2004 MN4

GCNRevenger · 2004-12-26 16:40:08

It would still have to be a pretty heavy probe... I wonder how many tons of conventional or ion fuel would be required if a propulsion pod were landed to do the pushing.

No Errorist, thats just to determine the composition inards of the asteroid.

ERRORIST · 2004-12-26 16:48:06

Thats what they say. However, I bet they will find out if it nudged the asteroid, also. If it does then a terrorist nation could nudge one our way, also.

Palomar · 2004-12-26 17:19:42

I would bet that North Korea is doing feasibility studies to have the asteroid land in the middle President Bush's Ranch.

*This discussion is getting progressively more and more absurd.

-This- asteroid, MarsDog? 2004 MN4?

Do some simple math. In 2029, President George W. Bush will not have been President for 20 years and will be 83 years old -- he might not even be alive then. If North Korea wants to "get" Bush's Ranch, they'll do it long BEFORE 2029 and with current Earth-based technology (although I certainly hope not!). Hello?

Thats what they say. However, I bet they will find out if it nudged the asteroid, also. If it does then a terrorist nation could nudge one our way, also.

*ERRORIST, you keep trying to make an issue out of Deep Impact. It's a U.S. science project as GCN says. How could a terrorist nation or -any- nation send an explosive device or what-have-you to nudge an asteroid "our way" without other nations finding out (given the plethora of satellites, sensors, tracking devices, etc., scattered about)? And how could they possibly control the asteroid to ensure it hits its intended target? Sorry, ERRORIST, but this is akin to your wondering if a photo posted a week or so ago by Graeme might have been a missile headed for Australia. There are threats in the world, I certainly can't deny that; however -- and I say this with the best of intentions -- you seem to have an unhealthy and overactive concern in this regard.

--Cindy

RobS · 2004-12-26 18:05:37

It seems to me that the asteroid in question is resonably small--400 meters in diameter--and could be successfully fragmented by a powerful nuke (100 megatonnes, for example). If you break it into fifty-meter chunks (about 500 of them) the pieces would do much less damage,

-- RobS

ERRORIST · 2004-12-26 18:25:11

*ERRORIST, you keep trying to make an issue out of Deep Impact. It's a U.S. science project as GCN says. How could a terrorist nation or -any- nation send an explosive device or what-have-you to nudge an asteroid "our way" without other nations finding out (given the plethora of satellites, sensors, tracking devices, etc., scattered about)? And how could they possibly control the asteroid to ensure it hits its intended target? Sorry, ERRORIST, but this is akin to your wondering if a photo posted a week or so ago by Graeme might have been a missile headed for Australia. There are threats in the world, I certainly can't deny that; however -- and I say this with the best of intentions -- you seem to have an unhealthy and overactive concern in this regard.

--Cindy

I think 911 really messed me up.How could a terrorist nation or -any- nation send an explosive device or what-have-you any group of people honestly fly airplanes into our buildings without us finding out first?

GCNRevenger · 2004-12-26 18:27:42

Errorist, the kind of infrastructure and technology needed to accuratly adjust the trajectory of a good sized asteroid like this to hit specific targets is simply not practical to hide.

Using a large nuclear device to intentionally break apart the thing is pretty risky, that if you don't break it down into small enough pieces, you risk turning it into a "cluster bomb" effect, which would be worse then a single concentrated impact that you could run away from.

If it is too heavy to nudge by some big kenetic impactor, the choices are to either send several propulsion devices, probobly a nuclear reactor hooked up to a high thrust electric drive like a Hall thruster or a flotilla of LOX/Methane or Hypergolic rockets... or to use a series of intermediate sized nuclear warheads, and push the thing like an Orion pusher plate. Luckily, we happen to have quite a few medium warheads sitting around, and we could easily spare hundreds of them if it came to it.

ERRORIST · 2004-12-26 18:34:40

All neat Ideas,
How about ionizing it with numerous giant solar arrays?

