Required solutions to prevent Asteroid-Earth collision

Here's the story so far: http://en.wikipedia.org/wiki/Near-Earth_Objects

Please accept my hearty thanks for your guidance to "The story so far....".

I am confident about mankind's ability to solve the problem and perhaps even turn it to advantage in some way.

Regards

D.Ramakrishna Naidu

There's a very low probability that it will hit the earth, but if there was a serious danger, the solution is relatively simple. NASA has developed a plan to send a "space tug" - essentially a relatively heavy satellite that would be deployed near the asteroid. The gravity of the satellite is sufficient to pull the asteroid the tiny bit required to move it into a safer orbit.

That said, we don't currently have the technology to detect smaller objects that may do us great harm, until it's too late to do anything. The Tunguska event, which devastated almost 1000 square miles was caused by a rock maybe only 120 feet across. It's unlikely that it would have been detected until it was almost upon us. It's highly unlikely that we could hit it with an air to ground missile, at it's projected speed of over 20,000 mph.

Yep. Consider earth a "proof of concept" model and build the next one outta the way of the asteroids.

Well we have enough atomic waste so before we bury it in a mountain lets put it on an old space ship and anchor it to the moon. Then as years go by we can add to that. So of we ever are threatened we can fly out put mount a big bomb on the stroage ship then tow it into the path of the Asteriod once scientist have determines the best place for the explosion that would protect the earth.

Wheather we use this or not it would save the USA from years of worry and cost of storing this radioactive waste.

Don't like this one.

The nuclear debris would then be distributed over the face of the earth as the centre of mass of the particles would still follow the trajectory of the original object. Instead of one big impact, there would be nuclear particle rain. I don't want USA's waste nuclear stuff falling in my back yard.

Oh by the way, where is the "old space ship"? Area 51?

All space objects rotate. To attach or apply a surface mounted force would be highly unpredictable as far as results. A static impact would likely shatter the object, and leave at least one fair sized piece on a still hazardous path. The only possible effective means of deflecting a large object would be the near-surface shaped charge of conventional explosives. Nuclear would be useless unless a below-surface detonation to propell mass. Nuclear devices do their damage by massive heating of surrounding air.

A shaped charge, expelling a ton of high velocity mass gas against the surface of an inbound object would be able to deflect with minimal fragmentation, and all such fragments would be accelerated in at least a similar direction, with little other than gas expelled in the opposite direction.

A tug would

1. Need to be hugely massive,

2. require huge energies to park parallel to and at a similar velocity to, and

3, result in

a. some degree of mutually attractive acceleration, then

b. a negation of any acceleration with the impact when the falling deadman hits bottom.

Once the object is parked, they can be considered a single frame, with a set center of mass and a set velocity. If you parked a 1000 kg mass 10,000 meters from a 1,000,000 kg object, you would move the net path and velocity of the alien mass about 10 meters over on a parallel path and with an equal velocity.

Apply 1000 kg of mass gas with a vector velocity of 10,000 m/s, and you will alter the course of the object significantly. The larger the object, the farther the detectability. Objects of megametric tons would be deflectd less, but from farther away.

The biggest factor would be the dependable vector regardless of rotation of the object. Just detonate 10 or 20 meters above the surface, and the nearly instantaneous vector force is applied with some distribution over a substantial portion of the surface area. Less fracturing of a large mass, and if it did occur, all of the detritus would have nearly identical acceleration, with no rebound pieces assuming unpredictable paths.

It would help if we had a suitable launch vehicle available, ready to launch within days, with the deflector head ready to attach and arm close by.

By the way, objects approaching from the day side of the earth are immensely less detectable, and with lesser assets scanning.

RichH

Hi NoSciFi and others,

your arguments are ok every detail to be agreed, but nuclear explosion is an option:

In the immediate vicinity of the detonation the pressure and velocity will be mmuch higher than with conventional explosions.

And why not shaping the gas jet by some "massive" shielding into the desired direction (roughly).

A small nuclear bomb (20kilotons explosive yield) has a mass of 20 to 100Kg.

What can you do with 20to 100Kg TNT?

So the explosion will blow to fragments any small to medium size meteorite, only a few small fragments will reach earth.

There is one other may be suitable suggestion existing: Evaporate the object at one side with a highly directional laser beam so that the vapor will push the object sideways. I think this unlikely to be realised as the required spotsize is not suitable with small sized optics.

