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Apophis can be steered to hit the Earth and used for geoengineering. It can launch dust and aerosols that cool the Earth. The dust fertilizes the oceans and sequesters carbon. The crater can strip mine.
Apophis is the size of a football stadium. The impact energy is 100 times that of a fusion bomb and it doesn't make radioactivity. It can trigger a volcano for extra energy.
It takes only a small nudge to make Apophis hit the Earth, easily done with a fusion bomb. Apophis will pass the Earth next in 2029, and the pass after that is 2036.
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Pinatubo cooled the Earth by .2 Kelvin in 1991.
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The "medieval warming period" had low volcanic activity.
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The following volcanoes give measurements for temperature change.
Volcano Magma Volcanic Year Temp Energy
km3 index change (K) Joule
Philippines Pinatubo 25 6 1991 -.2 5e16
Alaska Novarupta 28 6 1912 +.2
Guatemala Santa Maria 20 6 1902 -.1
Indonesia Krakatoa 20 6 1883 -.4 8e17
Indonesia Tambora 160 7 1815 -.5 3e18 Caused the "Year without a summer"
Iceland Laki 14 6 1783 -1
Unknown 7 535 -2
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Nutrients can be added to the oceans to promote biomass. Divide nutrients into micronutrients (metals) and macronutrients (phosphorus, silicon, etc). Micronutrients can be added cheaply. For macronutrients, you need an explosion to launch dust. The explosion can come from either a nuclear bomb, a volcano, or an asteroid. An asteroid can trigger a volcano.
Dry plant Ocean Ocean Crust Cost Cost Crust/ Soluble Nitrogen Photo-
ppm deplete ppm ppm $/kg $ plant fraction fixation synthesis
Silicon 50000 .02 2.2 282000 .1 5000 5.6 .05
Phosphorus 810 .05 .06 1050 5.4 4400 1.3 .33
Nitrogen 13000 .1 .05 19 2.0 26000 0
Zinc 30 .02 .0049 70 2.7 81 2.3 .4
Iron 200 .15 .002 56300 .8 160 282 .10 *
Selenium 5 .25 .0002 .050 22 110 0
Nickel 1 .25 .001 84 16 16 84 .4
Copper 5 .25 .00025 60 7.1 36 12 .4 *
Iodine .3 .6 .06 .45 35 10 1.5
Vanadium .25 .8 .0025 120 28 7 480 .5 * Toxic if too concentrated
Molybdenum 1 1 .01 1.2 26 26 1.2 *
Manganese 60 2 .0002 950 2.2 130 16 .35 *
Cobalt .5 3 .00002 25 33 16 50 *
Carbon 450000 .85 28 200 0 0 .0004
Boron 10 1 4.44 10 3.7 37 1
Sulfur 1500 1 905 350 .10 150 .23
Calcium 5000 1 412 41500 .1 11500 8.3
Potassium 50000 1 399 20000 2.9 145000 .4
Magnesium 2200 1 1290 24000 2.5 5500 11 *
"Crust/Plant" is the ratio of crust concentration to plant concentration.
"Ocean deplete" is the ratio of surface concentration to average concentration, and indicates how stressed the nutrient is.
The bottom group (Carbon through magnesium) are elements that are abundant in the ocean and don't need to be fertilized.
The top group is macronutrients and the middle group is micronutrients (metals).
"Soluble fraction" is for dust that falls in the ocean and is the fraction of the element in the dust that dissolves.
Silicon isn't required for life, but if it's abundant, diatoms use it for cell walls. It takes more energy to make a carbon cell wall than a silicon cell wall.
Selenium is mined at 3 Mkg/year. If it's used for ocean fertilizer, the demand will exceed this. The price won't go up because selenium is extracted from sulfur. All other fertilizer elements have abundant supply.
Data: Periodic table of ocean elements
The chief nitrogen fixing nutrient is molybdenum, so spike the ocean with moly.
Iron is also necessary for nitrogen fixation.
Vanadium can fix nitrogen, but moly is better. Vanadium isn't needed if moly is present. Vanadium is also toxic at high concentration.
Cobalt can fix nitrogen and is present in legumes. But if moly is present, cobalt isn't needed.
The most bioavailable form of molybdenum is molybdenate MoO4--.
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A dust cloud in the Antarctic tends to stay in Antarctic because of Hadley cells. The dust can be localized to a part of the Earth that's lightly inhabited.