ERRORIST · 2004-12-26 19:54:54

This thing would be about 5 times more devatating than the Tunguska event!http://www.psi.edu/projects/siberia/siberia.html

GCNRevenger · 2004-12-26 20:22:13

Um no. The size of array needed to focus enough sunlight to liquify signifigant quantites of the asteroid would be huge, and very difficult to get into position.

Only if it broke apart above-ground. The Sibera crater was never found because there wasn't one, the meteor never made it to the ground, which like an airburst nuclear bomb would cause much more widespread destruction. Most asteroids are metal or rock and not carbon, so this is unlikly.

ERRORIST · 2004-12-26 21:14:57

What time and where? What about a lunar impact?

http://neo.jpl.nasa.gov/risk/2004mn4.ht … 04mn4.html

Mad Grad Student · 2004-12-26 21:46:14

Wow, this is pretty interesting. So who's going to be losing sleep over 2004 MN4?

I'm sure not. For one, I barely get enough sleep as is, and more to the point the odds are ridiculously against this thing being a threat to anyone, let alone me personally. 1-in-45 odds sure don't sound great, and by no means are especially when compared to the bulk of the NEO population, but look at those numbers again. How much would you bet on a horse that has 1-in-45 odds of winning. Not much probably; I'm certainly not going to put any money on 2004 MN4 being on an impact course with Earth.

Even if 2004 MN4 does turn out to be on a collision course, we will have more than 25 years to do something about it. We went to the Moon in nine years to beat the Soviets, I think that we could move an asteroid in 25 years to beat a major local disaster. Heck, I'll play devil's advocate for a second here and say that it could turn out to be a good thing for the development of space and mankind in general, as tons of money would start flowing into the various space agencies to stop this thing. We just might be able to scare the governments into realizing that Earth just ain't big enough for all of us anymore if this asteroid turns out to be a threat.

Finally, even if against all odds 2004 MN4 turns out to be on a collision course and against more odds we can't stop it in two and a half decades, it wouldn't be the end of the world. Very heavy localized destruction if it hits a populated area, yes, but odds are it will hit the ocean or a vast empty space like siberia or Antarctica. An ocean hit would be bad, but if it's in the middle of the sea, the effects shouldn't be too much worse than a rather nasty earthquake-caused tsunami. Even if, against millions-to-one odds this asteroid ends up aimed straight for your house, you have 25 years to get out of the way. People will have months in advance to evacuate if it comes to that, and I really don't see any way that 2004 MN4 could cause more loss of life than a typical volcano or tsunami.

Sweet dreams.

ERRORIST · 2004-12-26 21:58:35

Fri. it was 1/300 in the morning and Sat. 1/63 in the morning and by Sat. night it was 1/43 by the evening. Today we don't hear nothing. Usually the numbers get better, in this case they are getting worse.What gives? Tomorrow may be some bad bad news.

MarsDog · 2004-12-26 22:05:41

Ground penetrating Nuke might be the way.

even]http://www.sciam.com/article.cfm?articleID=000871E7-7293-1D06-8E49809EC588EEDF]"even a one-kiloton warhead detonated at a depth of 20 feet would eject about one million cubic feet of radioactive debris from a crater about the size of ground zero at the World Trade Center."

Hitting it on one side, instead of right on ?

ERRORIST · 2004-12-26 22:21:18

I'll go plant the weapon. Send Me.

