[X] My Assistant

[Guest_PhilCo126_*]

The Near-Earth Asteroid 99942 Apophis ( former designation 2004 MN4 ) was headline news again this week both in Newspapers & TV news. Observations pointed out that the Asteroid climbed a bit higher on the Torino impact hazard scale ( equivalent cosmic ‘Richter’ scale ) and could hit the Earth ( Southern Hemisphere ) on April 13, 2036 ( a Friday 13th I believe ).

Anyway, Apophis should pass between the Moon & Earth ( distance 250.000 KM ) in April 2029 … an amazing sight visible from Europe!
Interesting to know is the fact that European Space Agency ESA plans a mission to find out if an asteroid could be deflected from its course ( Don Quichote mission: Hidalgo is an impacter & Sancho is the observer probe ). American astronauts LU & LOVE wrote a paper in NATURE about a tug-rocket and NASA is making plans for a mission called ‘ The Son of Deep Impact ‘ … to be continued…



More on the Asteroid at:
http://www.esa.int/gsp/ACT/mission_analysis/asteroid.htm


Philip

[Rob Pinnegar]

I guess these guys must be pretty certain about their calculated orbit for this object. If it is going to make a close pass by Earth in 2029, forecasting a near miss of Earth in 2036 is quite a trick.

Of course, I haven't done the math, but, for example, if you were to change the position of the object by 1 km during the 2029 encounter, how much would this change its forecasted position in 2036?

[ljk4-1]

Paper: astro-ph/0512204

Date: Thu, 8 Dec 2005 05:17:15 GMT (21kb)

Title: How unlikely is a doomsday catastrophe?

Authors: Max Tegmark (MIT), Nick Bostrom (Oxford)

Comments: 3 pages, 1 fig
\\
Numerous Earth-destroying doomsday scenarios have recently been analyzed,
including breakdown of a metastable vacuum state and planetary destruction
triggered by a "strangelet" or microscopic black hole. We point out that many
previous bounds on their frequency give a false sense of security: one cannot
infer that such events are rare from the the fact that Earth has survived for
so long, because observers are by definition in places lucky enough to have
avoided destruction. We derive a new upper bound of one per 10^9 years (99.9%
c.l.) on the exogenous terminal catastrophe rate that is free of such selection
bias, using the relatively late formation time of Earth.

\\ ( http://arXiv.org/abs/astro-ph/0512204 , 21kb)

[Guest_Richard Trigaux_*]

Paper: astro-ph/0512204

Date: Thu, 8 Dec 2005 05:17:15 GMT (21kb)

Title: How unlikely is a doomsday catastrophe?

Authors: Max Tegmark (MIT), Nick Bostrom (Oxford)

Comments: 3 pages, 1 fig
\\
Numerous Earth-destroying doomsday scenarios have recently been ...

I think it would be interesting to have this in the SETI thread. Such possibilities of destruction of an inhabited planet by space events (gamma ray burst, meteorites...) account much in the probability of finding other civilizations.

[Guest_Richard Trigaux_*]

I guess these guys must be pretty certain about their calculated orbit for this object. If it is going to make a close pass by Earth in 2029, forecasting a near miss of Earth in 2036 is quite a trick.

Of course, I haven't done the math, but, for example, if you were to change the position of the object by 1 km during the 2029 encounter, how much would this change its forecasted position in 2036?

The result could be a complete change in trajectory. This situation is similar to a gravitationnal assitance for a probe. It is used to send the probe in the wished direction.

This makes that forecast for asteroid position is very difficult, as a small uncertainty on such an encounter makes a very large uncertainty on the next encounter.

[JRehling]

The  result could be a complete change in trajectory. This situation is similar to a gravitationnal assitance for a probe. It is used to send the probe in the wished direction.

This makes that forecast for asteroid position is very difficult, as a small uncertainty on such an encounter makes a very large uncertainty on the next encounter.

Yes, in principle multibody orbits are chaotic, and in practice no matter how accurately we observe an object through an encounter like this, the small uncertainties will lead to large uncertainties in the future. As a rule of thumb, you can say that we will only know about the next close pass -- it is not possible to see two close passes into the future. Simulations can tell us about probabilities regarding far-future passes, but not certainties.

If a body like this were perceived as a long-term threat, the general solution might be to place a superb navigational device and a modest thruster on it, and try to make very small perturbations that could lead the object to collide, in a subsequent pass, with the Moon.

[RNeuhaus]

I have read a paper about "Gravitation Tractor for Towing Asteroids" It takes many years to deviate the asteroid's path. As an example:

if the asteroid is 200 meters diameter, with a density of 2g/cm^3, provided it can maintain a total thrust T = 1 N. The velocity change imparted to the asteroid per year of hovering is Δv = 4.2×10−3 (m/ 2×104 Kg)(d /100m)−2 (m/ s)( yr)−1. Because Δv is largely independent of the asteroid’s detailed structure and composition, the effect on the
asteroid’s orbit is predictable and controllable, as needed for a practical deflection
scheme.

The mean change in velocity required to deflect an asteroid from an Earth impact
trajectory is ~3.5×10−2 / t m/s where t is the lead time in years. Thus, in the example
above, a 20 ton gravitational tractor can deflect a typical 200m asteroid, given a lead time of about 20 years. The thrust and total fuel requirements of this mission are well
within the capability of proposed 100kW nuclear-electric propulsion systems, using
about 4 tons of fuel to accomplish the typical 15 km/sec rendezvous and about 400 Kg
for the actual deflection.

For a given spacecraft mass, the fuel required for the deflection scales linearly with the asteroid mass. Deflecting a larger asteroid requires a heavier spacecraft, longer time spent hovering, or more lead time. However, in the special case where an asteroid has a close Earth approach followed by a later return and impact, the change in velocity needed to prevent an impact can be many orders of magnitude smaller if applied before the close approach.

For example, the asteroid 99942 Apophis (2004 MN4), a 320m asteroid that will swing by the Earth at a distance of ~30000km in 2029, has a small 10−4 probability of returning to strike the Earth in 2035 or 2036. If it indeed is on a return impact trajectory, a deflection Δv of only ~10−6m/s a few years before the close approach in 2029 would prevent a later impact (Carusi, personal communication). In this case, a 1 ton gravitational tractor with conventional chemical thrusters could accomplish this deflection mission since only about 0.1 Newtons of thrust are required for a duration of about a month. Should such a deflection mission prove necessary, a gravitational tractor spacecraft offers a viable method of controllably steering asteroid 99942 Apophis away from an Earth impact.

We are still on time to catch it up.

Rodolfo

Attached File(s)

 Gravitational_Towing_for_Asteroides_0509595.pdf ( 144.11K ) Number of downloads: 329

 

[RNeuhaus]

Urge to Merge: Here Comes Andromeda

The above article mentions about looking at the last term of the Drake Equation, we see that it relates to the lifetime of technological civilizations – how long they last as technological (meaning interstellar communicating) entities. The three biggest considerations for our civilization at the moment could be characterized as a) getting along with each other, getting along with the environment, and c) staying technologically alert for large-scale concerns from space.

1) The dinosaurs lived more than 200 millions years and they didn't take any care to predict from the external cause of extintion.

2) Magnetic reversal, talks about the strong magnetic field of Jupiter that will be uninhabitable to Galliean moons since the magnetic field of Jupiter causes a 5 million ampere electric current to flow through it. The Earth magnetic field will be revert many times in the future so we must take the prevenitive measure to protect from the Sun radiations.

