Full Version: Earth's defense against NearEarthObjects
A short time ago a friend told me that there has been research of the means to stop a big object on its way to the Earth.
I always thought that we had enough nukes to stop any incoming space object. But he told me that this is not the case for the following reasons:
1. The ICBMs (US and former SU) are only capable to orbit and reenter the atmosphere at their designated targets. They cannot leave Earth's orbit.
2. Even if they could leave the orbit, they would not be able to destroy an object beyond a certain mass, e.g. the mass of Mount Everest, but only to cause damage on its surface.
3. Even if the object could be destroyed (into millions of smaller objects), the entire mass of it would not change. The consequences for the Earth would probably be even more disastrous (something I consequently tried to disbelieve and disproof).
Here is why: The atmosphere of the Earth would only cause the first entering objects to vaporise, building a heat shield for the following cloud of objects. The effect would be that most of these objects would impact, causing the same effect as massive (planetary) carpet bombing (with dense, radioactive, high-speed objects). In comparison to a single gigantic object this massive bombardment would stir up dust all over the globe, causing even more dust to enter the atmosphere, causing a nuclear winter and so on...
a) Does anyone have anything to disprove/prove any of these statements?
What do YOU think of this/ what is your opinion on this?
c) What could be done to counter this threat?
--
Please don't speculate about the statistical possibility of that, just think of the threat as a real one.
I always thought that we had enough nukes to stop any incoming space object. But he told me that this is not the case for the following reasons:
1. The ICBMs (US and former SU) are only capable to orbit and reenter the atmosphere at their designated targets. They cannot leave Earth's orbit.
2. Even if they could leave the orbit, they would not be able to destroy an object beyond a certain mass, e.g. the mass of Mount Everest, but only to cause damage on its surface.
3. Even if the object could be destroyed (into millions of smaller objects), the entire mass of it would not change. The consequences for the Earth would probably be even more disastrous (something I consequently tried to disbelieve and disproof).
Here is why: The atmosphere of the Earth would only cause the first entering objects to vaporise, building a heat shield for the following cloud of objects. The effect would be that most of these objects would impact, causing the same effect as massive (planetary) carpet bombing (with dense, radioactive, high-speed objects). In comparison to a single gigantic object this massive bombardment would stir up dust all over the globe, causing even more dust to enter the atmosphere, causing a nuclear winter and so on...
a) Does anyone have anything to disprove/prove any of these statements?
What do YOU think of this/ what is your opinion on this?c) What could be done to counter this threat?
--
Please don't speculate about the statistical possibility of that, just think of the threat as a real one.
From what I've read, the idea of sending nuclear weapons into orbit is not to blow up or obliterate any likely impact object, but to use the blast front to alter it's trajectory just enough to make it miss the Earth. Only smaller objects would actually be destryoed.
Ordinary ICBMs wouldn't be too hard to use, but a shuttle or ordinary satellite launch rocket (like Ariane) could take up a modified cruise missile easily enough in theory.
The trouble is, it's all in theory, because nobody takes the threat seriously enough to spend much money on it.
A British MP, Lembit Opik, has been campaigning in vain for many years for the UK to fund research into this - not only is some sort of aversion methodology required, but a great deal more astronomical observation is required, since these objects are relatively small and dark compared to those that most astronomers study. He actually succeeded in getting a feasibility study funded, but little more has happened since then. Here's a link.
Here's another, an email from Mr Opik himself.
Ordinary ICBMs wouldn't be too hard to use, but a shuttle or ordinary satellite launch rocket (like Ariane) could take up a modified cruise missile easily enough in theory.
The trouble is, it's all in theory, because nobody takes the threat seriously enough to spend much money on it.
A British MP, Lembit Opik, has been campaigning in vain for many years for the UK to fund research into this - not only is some sort of aversion methodology required, but a great deal more astronomical observation is required, since these objects are relatively small and dark compared to those that most astronomers study. He actually succeeded in getting a feasibility study funded, but little more has happened since then. Here's a link.
Here's another, an email from Mr Opik himself.
QUOTE
From what I've read, the idea of sending nuclear weapons into orbit is not to blow up or obliterate any likely impact object, but to use the blast front to alter it's trajectory just enough to make it miss the Earth.
