[Scenario] We have 4 years.

[Robotengineer]

I wonder why the

future5Dhumans

put the wormhole around Saturn.

It depends on which side of the causality fence you stand on.

[Starman4308]

Though, thinking about it, it might make a great sci-fi short story if you made the scenario more believable: 50-150 years of lead time, a few orders of magnitude less mass on the impactor, and a colossal solar sail project to redirect it, as well as a base on the impactor to help build and maintain the array.

[Whirligig Girl]

Heh 4 years? Might as well build a 600km-wide trampoline at the impact site.

No, the easy answer would be to nicely ask whatever god-like creature that was able to redirect Pallas enough to hit Earth to kindly undo that and not murder all of humanity.

I bet it was the same people who made the Black Hole tesseract and the Wormhole around Saturn.

[YNM]

Pallas mass is ~1% Moon's mass. I'm not sure but I think the Earth isn't gonna really be destroyed completely... no ? I mean, the giant impact needed 0.2 - 0.4 Earth mass. Moon's mass is <1% Earth mass. Pallas is then ~0.01% Earth mass. It all depens on the trajectory but I think Earth would stay there half charred at worst...

EDIT : also, 4 years is too long that the parameters would refine. I think over time the grazing orbit would just be reduced to passing orbit, then we'll see a new family of sungrazers !

Or Earth would spin faster. Or the obliquity of ecliptic would change dramatically that people won't really believing they're at Earth.

Edited December 9, 2014 by YNM

[Armchair Rocket Scientist]

For everyone proposing "bunkers" or "space ark in Earth orbit."

Here is a documentary on the effects of the larger impacts Earth suffered during its accretion, showing the damage a 500 km asteroid would do if it hit Earth today:

Note that the crust is peeled away, the oceans boil, and the surface is heated to red hot. Endolithic organisms several miles down MIGHT survive, but humans are ....ed. Even if we build a city deep underground in a mine shaft, humanity is doomed. The atmosphere loses most, if not all of its oxygen from burning every living thing on the surface and possibly oxidizing some minerals. It could be thousands of years before the planet cools enough that we could even consider doing anything on the surface, and we'd essentially have to "re-terraform" our own planet, a process which would require thousands, if not millions of years, and resources that the pathetic remnants of our civilization don't have.

Earth orbit? The sheer amount of debris blasted into space would mean instant Kessler syndrome, plus the Earth might be hot enough to roast an LEO station with thermal radiation. A moon colony is the most feasible option, but we'd still have no hope of launching a self-sustaining colony with enough genetic diversity to preserve our species in just four years.

Our best hope? Load as much data about Earth as possible onto some long-lasting medium like stone tablets, and place them at several points on the Moon, marked by giant reflectors. Essentially, we create a long-lived Tombstone of our species, and of Earth's entire biosphere, for any alien explorers, or life forms that evolve on Earth, to find.

Maybe they'll leave flowers.

[kerbiloid]

There are at least two ways.

1. Virginia antipodes is Australia. 10000 people is enough to keep genetic diversity. Of cause, you have a great chance to find yourself among these 10000 chosen in Australian mountain vault.

2. Enforce your spirit efforts and open a portal to another delightful world. Is more realistic any way.

[Nuke]

surface ablation with nuclear warheads (what i like to call poor man's orion) might nudge it enough where it wont hit. but its at most a temporary measure, if its likely to cross paths with earth in the near future. but it does buy you time to put a gravity tractor on station, or to produce additional plutonium for warheads.

detonation of warheads in existing craters might optimize energy transfer to the surface material and provide more thrust, and the crater would form a natural thrust bell. exploiting such natural features would require some mapping of the asteroid in question. if you could ablate a tons of material with each detonation, it would provide significant thrust. question is will this work on a rubble pile. what will happen to the material beneath the vaporization boundry as it violently expands. lower yeild warheads and multiple simultaneous detonations over a larger area may be needed to distribute the forces around more of the surface to prevent breakup.

warheads (or groups of warheads in case of simultaneous detonation) would need to come in one at a time so the detonation of one doesn't interfere with the guidance systems on the next. i think the biggest problem is manufacture of the neccisary rockets. though i suppose mirv type upper stages would be used, except each warhead would have its own engine, fuel and guidance system for the final leg of their journey and for station keeping on target during the detonation sequence.

Edited December 9, 2014 by Nuke

[jfull]

In 4 years? I don't think so it would be enough.

If our survival depended on it, yes, yes we could.