3) Moon Stabilizes Earth's Rotation. But the Earth rotation will become even slower that in the future its rotation period would not take one day but one month and the Moon will start to approach to Earth and at a certain distance, the Moon will be desintegrated and Earth will have rings like the Saturn. This also tells that in doing some of these kinds of calculations for Mars, it was discovered that the direction of Mars’ rotational axis could flip rather suddenly. Now this is not the normal "precession" (as it is called) of a few degrees that changes, for example, our north star though the millennia. Mars was calculated to have flipped its rotation axis up to 90 degrees in as little as a couple of million years. This was a result of the orbital angular momentum, under certain circumstances, being transferred to the rotational angular momentum and causing a coupling that led to such a flip in rotation axis direction.

4) The future collision between the Milky and Andromeda galaxies, in 6 billions years.

http://www.space.com/searchforlife/seti_do...rge_051208.html
Richard, this article might be good for the topic about Seti.

Rodolfo

[mike]

You mean to say that eventually we'll all die of something?! WHY WASN'T I NOTIFIED!

[dvandorn]

If a body like this were perceived as a long-term threat, the general solution might be to place a superb navigational device and a modest thruster on it, and try to make very small perturbations that could lead the object to collide, in a subsequent pass, with the Moon.

I would think that would be rather harder to do than to just aim it away from a collision course. However, lunar scientists would just about come in their pants if given the opportunity to observe the collision of a fair-sized asteroid with the Moon, I bet.

Of course, then you would have a fair number of people insisting that we were planning to do horrible things to the Moon's natural environment...

-the other Doug

[Guest_Richard Trigaux_*]

Important things in the discutio above, JRehling, RNeuhaus, dvandorn:


To avoid a future collision with an asteroid, it is enough to give it a very small push at the right moment (just before a close encounter with a planet) and this is mostly achievable with today or near future technology.

The chaotic aspect of their trajectory, which makes this trajectory difficult to predict, especially after a close encounter (this is called, I think, sensitive dependency to initial conditions) turns to our advantage: a very small tug just before a close encounter allows to completelly change the future trajectory.

Eventually crashing all the Earth threatening objects on other planets is not a bad idea. This would allow us for a safe future, even in the case in which we abandon any high technology.

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.

[Guest_Richard Trigaux_*]

I would think that would be rather harder to do than to just aim it away from a collision course.  However, lunar scientists would just about come in their pants if given the opportunity to observe the collision of a fair-sized asteroid with the Moon, I bet.

Of course, then you would have a fair number of people insisting that we were planning to do horrible things to the Moon's natural environment...

-the other Doug

I don't think there are enough people on the Moon to protest against the idea. The only concern is that I want the thing done when the Moon is visible from my country!!!

[tfisher]

The Near-Earth Asteroid 99942 Apophis ( former designation 2004 MN4 ) was headline news again this week both in Newspapers & TV news. Observations pointed out that the Asteroid climbed a bit higher on the Torino impact hazard scale ( equivalent cosmic ‘Richter’ scale ) and could hit the Earth ( Southern Hemisphere ) on April 13, 2036 ( a Friday 13th I believe ).

I think this is another case of the press misreporting things slightly. The risk assessment has been steady at 1 on the Torino scale, unchanged since recovery and precovery operations last december ruled out the 2029 impact.

The description of Torino level 1 is "A routine discovery in which a pass near the Earth is predicted that poses no unusual level of danger. Current calculations show the chance of collision is extremely unlikely with no cause for public attention or public concern. New telescopic observations very likely will lead to re-assignment to Level 0."

The last quantitative change in the risk assessment was a slight tweak in the estimated probability of impact, from 0.015% to 0.018%, based on radar observations this August. A history of the risk assessment is here.

As has been pointed out above, the close encounter in 2029 makes precise predictions for the following close encounter nearly impossible. There is an uncertainty of about .15 AU, or 14 million miles, as to where along its orbit the asteroid will be at the time of the encounter in 2036. (Source: NEODyS)

The only reason this is showing up in the press again is that someone has adopted it as the poster child for arguing for designing space missions to deflect asteroids. While I agree we absolutely should have plans for such a mission prepared (and even hardware built -- just in case), I'm still annoyed when doomsday scenarios are overplayed by the press...

[tty]

Urge to Merge: Here Comes Andromeda

The above article mentions about looking at the last term of the Drake Equation, we see that it relates to the lifetime of technological civilizations – how long they last as technological (meaning interstellar communicating) entities. The three biggest considerations for our civilization at the moment could be characterized as a) getting along with each other, getting along with the environment, and c) staying technologically alert for large-scale concerns from space.

1) The dinosaurs lived more than 200 millions years and they didn't take any care to predict from the external cause of extintion.

Actually more like 150 million years, though no individual dinosaur species lasted for more than a few million years. We mammals have already outlasted the dinosaurs.

2) Magnetic reversal, talks about the strong magnetic field of Jupiter that will be uninhabitable to Galliean moons since the magnetic field of Jupiter causes a 5 million ampere electric current to flow through it. The Earth magnetic field will be revert many times in the future so we must take the prevenitive measure to protect from the Sun radiations.

The last field reversal happened about 780,000 years ago. There were already humans around then (though not Homo sapiens), and they survived without taking any special precautions (presumably).

3) Moon Stabilizes Earth's Rotation. But the Earth rotation will become even slower that in the future its rotation period would not take one day but one month and the Moon will start to approach to Earth and at a certain distance, the Moon will be desintegrated and Earth will have rings like the Saturn. This also tells that in doing some of these kinds of calculations for Mars, it was discovered that the direction of Mars’ rotational axis could flip rather suddenly. Now this is not the normal "precession" (as it is called) of a few degrees that changes, for example, our north star though the millennia. Mars was calculated to have flipped its rotation axis up to 90 degrees in as little as a couple of million years. This was a result of the orbital angular momentum, under certain circumstances, being transferred to the rotational angular momentum and causing a coupling that led to such a flip in rotation axis direction.

That is a very slow process. I don't have the figures handy, but studies of the number of days in a month and a year (which are detectable in certain types of corals) shows that the day has lengthened about 2 hours since the Devonian (>350,000,000 years)

4) The future collision between the Milky and Andromeda galaxies, in 6 billions years.

Not to worry. Long before that the sun will have left the main sequence, turned into red giant and sterilized the Earth.

tty

[tty]

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 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

[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.

[Guest_Richard Trigaux_*]

Dvandorn and BruceMoomaw,

my point was certainly not to discuss which is the best from capitalism or communism, even if it is apparently a sensitive topic. I just noted that USSR failed its stated purpose, for the reasons you explained in detail, thanks you for it Bruce.

My point was just to recal that, to avoid self-extinction, we must be able to develop some form of awareness of the issue, and some way to "change human nature". The bargain is just that: if we do, we survive, if we don't, we disappear.
So we must find the right way, and if it does not exist yet, to create it. For this we need to heed at history lessons, see peoples who suceeded, and those who failed. USSR told us that violence is not the right way. Democracy proved better than dictature, as we were able to stop fluorocarbons and asbestos (After 30 years of fight. it is welknown that the levers of power in a democracy are money, TV, medias, psychology...). The only persons who succeeded to "change human nature" were those who were engaged into practical spirituality, or at least some form of practically engaged rationality or humanism. The reason is that changing our opinion is not enough; it needs years of training (and a thorough education of our children) to be practically able to behave in the right way without having to sustain a terrible effort at every instant.
Things are like that: without education we are just chimpanzees. What makes humans civilized is transmitted by education, that it is learning things or training to do things.

[dvandorn]

And on this, Richard, we must agree to disagree. I am of the opinion that basic human nature is immutable; that, as a race, it cannot be changed via *any* degree of education or training.

Individual examples of behavior modification exist, yes. But they are accomplished by using the very traits (fear, mostly) that must be eradicated for any real, lasting change in human nature to come about.

I'm sorry, but I am of the very definite opinion that *any* plan or architecture to bring about an improvement in the human condition that begins with "all we have to do is change human nature" is just plain doomed to fail, and pursuing such goals is, basically, a waste of time. Time that could be better spent working *within* the limitations of human nature to do the best possible job at keeping as many people happy as possible...