ERRORIST · 2004-12-26 22:36:56

Neat calculation table I used:

Impact Effects
Robert Marcus, H. Jay Melosh, and Gareth Collins
Your Inputs:
Distance from Impact: 120.75 km = 74.99 miles
Projectile Diameter: 400.00 m = 1312.00 ft = 0.25 miles
Projectile Density: 3000 kg/m3
Impact Velocity: 20.00 km/s = 12.42 miles/s
Impact Angle: 45 degrees
Target Density: 1000 kg/m3
Target Type: Liquid Water of depth 100.00 meters, over typical rock.
Energy:
Energy before atmospheric entry: 2.01 x 1019 Joules = 4.80 x 103 MegaTons TNT
The average interval between impacts of this size somewhere on Earth during the last 4 billion years is 7.5 x 104years
Atmospheric Entry:
The projectile begins to breakup at an altitude of 56600 meters = 186000 ft
The projectile reaches the ground in a broken condition. The mass of projectile strikes the surface at velocity 18.4 km/s = 11.4 miles/s
The impact energy is 1.70 x 1019 Joules = 4.06 x 103MegaTons.
The broken projectile fragments strike the ground in an ellipse of dimension 1.27 km by 0.896 km
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 Earth's rotation period or the tilt of its axis.
The impact does not shift the Earth's orbit noticeably.
Crater Dimensions:
What does this mean?

The crater opened in the water has a diameter of 8.55 km = 5.31 miles

For the crater formed in the seafloor:
Crater shape is normal in spite of atmospheric crushing; fragments are not significantly dispersed.

Transient Crater Diameter: 4.88 km = 3.03 miles
Transient Crater Depth: 1.73 km = 1.07 miles

Final Crater Diameter: 6.03 km = 3.74 miles
Final Crater Depth: 0.508 km = 0.316 miles
The crater formed is a complex crater.
The volume of the target melted or vaporized is 0.0784 km3 = 0.0188 miles3
Roughly half the melt remains in the crater , where its average thickness is 4.2 meters = 13.8 feet
Thermal Radiation:
What does this mean?

Time for maximum radiation: 0.28 seconds after impact

Visible fireball radius: 4 km = 2.48 miles
The fireball appears 7.52 times larger than the sun
Thermal Exposure: 4.00 x 104 Joules/m2
Duration of Irradiation: 6.68 seconds
Radiant flux (relative to the sun): 5.99

Seismic Effects:
What does this mean?

The major seismic shaking will arrive at approximately 24.2 seconds.
Richter Scale Magnitude: 6.9
Mercalli Scale Intensity at a distance of 120.75 km:

VI. Felt by all, many frightened. Some heavy furniture moved; a few instances of fallen plaster. Damage slight.

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.

Ejecta:
What does this mean?

The ejecta will arrive approximately 159 seconds after the impact.
At your position the ejecta arrives in scattered fragments
Average Ejecta Thickness: 2.87 mm = 0.113 inches
Mean Fragment Diameter: 2.27 cm = 0.895 inches

Air Blast:
What does this mean?

The air blast will arrive at approximately 366 seconds.
Peak Overpressure: 13400 Pa = 0.134 bars = 1.9 psi
Max wind velocity: 29.9 m/s = 66.8 mph
Sound Intensity: 83 dB (Loud as heavy traffic)
Damage Description:

Glass windows will shatter.

BWhite · 2004-12-26 22:39:20

If anti-US forces could aim it, Diego Garcia would be a prime target, IMHO. And a not-so-near miss could still swamp the entire island chain.

I have been off-line since Christmas morning and just read about the Indonesian quake and tsunami this evening. Anyone know whether Diego Garcia suffered damage in the recent tsunami? The average elevation appears to be 4 feet above sea level and 40 foot walls of water were moving about the Indian Ocean.

Edited By BWhite on 1104123426

ERRORIST · 2004-12-26 22:55:54

Very scary place to be.

Euler · 2004-12-26 23:56:01

If it is too heavy to nudge by some big kenetic impactor, the choices are to either send several propulsion devices, probobly a nuclear reactor hooked up to a high thrust electric drive like a Hall thruster or a flotilla of LOX/Methane or Hypergolic rockets... or to use a series of intermediate sized nuclear warheads, and push the thing like an Orion pusher plate. Luckily, we happen to have quite a few medium warheads sitting around, and we could easily spare hundreds of them if it came to it.