[magnemoe]

I don't think you quite understand the sheer size of Pallas. It is 2.11*10^20 kg. A billion tons of impactors going at 10 km/s would change its velocity by something on the order of 50 micrometers/second

Even a hundred years of lead time would be difficult. In order to get a 50 mm/s velocity change over 80 years, ignoring the mass of the solar sails, you would need 500 million km^2 of solar sail. I may have done the conversions wrong at some point, but given my only reference value (10 g/m^2), that is 5 billion tons of solar sail.

EDIT: I also assumed (really badly) the same thrust you'd get at Earth. Pallas is further out, the thrust should be lower there. I also slipped a few zeros on the impactors, on account of dividing by a billion kilograms instead of a billion tons.

EDIT #2: Where did I get ^21? Woohoo, I get to slip a zero. Not going to change the final results much.

Yes, forget impactors, how about nukes as in orion pulse engine drive charges, obviously sized up to an suitable size detonated at an suitable distance.

Benefit is you don't have to match speed and each bomb is independent so if one fail it don't affect the others.

Secondary option would be an orion pulse rocket ship itself, it would have to match trajectory after it has you would use the oversized drive charges again to move the asteroid.

[cicatrix]

Here are the estimations or the impact:

http://impact.ese.ic.ac.uk/cgi-bin/crater.cgi?dist=20000&diam=580000&pdens=2800&pdens_select=0&vel=20θ=30&tdens=2500&tdens_select=0

Pallas density is taken from wiki. I set the speed 20 km/s and impact angle 30 degree.

You can play with the parameters of the distance from the impact (20000 km is the maximum possible distance from the impact site).

Depending on where you are you can even stay alive.

There would be no mass extinction event - oceans will preserve some lifeforms. Even humans will live (though difficult).

Your Inputs:

• Distance from Impact: 20000.00 km ( = 12400.00 miles )
  
• Projectile diameter: 580.00 km ( = 360.00 miles )
  
• Projectile Density: 2800 kg/m3
  
• Impact Velocity: 20.00 km per second ( = 12.40 miles per second )
  
• Impact Angle: 30 degrees
  
• Target Density: 2500 kg/m3
  
• Target Type: Sedimentary Rock
  

Energy:

Energy before atmospheric entry: 5.72 x 1028 Joules = 1.37 x 1013 MegaTons TNT

The average interval between impacts of this size is longer than the Earth's age.

Such impacts could only occur during the accumulation of the Earth, between 4.5 and 4 billion years ago.

Major Global Changes:

• The Earth is not strongly disturbed by the impact and loses negligible mass.
  
• The impact does not make a noticeable change in the tilt of Earth's axis (< 5 hundreths of a degree).
  
• Depending on the direction and location of impact, the collision may cause a change in the length of the day of up to 6.45 minutes.
  
• The impact does not shift the Earth's orbit noticeably.
  

Crater Dimensions:

• Transient Crater Diameter: 1420 km ( = 879 miles )
  
• Transient Crater Depth: 500 km ( = 311 miles )
  
• Final Crater Diameter: 3660 km ( = 2270 miles )
  
• Final Crater Depth: 3.5 km ( = 2.17 miles )
  
• The crater formed is a complex crater.
  
• The volume of the target melted or vaporized is 2.55e+08 km3 = 6.11e+07 miles3
  
• Roughly half the melt remains in the crater, where its average thickness is 162 km ( = 100 miles ).
  

Thermal Radiation:

• The fireball is below the horizon. There is no direct thermal radiation.
  

Seismic Effects:

The major seismic shaking will arrive approximately 1.11 hours after impact.

Richter Scale Magnitude: 13.4 (This is greater than any earthquake in recorded history)

Mercalli Scale Intensity at a distance of 20000 km:

VII. Damage negligible in buildings of good design and construction; slight to moderate in well-built ordinary structures; considerable damage in poorly built or badly designed structures; some chimneys broken.

VIII. Damage slight in specially designed structures; considerable damage in ordinary substantial buildings with partial collapse. Damage great in poorly built structures. Fall of chimneys, factory stacks, columns, monuments, walls. Heavy furniture overturned.

Ejecta:

• Little rocky ejecta reaches this site; fallout is dominated by condensed vapor from the projectile.
  

Air Blast:

• The air blast will arrive approximately 16.8 hours after impact.
  