RHABE

A small nuclear device, of 20 kton size, would only have the mass of about 500 kg. if you tried to use a kton 'deflector", it would need to be ktons in size. Almost all of the power of a nuclear bomb in atmosphere is derived from the really rapid heating of the gas in the immediate vicinity of the bomb. Very similar to, but much higher temperature than, a bolt of lightning. Air bursts are used because the atmospheric shock wave distributes over a much larger area, causing far greater damage, shock wave, and the instantaneous heating caused by this shock wave. Without the gas to convert the thermal energy to kinetic, either you need to vaporize some object mass through penetration prior to detonation to achieve propulsion, or you would have the vapor effect of some of the mass and a substantial amount of thermal, xray, and gamma radiation to transfer the force. The kiloton rating of a device would not transfer into the equivalent amount in a vacuum.

The problem with penetration would be the distribution of the ejected mass v. the center of mass of the object, as far as the direction of the expelled ejecta. Add in the rotation of the object, and the potential of softer material on an angle, and a variable amount of the force would result in rotation.

Stick with the above-surface conventional, and if it crashes on liftoff, we don't contaminate real estate, or people.

RichH

Hi RichH,

if you go back to your original suggestion of a shaped charge and substitute the chemical explosive with a nuclear bomb (small one) and shield one side of the nuke with may be 1 to 10 tons of mass and the other side with the conical shaped charge - oriented towards the object.

This will yield a huge amount of super high velocity gas and enough energy to destroy the asteroid.

Survival time of a concentrated gas jet in vacuum to be calculated.

But as the center of an exploding nuclear device will heat the surrounding material to some million degree there will be a large amount of energy available.

On earth there is indirect energy transfer by heated air - ok as you state.

In space only the material around the device will be evaporated.

The pressure will be much higher than any possible strength so movement of material is pure hydrodynamic (in reality inertia dominated) action.

In a 20 Kton nuclear detonator there is energy equivalent to 2Ktons of coal or 20Ktons of TNT. Forget about the share of gamma and particle radiation, this is a minor part.

The very first micro- or milliseconds radiation will be captured and dissipated to heat and pressure also in space. The later confinement in atmosphere in a big ball glowing for some time and damaging by heat earthbound structures is not existing in space.

But the very first ultrafast pressure buildup in vaporised material will be enough.

Make a rough calculation how much velocity and how much mass you would need to destroy.

a. a comet as a loose heap of ice and dust

b. a stone meteorite as a brittle silicatic rocky object

c. (worst case) a iron - nickel meteorite with substantial density and strength.

RHABE

Where does any remains of the shield end up? To be effective, the shield needs to be stout enough to survive the blast more or less intact. Perhaps it would move out of the solar system at escape velocity. Maybe even out of the milky way. And how much of the energy striking it will be reflected? And how large of a charge do you need to fragment a 120 ft diameter, 150 kiloton chunk, of what?

If the chunk were not crumbled and dispersed, the evaporated surface material whether ice of iron, would be disbursed over a roughly half sphere direction, converting less than 25% of the boil-off into directed acceleration without a crater/nozzle of an impacted device.

There have been very few ground bursts since the Manhattan project, because the amount of radioactive debris created. Air absorbs most of the beta and gamma radiation forming things like C14 or ionic atoms and electrons, which disipate. The cloud of radioactive dust and rocks created with a nuclear strike, or near-strike, would orbit the sun forever, and maybe on every 75th year the earth would passage through the orbiting cloud, enjoying a new meteor shower, raining down radioactive dust that would act as a time strip around the world, as the iridium does now for large meteor strikes.

The main idea is that a "tractor" tug would require really extreme amounts of mass, and would end out having very little real effect other than the momentum (relative the foreign object) it came in with. Once the tug and the object became a coupled pair, there would really be no additional effect. The pair would be traveling the same relative path throughout eternity, offset only by the difference between the center of mass of the object, and the center of mass of the pair, except for the addedd momentum the tug brings with it, whether falling to the surface, or orbiting the object.

Sometimes an engineer should be able to say "Nice idea, but unfortunately, it wouldn't work, so don't waste money on any further cold fusion projects."

"... tugs."

"...skyhook elevators."

"...fuel-cell powered heavier-than-air commercial aircraft."

"...superconducting electric motor propelled heavier-than-air craft."

and about a hundred other half thought out ideas.

RichH

"To be effective, the shield needs to be stout enough to survive the blast more or less intact."

