Electric Asteroids

[Tommygun]

I came across this NASA article about how solar winds may charge asteroids up with dangerous amounts of electricity.

NASA is looking into this as a potential danger to a spacecraft or astronaut trying to approach one of these objects.

I found it really interesting. It never occurred to me that they could act as giant capacitors.

http://www.nasa.gov/content/goddard/new-nasa-model-gives-glimpse-into-the-invisible-world-of-electric-asteroids/#.U_mqb2Ox1W-

[Scotius]

Aren't space suits insulated? I hope so, because it would be very bad to travel millions of kilometers, and be electrocuted just after landing

[Tommygun]

If the change is high enough even insulation can act as a conductor.

That is a big problem around high voltage power lines.

[Jesrad]

Faraday cages.

[cantab]

You would presumably approach with caution and a conductor, seeking to get your potential to match the asteroid.

[lajoswinkler]

Yes, it's a fact. Planetary bodies of all kinds are charged and differ by the amount of charge on them. It's simply something that must happen when you've got vacuum and a source of electrically charged particles emanating from a star.

If the change is high enough even insulation can act as a conductor.

That is a big problem around high voltage power lines.

No, that's a completely separate problem. Huge charge differences can cause a breakup of the insulator.

High voltage power lines are alternate current based, and such current can flow through insulators.

Edited August 24, 2014 by lajoswinkler

[Nuke]

when you start doing ac, capacitors start looking like resistors. all kinds of weird stuff happens. you can plant florescent bulbs in the ground under high tension lines and get them to illuminate for example.

the interaction between asteroids and spacecraft will mostly be dc. you can just use a resistor probe to safely equalize electric charges. much in the way you make a power supply or crt monitor safe to work on. does make me wonder if you cant use a bunch of insulated objects and tap power off of their electrical differential, mainly because objects of different sizes and shapes of objects will develop charges at different rates. might be a useful alternative to solar power in space stations.

Edited August 24, 2014 by Nuke

[Tommygun]

Oh that's right, I'm so used to working with higher voltage AC and low voltage DC control lines, I tend to not think of killer DC charges.

At least not with the type of factory equipment I repair.

[Idobox]

You would presumably approach with caution and a conductor, seeking to get your potential to match the asteroid.

That would work with metallic asteroids, but rocky ones are not conductive, and the charges would stick to the surface.

A better approach would be to blow plasma towards it, since it behaves like a conductive gas. That is used a lot on industrial machines where friction can cause electrostatic build up, although it's usually referred as ionizers (because the ratio of ionized molecules is very low, it's usually not considered a proper plasma).

[lajoswinkler]

Does anyone here know how was this problem mitigated during the Moon landings?

[B787_300]

yes... you know the long points on the bottom of the LEM legs that looked like stakes... Those grounded the LEM to the Moon

[Sky_walker]

Well, when Luna 2 and 3 landed on a moon and survived - it was quite certain that there is no deadly amount of electric charge there.

But LM got it's own grounding.

[Nibb31]

yes... you know the long points on the bottom of the LEM legs that looked like stakes... Those grounded the LEM to the Moon

They were sensors designed to cut the engines before reaching the ground.

[lajoswinkler]

yes... you know the long points on the bottom of the LEM legs that looked like stakes... Those grounded the LEM to the Moon

Those were the tactile sensors for the approaching ground.

I don't know whether there was any charge equalizating system onboard.

They were sensors designed to cut the engines before reaching the ground.

Nope, they would just light up the little control panel light in the cabin. The pilot would then shut down the engine.

Edited August 26, 2014 by lajoswinkler

[lajoswinkler]

Well, when Luna 2 and 3 landed on a moon and survived - it was quite certain that there is no deadly amount of electric charge there.

But LM got it's own grounding.

One would assume the Moon has collected enough charge already...

How was the grounding arranged? Capacitors, resistors? How does that work?

[Tommygun]

Does anyone here know how was this problem mitigated during the Moon landings?

I found this from a NASA document tiled: "Static Electricity in the Apollo Spacecraft"

I'm assuming similar equipment was used on the LM?

The NASA link is massively slow and I refreshed numerous times.

Edit: it will work better if you right click on the link below and select "Save Link As" from the pull down menu to get the pdf file.

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19700004167.pdf

Static electricity ignition hazards in the Apollo spacecraft were studied. Sparks with energies up to 2 millijoules can be generated by a space-suited man. This amount is sufficient to ignite flammable gas vapors and mists, but is not sufficient to ignite flammable solids such as logbook paper and cotton cloth present in the Apollo spacecraft. Biomedical sensors were used to ground the space-suited man to the spacecraft and eliminate static electricity ignition hazards. Temporary interference with cardiac readings from the biomedical sensors occurred during static charge drainage. This interference was minimized by adding a 0. 1- to 1-megohm resistor in parallel to the ground circuit. Insulating fabrics used for the couch covers became electrified during use. The electrostatic charge on the couch covers was minimized by installing a grounded metal screen underneath the couch cover fabric.

Storage lockers on the spacecraft floor and lithium hydroxide canisters stowed in the storage lockers were capable of accumulating several millijoules of electric energy before they were grounded to the spacecraft structure. No evidence existed of static electricity interference with the operation of the communications system of the portable life support system.

I found this short article on electrical sparking in Lunar soil as well. Although it's about how the electrical arcing has changed Lunar soil.

http://sservi.nasa.gov/articles/electric-sparks-may-alter-evolution-of-lunar-soil/

Edited August 27, 2014 by Tommygun

[xman1]

Someone said Faraday cage. That is the answer.

Love this video:

-X