• Peak Overpressure: 1.05e+06 Pa = 10.5 bars = 149 psi
  
• Max wind velocity: 781 m/s = 1750 mph
  
• Sound Intensity: 120 dB (Dangerously Loud)
  

Damage Description:

• Multistory wall-bearing buildings will collapse.
  
• Wood frame buildings will almost completely collapse.
  
• Multistory steel-framed office-type buildings will suffer extreme frame distortion, incipient collapse.
  
• Highway truss bridges will collapse.
  
• Highway girder bridges will collapse.
  
• Glass windows will shatter.
  
• Cars and trucks will be largely displaced and grossly distorted and will require rebuilding before use.
  
• Up to 90 percent of trees blown down; remainder stripped of branches and leaves.
  

Edited December 9, 2014 by cicatrix

[Jouni]

Yes, forget impactors, how about nukes as in orion pulse engine drive charges, obviously sized up to an suitable size detonated at an suitable distance.

Benefit is you don't have to match speed and each bomb is independent so if one fail it don't affect the others.

Secondary option would be an orion pulse rocket ship itself, it would have to match trajectory after it has you would use the oversized drive charges again to move the asteroid.

Nuclear pulse propulsion is essentially the same as impactors, or at least within an order of magnitude of it. If you have enough nukes that you could make a 2 billion tonne ship move at 1000 km/s (or a 200 billion tonne ship at 10 km/s), you could use them to redirect the asteroid.

[Whirligig Girl]

Let's say that we've been able to push the asteroid off-course. Yay! It's a temporary measure, as some have stated. Now we have to do more to it. We've probably bought ourselves another ten years or so. Earth's gravity probably redirected into an orbit which crosses Venus' and Mars' orbit (I believe it would be equivalent to a Radial-Out rocket burn for a spaceship), so we can either have it hit Mars or Venus to get rid of it. Venus might be easier, as it's larger gravity and the orbital period is shorter. Plus we don't really want to destroy Mars' surface. Redirecting it to Venus would clearly be the best solution, because Venus is hell already, and it's not like we're planning on colonizing it any time soon.

[Whirligig Girl]

Here are the estimations or the impact:

http://impact.ese.ic.ac.uk/cgi-bin/crater.cgi?dist=20000&diam=580000&pdens=2800&pdens_select=0&vel=20θ=30&tdens=2500&tdens_select=0

Pallas density is taken from wiki. I set the speed 20 km/s and impact angle 30 degree.

You can play with the parameters of the distance from the impact (20000 km is the maximum possible distance from the impact site).

Depending on where you are you can even stay alive.

There would be no mass extinction event - oceans will preserve some lifeforms. Even humans will live (though difficult).

Your Inputs:

Distance from Impact: 20000.00 km ( = 12400.00 miles )

Projectile diameter: 580.00 km ( = 360.00 miles )

Projectile Density: 2800 kg/m3

Impact Velocity: 20.00 km per second ( = 12.40 miles per second )

Impact Angle: 30 degrees

Target Density: 2500 kg/m3

Target Type: Sedimentary Rock

Energy:

Energy before atmospheric entry: 5.72 x 1028 Joules = 1.37 x 1013 MegaTons TNT

The average interval between impacts of this size is longer than the Earth's age.

Such impacts could only occur during the accumulation of the Earth, between 4.5 and 4 billion years ago.

Major Global Changes:

The Earth is not strongly disturbed by the impact and loses negligible mass.

The impact does not make a noticeable change in the tilt of Earth's axis (< 5 hundreths of a degree).

Depending on the direction and location of impact, the collision may cause a change in the length of the day of up to 6.45 minutes.

The impact does not shift the Earth's orbit noticeably.

Crater Dimensions:

What does this mean?

Transient Crater Diameter: 1420 km ( = 879 miles )

Transient Crater Depth: 500 km ( = 311 miles )

Final Crater Diameter: 3660 km ( = 2270 miles )

Final Crater Depth: 3.5 km ( = 2.17 miles )

The crater formed is a complex crater.

The volume of the target melted or vaporized is 2.55e+08 km3 = 6.11e+07 miles3

Roughly half the melt remains in the crater, where its average thickness is 162 km ( = 100 miles ).

Thermal Radiation:

What does this mean?

The fireball is below the horizon. There is no direct thermal radiation.

Seismic Effects:

What does this mean?

The major seismic shaking will arrive approximately 1.11 hours after impact.