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A current rings Antarctica. The chief downwelling zone is in the Atlantic sector. Diatoms can capture carbon and then currents send the carbon to the bottom of the ocean.
The thermohaline circulation time is 1000 years.
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A volcano can amplify an explosion. Antarctica has active volcanoes, the most active being Mount Erebus.
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Last eruption
Mount Erebus 2018
Deception Island 1970
Penguin Island 1905
Mount Melbourne 1892
Mount Rittman 1252
Hudson Mountains -210
The Pleiades -1050
Mount Takahe -5550
Mount Berlin -8350
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There is a narrow canyon in Queen Maud's land that can be dammed with a nuke or asteroid. The ice flow through the canon is on the order of 100 km3/year. 1 mm of ocean level is 360 km3 of water.
The Amery glacier can also be dammed, although the Queen Maud canyon is a better candidate.
For a megathrust earthquake, between .1 and 1% of the earthquake energy becomes tsunami wave energy.
A fusion bomb can cause a dangerous tsunami. You don't want an asteroid hitting the open ocean. You want it to hit land.
Magnitude Earthquake Tsunami Tsunami Year
Richter Joule Joule fraction
Japan, Tohoku 9.0 2.0e18 3.0e15 .0015 2011 Fukushima nuclear disaster
Chile, Offshore Maule 8.8 1.0e18 2010
Indonesia, Sumatra 9.1 2.8e18 2.1e16 .0075 2004
Alaska, Anchorage 9.3 5.6e18 6.0e14 .00011 1964
Chile, Valdivia 9.5 11.2e18 1960 Largest quake in recorded history
Pacific Ocean, Cascadia 9.0 2.0e18 1700
A fusion bomb makes dust, which goes into the oceans and adds 1 Bkg of phosphorus. Aphophis has the energy of 100 fusion bombs. The phosphorus in ocean plants is 6 bkg.
For oceans,
Plants = 6000 Bkg Plankton = 1900 Bkg Animals = 30000 Bkg Zooplankton = 14400 Bkg Crustacian = 4800 Bkg Fish = 4200 Bkg Fish capture = 120 Bkg/year Squid = 55 Bkg Whale = 40 Bkg Dolphin = 7 Bkg Seal = 6 Bkg Biomass concentration = 17 ppb Plant phosphorus fraction = .0003 Plant phosphorus = 6 Bkg Crust phosphorus fraction = .00105 Fusion bomb ejecta = 1000 Bkg A bomb with 10 MTon TNT equivalent of energy Phosphorus in ejecta = 1 Bkg Natural dust going into oceans= 1200 Bkg/year
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Ocean animal biomass exceeds plant biomass. Whales dominate ocean mammal biomass.
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Hydrogen bombs are the best way to deflect asteroids. We should have bombs in space ready to go if an asteroid is found. We also need wide-angle telescopes to detect asteroids, like the Rubin telescope.
Suppose you bomb an asteroid. The goal is to maximize momentum delivered to the asteroid, which means ejecting as much mass as possible from the asteroid.
Ejecta energy = Ee Ejecta mass = me Ejecta momentum = Qe = (2 me Ee)½
If you have enough time to land on the asteroid, bury the bomb as deep as possible. If you don't, then settle for putting the bomb on a glancing collision course with the asteroid and detonate it just before it hits. The mass ejected can be increased by hitting the asteroid with a pre-impactor, to launch material into space which is then heated by the bomb.
The ejection speed should be slow, to maximize mass ejected, but it should larger than the escape speed. We usually set it to be 3 times the escape speed. The relationship between momentum and energy is
Ejecta speed = ve Ejecta momentum = Qe = 2 Ee / ve
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A mass can be launched from Earth to impact the asteroid and give it a glancing blow to deflect it sideways. The fact that the asteroid is already moving toward Earth adds to the impact speed.
For an impact crater, the ejected momentum tends to have the same magnitude as the impactor momentum.
The asteroid Apophis is moving toward Earth at 6 km/s.
We calculate the minimum mass of the impactor, using Apophis as an example.
Asteroid mass = M Asteroid sideways deflection distance = X = 10 Mmeter Size of Earth Time before asteroid hits Earth = T = 10 Msecond 3 months Asteroid min sideways deflection speed = V = X/T = 1 meter/second Asteroid distance from Earth when hit = L Impactor mass = mi Impactor speed = vi = 6 km/s Impactor momentum = Qi = mi vi Ejecta momentum = Qe = Qi Required deflection momentum to asteroid = Q = Qe = M V Impactor mass requirement = mi > M V / vi
Ejecta energy is typically much less than impactor energy.