-the other Doug

[Guest_Richard Trigaux_*]

And on this, Richard, we must agree to disagree. 

Not as you think

I am of the opinion that basic human nature is immutable; that, as a race, it cannot be changed via *any* degree of education or training.

True that the basic "chimpanzee" layout of the brain, as coded by the genes, cannot be changed, at least not until we are able to re-engineer it. (I wrote a novel about this "Dumria", a planet where they did, with the advantages and inconveniences of it).

But what we do with this can be changed. Simply it cannot be changed by wishes, opinions, laws or constrains. It can be changed by education and training, this is basic neurology stuff, and it is proven to be changeable. Alas, as you say, fear and hope are the only methods useful for persons who do not actively involve themselves in the process. But when we do it VOLONTARILY, when we lead ourselves the process, there are many other means, and much more pleasant means. Read Ghandi's life, how he managed.

Time that could be better spent working *within* the limitations of human nature to do the best possible job at keeping as many people happy as possible...

Immediate practice is worthy too. In fact we cannot do an opposition utopia* versus pragmatism. My experience showed me that these two are non-dual, you cannot succeed in one without accounting with the other.


What I think is that, if scientists are rational people, they must rationaly question the matters of mind and the ways to solve these problems, especially this one: how to become selfless and responsible enough to be able to survive without choking under our own s*** and psychological problems. And this is a mind problem, a problem of how we involve in life. So the solution can be only here.


Perhaps you will prefer to involve into things like humanitary action, than into inner questionning. You are perfectly right to do so. But just not forget that these two are just two aspects of the same thing. Even if you see the unity point only once in your life, it will be very important.



*of course I use this word "utopia" in its original meaning of "blueprint" not in the newspeak meaning of "impossible".

[RNeuhaus]

Setting back to the topic, after a nuke explotion on an asteroide, the radiactive particles will also hit on the Earth and consequently the Earth will be contaminated. Is the nuke a good solution to minimize the threat to Earth in spite of the fact that after the explotion, the impact debris from asteroide will be smaller but greater amount, and the distribution of impact will be even bigger and many will be evaporated in the atmosphere. But, where the radiactive particles will go? Anyway, they will hit on Earth.

Maybe, that the nuke solution must be changed by the gravity tugging technique.

Rodolfo

[ljk4-1]

Not as you think
True that the basic "chimpanzee" layout of the brain, as coded by the genes, cannot be changed, at least not until we are able to re-engineer it. (I wrote a novel about this "Dumria", a planet where they did, with the advantages and inconveniences of it). 

Humans may be able to change for the better, but it will require some radical methods that will essentially render us a different type of being. We are currently trying to live in a civilized, technological society where the majority of people are still biologically programmed to behave as our distant ancestors did. It may have worked out on the savannah, but not in the city.

I am also of the inclination that we are not the end product of evolution and that what comes next will come from our minds, not our loins:

http://www.kurzweilai.net/articles/art0134.html?printable=1

When that happens, we will truly be able to survive just about anything the Universe throws at us, including its eventual demise.

http://prospectmagazine.co.uk/article_details.php.6701.html

[tty]

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

It's not quite that simple. The primary killing mechanism in the Chicxulub impact seems to have been heat in the form of IR radiation from vast numbers of re-entering fragments of material ejected from the primary crater. This affected essentially the whole Earth, though probably rather unevenly.
Breaking up the primary impactor into chunks small enough to vaporize before impacting would actually increase the kinetic energy liberated in the atmosphere since a lot of it is absorbed in the cratering process.
"Spreading out" the energy from a Chicxulub-class impact (10 km impactor) is not a viable mitigation strategy because the energy is simply too large (equal to 10-20 Hiroshima-sized explosions for each square kilometer of the entire Earth).
However if the impactor could be fragmented without the material stringing out along the trajectory it would mean that about half the Earths surface would not be directly affected. The secondary effects (stratospheric dust, NOx, smoke, Ozone, CO2 etc) would still be extremely nasty, though perhaps survivable.

tty

[Guest_BruceMoomaw_*]

Believe me, when the human race starts modifying the structure of its own mind, it's a safe bet that they will do so in the most destructive manner imaginable. Just consider, for instance, what people will do when really effective emotion-control drugs become available in the coming decades...

(While SF writers have been routinely writing stories about this kind of Lotus Eaters' Apocalypse for half a century, they're not the only ones to notice the implications anymore -- "The Economist" did a cover story on the problem a few years ago. Nor do I see any conceivable solution to the problem.)

[Guest_BruceMoomaw_*]

While we're on this cheery subject: I've always thought that humanity's acquisition of the ability to deflect asteroids will almost certainly greatly ACCELERATE the destruction of life on Earth, rather than delaying it. Natural Dinosaur Killers come along only every few tens of millions of years -- but if we develop a Solar System-wide civilization capable of deflecting asteroids, it's highly probable that some political faction will DELIBERATELY and precisely aim one at Earth some time in the next few thousand years. Man is born to trouble as the sparks fly upward -- or, in this case, downward.

[tty]

Believe me, when the human race starts modifying the structure of its own mind, it's a safe bet that they will do so in the most destructive manner imaginable.  Just consider, for instance, what people will do when really effective emotion-control drugs become available in the coming decades...

(While SF writers have been routinely writing stories about this kind of Lotus Eaters' Apocalypse for half a century, they're not the only ones to notice the implications anymore -- "The Economist" did a cover story on the problem a few years ago.  Nor do I see any conceivable solution to the problem.)

Cheer up - it's largely a one-generation problem. The lotus eaters either won't procreate or not take care of their children, so evolution will take it's normal course.

It's not a coincidence that inuits and native americans can become alcoholics in a few months while europeans have to work on it for years. In Europe the more sensitive genotypes became extinct long ago.

tty

[ljk4-1]

While we're on this cheery subject: I've always thought that humanity's acquisition of the ability to deflect asteroids will almost certainly greatly ACCELERATE the destruction of life on Earth, rather than delaying it.  Natural Dinosaur Killers come along only every few tens of millions of years -- but if we develop a Solar System-wide civilization capable of deflecting asteroids, it's highly probable that some political faction will DELIBERATELY and precisely aim one at Earth some time in the next few thousand years.  Man is born to trouble as the sparks fly upward -- or, in this case, downward.

There is the hypothesis that if you go along with the concept of all life on Earth being part of a superorganism called Gaia that regulates itself, then humans were made to keep it safe from another major celestial impact (it learned the lesson the hard way back about 65 million BCE -- actually it was trying to get the dinosaurs to evolve up to making tools, but they took too long).

Read "Are Humans Gaia's Immune System?"

http://www.reason.com/rb/rb073102.shtml

Apparently any political factions that threaten Gaia will be taken care of as well.

[tuomio]

Great power brings great responsibilities. Ongoing evidence with nuclear weapons shows, that we can survive. Developement has been insanely rapid upwards move in last 100 years. Maybe some nut could trigger nuclear war, maybe not. Its one of the uncertanities in the chaotic universe. Heck, nuclear war could even be triggered by some unlucky roll of electronic malfunctions for all i know. If that day comes, i will grab my sunglasses and go drink my last Margharita on some nice viewing spot with grin on my face.

The feared Greenhouse effects _will_ come and they _will_ come with furious power some day, there is no escape. Will it kill us? No way, maybe the Chinese farmers will die in mudslides, but we westerners have capabilities to adapt with the help of technology and capital. Planet earth hosts 5 billion people on it and we posting on this board represent about 1-2% of it. Most of the others work their asses off in farms to get daily cup of rice. Talk them how to be unselfish...bah..