Richter Scale Magnitude: 13.4 (This is greater than any earthquake in recorded history)

Mercalli Scale Intensity at a distance of 20000 km:

VII. Damage negligible in buildings of good design and construction; slight to moderate in well-built ordinary structures; considerable damage in poorly built or badly designed structures; some chimneys broken.

VIII. Damage slight in specially designed structures; considerable damage in ordinary substantial buildings with partial collapse. Damage great in poorly built structures. Fall of chimneys, factory stacks, columns, monuments, walls. Heavy furniture overturned.

Ejecta:

What does this mean?

Little rocky ejecta reaches this site; fallout is dominated by condensed vapor from the projectile.

Air Blast:

What does this mean?

The air blast will arrive approximately 16.8 hours after impact.

Peak Overpressure: 1.05e+06 Pa = 10.5 bars = 149 psi

Max wind velocity: 781 m/s = 1750 mph

Sound Intensity: 120 dB (Dangerously Loud)

Damage Description:

Multistory wall-bearing buildings will collapse.

Wood frame buildings will almost completely collapse.

Multistory steel-framed office-type buildings will suffer extreme frame distortion, incipient collapse.

Highway truss bridges will collapse.

Highway girder bridges will collapse.

Glass windows will shatter.

Cars and trucks will be largely displaced and grossly distorted and will require rebuilding before use.

Up to 90 percent of trees blown down; remainder stripped of branches and leaves.

This can't be accurate. Are you sure you didn't miss a zero? Also, delete the "What does this mean?" parts.

[Frozen_Heart]

We would need a rather large bomb...

How big in theory is it possible to make a fusion bomb?

[YNM]

This can't be accurate. Are you sure you didn't miss a zero? Also, delete the "What does this mean?" parts.

I used the same thing and it returned the same result. EDIT : Already considered Earth's gravity ,just add Earth escape velocity from the 7,4 km/s that I got as relative heliocentric velocity. Granted this assumes an aphelion of Pallas' aphelion and Earth's perihelion, so it's totally dependent on the trajectory. Also, 4 years would result in the changes being highly noticeable : an orbit like this will have a sidereal revolution period of 1.6 years.

EDIT : I used these parameters :

Density : 2800 kg m^(-3)

Aphelion : 5.104*10^11 m

Perihelion : 1.47098*10^11 m

Semi - major axis : 3.28749*10^11 m

Sun's mass : 1.9888*10^30 kg

Radius : 544 km

Impact angle : 30°

Distance from impact : 20000 km (the program doesn't take any value larger than this, theoretically you can reach ~15 km farther than this)

Impact velocity : 18.6 (+- earth rotational velocity; max 0.4) km/s

The link : http://www.purdue.edu/impactearth

results are mostly equal to cicatrix's results.

Edited December 9, 2014 by YNM

[cicatrix]

This can't be accurate. Are you sure you didn't miss a zero? Also, delete the "What does this mean?" parts.

It's not me. I provided a link:

http://impact.ese.ic.ac.uk/cgi-bin/crater.cgi?dist=20000&diam=580000&pdens=2800&pdens_select=0&vel=20θ=30&tdens=2500&tdens_select=0

Here, you can play with your own parameters:

http://impact.ese.ic.ac.uk/ImpactEffects/

[Nibb31]

In 4 years, there isn't much you can do. If you know the impact area (which isn't realistic) then evacuate as many as possible. On the rest of the planet, build thousands of shelters as deep as you can and brace for the impact.

Stockpile supplies, vehicles, communication equipment, breathing equipment, generators, seeds, genetic material, and archives.

You would need to design the equipment so that you can pull it out of the bunker and jumpstart something like a Mars colony. Even if only a small percentage of those shelters survives the impact and its aftermath, it would still save orders of magnitude more lives than sending people off into space.

If our survival depended on it, yes, yes we could.

We can't even agree on greenhouse gas emissions, and our survival depends on it. It would take more than 4 years to schedule the G8 meetings to discuss the problem.

In the given timeframe, there could be no worldwide cooperation. Each nation would have to take it into their own hands.

Edited December 9, 2014 by Nibb31

[Starman4308]

We can't even agree on greenhouse gas emissions, and our survival depends on it. It would take more than 4 years to schedule the G8 meetings to discuss the problem.

In the given timeframe, there could be no worldwide cooperation. Each nation would have to take it into their own hands.

Greenhouse gas emissions are a long-term threat whose significance has been much clouded in the public mind. It's just not the sort of thing to trigger "MUST SOLVE NOW" in the human brain.