Impactor energy = Ei = ½ mi vi2 Ejecta energy = Ee = ½ me ve2 = Ei ve / vi
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If there is insufficient time to deflect the asteroid, then destroy it. This means gravitationally unbinding it. It still hits the Earth but in pieces. This makes a big difference for tsunami.
If an impactor intercepts an asteroid, we calculate the mass required to unbind the asteroid.
Asteroid radius = R = 1000 meter Asteroid density = D = 3200 kg/meter3 Asteroid mass = M = 4/3 π D R3 = 13 Tkg Asteroid gravitatioal energy= Eg = 3/5 G M2 / R = 7.2 TJoule Asteroid escape speed = v = (8/3 π G D)½ R = 1.34 meter/second Ejection speed factor = f = = 3 Ejection speed = ve = f v = 4.02 meter/second Ejection mass = me Impactor mass = mi Impactor speed = vi = 6 km/s Impactor momentum = Qi = mi vi Ejection momentum = Qe = me ve = Qi Ejection energy = Ee = ½ me ve2 = ½ me ve vi Impactor mass = mi = 16/15 6-½ π2 G½ D3/2 vi-1 R4 = 1.06e9 (R/1000)4 kg
If the asteroid is large, it's easier to deflect than destroy. If small, it's easier to destroy than deflect. The astroid radius for which the impactor mass required is the same for cases is:
Asteroid radius = R = 5/12 (3/π)½ (GD)-½ f X/T = 2640 X/T meter
First, cameras arrive and pass by the asteroid and survey. Have at least 4 cameras, one passing over the top, one over the bottom, and 1 passing by each side.
The cameras don't slow down so that they can get to the asteroid fast.
A set of impactors arrives just before the cameras and hits a diverse set of spots on the asteroid. Cameras observe.
A second wave of cameras slows down and parks at the asteroid. Then another set of impactors hits and cameras observe. Impact spots are informed by the first wave of observations.
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For a meteor impact, only a small fraction of the incoming kinetic energy becomes ejecta kinetic energy. It may be possible to improve the ejecta energy by tamping, like a gun barrel.
If you sent a nuke to an asteroid, have pre-impactors make a hole. Send the nuke down the hole and detonate it at the bottom. You can have post-impactors that close the hole after the nuke goes in.
For a gun, bullet energy is 1/3 powder energy. This is the limit on what the buster strategy can do.
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The smallest asteroid capable of penetrating the atmosphere is 50 meters. Such an asteroid has the energy of a 10 Megaton fusion bomb. The minimum for creating a megatsunami is 200 meters. The LSST telescope will find all 200 meter and larger asteroids that are in near-Earth orbits, and hydrogen bombs can redirect any that will impact the Earth. For asteroids from more distant regions of the solar system it won't find them soon enough to deflect them. For this we need more powerful telescopes.
The following table shows impact damage as a function of asteroid size.
Asteroid Energy Tsunami Crater Impact Equivalent energy
diameter height diameter interval
meters EJoules meters km years
8 .0001 0 0 5 Fission bomb, 25 kton TNT equivalent
80 .100 0 1 3000 Fusion bomb, 25 Mton TNT equivalent
200 1 10 3 20000 Krakatoa Volcano, 1883
400 10 20 5 100000 Mag 9.5 quake. Chile, 1960.
2000 1000 200 40 1000000 Hurricane
10000 100000 4000 200 100000000 Asteroid that killed the dinosaurs
1 EJoule = 1018 Joules.
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Near Earth asteroids (NEA) approach the Earth at a characteristic speed of ~ 20 km/s. Retrograde comets can approach the Earth as fast as 75 km/s.
NEA: near Earth asteroids SPC: short period comets HTC: Halley-type comets LPC: long period comets"Near-Earth object velocity distributions and consequences for the Chicxulub impactor" S. V. Jeffers, S. P. Manley, M. E. Bailey, D. J. Asher, Mon. Not. R. Astron. Soc. 327, 126–132 (2001)
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The Pan-STARRS telescope specializes in finding asteroids. It has a wide field of view and takes short exposures, allowing it to cover the entire sky in 8 days. The upcoming Large Synaptic Survey Telescope (LSST) will cover the sky every 2 days.