All the oil will be consumed and burned horribly inefficently in Indian mopeds, thats a fact and there is nothing we can do about it. Just wait till we get back to the coal, that is the next step and no matter how nasty sunburns we will get, its probably the only way for a long time to come.

I am waiting the disasters with great interest, because when it hits, there is one less uncertanity in the back of my mind. Unselfish human race would consist of one man, is that the objective, i think not.

[mike]

Eh, the whole 'technology is bad' issue comes down to whether you think humanity is inherently good or inherently bad. I've never understood why someone would want to think humanity is inherently bad, since that would mean you were inherently bad yourself. I could blame christianity and the like for the problem, but I imagine the issue would arise in some form or another regardless..

As far as concrete examples, when we do indeed develop the technology to deflect asteroids onto planets, we will therefore also have the technology to deflect them back away. Supposing a large-scale nuclear war were to erupt, we would either die out and be replaced by a better (in this case, less likely to erupt into large-scale nuclear war) species, or we would survive, with the weaker members no doubt dying while the strong survived, arguably making the species better, and surely wiser. I personally feel that the entire nuclear threat is highly overplayed, myself.. A nuke to New York City or Washington, DC or London would be politically and economically painful for some period of time, but I don't think it would have much effect on humanity as a whole. Once we have the technology to really destroy the planet (insofar as concerns the human species' survival, anyway), we'll also have the technology to prevent that destruction.

At any rate, life is entirely what you make of it, and it seems some people are just predisposed to be pessimists. Obviously, though, the optimists are more influential, since we're not all living in caves and picking fleas off of each other...

[Bob Shaw]

While we're on this cheery subject: I've always thought that humanity's acquisition of the ability to deflect asteroids will almost certainly greatly ACCELERATE the destruction of life on Earth, rather than delaying it.  Natural Dinosaur Killers come along only every few tens of millions of years -- but if we develop a Solar System-wide civilization capable of deflecting asteroids, it's highly probable that some political faction will DELIBERATELY and precisely aim one at Earth some time in the next few thousand years.  Man is born to trouble as the sparks fly upward -- or, in this case, downward.

Bruce:

Latest research shows that the dinosaurs were doing just fine until they developed the Iridium Bomb...

Bob Shaw

[Guest_BruceMoomaw_*]

"Cheer up -- it's largely a one-generation problem. The lotus eaters either won't procreate or not take care of their children, so evolution will take its normal course."

Of course, evolution taking its "normal course" in this case will consist of Homo sapiens bumping itself off completely. Exactly how many people are going to be able to resist the temptation to completely control their own emotions and erase any feelings of sadness or fear -- including those necessary to keep the species going? Damn few. (That's if we don't devise some genetically engineered doomsday plague, of course. In that case, evolution "taking its normal course" just might involve us managing to obliterate life on Earth -- or, at a minimum, animal life on Earth -- completely.)

As for my believing that humans are "most good" or "mostly evil": it's (obviously) irrelevant. The point is that advances in our understanding of biology are about to give us unprecedented power -- power far beyond that which even splitting the atom has given us -- and the most fundamental physical law of the universe is that it's always easier to use power to destroy than to create. The only thing that's kept humanity from not doing so up to now is that we haven't really understood very much about the operations of our own bodies and cells. Now we're about to. And I also have no doubt that every intelligent race in the Universe automatically and uncontrollably destroys itself when it reaches our level of technology -- how could it NOT do so? -- which in turn is one likely explanation for why we're not picking up radio signals from other civilizations (and for why the first race to achieve technology hasn't spread across the entire galaxy with Von Neumann machines).

[Guest_BruceMoomaw_*]

As for "Gaia being a superorganism that deliberately created humans in order to preserve itself from another asteroid impact": puh-leese. You're just reviving Intelligent Design, with "Gaia" replacing God -- and there's no more evidence for evolution being controlled by the former than by the latter. The whole point about Darwinian evolution is that it's a BLIND watchmaker, which does its work as an incidental byproduct of incredible amounts of mass slaughter.

[Tom Ames]

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.
...
As far as species disappearing, eh, maybe they weren't that great in the first place.

Yeah, who needs megafauna like elephants and tigers anyway? Especially when so many people are in need of their ivory and gall bladders.

[dvandorn]

In re the "good vs. evil" issue -- I think that human nature is basically not to be more attracted to (always subjective) standards of either good OR evil. I think people, by and large, will always take the easiest of the paths they see available to them. If the easiest path is deemed evil, fear of punishment might keep them off of it -- for a while. Depends on how afraid you can make them.

People are also most likely to lose their fear of punishment for "evil" deeds when acting in groups. This "mob mentality" phenomenon (which, by the way, works into most forms of military training) is responsible for more "evil" deeds than individual actions could ever possibly hope to match.

Now, don't get me wrong -- people do hard things. They have done hard things throughout human history, and every day, people do hard things. But they usually do them because doing those hard things are the easiest ways they can think of to accomplish their goals. In fact, a lot of people make things much harder than necessary, simply because they don't see the easier paths as being available to them... or can't admit to believing that any easier path exists at all.

Oh, and as for Bruce's comment that the ability to change an asteroid's trajectory might doom the race rather than save it? I think he's 100% correct. How many military machines, at the brink of losing a war, have implemented scorched-earth policies? It's not only conceivable that a "sore loser" in a conflict would direct an asteroid into a collision course, it's predictable.

What would be a tremendous shame would be if the losing side of a deep-seated conflict (say, an aeons-old religious conflict) were to place an asteroid on a course that would result in an Earth impact some 200 to 300 years hence, and that the resolution of the conflict resulted in the loss of the ability to re-direct this doomsday weapon. A human civilization slowly climbing out of the abyss of such a cataclysmic war would be wiped out by the ghost of the madness they had finally left behind them...

-the other Doug

[mike]

Eh, you guys are just afraid that humanity might actually use these new technological advances to do truly amazing things. Wait and see, my friends...

[Guest_Richard Trigaux_*]

Cheap cabaret philosophy just to continue doing nothing!

(This remark not for mike, it is for certain others. I agree with you mike that technology is not ats is end, it could in a near future make things possible we cannot yet imagine).


Back to topic, it seems that pulling gently a threatening asteroid and neutralize it on another planet is much better than bombing it, as the debris may bring more energy into Earth atmosphere, not to speak of nuclear wastes when using a nuke. Anyway thanks to the sensitive dependency to initial conditions, it is enough to pull them very gently at the right moment to achieve drastic changes in the future orbit. The only problem is that we need a very accurate tracking of the asteroid position, if we do not want to just transform a near probability of a catastrophe into a future certainty of catastrophe. The best way to achieve this would be to attach a radio beacon to threatening objects, and also to all neighbouring planets. For this we do not need to make a very soft landing like on Eros or with Hayabusa. An alternative to sending threatening bodies on the Moon would be send them on the sun, but this requires much more energy.

[tty]

Cheap cabaret philosophy just to continue doing nothing!
. An alternative to sending threatening bodies on the Moon would be send them on the sun, but this requires much more energy.

Causing an threatening asteroid to miss the Earth requires at the most shifting its orbit 6350 km. Causing it to hit the Moon in most cases requires shifting it a great deal more.
To get an asteroid to hit the Sun you must get rid of almost its entire kinetic energy.
It might be simpler to move the Earth out of the way....

tty

[Guest_Richard Trigaux_*]

Causing an threatening asteroid to miss the Earth requires at the most shifting its orbit 6350 km. Causing it to hit the Moon in most cases requires shifting it a great deal more.
To get an asteroid to hit the Sun you must get rid of almost its entire kinetic energy.
It might be simpler to move the Earth out of the way....

tty

Yes. In the case a far object suddenly appears from behind the Sun, we have very few time to do something, and it will have to be drastic. But in the general case, threatening objects are known. And, in astronautics, the problem is not "shifting the orbit 6350kms" but shifting it of an angle. And the sooner we do it, the smaller the required deviation angle.
My point was that, if we use sensitive dependency to initial conditions, a very small tug on even a large asteroid like Eros is enough do deflect it in a safe trajectory, as at each approach to a planet the effect of this very small tug is increased manyfold. So we need very little energy, provided we are able to predict future trajectories with a great accuracy. I think this is the solution.