An asteroid is a concrete thing, much more like the threat of nuclear annihilation hanging over America in the 1960s. There would be a huge response to an asteroid, much like the American effort into rocketry in the 1960s. It would be a "MUST SOLVE NOW" problem. There would be a huge international effort, which would utterly fail, because Pallas is simply too big to move, and the timeframe far too short to set up any sort of viable interplanetary colony.

With a few more decades, we might dust off Project Orion, and use it to deliver solar sails to Pallas and/or just use nuclear pulse propulsion directly, but 4 years is basically doom-for-everyone. And don't think it would be a few Orion vehicles. It'd have to be probably thousands to millions of the things. For that matter, it might be capped by the amount of radioactive material we're willing to spew onto Earth's surface and atmosphere, forcing us to supplement it with conventional rocketry.

Edited December 9, 2014 by Starman4308

[Nibb31]

An asteroid is a concrete thing, much more like the threat of nuclear annihilation hanging over America in the 1960s. There would be a huge response to an asteroid, much like the American effort into rocketry in the 1960s. It would be a "MUST SOLVE NOW" problem.

It wouldn't. There would be deniers, studies, reports, more studies, protests, conferences, political debate, and many hard political decisions to make. It would take months or years before we actually reach a consensus that something needs to be done NOW (or 4 years ago). Then you have to make all the tough political decisions about WHAT to do exactly. Even in this thread we can't agree on a common course of action, so imagine what it would be like in an emergency G8 or UN conference.

Imagine the problem of evacuating North America, since it's going to be turned into a giant crater. Does the US Congress peacefully and unanimously agree to dissolve the USA, give away their assets (including military stuff) and send everyone abroad? How many countries are going to agree to accept the millions of refugees? Under what conditions? What about land owners, corporations, financial interests, insurance companies? Who defines who the winners and losers are going to be after such a devastating event?

If the decision is made to attempt to deflect the asteroid, there are the questions of who is going to pay, which companies get the contracts, who commands the mission, and what happens if it fails. The simple act of nominating a science committee to evaluate solutions will require months of negociation.

It might look obvious that we would all unite under the banner of Humanity in times of crisis, but reality is much harsher when it comes to making the political decisions and reaching agreements, especially when there is so much to lose and nobody wants to lose more than the other guy.

Edited December 9, 2014 by Nibb31

[ZetaX]

The program is probably simply not intended for that size. It's not like it would do an actual simulation, it is just plugging this into some given formulas.

We would need a rather large bomb...

How big in theory is it possible to make a fusion bomb?

It's called a supernova.

[NASAFanboy]

If in more than fifty years, send some people to space and keep others on the ground, in protected shelters.

If in four years, then take out the shovels and hunker down. Load genetic matieral into these vaults or into satellites whose orbit will decay and bring the matieral back into the atmosphere in little capsules. Try to deflect it with the remaining rockets and nuclear arsenal of humanity; we won't be using them anyway if it hits, might as well do something about it. Space is not a valid option in a mere four years; it takes years to design and build it itself, nevermind prepare and test it for launch.

[tomf]

What would happen to all the splash from this impact? Would it have enough energy for enough to get to the moon that most of its surface would receive impacts?

[-Velocity-]

Let's assume it's on a grazing trajectory, which means it will just barely hit the Earth. Perhaps huge ground-built lasers could blast Pallas and make part of it's surface act as a thruster. You'd not need too much for a change that makes Pallas fly by the Earth just outside the rouche limit. Maybe send a few thousand Mass-Drivers to the surface to throw the surface out and act as a thruster, or even blast it with the world's supply of nukes to redirect it. (not blow it up)

We don't have to push Pallas, maybe Pallas can push itself.

Even if Pallas completely misses Earth, it's still probably an extinction event. Pallas is not small, and the tidal buldges it raises as it passes Earth may by itself be enough to cause massive earthquakes and volcanic eruptions. I read once that a near miss by Mars would turn Earth's surface entirely molten from the deposited tidal energy, but I don't know if that scales down to Pallas too. Still, it would NOT BE GOOD.

Secondly, it may change Earth's orbit enough to significantly alter the climate.

Finally, a near miss does not erase the possibility of a future impact. In the "best" case for negating the possibility of a future impact, where Earth ejects Pallas from the solar system entirely, could mean that Earth deposits so much of its orbital energy into Pallas that our perihelion is too close to the Sun for Earth to remain habitable. Even as it currently stands, Earth is supposedly just inside the inner edge of Sol's habitable zone. If we got just a bit closer, the planet will supposedly go into runaway greenhouse mode, like Venus.

