The mystery of rust on the Moon

Link here. The data shows that there is rust on the Moon, in an environment lacking oxygen and water that should make it impossible for it to form.

Yet the rust is there, in the form of hematite, and in fact the data from India’s first lunar orbiter, Chandrayaan-1, has found that the Moon’s nearside has much more of it. To explain how it got there the scientists have come up with a complex hypothesis, first requiring the Moon to be shielded from the Sun’s solar wind by the Earth’s magnetic field for part of its orbit, then having that magnet field transport oxygen from the Earth’s upper atmosphere to the Moon.

This oxygen then reacts with the tiny amount of water that some scientists believe Chandrayaan-1 detected scattered in the Moon’s regolith, the equivalent of its topsoil. The result, according to this hypothesis, is that over time that oxygen and water reacted with the surface iron on the Moon’s nearside, facing the Earth, causing it to rust.

The explanation is elegant, and fits the known facts (though the presence of that water in the lunar regolith remains unconfirmed). It is also complex, which should raise doubts. Regardless, the nearside of the Moon appears to have more hematite than the farside, and the formation of that iron oxide remains baffling.


  • Ryan Lawson

    Could the rust have originated on the Earth and simply been blasted up to the moon by asteroid impacts on the Earth over billions of years?

  • James Street

    I was strolling through YouTube videos by theoretical physicist Michio Kaku and one of them was about aliens (if they exist) coming to earth. He said they probably wouldn’t come to earth to steal our natural resources like water the way they do in movies, because the universe appears to be filled with resources.

  • Chris

    This is how the rust showed up:

    On a different note is there any news on how to handle the very sharp and very statically charged regolith? As I understand it one of the Apollo EV missions was cut short due to the amount of regolith adhering to the astronauts suit.
    Regolith is also very sharp even in microscopic sizes. Therefore it is extremely hard on airways and lungs.

  • Chris: So far I know of no real solution to the lunar dust problem.

  • Andrew _W

    Wouldn’t the heat released from impacts on the Moon be enough to cause molecular dissociation, releasing atomic oxygen?

  • @Ryan Lawson:

    I was thinking along similar lines. That the hematite is there is fact; how it got there (hands up)? The proffered hypothesis may explain the deposits if one assumes they were formed in place. Like you and many others on the forum, I prefer the simple over the complex.

  • LocalFluff

    60% of the Moon’s mass is oxygen, and iron is also plentiful Can’t the Solar wind protons or cosmic rays cause them to combine? In the right (light) radiation environment even helium molecules are formed in interstellar gas clouds.

    As I understand it, the Moon is covered by 10s if not 100s of meters asteroid dust. Most boulders are “young” results of impacts because micrometeorites erode between 0.1 and 1 mm per million years. That’s 0.1 to 1 meter (three feet) per billion year, or up to 4 meter since the Moon formed.

    The Moon might’ve had an atmosphere and liquid water when it had formed and cooled. The Earth did, so why not?

  • Chris

    Very interesting Jeff – thanks for posting

  • Max

    “The simple over the complex”

    Occam’s razor, words to live by.

    For instance the dust problem is easily solved by having an outer chamber that you can partially heat/pressurize and take a automated medium pressure spray/shower to wash off the dust with Static killing water. The water drainage can be filtered and reused indefinitely without any health affects that you might receive from chemicals. (In Syfy it’s called a decontamination chamber) then the air is removed and the water residue immediately will begin boiling/vaporizing. The clean/dry astronaut can move at this point into the airlock.

    As for the presence of rust, most meteorites and comets they have a large amount of water in its interior? I suspect that the cause is similar to what made Mars red.

    The solar system passing through a cloud of supernova remains explains much of what we see. Every gravity well would receive large quantities of frozen gases of all types as the sun goes dark. I suspect there’s a lot of rusty iron particles under the lunar surface.

  • pzatchok

    The moon has a very thin atmosphere. So of course rust will occur over millions of years.

    They have to first prove to me why what the moon already has would not form rust over huge amounts of time.

    They are claiming that charged hydrogen blocks ALL oxygen iron reactions. All the time 100%.
    If just one in a million oxygen iron interactions make hematite then over time all iron will be changed to rust.
    Unless something changes it back.

  • wayne

    “Widespread hematite at high latitudes of the Moon”
    Shuai Li, et al

  • Jeff Wright

    Useful for ISRU needs?

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