Static electricity issues with the landings

[onebigmonkey]

Hoax believer asks reasonably intelligent question shocker.

A guy over at ATS has said the landings couldn't have happened because they would have received a massive static charge when they touched down.

I have a suspicion there's a bit of Electric Universe stuff going on in his ideas, but there is research that shows that the moon does acquire and discharge static. We also all know the issues Apollo astronauts had with dust clinging to their suits.

My question is: what measures (if any) did they take to minimise problems of static electricity? Did they even  realise it was an issue? What levels of charge are we talking here?

Please bear in mind I am not a physicist!

[Echnaton]

You could point out that since the Soviet Luna program and the NASA Surveyor program had landed working space craft on the moon before Apollo, there was a good reason to think static would not be any more of an issue for the LM than had already experienced.  Pointing out that HBs are calling the Soviet Union lairs is frequently a good way to get them to go away for a while.   

[Bob B.]

Can he quantify "massive"?

[onebigmonkey]

Oh I already mentioned the unmanned stuff, including China, and I did suggest that he go and do some maths to prove his point.

I am genuinely curious if any measures were taken to counter any problems, or if any thought was given to it.

Or I may actually start just using the same sort of arguments they do and to hell with it.

"You know, I just feel like they went - it kind of feels like they did..."

[Bob B.]

There's this...

Static Electricity in the Apollo Spacecraft

[Glom]

Don't you just hate it when it turns out NASA themselves have written a report in the very issue you thought you got them with?

[onebigmonkey]

That's a good link - interesting that they did indeed take measures to counter static, though that static seems to be mostly what they anticipated generating themselves rather than what they would encounter on the surface!

[Bob B.]

Here's another paper:

Lunar Surface Charging:  Magnitude and Implications as a Function of Space and Time

Implications for Exploration:  In addition to the clear scientific relevance of lunar surface charging, surface electrification also has potentially significant implications for human and robotic exploration and in situ resource utilization.  The electric fields themselves may affect machinery on the surface – this process has been demonstrated to be a leading cause of spacecraft failures in space.  Surface electric fields had few demonstrably significant effects on the Apollo missions, but these missions were conducted with limited exposure to the terrestrial plasmasheet of SEP events, and astronauts only experienced the lunar surface in the relatively benign surface charging environment in the morning sector, with electric fields therefore expected to remain at relatively low levels.  In a more energetic plasma environment, surface electric fields might have more significant effects, especially considering the abrupt changes in surface potential often encountered.

And another:

Lunar Surface Charging:  A Global Perspective using Lunar Prospector Data

We see that at lunar noon the surface is positively charged and at lunar night it is negatively charged.  The transition occurs on the daylight side of the terminator in what is lunar morning and evening.  The charge is minimal in the area where Apollo landed.

(edited to add)

The following figure is taken from the second paper.  I've added the yellow and cyan shading.  The yellow represented the range of θ in which the landings occurred, and the cyan represents the range of θ in which the surface EVAs occurred.  It looks like the surface potential at the time of landing was about -10 V on average.  Unfortunately I don't know of to figure out what, if any, hazard might be present.

[ka9q]

My understanding is that the main effect of electrostatic charging on the lunar surface is dust transport. The lunar reflectors left by Apollos 11, 14 and 15 seem to be performing consistently below spec, and the leading hypothesis is that they've been covered by thin layers of dust placed there by electrostatic charging cycles occurring every lunar day.

[Dalhousie]

My understanding is that the main effect of electrostatic charging on the lunar surface is dust transport. The lunar reflectors left by Apollos 11, 14 and 15 seem to be performing consistently below spec, and the leading hypothesis is that they've been covered by thin layers of dust placed there by electrostatic charging cycles occurring every lunar day.

It would be interesting to track these (and the Lunokhod reflectors) through several diurnal cycles to see if there are various associated with dust movement.

[JayUtah]

My understanding is that the main effect of electrostatic charging on the lunar surface is dust transport. The lunar reflectors left by Apollos 11, 14 and 15 seem to be performing consistently below spec, and the leading hypothesis is that they've been covered by thin layers of dust placed there by electrostatic charging cycles occurring every lunar day.

I would put real money on that scenario.  I recall vaguely some observation that light scattered at the edge of the lunar disc, on the lit side (i.e., accounting for present phase).  The working hypothesis was that electrostatic charging caused a cloud of charged regolith particles to rise above the surface and hold there so long as the electrostatic conditions persisted.  I have to believe this would deposit dust on the LRRR.