Edited December 9, 2014 by |Velocity|

[YNM]

I just realized the website asked for diameter and I inserted the radius. So a more "better" looking result is this :

Your Inputs:

Distance from Impact: 20000.00 km ( = 12400.00 miles )

Projectile diameter: 1160.00 km ( = 720.00 miles )

Projectile Density: 2800 kg/m3

Impact Velocity: 19.00 km per second ( = 11.80 miles per second )

Impact Angle: 35 degrees

Target Density: 2500 kg/m3

Target Type: Sedimentary Rock

Energy:

Energy before atmospheric entry: 4.13 x 1029 Joules = 9.87 x 1013 MegaTons TNT

The average interval between impacts of this size is longer than the Earth's age.

Such impacts could only occur during the accumulation of the Earth, between 4.5 and 4 billion years ago.

Major Global Changes:

The Earth is not strongly disturbed by the impact and loses negligible mass.

The impact does not make a noticeable change in the tilt of Earth's axis (< 5 hundreths of a degree).

Depending on the direction and location of impact, the collision may cause a change in the length of the day of up to 46.4 minutes.

The impact does not shift the Earth's orbit noticeably.

Crater Dimensions:

Transient Crater Diameter: 2490 km ( = 1540 miles )

Transient Crater Depth: 880 km ( = 546 miles )

Final Crater Diameter: 6910 km ( = 4290 miles )

Final Crater Depth: 4.24 km ( = 2.63 miles )

The final crater is replaced by a large, circular melt province.

The volume of the target melted or vaporized is 2.11e+09 km3 = 5.06e+08 miles3

Melt volume = 1.05 times the crater volume

At this size, the crater forms in its own melt pool.

Thermal Radiation:

Time for maximum radiation: 13.1 minutes after impact

Visible fireball radius: 2150 km ( = 1340 miles )

The fireball appears 24.5 times larger than the sun

Thermal Exposure: 3.18 x 1010 Joules/m2

Duration of Irradiation: 53.8 hours

Radiant flux (relative to the sun): 165

Effects of Thermal Radiation:

• Clothing ignites
  
• Much of the body suffers third degree burns
  
• Newspaper ignites
  
• Plywood flames
  
• Deciduous trees ignite
  
• Grass ignites
  

Seismic Effects:

The major seismic shaking will arrive approximately 1.11 hours after impact.

Richter Scale Magnitude: 14.0 (This is greater than any earthquake in recorded history)

Mercalli Scale Intensity at a distance of 20000 km:

• VII. Damage negligible in buildings of good design and construction; slight to moderate in well-built ordinary structures; considerable damage in poorly built or badly designed structures; some chimneys broken.
  
• VIII. Damage slight in specially designed structures; considerable damage in ordinary substantial buildings with partial collapse. Damage great in poorly built structures. Fall of chimneys, factory stacks, columns, monuments, walls. Heavy furniture overturned.
  

Ejecta:

Little rocky ejecta reaches this site; fallout is dominated by condensed vapor from the projectile.

Air Blast:

The air blast will arrive approximately 16.8 hours after impact.

Peak Overpressure: 4.59e+06 Pa = 45.9 bars = 652 psi

Max wind velocity: 1700 m/s = 3810 mph

Sound Intensity: 133 dB (Dangerously Loud)

Damage Description:

• Multistory wall-bearing buildings will collapse.
  
• Wood frame buildings will almost completely collapse.
  
• Multistory steel-framed office-type buildings will suffer extreme frame distortion, incipient collapse.
  
• Highway truss bridges will collapse.
  
• Highway girder bridges will collapse.
  
• Glass windows will shatter.
  
• Cars and trucks will be largely displaced and grossly distorted and will require rebuilding before use.
  
• Up to 90 percent of trees blown down; remainder stripped of branches and leaves.
  

[Frozen_Heart]

With only 4 years I'm pretty sure that there isn't much we can do apart from firing the worlds nuclear arsenal at the thing with all existing rockets. Probably wouldn't work though.

With 10 years maybe making a large fusion bomb (~100 tons) and launching it to LEO on an SLS. I'm pretty sure in this case NASA would get the militaries budget and so the SLS could be ready fast...

A second SLS (and maybe a third) could stick on a transfer stage and fire it off.

Still probably not enough but I'd love to see the numbers on a 100 ton fusion bomb... Might be able to nudge it enough with a 10 year lead?