This would be best but much less is sufficient. Only the meteorite needs a velocity that it will not hit earth.

So depending on mass relation and distance from earth from impulse conservation can be estimated the necessary mass times velocity of the shield after the blast.

"And how large of a charge do you need to fragment a 120 ft diameter, 150 kiloton chunk, of what?"

A shaped conventional charge (cylindrically elongated) of 2.5" diameter will cut through 20" of best steel (at room temperature - much more difficult as steel (or iron-nickel) is brittle at low temperatures.).

If we plan the nuclear device to arrive at the side of the meteorite to blast it out of the plane of the orbit of earth around sun, a little bit head on and ignite the nuclear (without any shaped charge) 1 microsecond before hitting the meteorite then the hyper-hot gas ball (millions of degrees, 100kg, energy of 2000 to 10,000kg of coal burnt with oxygen or (20...100)x10⁶Kcal or (80...400)x10⁹Ws) will penetrate the meteorite and blast it to small pieces at expanding. This is only the explosive energy equivalent!

Underground 20 to 100Kton explosions create big spherical holes of 20 to 60 '.

So sideway explosion ignited immediately before impact will enter the target with enough velocity and small size so that hot dense gas will enter the target and will easily crack it.

Hit at the side will ensure deviation of orbit out of earth-sun orbit so likelihood of another encounter is low. (Most, not all debris.)

"The cloud of radioactive dust and rocks created with a nuclear strike, or near-strike, would orbit the sun forever"

That's right but with side impact it is not critical and earth has survived without much damage the ground bursts of early tests.

"The pair would be traveling the same relative path"

That's ok so we need to add the explosive energy to fragment the object.

"so don't waste money on any further cold fusion"

I agree completely.

RHABE

A suggestion: Perhaps we should increase our efforts to have a permanent presence on the Moon and other bodies in space.

The advantages would be three-fold: 1) we would have more "eyes on the sky" so to speak, with increased parallax views 2) there would be an increased probability of survival, not having "all of our eggs in one basket" and 3) the technologies created to make the colonization possible would (we hope) be used to improve the quality of life on Earth.

Just my opinion Dragon

I had hemorrhoids once, now they were hard to ignore. May have been partly caused by thermal expansion near a crack.

Ease off the asian food, then.

What are we going to do, when the one object that we are currently tracking, that has an orbital juncture with Earth in April, of 2029? The information is sketchy as yet, but preliminary calculations show that it will pass within 40,000 +/- miles of our planet. Mass estimates at this time are completely unprovable, and the actual path fluctuates daily. Regardless of its' path, or mass, it will surely be one hell of a show.

That would be a wonderful moving object in the sky. I would love to live till then to see it........... Do not worry, nothing is going to happen.

Some monthes ago,i don't remember if it was Discovery,Natgeo or history channel were joined several scientists to this same discussion.I couldn't keep on tv but it seems to me were not the kind of easy proposal that commonly we heard in sci-fi:As a sample :a simple explosion don't change the asteroid center mass orbit or path...So what for ?

..So what for ?

We'd then be distributing the mass of Asteroid into smaller pieces and also distributing the area of impact(s), thus "diluting" the intensity of damage.

Also, some of the pieces could burn up in our atmosphere-hopefully.This is like making the best out of a hopeless situation.

Considering all the replies so far, our best bet would be to divert the asteroid ever so little and may be it'll "bounce off" of our atmosphere.

Further, since the earth is slowing down (perhaps by a second annually), I wonder whether our NEO observers have taken into account this retardation (equivalent to "braking" ahead of a collision), and seen the potential for impact.

Assuming, 44000 MPH (present estimate) for the velocity(?) of the asteroid, there could be a varying acceleration as it nears our gravitational field and this could increase/decrease our survivability. This can be established with some reasonable accuracy/certainty only when it would be too late to do something about it.

Where are all our mathematicians who pride themselves in being able to mathematically model any situation? Can we please get an accurate trajectory of the asteroid and that of the earth/moon?

At least now the arrogance of a part of the human race which denies the existence of a "Superior" power will be put to the test. Getting the right ideas at the right time is also a "Gift" and not some extra-ordinary "Power" of an unaided individual.There can be some benignity only if this arrogance is given up and humility in the approach to a solution.

D.Ramakrishna Naidu

Recent experiences tells we coud go to the asteroid fix the the ship or some engine as a rocket engine and move it to a secure orbit and keeping it in some orbit watched by us as a souvenir from the space.this is regarding above participant about the real necessary effort to move it.And of course the idea to put this equipment out of the earth gravity before seems a great idea to me.