To alter the course of a big object might be possible if it is still far away so that a small change in it's trajectory would ultimately bring a lot of distance between it's original path to Earth and it's new path. But there are two problems:
1) To spot an object far in advance is very unlikely for the reasons you gave, plus there are some very dark objects which reflect so little sunlight that it may just impossible to find them.
2) The Ariane rockets may bring the nuclear warhead into the orbit and little beyond, but these weapons have no own propulsion system as all spacecraft have to pick up speed and maneuver. So it would take quite some time to prepare a warhead with the capability to actually fly deep into space to rendezvous with the object.
If we are lucky to spot the object far in advance it will not be the problem to act upon the danger accordingly, but it might be much more probable that we don't have that amount of time.
QUOTE
"The smallest known metallic (M-type) asteroid, 3554 Amun, is a NEA with a radius of 500 meters. It contains over $1,000 billion worth of cobalt, $1,000 billion worth of nickel, $800 billion worth of iron, and $700 billion worth of platinum metals. The total value of this single small asteroid is approximately equal to the entire national debt of the United States. " - Rain of Iron and Ice John S. Lewis ISBN 0-201-48950-3
Just let everyone know these facts and I'll bet that not one asteroid or comet EVER hits the Earth!
Although it may be more readily available to our current technology, nuclear devices may not be the best long-term solution.
http://en.wikipedia.org/wiki/Asteroid_deflection_strategies
I couldn't find anything to disprove the theory that breaking an object into smaller objects would be more dangerous. But it seems to me that with more and smaller pieces, more explosive force would be dispersed into the upper atmosphere and space. I don't see how a "heat shield" could form that would allow smaller objects to reach the surface more easily than one large object.
http://en.wikipedia.org/wiki/Asteroid_deflection_strategies
QUOTE
However, NASA scientist Dan Durdan has argued that if an asteroid was of low density and high porosity, it would be more likely to absorb the energy from a stand-off explosion, rather than be deflected. Although 1950DA is dense, many other asteroids in the Solar System were found to be of low density and high porosity, and therefore could not be deflected in this way.
Researcher Jay Meloch has proposed that it may be possible to deflect the orbit of an asteroid by focusing solar energy on its surface. This would create a small thrust from the resulting vaporisation of material, which over time would be enough to deflect any incoming asteroids, regardless of their density and porosity. Such a 'solar collector' is not as far fetched as it sounds, as the US military have already launched satellites designed to collect and focus radio waves.
Other proposals include:
Setting up mass drivers on the object to scoop up dusty material and shoot it away, giving the object a slow, steady nudge. Flying a big sheet of reflective mylar to wrap itself around the asteroid, acting as a solar sail to use the pressure of sunlight to shift the object's orbit. Dusting the object with powdered chalk or soot to perform a similar adjustment, using the Yarkovsky effect.
Researcher Jay Meloch has proposed that it may be possible to deflect the orbit of an asteroid by focusing solar energy on its surface. This would create a small thrust from the resulting vaporisation of material, which over time would be enough to deflect any incoming asteroids, regardless of their density and porosity. Such a 'solar collector' is not as far fetched as it sounds, as the US military have already launched satellites designed to collect and focus radio waves.
Other proposals include:
Setting up mass drivers on the object to scoop up dusty material and shoot it away, giving the object a slow, steady nudge. Flying a big sheet of reflective mylar to wrap itself around the asteroid, acting as a solar sail to use the pressure of sunlight to shift the object's orbit. Dusting the object with powdered chalk or soot to perform a similar adjustment, using the Yarkovsky effect.
I couldn't find anything to disprove the theory that breaking an object into smaller objects would be more dangerous. But it seems to me that with more and smaller pieces, more explosive force would be dispersed into the upper atmosphere and space. I don't see how a "heat shield" could form that would allow smaller objects to reach the surface more easily than one large object.
QUOTE
...the first idea that usually comes to people's minds when this question (what exactly should we do?) is raised, almost independent of their education or technical background, is, "Why not blow it up?" Clearly the prospect of a gigaton surface impact is more formidable than that of a ten-megaton impact. The latter, however terrible, is now in the realm of practical human experience; the former partakes of all of those unpleasant over tones of unfamiliarity and extreme size. But supposing we split the an approaching one-gigaton object into ten equal pieces, of one hundred megatons energy each, which strike Earth like a giant shotgun pattern. The radius of the area destroyed by an explosion is closely proportional to the cube root of the explosive yield. When you work out the arithmetic, intentional breakup looks very unwise. Ten one-hundred-megaton-surface explosions devastate an area 2.16 times as large as that destroyed by a single one-gigaton explosion with the same total yield! Splitting the one-gigaton body into a hundred ten-megaton objects causes the area of destruction to increase by a factor of 4.65. The main effect of breaking up the threatening impactor is to increase the damage done by a factor of several.