To give an accurate push would rather require classical rockets. Nukes are more powerfull, but their effect on the asteroid may be very unpredictable, small deviation, large deviation, breaking it, not breaking it...

My remark about cheap cabaret philosophy was to settle some off-topic discutions above, unrelated with asteroids and even with their effects on life. Asteroids are a problem of astrophysics and astronautics, there is no philosophy point about them, except of course to avoid their threat.

[RNeuhaus]

My point was that, if we use sensitive dependency to initial conditions, a very small tug on even a large asteroid like Eros is enough do deflect it in a safe trajectory, as at each approach to a planet the effect of this very small tug is increased manyfold. So we need very little energy, provided we are able to predict future trajectories with a great accuracy. I think this is the solution.

So, then the most economical and effective solution to take care the Earth from asteroids is to have a very good radar with very long range scan and good memory to pinpoint all the way in order to calculate the precise path.

This will help us to send a most adecuate spaceship size to tug the asteroide with much sooner anticipation.

So, to raise the funds for a very good rastring to asteroids is the best and cheapest solution.

Rodolfo

[lyford]

Rodolfo -

I agree completely - we should be enthusiastically funding a NEO catalogue program - we really should know with plenty of lead time if there are any planet killers out there, even "city killers." It's a good value considering the alternative!

[ljk4-1]

As for "Gaia being a superorganism that deliberately created humans in order to preserve itself from another asteroid impact": puh-leese.  You're just reviving Intelligent Design, with "Gaia" replacing God -- and there's no more evidence for evolution being controlled by the former than by the latter.  The whole point about Darwinian evolution is that it's a BLIND watchmaker, which does its work as an incidental byproduct of incredible amounts of mass slaughter.

You make some valid points, but since most humans still seem to need religion, at least this one has a tangible god and goal.

You've got people waiting for the Rapture, so why not an NEO? At least we know they exist and some do threaten life on Earth.

It will give people some purpose to their lives - and it will educate them and protect Earth in the process. Better than most religions I know.

[RNeuhaus]

The paragraph was extracted from http://www.space.com/businesstechnology/05...r_hayabusa.html

The B612 group has advocated placing an active radio transponder on the object. Doing so at a fairly early date would yield the requisite orbital accuracy of the asteroid as it careens through space.

That solution, a active radio transponder on the asteroide, will give us a even much better orbital accuracy. The other solutions is by placing at least three spacecraft in triangular form in the Earth orbit scanning for any new asteroides.

On the other hand, a new private group which advocates a mission similar to NEO of NASA.

The group’s name stems from the asteroid home of the Little Prince in Antoine de Saint-Exupery's child’s story: The Little Prince. The foundation advocates honing the capability and technological wherewithal to anticipate and impede Earth-impacting asteroids.

That new mission was brought out by the awakening interes on the Falcon mission as a proof-of-concept engineering mission, not as a science mission.

Rodolfo

[JRehling]

The real hope for our civilization is that science-related message boards could one day replace more of the science-related discussion with more and more speculative ideas, and a healthy amount of pontification on philosophy, ethics, and human nature. With enough diffuse speculation, how can any goal be unattainable?

[Bob Shaw]

Yeah, who needs megafauna like elephants and tigers anyway? Especially when so many people are in need of their ivory and gall bladders.

Tom:

Well put!

Bob Shaw

[Bob Shaw]

As for "Gaia being a superorganism that deliberately created humans in order to preserve itself from another asteroid impact": puh-leese.  You're just reviving Intelligent Design, with "Gaia" replacing God -- and there's no more evidence for evolution being controlled by the former than by the latter.  The whole point about Darwinian evolution is that it's a BLIND watchmaker, which does its work as an incidental byproduct of incredible amounts of mass slaughter.

Bruce:

There's nowt wrong with Gaia as a metaphor, or as a semi-poetic personification of the general principle which underlines the interconnected nature of Terrestrial life - it's the soggy spiritual guff which give it all a bad name. As a fully-paid-up Greenie I despair at the romantic pap which permeates what *should* be a hard-headed calculation about our planet's finite breadth. Ah, well...

Bob Shaw

[Guest_Richard Trigaux_*]

You make some valid points, but since most humans still seem to need religion, at least this one has a tangible god and goal. 

You've got people waiting for the Rapture, so why not an NEO?  At least we know they exist and some do threaten life on Earth.

It will give people some purpose to their lives - and it will educate them and protect Earth in the process.  Better than most religions I know.

The Gaïa hypothesis has nothing to do with religion or spirituality. If is a remark of biologists comparing the self-regulations of ecology with that of an organism. So they called this organism "Gaïa" (the ancient Greek godess of Earth) and its whole body is the Earth ecosphere.
But in no case Gaïa would be clever enough (and even not conscious like us) to take decisions to "create species" and all the less to anticipate a meteorite fall. Biologists never said things like that.

[Guest_Richard Trigaux_*]

That solution, a active radio transponder on the asteroide, will give us a even much better orbital accuracy. The other solutions is by placing at least three spacecraft in triangular form in the Earth orbit scanning for any new asteroides.

The idea of three satellites is to have a stereo view of our system. But it would allow too to see "behind" the Sun, in case some bad surprise comes from here, unnoticed, lefting only some weeks of warning.

[Guest_Richard Trigaux_*]

The real hope for our civilization is that science-related message boards could one day replace more of the science-related discussion with more and more speculative ideas, and a healthy amount of pontification on philosophy, ethics, and human nature. With enough diffuse speculation, how can any goal be unattainable?

Physical science relates to the way of doing technological things. WHAT technological things to do is a matter of philosophy, ethics, spirituality, and even pleasure. This is the reason why a general science discution has to deal with these topics.

[Guest_BruceMoomaw_*]

"With enough diffuse speculation, how can any goal be unattainable?"

That's exactly what I'm afraid of...Give us a few more centuries and we might figure out how to blow up the whole damn universe. My point, again, is that the most fundamental of all physical laws (because -- to quote Einstein -- it's actually based on mathematics) is that it is tremendously easier to use power to destroy than to create (a point brought home rather forcefully on 9-11); and humans are now getting their hands on unprecedented amounts of power, with entirely predictable consequences.

[RNeuhaus]

The idea of three satellites is to have a stereo view of our system. But it would allow too to see "behind" the Sun, in case some bad surprise comes from here, unnoticed, lefting only some weeks of warning.

Yes, exact.

[ljk4-1]

The Gaïa hypothesis has nothing to do with religion or spirituality. If is a remark of biologists comparing the self-regulations of ecology with that of an organism. So they called this organism "Gaïa" (the ancient Greek godess of Earth) and its whole body is the Earth ecosphere.
But in no case Gaïa would be clever enough (and even not conscious like us) to take decisions to "create species" and all the less to anticipate a meteorite fall. Biologists never said things like that.

Of course in addition to protecting itself from nasty space rocks, Gaia has also created us to develop spaceflight so it can one day bud off part of itself to other worlds to avoid the eventual red giant frying Earth stage of the Sun.

http://www.washington.edu/newsroom/news/20...e/k011303a.html

[dvandorn]

This is something that we need to spend some time considering -- the dynamics of extraordinarily complex systems often *seem* to appear like intelligent, or at least intentional, behavior.

Earth does have a remarkable set of complex responses to stimuli -- and as such, *appears* to act like some kind of meta-organism. Even appears to be acting with intent, even.