Something else:I said before its center mass will keep its trajectory without thinking:¿is it truth when you have not a constant grav.Field?

Dragonsfarm is right about having a permanent presence on the Moon and probably in more orbiting satellites as well. Since you are dealing with two moving bodies which must be traveling at just exactly the right speeds and directions in order to collide, then it becomes a matter of changing speed or direction of one of them. The asteroid or comet is easier to change. You can approach it from the rear, touch down softly and then let loose your rocket motors full blast and speed it up enough to miss. You can let it catch up to your diversion vehicle slowly, touch down, then give it a full retrofire and slow it down enough to miss. If the rotation is wrong, then the rocket would have to fire only when in the correct position, but it could still work. Changing the direction could be tricky if the asteroid was rotating, but repeated rocket firings could do it. Lasers would be less effective.

Shattering a big one would result in many smaller ones all going in the same direction in a slowly growing pattern. You would avoid the world killer, but then would have multiple strikes like a carpet-bombing. It might not be a world-killer, but it would do a lot of damage.

As I see it, changing the objects course is safer and more sure and that requires having the equipment based in space ahead of time in order to do it. What would be great would be to capture one and place it into a stable orbit. Then it could be used for other purposes, such as a huge interstellar generation-ship or a big space habitat.

Might I suggest L4 for industry and L5 for habitation. Later E4 for industry and E5 for major habitation. Not my concept but logical.

As for the Moon I don't want to live on it but in it. I think I figured 16 feet of glass at lunar gravity to contain 14.7 psi atmosphere. Just add some lead to the glass and make it a modular system so micro pits in the surface can be removed and replaced. The plastic in auto windshields to take up the room between the blocks might work.

Just a thought

Brad

Under the Lunar surface is much safer for living, but since the entrance is on the surface, it is common to say a colony is on the Moon. Just as you would live on Maple St., even if you had an underground house, due to the location of the entrance.

Where to park an asteroid will likely be in one of those positions, but the use is likely to be mixed as people need to live near where they work. Commuting in space is not cost efficient. Asimov wrote some good stuff about Lunar colonies.

Commuting in space is not cost efficient.

It's splitting hairs but only the speed of commuting in space is not cost efficient or to say acceleration and deceleration. As long as you don't need to hurry or travel a strait line. Energy is overly abundant, the trick is to use mass to the greatest effect. Say a 50 foot CO2 laser, Sun pumped to turn some mass into plasma in a magnetic field to accelerate. ( Hey folks this is your captain would someone please feel free to use the privy, we are a little low on reaction mass). I know, actually organics would be a commodity.

Brad

Speed can be pretty important to someone with only a few hours of air. Also the mass thrown out to accelerate and decelerate has to come from somewhere. [Energy is not the problem.] That is why in such a habitat you would have both industry and living areas so people could walk to work. No air supply to worry about, no long commute through the hazards of space, no ship to build, no fancy drive "to turn some mass into plasma in a magnetic field". KISS! The simpler the solution the better.

Good Answer. When I said "a permanent presence on the moon", under the surface was what I implied.

Tunneling under the surface then fusing the rock strata to prevent pressure failure would be the preferred method. Lining the chambers, (multiples for safety in the event of a meteorite impact) with an airtight polymer would prevent any but the most minuscule leakage, easily replaceable.

Energy would be readily available in the forms of solar, (especially if the base were located near a polar region, to avoid the two weeks of "night" on the lunar surface) HE³ Fusion, obtainable from lunar regalith and collected right off of the solar wind. And there are also several other forms of energy production.

We have the technology all we need is the will.

Regards Dragon

Hi Taganan,

I suspect that there will barely enough fuel to reach the object - as in any space-mission.

So it will be necessary to hit either head-on and then have an impulse to the side.

This is much more effective than acceleration or deceleration (with respect of change of trajectory.)

RHABE

Hello RHABE,

This is much more effective than acceleration or deceleration (with respect of change of trajectory.)

In spherical trig with multiple gravity wells, aka orbital mechanics this is not always the case. The farther in gravity well you wish to go the slower you will need to go. To raise your orbit, speed up. Likewise if you change your vector but not your speed your orbit can become flatter( more circular) or more elliptic. For Apollo Asteroids this means they are still Earth crossers who will contact something in their path either sooner (least likely) or later possibly much later.

