favorably with the contrasting result of a large impact on Earth. Plus, the Moon is going to be hit by impactors anyway -- we would just be diverting all of the Earth-Moon system's share to it.

[Guest_Richard Trigaux_*]

Two benefits of pushing the threatening object into an eventual collision with the Moon are that you could push quite gently, and not break it up into more threatening objects of smaller size. And, you would permanently eliminate the object totally. Pushing an object away from Earth on one encounter would likely mean we would see it again in the future. Considering the threat that such an object could pose to a terrestrial target, one has to smile at the thought of the counterthreat that our Moon poses to *it*.

An orchestrated program of pushing these things into the Moon would move us ever-closer to a future with no *potential* threats in orbits with eccentricity <0.9. Of course, Oort-cloud rejects would remain a smaller, but distinct, threat.

I think that the problem of negatively affecting the Moon compare rather favorably with the contrasting result of a large impact on Earth. Plus, the Moon is going to be hit by impactors anyway -- we would just be diverting all of the Earth-Moon system's share to it.

Yes an impact on the Moon will alway make less harm than on the Earth.
I like too the idea of finding a definitive solution. Imagine we push a hazardous object, and that, some centuries later, it hits Earth, while it would not if we did not pushed it???

Alway remember that we can ABSOLUTELY NOT know which choices our descendents will do. They have full right to do different choices than ours, including abandoning higher technologies, if they have good reasons to do so. Anyway a set back in technology level of such a magnitude already took place at the end of the Antiquity, and we began to recover only one millenia after. So we must not be irresponsible and create a certain impact in the future to avoid a probable one today.

[dvandorn]

... many countries (USSR) or philosophical movements tried to foster altruism (or at least enough citizen sense) but failed because they proposed no practical mean to really change our mind and become selfless...

That may have been the idea when the USSR was first founded, but the Revolution was betrayed, quite early on, by a self-styled "ruling class" in that supposedly classless society which had absolutely no interest in preserving the environment.

If you want some really true ecological horror stories out of the 20th century, almost all of them occurred in the former Soviet Union. Industrial wastes were regularly dumped into streams and rivers, and there was no regulation (or enforcement) to stop them. Since in the USSR the industrialists were also the State, anything that saved industry time or money was "good for the People." Regardless of how many of the People were killed or sickened by it.

And, as far as "becoming selfless" is concerned, Richard, you're suggesting what almost every human civilization has tried to accomplish since the beginning of Mankind itself -- changing human nature so that we don't have reason (rational or not) to hurt each other, or ourselves. Every attempt has proved fruitless. Human nature just cannot be changed to make Mankind selfless. It's a goal beyond the reach of accomplishment. IMHO.

-the other Doug

[mike]

If I weren't at least a little selfish, I'd give all my food away to other people and soon die.

[Guest_BruceMoomaw_*]

We're getting rather off the subject here; but the tragic lesson of Leninistic socialism (the single most important event of this incredible past century) was that dictatorships turn rotten and self-interested almost instantly, no matter how unselfish the motives of the revolutionaries who set them up may have been. (It was Stalin who said that in the end there really wasn't that much difference between Communism and Fascism, which explains why he got suckered by Hitler.) And the reason Lenin didn't see this was that he was intellectually arrogant to the point of being a megalomaniac (a trait he apparently had even as a teenager) -- proving once again that the traditional Christians were correct when they identified pride (including intellectual pride, our terror of being proven wrong) as an even worse sin than greed. (More precisely, he didn't see it until he was on his deathbed from his second stroke -- at that point he started expressing sympathy with Martov, the genuinely democratic socialist who had become his sworn political enemy. But by then it was too late; Stalin was busily grabbing the levers of power.)

Anyway, the end result was indeed that the Soviet Union was run by a ruling class who were obsessed above all else with maintaining their own power -- which meant that they could never dare to publicly question their ideology, which meant in turn that they had to cling to the economically inefficient socialism that polluted the hell out of their country for a paltry industrial output.

By the way, Marx himself wrote that he agreed that the primary motivator of humans in any society must be self-interest, and that it's futile to try to change this in any big way. His assumption seems to have been simply that the economic superiority of socialism to capitalism would soon become so clear that the average man would accept socialism's superiority as reflexively as people accept the superiority of democracy to dictatorship. And he does seem to have had in mind a standard political democracy; that sinister phrase "dictatorship of the proletariat" is a mistranslation of the original "directorship of the proletariat", by which he and Engels (as pointed out even by a right-wing academic like Thomas Sowell) meant a govenment with regular elections, multiple parties, freedom of the press, and freedom of religion (although he and Engels disbelieved in it). The trouble is that his statements on why democracy was superior to dictatorship were fuzzy and ambiguous enough that it was easy for Lenin and company to twist Marxism into the idea that dictatorship was acceptable, provided it was SOCIALIST dictatorship (run, of course, by Enlightened Fellows like themselves). Had the Soviet socialist state been democratic, it could eventually have realized its economic errors and veered back in the direction of social-democratic capitalism.

Here endeth the political sermon.

[Guest_PhilCo126_*]

An impact on the Moon would be an amazing sight ... the last recorded impact dates back from the Middle Ages and the 'schockwave' on the lunar body could still be measured by the Earth-Moon lasers of the Apollo program.

[Guest_Richard Trigaux_*]

An impact on the Moon would be an amazing sight ... the last recorded impact dates back from the Middle Ages and the 'schockwave' on the lunar body could still be measured by the Earth-Moon lasers of the Apollo program.

I think you refer to the affair of the Giordano crater and the event witnessed in 1178. I found the full story described here on the NASA website
This event in 1178 is usually interpreted as the formation of a crater impact (Giordano crater) although many doubts subsist. (see the link).
The idea looks rather poetical, seeing a Moon impact would be a really unforgettable view: a sudden display of cosmic violence and beauty surging into the peaceful and reassuring vision of the Moon in the sky.