Javier Luis López

A bolide is not a terribly efficient way of creating a population of micron-scale scattering bodies - if the object is large, only a small fraction of the mass is ablated, and you end up with a potential city-killer.

If the object is small then one has gone to a *lot* of trouble (years to an asteroid, somehow deflecting it, years to get it to Earth) to add only a few tonnes of particulate matter to the stratosphere.

Why not just have missiles or stratospheric aircraft inject particulates directly?

Having said that, it's not a terribly good idea - as it's hard to turn 'off' as residence times in the stratosphere are multi-year scale.

Any geoengineering with the planet and climate change is terrible and highly dangerous. There is no way to foresee some awful unintended consequences of any human intervention in such a delicate and highly non-linear stochastic system as the Earth climate system (be it an asteroid or missiles spreading particles in stratosphere, or anything else similarly dangerous).

Please leave the planet alone and do not destroy it by any unwise human actions, and it will adapt itself to any changes, be it an atmospheric carbon dioxide or any other factor.

James,

To throw an Asteroid in a controlled manner is not to make a city killer: The Asteroid can wait at 500km over the Eart before falling to the right place. What can be the accuracy?

We can calculate the energy of the Asteroid (mass*500km height*gravity), then knowing the sublimation energy of rocks it can be calculated the exact amount of matter sent to the atmosphere. As more heat, the particles will climb higher.

Also, it must be calculated if an earthquake would be produced.

A test could be made before, perhaps with a small one tonne asteroid.

I think there is a budget to pay because it is a Space Mining method.

Javier Luis López

This post is a vivid example of an idea generated with no knowledge of the subject matter and no knowledge of the basic physics behind it.

1-st, the energy of an asteroid upon impact of the earth surface depends on its kinetic energy (KE) which is =mass*impact speed^2/2, not on its potential energy (PE)=mass*500km* gravity (acceleration).

2-nd, even if the potential energy plays any role, its calculation should have included the variable gravity acceleration which varies with distance from the earth surface H=500 km (its value=9.8 m/s^2 only at the surface), i.e. PE=mgR^2(1/R-1/(R+H)), where R is the earth radius.

3-rd, let's assume, say, an asteroid diameter =10 m, its average density 2500 kg/m^3 (from the range 1800- 4200 kg/m^3), the speed before it enters atmosphere is about, say, 17 km/s. ( The escape speed is 11 km/s, the orbit speed is ~7.9 km/s, the earth moves on its orbit at ~30km/s + its angular speed. So, the low estimate is about 17 km/s, but can vary, of course). Typical impact angle is 45 degrees (vertical impact is 90 deg).

Calculation results:

Energy:

Energy before atmospheric entry: 1.89 x 1014 Joules = 0.45 x 10-1 MegaTons TNT

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

Atmospheric Entry:

The asteroid begins to breakup at an altitude of 59500 meters = 195000 ft. It bursts into a cloud of fragments at an altitude of 32300 meters = 106000 ft.The residual velocity fragments after the burst is 13.1 km/s = 8.14 miles/sThe energy of the airburst is 7.66 x 1013 Joules = 0.18 x 10-1 MegaTons.No crater is formed, although large fragments may strike the surface.

So, no real impact on aerosol cooling. Besides, there is no idea how much cooling some additional aerosol will result in.

Attached is the paper that provides all details and analysis of inevitable uncertainty of this kind of calculation.

I asked to ESA in Netherlands (I worked for them some years ago) and his response was that they are working in alternative system to solve the problem due the Asteroid would damage the Lithosphere.

An alternative method is to throw small asteroid parts to evaporate them before reaching the atmosphere. A previous analysis of samples must be done before to avoid dangerous gases.

This alternative method could be used to deviate Hurricanes or reduce its strength by create small ones far from the coast line.

Javier Luis López

Perhaps we met! I worked partly at ESTEC in the 2000s, and partly at Leiden University!

The problem of diverting any object so that it intersects (or not) with the Earth is that you have to deliver the device that moves the object to a very distant place, match speeds, and perform its job.

The energy to do that, for launching from the Earth, is very great, and at least two (or three) orders of magnitude more than lifting terrestrial material (dust, aerosols) 20km into the sky.

But it's still not a great idea.

I worked in the design of a plasma thruster to deliver 700N to try nuclear fusion.

I calculated it would work over 80km height if it would be used in a spacecraft

Does it would be enought or need more thrust?, It could be used some of them in parallel

I do not know if it is enough to create some temperature reduction at Eart but perhaps to deviate hurricanes at South USA, or perhaps Europe if Climate Change increases