Do to our still limited data/knowledge of our solar system the error factor multiplies as a function of time. Start with a small data set and this becomes a very large number very quick.

This is why a small ion engine or similar, years ahead, is better. The actual thrust vectors may seem counter intuitive and even reversing due to factors that increase or decrease with small changes in speed or vector in our very busy solar system's gravity well.

Brad

Hi Brad,

I agree completely.

So safe orbits will require either an ellipse that is completely outside the orbit of earth - or completely inside. So no crossings of orbits.

I considered this as unlikely to achieve in an emergency situation. But if planned in advance and with next generations ion thruster (Vazimir?) it may be possible.

I thought about an out of plane impulse. (how much to be debated, 0.5°?) This would reduce the probability of hits to much lower figures than an impulse that lets the asteroid in plane of earths orbit (avoiding an imminent crash, ok, but to be observed and maybe to be iterated).

My favorite is still a nuclear explosion near head-on, to be ignited microseconds before the crash of the nuclear device into the asteroid.

But further evaluation seems to be necessary.

RHABE

But further evaluation seems to be necessary.

Very true, the best method can only be determined by composition and trajectory. Worst case is several hundred feet of snowy fluff over a mass of large iron core parts on it's last leg of it's journey to Earth

But until we know what we are dealing with we can only speculate not take effective action. As the saying goes there are many paths to the top of the mountain, just make sure it is the right mountain.

Personally this asteroid should be moved to L4 or E4 for study and mining. If we have to move it, let's make it worth our time and effort.

Brad

"Personally this asteroid should be moved to L4 or E4 for study and mining. If we have to move it, let's make it worth our time and effort."

This will require much more energy (money) than other methods of "only" avoiding collision.

Have a look what the cost will be to move the James Webb Space Telescope!

What might be possible: search for pieces of high value? Platinum? out there in the three belts of asteroids? Identify possible objects and move towards earth? Very dangerous if out of control. Cut to pieces and decelerate these at swing-by at various planets and moon.

Direct one at a time (1000tons each?) towards one of the deserts (Utah, Sahara, Kalahari, Gobi?). If 1 million tons are accumulated it may be worth while to recover if iron, iron-nickel, platinum content???

This schematic will require only minimum energy but is far away may be 100 years.??

What is the mass that can be decelerated in the atmosphere (from a 500km orbit?) so that there is no deep penetration into earth nor explosive action?

May be we can clear some part of the space junk as a byproduct.

RHABE

At the cost of 10,000 US currency (currently worth less so should be higher) per pound to put something into orbit. An asteroid in high orbit is worth Millions of Trillions of US currency.

A quarter mile diameter metallic asteroid is estimated to have 20 metric tons of the gold and platinum group in it. With approximately 4,412,885,000,000. pounds of nickel iron, the first Space Ship Yard would be possible. So would the first Space Colony.

Even if the cost dropped 2 orders of magnitude for volume we could never afford the financial and resources to put that much into orbit in several hundred years.

It is a long term investment if we are ready to do it.

As for using the resources here the only thing we might do is use O₂ for reentry to replace what is lost to our magnetic field from a comet/Kuiper type asteroid. The rest is more cost effective in space.

Brad

If the asteroid goes faster it passes ahead of Earth and if we slow it, it passes behind the Earth's path. Try to hit a moving billiard ball with another. Too much speed or too little will cause a miss. There is no change in trajectory, just speed, and it arrives at Earth orbit too early or too late.

The real problem is that it is likely to be rotating and tumbling, requiring the thrust to be carefully timed. Also critical is how far out we can begin to divert it or blow it up. Sideways thrust on such a body would also require careful timing as it rolls and tumbles, so that it will divert up or down from the Earth's orbit.

KISS says to land on the oncoming surface and do retrofires whenever the object is near the right position to slow it down.

I agree, the difficulty in timing the thrust impulses is not solved.

To hit one object with a probe has been solved sometimes.

My suggestion to move the orbit of the asteroid out of the plane of earths orbit will have as consequence a total change of possible hit points.

in an orbit that has the same plane for asteroid and earth there are two points of intersection of orbits.

in an orbit that is out of plane the asteroid the intersection of asteroids orbit with earth-orbits plane is two points that are most often far away from earth orbit.

So the probability of a subsequent hit will be lowered dramatically if the asteroids orbit is changed by thrust perpendicular to earths orbit.

RHABE