Static charge on spacecraft

[AstroBrant]

While studying about radiation in the VAB, it occurred to me that the metal components of the CM/CSM hull, (and other spacecraft going through the outer belt), would have developed a large static charge. I was wondering how this charge was dissipated.

Then I got to wondering about the fact that this accumulated charge would repel incoming electrons. Any electrons striking the hull would be weakened by that repulsion before impact, wouldn't they? Now, I anticipate the explanation that the loss of inward energy of the approaching electron would be transferred to the electrons in the hull, but it seems that energy would be spread out over many electrons, effectively dividing the energy among them, resulting in less penetrating power to each one.

IOW, wouldn't the charge accumulated by the craft actually increase its shielding effect?

[ka9q]

Yes, spacecraft electrostatic charging is a real phenomenon. The major risk is a damaging discharge, so bonding of exterior surfaces is important.

Electric charges are accelerated (or decelerated) by electric fields, not electric charges per se. Even a large electric charge will not generate a strong electric field if it can spread out on a physically large and smooth object. This is why you find those little steel balls on the tips of car radio antennas, and why Van de Graf generators (and many other pieces of high voltage equipment) have those big smooth metallic electrodes. It's also why many very high voltage power lines use conductors that are actually bundles of cables with conducting spacers separating them.

I haven't done the math but my intuition tells me that any charge you'd build up on something like an Apollo capsule would not have any significant effect on the impact energies of additional incoming charged particles.

[AstroBrant]

I haven't done the math but my intuition tells me that any charge you'd build up on something like an Apollo capsule would not have any significant effect on the impact energies of additional incoming charged particles.

Thanks for the feedback. I certainly have no reason to doubt your appraisal. Hope to see more discussion.

[chuckle] I've been reading so many comments from hoax nuts that I couldn't help running through my mind what kind of response one of them would have given you, if this was something that they believed supported a hoax theory. They would probably go on with "yeah, but" this and "yeah, but" that, making some irrelevant comparisons or outraged retorts like, "Are you trying to tell me that ALLLL those electrons don't turn that craft into a frigging electron WALL??? LOL! HAHAHAHAHA!"...calling you a shill, etc. All to protect their fragile little egos and keep their pet theory alive.

But people who really care about the truth don't behave that way. I am a happy member of that crowd.

[cjameshuff]

Electrostatic radiation shielding has been investigated, but it takes a rather different approach than just charging up the spacecraft:
http://science.nasa.gov/science-news/science-at-nasa/2005/24jun_electrostatics/
http://www.nasa.gov/pdf/718390main_Tripathi_2011_PhI_Electrostatic_Radiation_Protection.pdf

[JayUtah]

I haven't done the math either.  But in the copious amount of technical literature on the electrostatic charging of spacecraft, there is no mention of accumulating such a charge that future particle deposition is discouraged.  It's the sort of thing that would be modeled there if it were a factor.