Telescope Diameter Field of Exposure Sky survey Year
(meters) view (deg) (seconds) time (days)
Pan-STARRS 3 3.0 60 8 2010 Hawaii
LSST 8.4 3.5 15 2 2021 El Penon, Chile
Flux limit Magnitude
(Watts/m2) limit
Human eye 3e-11 7
Pan-STARRS 5e-18 24
LSST 2e-18 25
Keck 10 meter 1e-19 28
Hubble 1e-20 31
Webb 5e-22 34
The largest single-stage fusion bombs have an energy in the range of 25 ktons TNT equivalent. Larger bombs can be made with 2-stage desgins but they have similar energy/mass as a single-stage bomb.
Energy of a large fusion bomb= E = = 1017 Joules = 25 MTons TNT equivalent Mass of a large fusion bomb = M = =4000 kg Fusion bomb energy/mass = e = E/M = 25 TJoules/kg = 6 kTons TNT equivalent per kg TNT energy/mass = z = = 4.2 MJoules/kg
Departure from the Earth is done with the Oberth maneuver, which uses the Earth to amplify a rocket impulse. The Oberth maneuver is executed by starting the rocket in an elliptical orbit with the perigee as close to the Earth as possible, and the rocket is fired at perigee. Example numbers:
Earth escape speed = Ve = 11.2 km/s Rocket speed change = Vr = 6 km/s Earth departure speed = Vd = (Vr2 + 2 Vr Ve)½ = 13 km/s
A substantial fraction of an asteroid's kinetic energy goes into heating the atmosphere. An asteroid 10 km or larger heats the atmosphere enough to cause a mass extinction, such as what happened to the dinosaurs.
Heat capacity of air = 1.0 Joules/kg/Kelvin
Mass of atmosphere = 5.1 kg
Mass of asteroid Speed of asteroid
Heating ~ 40 kelvin * ---------------- * ( ----------------- )^2
10^15 kg 20 km/s
A 10 km asteroid has a mass of 1015 kg.
Q = Radius of closest approach / Radius of Earth
Q Diameter Date Energy
(meters) (Mtons TNT)
Chelyabinsk 1.0 19 2013 .44
Tunguska 1.0 50 1908 12 Flattened a forest
Arizona asteroid 1.0 50 -50000 10 1 km crater
1972 Fireball 1.0089 ~ 6 1972 Skimmed the upper atmosphere
2011-CQ1 1.87 1 2011
2008-TS26 1.96 1 2008
2011-MD 2.94 10 2011
2012-KT42 3.26 ~ 7 2004
Apophis 4.9 325 2029 510
2013-DA14 5.35 30 2013
2012-KP24 8.99 25 2004
2012-BX34 10.3 8 2012
2012-TC4 14.9 17 2012
2005-YU55 60.00 400 2005
Distance (AU)
2004 December 21 .0096
2013 January 9 .097
2029 April 13 21:46 UT .000254 = 6.0 Earth radii = 38000 km
2036 March 27 .31
2051 April 20 .042
Radius = 170 meter Density = 2600 kg/meter3 Mass = 5.4e10 kg Approach speed = 6.0 km/s Apohis escape speed = .205 m/s Impact speed = 12.7 km/s Impact energy = 4.4e18 Joule Fusion bomb, 10 MTon = 4e16 Joule Earth escape speed = 11.2 km/s
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Wind delivers desert dust all over the world.
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Dust produced by the world = 1200 Bkg/year Dust produced by the Sahara = 550 Bkg/year Dust received by Amazon = 20 Bkg/year Iron fraction that dissolves = .005 For dust that falls in the ocean Ocean silicon input = 340 Bkg/year Ocean phosphorus input = .95 Bkg/year Ocean zinc input = .175 Bkg/year Ocean iron input = 32 Bkg/year Ocean nickel input = .086 Bkg/year Ocean copper input = .063 Bkg/year
Most bioavailable form:
Molybdenum MoO4--
Energy to make gravel = .003 MJoule/kg Energy to make sand = .008 MJoule/kg Energy to make dust = .02 MJoule/kg Energy to make micron dust= 4.4 MJoule/kg Energy to make lava = 1 MJoule/kg Energy to make vapor = 10 MJoule/kg Energy to throw = .01 MJoule/kg Energy of fusion bomb = 4e16 Joule Mass of rock thrown =4000 Bkg Mass of rock melted = 40 Bkg Rock Phosphorus = .04 Bkg Mass of rock melted = 33 Bkg Mass of rock crushed =4100 Bkg Mass of crater ejecta =4000 Bkg/Mton Experimental result
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The Taupo volcano is the lake in the center.
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