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Can an asteroid be dissolved?

It seems most asteroids are rubble-piles. They are made of a loose aggregate of stones and dust kept together by gravitation.

The gravitational force that keeps the asteroid together can be counterbalanced by the electric force. If the stones and the dust are electrically loaded by a man-made device, they will separate and inflate in an ever widening cloud. While this works for sure in principle, the question is whether it is technologically feasible.

The most obvious way to load the rubble is to aim a low energy particle accelerator towards the asteroid. Either electrons or ions can be send towards the rocks, with just enough energy not be deviated and to bore themselves superficially inside the materials. (The results below are so optimistic I suppose I made yet another calculation error. I'll need to compute this out again.)

How much Coulombs (electrons) are needed to separate two masses of 0.5 kg held together by gravitation?

The Gravitational Force is FG = 6.67e-11 x (0.52 / r2)

The Electric Force is FE = 9e+9 x ((q / 2)2 / r2)

This yields the masses have to be homogeneously loaded with q = 8.6e-11 Coulombs to counterbalance the gravitational attraction.

Symmetry yields you need a little more than 8.6e-11 Coulombs to separate 1 kg of whatever stones or gravel.

8.6e-11 Coulombs is about 5e+8 electrons. This makes 8.3e-19 mole of electrons. Those 8.3e-19 mole of electrons can be harvested out of 8.3e-19 gr of hydrogen.

Hence you need to ionize and accelerate 8.3e-22 kg of hydrogen to get enough electrons or protons to separate 1 kg of asteroid rubble.

Asteroid Itokawa has a mass of roughly 4e+10 kg. Hence in the order of 3.4e-11 kg of hydrogen need to be ionized and accelerated to break it apart. This seems feasible. Spending 1 MeV per hydrogen atom, the energy required would be 3e+6 J. That makes 35 W during a day.

The calculations above are unrealistic. On the one hand, much more electrons or protons are needed because the asteroid can be "dissolved" only layers at a time. On the other hand, the fact most asteroids rotate close to their dislocation speed helps. Calculations and simulations are needed to compute this further out.

High energy particle accelerators can be made to aim very precisely. Maybe such an accelerator in low Earth orbit or on the Moon can aim at an asteroid far away to dissolve it?

The dissolved asteroid can later on be reassembled or reordered by changing the electric charges. I don't know the time the solar wind needs to neutralize the electric charges of the items that compose the inflating cloud.

Eric Brasseur  -  January 14 2006