Unforeseen problems with prospective moon dwellers

NASA research on the Earth's magnetic field has uncovered a bit of a problem for future moon dwellers. It turns out that during the full moon, the moon is strongly whipped by the Earth's magnetotail, causing violent dust storms and electromagnetic activity which could have serious consequences for any surface dwellers or at best will require careful planning and a lot more cost to deal with than has been considered up to now.



At full moon, the moon passes through an oscillating "plasma sheet" — hot ionised gas particles trapped in the tail. Being hot, the electrons are fast moving with high kinetic energy and these electrons impact all over the moon's surface giving the moon a net negative charge. On the moon's dayside this effect is mitigated by the photoelectric effect due to sunlight, where photons release electrons from the surface, reducing the negative charge. But on the night side, the electronic charge stays built up and can accumulate to a relative potential of thousands of volts.

You may ask how did NASA not know this?
Well it had been seen before but it seems none of the Apollo missions never landed at full moon so there's been no direct experience of the effect to date. The effect was first noticed in 1968, when the Surveyor 7 lander photographed a strange glow on the horizon after dark, but nobody knew what it was.

See Space.com.