I think the question that begs asking is how much of this is anthropomorphism (our perception of complex responses as intentional and/or intelligent), and how much is a real, objective phenomenon.

-the other Doug

[JRehling]

"With enough diffuse speculation, how can any goal be unattainable?"

That's exactly what I'm afraid of...Give us a few more centuries and we might figure out how to blow up the whole damn universe.  My point, again, is that the most fundamental of all physical laws (because -- to quote Einstein -- it's actually based on mathematics) is that it is tremendously easier to use power to destroy than to create (a point brought home rather forcefully on 9-11); and humans are now getting their hands on unprecedented amounts of power, with entirely predictable consequences.

So the solution is to bog down science boards with "where is civilization going" threads that will halt the very progress that endangers us?!

[JRehling]

Physical science relates to the way of doing technological things.  WHAT technological things to do is a matter of philosophy, ethics, spirituality, and even pleasure. This is the reason why a general science discution has to deal with these topics.

I quite agree about the importance of these topics. Not so much in an asteroid-titled thread. And it seems to me like the thread has become a gathering place for original thoughts that are coming to the poster in real time, apart from the vast amount of thought that has been done on these topics and is available for consumption elsewhere. I may be uncharitable, but the strength of this board has been amazing participation from people with lots of know-how in space science, and it doesn't behoove it to become a "junior varsity" board on philosophy and history of science (which are fascinating topics).

[mike]

"With enough diffuse speculation, how can any goal be unattainable?"

That's exactly what I'm afraid of...Give us a few more centuries and we might figure out how to blow up the whole damn universe.  My point, again, is that the most fundamental of all physical laws (because -- to quote Einstein -- it's actually based on mathematics) is that it is tremendously easier to use power to destroy than to create (a point brought home rather forcefully on 9-11); and humans are now getting their hands on unprecedented amounts of power, with entirely predictable consequences.

You can't predict that far into the future, and don't even pretend that you can. Frankly, if you have such a negative viewpoint of humanity why haven't you killed yourself already?

[Guest_BruceMoomaw_*]

OK; but then, when the Sacred Asteroidal Republic of Krishna Consciousness deliberately drops that big rock on our heads in 2213, don't say I didn't warn you...

[Guest_BruceMoomaw_*]

And in response to Mike: why should I go to the trouble of killing myself when the species will do it for me in so much more spectacular a way?

(Nor do I have a particularly negative view of "humanity" -- given that within half a century we will be living in a world in which one small society of nuts can release a doomsday plague from their basement, how could humanity NOT do itself in? The same sort of thing, I have little doubt, happens automatically and unavoidably to every intelligent race in the Universe as soon as it reaches our stage of technological development, which may be one reason why we're not picking up alien TV sitcoms on our radio telescopes. It's not so much that I have a negative view of humanity as that I have a negative view of the design of the Universe itself -- a sensibly negative view, I believe. To quote Arthur C. Clarke: "No individual lives forever; why on Earth should we expect our species to do so?")

[Chmee]

"With enough diffuse speculation, how can any goal be unattainable?"

That's exactly what I'm afraid of...Give us a few more centuries and we might figure out how to blow up the whole damn universe.  My point, again, is that the most fundamental of all physical laws (because -- to quote Einstein -- it's actually based on mathematics) is that it is tremendously easier to use power to destroy than to create (a point brought home rather forcefully on 9-11); and humans are now getting their hands on unprecedented amounts of power, with entirely predictable consequences.

I would have to completely disagree here. While the power to destroy things has increased significantly, are application of power has been trending toward much more creation than destruction.

Several cases in point. Despite World War II, the worst and most destructive conflict ever, where a large number of cities were leveled, Europe was almost completely rebuilt in a matter of 2 decades and has continued to develop in population, wealth, and infrastructure at a tremendous rate.

Even taking the extreme examples of Hiroshima and Nagasaki, where they were completely vaporized by atomic weapons and lingering radiation effects, they were rebuilt within 20 yeart and are now many times their former size.

Death by violence, as a percent of population, has been trending sharply down since paleolithic times and during historic times. There have been studies with ancient human skeletons that have shown that 25% of males died of obvious violence (rather than natural causes).

Compare that with World War II, where it is estimated 50 million people died (out 2.5 Billion at that time). That is about a 2% chance of violent death.

Right now, about every 20 people out of 100,000 die from violent deaths, that is a .02% chance of you dying by violence.

So even though we have atomic weapons, handguns, and B2 bombers our destructiveness and violence has actually declined enourmously.

We are actually using our greater power for creation not destruction.

[Guest_Richard Trigaux_*]

I quite agree about the importance of these topics. Not so much in an asteroid-titled thread. And it seems to me like the thread has become a gathering place for original thoughts that are coming to the poster in real time, apart from the vast amount of thought that has been done on these topics and is available for consumption elsewhere. I may be uncharitable, but the strength of this board has been amazing participation from people with lots of know-how in space science, and it doesn't behoove it to become a "junior varsity" board on philosophy and history of science (which are fascinating topics).

Yes too. When I reached this forum two or three months ago, it was nearby 100% space, or the philosophy/beauty of space exploration. Recently some subjects appeared which allowed for more general discutions, like Intelligent Design, or SETI. It was interesting, and still perfectly matching with he idea of scientists being responsible of the power they give, or being involved in our situation of conscious happiness-seeking beings. But when we come to angry nit-picking about the necessity of evil or which specy must be eliminated, it is too much I think.

[mike]

And in response to Mike: why should I go to the trouble of killing myself when the species will do it for me in so much more spectacular a way? 

If you really do believe that mankind is destined to inevitably utterly kill itself, then why bother hanging around at all? Aren't you just wasting time, lying to yourself, knowing that it's all completely pointless? By your logic, of course you are.

Therefore, you are either a ) a fraud or b ) lying about having no hope about humanity whatsoever. Which one is it?

[lyford]

You've got people waiting for the Rapture, so why not an NEO?  At least we know they exist and some do threaten life on Earth.
It will give people some purpose to their lives - and it will educate them and protect Earth in the process.  Better than most religions I know.

Too late!

[Guest_BruceMoomaw_*]

Well, while we really ARE geting off the subject of asteroids, to Mike I can reply that most terminally ill people -- unless they happen to be Burt Reynolds in "The End" -- don't see the fact that they're going to die soon as reason to do themselves in even sooner. I take for granted -- and have for decades -- that humainty will almost certainly have exterminated itself by 2100 (there are so MANY ways we'll be able to do it). But then, as Clarke said, every individual human dies within about 80 years; I fail to see why one event should produce more despair than the other. As Poul Anderson said in a story about precisely that event, "The Universe will go on regardless."

But I am getting rather tired of listening to sentimentality-driven space cadets who see a Great Big Beautiful Tomorrow out there (if only we Colonize the Galaxy!) when the evidence is overwhelmingly against it. Up to now we've avoided a world nuclear war by a succession of miracles (having come within 15 minutes of one in 1962, and avoided it solely by the unlikely chance of a President less hawkish than most of Washington and almost all of his own Cabinet). We can't stay on that tightrope much longer, to say nothing of the ever-growing multitude of newer threats that will be coming our way in this marvelous new century. I don't regard this view as "philosophy"; I regard it as elementary common-sense recognition of the nature of the material universe.

Now let's get back to what we'll be doing to entertain ourselves in the shorter run.

[mike]

Avoided nuclear war by 'a succession of miracles'? How do you know that? And please, given your amazing psychic powers, tell me the winning lottery numbers for any major lottery drawing in the next week. Since you are magically able to predict the future of humanity hundreds of years in the future, this should be nothing.

And you can ignore my real question all you want, but the fact is that if you believe that humanity is just a collection of idiotic rabble forever doomed to kill itself, YOU should have killed yourself long ago because it's all just oh so pointless and everyone is just oh so dumb (poor you!). And yet, you haven't. Therefore, you are either a coward or a liar.