...
Thus the real effect of splitting a moderately strong gigaton body into ten to one hundred smaller pieces is to increase the area devastated by the impact by a factor of 4 to 10. The disruption of a threatening impactor is clearly not a sensible option unless almost all of its fragments can be diverted so as to miss the Earth.
Rain of Iron and Ice John S. Lewis ISBN 0-201-48950-3.
...
Thus the real effect of splitting a moderately strong gigaton body into ten to one hundred smaller pieces is to increase the area devastated by the impact by a factor of 4 to 10. The disruption of a threatening impactor is clearly not a sensible option unless almost all of its fragments can be diverted so as to miss the Earth.
Rain of Iron and Ice John S. Lewis ISBN 0-201-48950-3.
This quote from John S. Lewis tells it all. Blowing up the threatening object is a bad choice.
On the other hand, putting the threatening object in orbit around the Earth would supply untold wealth into the world economy!
I honestly think that there is no way for people in earth to avoid an asteroid because of its size and lack of interest in that threat. I think no individual country like the US would ever invest enough money in such a project to make a difference. I also think that the US shouldn't. The US won't be the only country affected if an asteroid hits the earth. Its a global catastrophy waiting to happen and should have global importance. I wonder why the UN or some other international organization doesn't ask its members to fund something against the threat of asteroids. The UN probably won't be aversely affected by such funding.
Another method to deflect asteroids, similar to the wrap method already posted, is to attach sails to the asteroid and to use solar wind and radiation to pull the asteroid out of orbit. I read this article that had this poster on the different methods of destroying an asteroid. The second to last defense mechanism (they were ordered in time needed to succeed) was to have a laser attack the asteroid. Obviously, there is no laser in space now, but the potential there is pretty good (assuming a laser is developed). It probably has more range than any nuclear missile and solves the accuracy problem.
Another method to deflect asteroids, similar to the wrap method already posted, is to attach sails to the asteroid and to use solar wind and radiation to pull the asteroid out of orbit. I read this article that had this poster on the different methods of destroying an asteroid. The second to last defense mechanism (they were ordered in time needed to succeed) was to have a laser attack the asteroid. Obviously, there is no laser in space now, but the potential there is pretty good (assuming a laser is developed). It probably has more range than any nuclear missile and solves the accuracy problem.
We have no defense against near earth objects. Nukes won't work as already stated unless we use them to alter the trajectory, even that would be a one shot in a million thing
There is no possible way to defend Earth at this time against an asteroid
There is no possible way to defend Earth at this time against an asteroid
QUOTE(GoAmerica @ Mar 20 2004, 09:49 PM)
We have no defense against near earth objects. Nukes won't work as already stated unless we use them to alter the trajectory, even that would be a one shot in a million thing
There is no possible way to defend Earth at this time against an asteroid
There is no possible way to defend Earth at this time against an asteroid
Did you guys read my posts? Greed is a very potent tool!
With technology as it is, unless something is being kept a secret we can't stop a celestial object of any great size. The best and most plausable way to survive as a race would be to expand. Can't have all your eggs in one basket, right?
The moon would be no help in an Armaggedon type situation. Mars is the easiest choice, though I use the term "easy" loosely. The only problem with all this is that it simply won't happen. The world won't cooperate enough with the current state of affairs to build anything remotely close to being required to make this.
Of course, I'm of the opinion that humanities over-riding concern should be expansion off this planet.
The moon would be no help in an Armaggedon type situation. Mars is the easiest choice, though I use the term "easy" loosely. The only problem with all this is that it simply won't happen. The world won't cooperate enough with the current state of affairs to build anything remotely close to being required to make this.
Of course, I'm of the opinion that humanities over-riding concern should be expansion off this planet.
This is a simplified version of our main content. To view the full version with more information, formatting and images, please click here.