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Tom Shaw Blogs: From Grizzly Peak to Mars the Moon and Back!
This post will dig deeper into compass use by weaving geology, physics, planetary science, and outdoor navigation all into one as well as sharing my experiences as a graduate student in the MOAEL program at SOU. This is the third of 3 blog entries on this topic.
In the last post, I mentioned meteorites can impact your compass. That’s right, if you’re looking for meteorites, use your compass. Big Red (the red end of your compass needle) won’t necessarily point directly at them, but….since they almost always contain magnetized iron or nickel, Big Red WILL be moved by them. The exceptions are meteorites from Mars or the Moon Those meteorites are nearly ironless chunks of rock that will not have any real impacts on redirecting your compass needle. Now, if you know anything about Mars you’re probably scratching your head right about now and asking yourself, isn’t Mars full of iron? Isn’t its surface reddish in color because it contains rusted iron? Shouldn’t Martian meteorites be chunks of reddish oxidized iron!? Truth! But, for some reason, Martian meteorites do not carry much of this iron to the Earth’s surface and hence do not possess a magnetic field strong enough to influence your compass. You might also think since the Moon is made out of cheese (just kidding!) instead of iron it makes sense those lunaites (lunar meteorites) would not carry a magnetic field either, but….. as it turns out, the Lunar surface facing us is littered with basalt rich lava fields and not cheese!! More on that shortly. First, let’s go to Mars.
Mars will be home to humans one day soon, and when that happens a whole new world of outdoor adventuring will open up. Will the adventuring and survival skills we use here on Earth be helpful on Mars? Will using your compass help you to navigate the Martian Wilderness? The answer to the second question is yes and no. Mars once had a magnetic field like the Earth’s, but alas it died out 3.5 billion years ago. As a result, Big Red will not be attracted to a Martian Magnetic North Pole. However, since the Magnetic North Pole did exist once upon a time, and the Martian landscape is not lacking in basaltic iron-rich lava beds, some of this basalt rock did get magnetized. When walking on those lava fields, your compass may be valuable. As a matter of fact, large portions of Basaltic rock all over the southern hemisphere of Mars are magnetized. It’s actually a mystery as to why the iron-rich rock on the Northern half of the planet is not magnetized. So maybe you could use your compass to navigate around these basaltic lava fields?
Mars also has the largest system of volcanoes in the Solar System with Olympus Mons as the big kahuna of all volcanoes in the Solar System. It is 2.5 times larger than Mt Everest. Now is your mind going where my mind is going? Did any of the lava beds on Olympus Mons exist 3.5 billion years ago or earlier? Was Olympus Mons around before Mars’s magnetic field died out? If so, will the first mountaineers on Mars be able to use their compasses to guide them up Olympus Mons’s Basalt slopes? Will a compass be impacted by igneous rock on the Martian volcano just like it is on Grizzly Peak? The answer, sadly, is no. It appears Big Red will be of little value on Olympus Mons simply because the lava fields there are only a few hundred thousand years old, long after Mars’s magnetic field died away. Thus, the iron rich rock was never magnetized. Alas, compass skills will not likely be helpful should you one day attempt to summit the largest Mountain in the Solar System.
Now, back to the moon! You remember that Harvest Moon I was admiring when I was on my hike with the MOAEL graduate cohort K2 back in the fall? Well, all of the dark spots I was looking at on the face of that full moon are actually ancient basaltic lava beds. They are called Maria because early astronomers thought they were oceans. It appears those Maria have some but not much of a magnetic field. What’s more interesting is apparently the lunar impact craters have a stronger magnetic field than the actual lunar lava beds. These craters magnetic fields are still small compared to the Earth’s magnetic field. Should you be adventuring on the Moon’s ancient lava fields, I don’t think Big Red will tilt one way or another. I do believe, however, that the next adventurers to land on Mars or the Moon will at least be measuring the magnetic fields on the planet’s surface for research more than Wilderness Navigation.
It’s kind of cool to think that during the Harvest Moon hike I was standing on 23 million-year-old volcanic rock whilst looking up at the moon and viewing its own nearly 4 billion-year-old field of igneous basalt rock. Now only if Big Red could help me get there!