This asteroid is much smaller than you seem to think it is. If we pessimistically assume a density of 3000 kg/m^3, then it will weigh about 10^11 kg. That sounds big, but it is about 16,000 times smaller than the asteroid that killed the dinosaurs. If it hit Earth, it would release about the same amount of energy as the maga-earthquake that just killed 12,000 people in the Indian Ocean. Due to the differing ways that asteroids and earthquakes release their energy, it would probably cause more devastation than a giant earthquake but it would still be a regional, rather than global, catastrophe.

Given the long lead time available, one delta IV-launched ion engine probe might be able to deflect it enough to avoid an impact with Earth. However, that would be fairly marginal, so it would be better to send several or use an HLLV.

It really should be easier to destroy the asteroid rather than deflect it. The gravitational binding energy of the asteroid should be on the order of 2*10^9 J, or equivalent to the energy released by 500 kg of TNT (this is 10,000,000 times smaller than the gravitational binding energy of the dinosaur killer). As MarsDog pointed out in the other thread, the accretion process should not have released enough energy to melt the asteroid, so it should be composed of chunks that are only loosely bound together. A 10 ton impactor traveling at 50 km/s would have 1.25*10^13 J of kinetic energy, or the equivalent of 3 kilotons of TNT. Nuclear warheads run up to 100 Megatons. Either should be more than enough to destroy the asteroid and ensure that most of the pieces easily miss Earth.

ERRORIST · 2004-12-27 00:26:40

Suppose the thing was going to hit the USA and then WWlll broke out and all launch facilities on Earth were destroyed by war?

MarsDog · 2004-12-27 05:07:04

http://2004mn4.info/]Here it comes

The Moon is going to hide behind the Earth ?

Get those nukes ready to launch

Grypd · 2004-12-27 06:08:59

The problem with all NEA class of asteroids is that they will hit Earth sometime and that is quite unacceptable.

So we wanted to try out mining asteroids well 2004 MN4 should be our first candidate. We have seen that our capabilities with magnetics has improved since O'Neills day and he had worked out the calculations to use mass drivers to move asteroids. But we can send a mission to this asteroid and useing its own mass move it.

Of course we have still to find out the composition of 2004 MN4 and it might well be it makes sense to try to capture it and see if we can make money from the venture by using its resources.

Still until we really know the composition of 2004MN4 we cant really decide what way is needed to deflect it. If its a collection of boulders held by weak gravity then it means any Nuclear device will simply create a shotgun effect for us.

GCNRevenger · 2004-12-27 08:19:41

Still until we really know the composition of 2004MN4 we cant really decide what way is needed to deflect it. If its a collection of boulders held by weak gravity then it means any Nuclear device will simply create a shotgun effect for us.

Up to 1-in-37 now

...which would render it harmless most likly if it is weakly bound together as it probboly is.

The obvious thing to do would be to do both. Send a large probe with a rockets and a second one.. an orbiter perhaps.. loaded with nuclear penitrators.

MarsDog · 2004-12-27 09:15:25

Nuclear device will simply create a shotgun effect

Think of it as a rack of http://www.euclideanspace.com/physics/d … tm]snooker balls.
The expelled material, created by the penetrator Nuke, being the cue ball.

The cue ball moves one direction, while the center of gravity of the asteroid pieces in the other direction, according to conservation of momentum.

If you hit the rack at an angle, an impulse will be transferred to its center of gravity and to its angular momentum.

http://www.aoe.vt.edu/~cdhall/papers/neopaper.pdf]More details

ERRORIST · 2004-12-27 09:35:18

I think it should be done like in the movie Armageddon. If something goes wrong on the way it could still be done manually. Drill into it then blast it? Or drill right through the center of it then install a thruster in the hole you made to push it away.

GCNRevenger · 2004-12-27 09:43:30

Its not that big Errorist, there probobly isn't even enough gravity to land on it, perhaps not even enough for a slow orbit. High-speed bunker buster type missiles with nuclear warheads would be more then sufficent to do the job.

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