Personally, I tend to believe that almost everyone is an idiot but that there are enough non-idiots that things aren't completely without hope. I also believe that the non-idiots will manage to enlighten humanity about why the universe is a wonderful place, though it may take a while (just short of forever, perhaps).

If you want to wallow in self-pity and bemoan how everyone is just a big idiot while not actually doing anything to try to help, then I suggest you commit suicide. Otherwise you're not helping anyone, and in fact are living in an endlessly depressed state, which is not helpful for you. I would suggest, though, that you at least TRY being optimistic for some period of time and see how it works. If, indeed, you find that it does not work, then perhaps this universe isn't for you. There's already enough people who do nothing but complain, I don't think we need any more.

[Guest_BruceMoomaw_*]

So who's complaining? Why complain about the inevitable? And I've already given the (obvious) reasons why I'm not willing to take the highly probable imminent death of the human race as a reason to kill myself even sooner. I AM, however, getting tired of those space cadets who envision the colonization of the Solar System as likely to reduce the chances of that extermination, when the truth is that we'll take our deadly little toys everywhere in the Solar System we go (and, in fact, will be able to spread them around far more easily than we spread ourselves). I might add that, judging from my readings, most even halfway intelligent SF writers take my view of the situation.

We certainly have come a long way in this exchange since I simply pointed out (correctly) that the same technology that enables humanity to deflect asteroids away from Earth will allow political factions in the future to deflect them TOWARD Earth (and if I had a nickel for every SF story I've read in the last 15 years pointing out that fact and its obvious implications...)

[Guest_BruceMoomaw_*]

P.S.: Regarding the fact that we've avoided nuclear war by "a succession of miracles": well, there was the fact that Stalin oblingingly dropped dead just when he was showing signs of going completely nuts; there's the Cuban Missile Crisis (in which the avoidance of WW III was a miracle in itself); there's the fact that the downright paranoid Andropov also dropped dead before he could do anything (other than ordering the USSR's armed forces to go on Red Alert in November 1983 because he interpreted a perfectly ordinary NATO military exercise as a likely imminent invasion); there's that Norwegian research rocket that the Russian early warning system interpreted as a likely ICBM launch against Moscow, only to be personally overruled by Yeltsin...

...and above all else, there are the facts that (1) only one dictatorship to possess the Bomb has fallen from power so far, and that one did so in an orderly way which allowed it to keep its supply of Bombs under control; and (2) the fact that until now it hasn't been possible for a nation to undergo an attack with smuggled nukes while remaining unsure just who attacked it and who to retaliate against. Both those situations are about to change.

Have a nice day.

[mike]

By calling them 'miracles' you are acknowledging the existence of some sort of higher power making things that could not otherwise occur happen.

Have fun being depressed knowing that we're all doomed!

[lyford]

Don't forget these narrowly avoided rays of sunshine!
To segue, if possible, from "nucular" war to the NEO threat, has the popular idea of using nukes to bump an impending collision off track become completely baseless?

[Guest_BruceMoomaw_*]

Yeah, Lyford, I didn't mention the narrow India-Pakistani escape. By the way, the story out now is that Pakistan's plan for a 1999 nuclear first strike against India was averted only because one horrified Pakistani clerk who overheard the generals planning it leaked the information to the British government -- and then ran for his life to Britain.

But even the possibilities of nuclear warfare pale next to those that genetic engineering will produce in another few decades -- whether deliberate or accidental. Should you really wish to brighten your day, read

http://www.washingtonpost.com/wp-dyn/artic...-2004Feb17.html

http://www.washingtonpost.com/wp-dyn/conte...5101301783.html

...and consider that they're only talking about the biotechnology which will be available in the 2005-15 period. (The "molecular biologist" that Anne Applebaum quotes, by the way, is probably Joshua Lederberg.) Now just think what things will be like in 2040 -- not just for us, but for the rest of the biosphere. (Of course, that technology will also allow us to develop defenses -- probably including even deliberately released "infectious vaccines" -- but the destructive forces will always be created faster than the corrective ones. It is, as I say, always much easier to destroy than to create -- or, as Arthur Clarke put it back in 1970, "With increasing technology comes increasing vulnerability.")

And, incidentally, Mike, by "miracle" I meant "extremely unlikely event", of course. Frankly, while the idea that humanity's goose is cooked within this century is depressing, I don't exactly find that it deprives me of all will to live -- to quote Clarke again, everyone of us dies individually; and humanity for most of its existence did not believe in ever-upwards-and-onwards progress for the race. Nor do I think that the meaning and importance of human existence lies -- by a long shot -- entirely within the realm of time.

Well. In the extremely unlikely event that a dangerous asteroid does come along before we cut our OWN throats, nuclear explosions seem less and less advisable to deflect it if something else is available, since they'll only disperse a "rubble pile" into a closely knit cloud (if they even do that) -- but they're better than nothing. A big enough one might spray such a rubble cloud widely enough that most of its material missed Earth -- and a smaller one, if it hit the rubble pile while it was still far enough away from Earth, might well still deflect it enough to miss the planet. Frankly, though, given the fact that nothing Tunguska-sized is likely to hit us for 500 years or more, the best use for an early-warning system is probably just to let people know where the thing is likely to hit in time for evacuation -- and to let any nuclear-armed nation hit by it know that it was NOT a nuclear attack by one of their enemies.

[mike]

It certainly does seem to be easier to destroy than create.. and yet, look all around you and I'm sure you will see buildings, streets, cars, and, yes, the very Internet via which we are now conversing. These things are not heaps of rubble.

As far as your comment that 'most science fiction readers agree that mankind is doomed to destroy itself', I'd be curious to see any sort of evidence whatsoever.

[ljk4-1]

Humanity will survive for the same reason Americans will overcome terrorism: We like our cushy lifestyles too much to give them up, no matter what the threat.
Plus there is that ingrained and ancient survival instinct.

Mike, I think you were taking the term "miracle" a bit too literally as used here.

Having grown up in the Cold War era and expecting a nuclear attack every day (I even worked out a plan to run home to my basement in case the bombs started falling during school), I think it is amazing that we are still here. But we aren't out of the woods yet.

I am often disappointed and frustrated with the human species, but I think we have the potential to be truly great and will overcome our failings. Not without losses along the way, but look how far we have come in just a few thousand years since civilization began. When we do use our brains properly, look what we accomplish.

It took life billions of years to go from microbes to simple multicellular beings. Our progress has been in a cosmic blink of an eye.

[chris]

Nick Bostrom from the University of Oxford Philosophy faculty, whose paper was mentioned earlier in this thread, has written about assessing the risks that our technological progress expose us to. He makes the point that unlike threats that have historically faced the human species, some more recent risks cannot be dealt with using a trial-and-error approach, as if they come to pass we will won't be around to learn the lesson. These so called "existential risks" therefore require assessing in a different manner.

The paper is here http://www.nickbostrom.com/existential/risks.pdf

Its well worth a look having at some of the other stuff he has written - you may or may not agree, but its interesting and well argued. It all there on his website.


Chris

[tty]

P.S.: Regarding the fact that we've avoided nuclear war by "a succession of miracles": well, there was the fact that Stalin oblingingly dropped dead just when he was showing signs of going completely nuts;

That was probably not a miracle - there is fairly strong evidence that he was helped along (probably by Beria)

tty

[Guest_BruceMoomaw_*]

More on Lyford's question at http://www.lpi.usra.edu/meetings/lpsc2005/pdf/2249.pdf

[lyford]

Thanks Bruce - interesting

Here we consider the limiting case of a highly cohesive rock (i.e. pristine basalt) and a much weaker material [7], i.e. weakly cemented basalt (WCB), which has a tensile strength of ~106 cgs and is more representative of rock at large scales.it.

I wonder how these assumptions hold up against Hayabusa's experience - I seem to recall Itokawa being described as an aggregate of smaller bodies - such a fine line between deflecting and shattering! Did the mission yield any more info on that? The latest chapter in its engineering soap opera has unfortunately fogged my memory....

[Bob Shaw]

Bruce:

Perhaps we should *encourage* all sorts of Bad Things to happen, on the basis that it'd be at least 'entertaining'? A NEO impact could be really fun (briefly).

Here's a (dare I say) Modest Proposal: On a more immediate note, if humanity is doomed in general, and all humans are due to cast off this mortal coil sooner rather than later, then perhaps we should give up on unmanned spacecraft and instead concentrate on 'briefly-manned' spacecraft. For example, the James Webb Space Telescope could be reconfigured to take account of the presence of a suicide squad of highly-motivated IR astronomers who'd ensure that the darned thing unfolded before quietly expiring. Just choose astronomers with terminal illnesses, or difficult spouses, and with a desire for a career highlight and there'd be lots of potential candidates!

Or, we could vote regarding potential candidates...

Bob Shaw

CF Robert L Forward: Dragonfly

[edstrick]

Note that Cis-Lunar manned transportation capacity provides the ability (though at serious cost) to service spacecraft in the Earth-Sun L-1 and L-2 points. Usually, if such servicing is desired, it'd be better to retrieve a spacecraft to high Earth orbit for servicing on a week long mission, rather than taking months to get to an L point and months to get back.

There is nothing wrong with the idea of on-orbit servicing of satellites. It's just that the Shuttle can't do it Cheaply, Safely, and Frequently. Only the highest-value target, Hubble, is at all intrinsically valuable enough for Shuttle servicing, and at the real cost of a shuttle flight, not really.

NASA, DOD, and their bed-partners in the Military Industrial Complex have utterly failed to provide the safe, frequent, and cheap access to space that is needed. It's unlikely that it can ever be done as well as we'd like with rocket technology, but as I hope Elon Musk and SpaceX is about to prove, we can make big inroads on the cost and difficulty of space access.

[ustrax]

Nice thing to play with...

http://www.lpl.arizona.edu/impacteffects/

[ljk4-1]

THE COMING DARK AGE

Newsletter

December, 2005

1. INTRODUCTION

This newsletter deals briefly with the super-long-term history of the
human race.

Past editions of the newsletter are on the coming dark age website. I
welcome all comments, suggestions and contributions, especially the
latter.

http://www.darkage.fsnet.co.uk/

Please forward this newsletter to anyone you think might be interested.

Marc Widdowson - news@darkage.fsnet.co.uk


2. SUPER-LONG TERM HISTORY OF HUMANITY

Dark age theory, as my friend DB recently reminded me, states that “on
sufficiently long timescales, no gains are permanent”. If modern
cosmology is to be believed, the universe itself may one day collapse
back into who knows what, or at any rate may suffer a “heat death” when
all thermodynamic potential is used up and complex phenomena, such as
life, become impossible. In this case, even the human race is limited
by the laws of physics and its future achievements, however great, must
eventually go for nothing as the universe runs out of steam, or falls
back on itself in a Big Crunch. It follows then that indeed, on long
enough timescales, no gains are permanent, and whatever may be
accomplished by individual humans, or by the species as a whole, it
cannot help but be wiped out in the long run.

To be set against this is the notion of dark age theory that the basic
story of human existence is one of perpetual progress, where temporary
setbacks—of which dark ages are the most extreme manifestation—are
simply part of the mechanism by which progress is achieved. In this
respect, dark age theory foresees a tremendous future for the human
race and supposes that it is humanity’s destiny to conquer first the
earth, then the solar system, then the galaxy, and finally the entire
universe. In this respect, ‘conquest’ does not mean simply travel and
exploration, but is more importantly about understanding and control.
Dark age theory thus asserts that the universe is a great enigma, of
which the human race, in its present condition, comprehends next to
nothing (pace Stephen Hawking et al.). Ahead of humanity lies a great
journey of discovery, whose eventual destination is a final and perfect
insight into the mysteries of existence.

According to biologists, the typical lifespan of a terrestrial species
is about a million years. The timescale for the end of the universe, by
contrast, is over a billion times greater. If humans do eventually
conquer the universe, they will surely not look like humans do today.
They will have been transformed into something far more capable and
exotic, perhaps through genetic engineering and/or some kind of
cyberisation. Such highly evolved entities, when they finally
comprehend the universe, may be capable of re-creating it. It is
possible, however, that they may themselves be annihilated in the
process. This would be the ultimate realisation of the phoenix
principle, comprising the destruction and re-birth of the entire
universe. Such has, of course, been the theme of various science
fiction novels. The work of Olaf Stapledon is recommended. It may
nevertheless be true, and the fundamental point remains: “on
sufficiently long timescales, no gains are permanent”.

Dark Age Watch

news@darkage.fsnet.co.uk

http://www.darkage.fsnet.co.uk/

[ustrax]

THE COMING DARK AGE

http://www.darkage.fsnet.co.uk/

I liked reading this...
Any more bibliography advised?

[ljk4-1]

A NEO to monitor:

http://neo.jpl.nasa.gov/risk/2004vd17.html

Higher on the scale than Apophis:

http://neo.jpl.nasa.gov/risk/

Should we start paging Bruce Willis?

[ljk4-1]

TOP STORIES

COMETS & ASTEROIDS - our new Special Report

They are remnants from the birth of our solar system. And if one
hits Earth, it could be the end of human civilisation. Read the
latest, plus our Instant Expert, Impacts Timeline and Top Ten

http://www.prq0.com/apps/redir.asp?link=Xc...I&tid=WicdhafCF

[ljk4-1]

STELLAR CHEMISTRY

- Killer GRB Unlikely In The Galactic Neighborhood

http://www.spacedaily.com/reports/Killer_G...ighborhood.html

Ohio State University - Columbus OH (SPX) Apr 18, 2006 Are you losing sleep at
night because you're afraid that all life on Earth will suddenly be annihilated by a
massive dose of gamma radiation from the cosmos? Well, now you can rest easy.

[Guest_Richard Trigaux_*]

Interesting result. But it eliminates the only simple solution to the Fermi paradox: life should exist for long into our galaxy, perhaps even before Earth.

[ljk4-1]

We are not really prepared to stop a space rock from impacting
Earth, are we?


DEEP IMPACT

- Deflecting Asteroids Difficult But Possible

http://www.spacedaily.com/reports/Deflecti...t_Possible.html

Moscow, Russia (RIA) Apr 23, 2006 - Col. Gen. Vladimir Popovkin, commander of
the Russian Military Space Forces, told a news conference Friday that the
national satellite network lacked a spacecraft capable of preventing an asteroid
strike.


- One-Of-A-Kind Meteorite Unveiled

http://www.spacedaily.com/reports/One_Of_A...e_Unveiled.html

[Guest_Richard Trigaux_*]

To deflect an asteroid, we would need the equivalent of the Hayabusa mission, to land on it. But if it uses a chemical rocket to deflect the asteroid, it need to be the size of a Saturn V rocket. A ion drive would be smaller, if powered with solar cells, working with a long time. Still some way to go from now...

[Bob Shaw]

Richard:

The 'gravitational tractor' concept seems well worth exploring as it works without reference to the make up of any materials being moved, just their mass (no landing - in fact, Hayabusa has already demonstrated the concept by hovering over Itokawa) - and see my comments re VASIMR in the 'Earth to Mars in 3hrs...' thread.

Bob Shaw

[Guest_Richard Trigaux_*]

The gravitation is a very weak force, and a gravitational tractor would require a mass of billions of tons to have any noticeable effect. We are "a little bit more ahead" of what is feasible, than with a classical rocket or ion drive.