Vol. 24: Space Rock Hounds
A Q&A with the Meteorite Men.
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Q&A With The Meteorite Men
Geoff Notkin and Steve Arnold hunt for visitors from outer space, but they aren't looking for little green men. Their treasure is of the geologic sort: meteorites that bring to Earth clues of astronomical and planetary development in the universe. Notkin and Arnold have searched for meteorites together for years, and now share their hunting adventures in the Science Channel's Meteorite Men television program. We checked in with the pair to get their tips and insights for DIY meteorite hunters.
What is the simplest form of meteorite hunting that the DIY enthusiast can tackle?
Meteorites fall randomly over the entire surface of the earth, so theoretically you could search for them anywhere—even underwater if you happen to have your own submarine, and it wouldn't surprise us a bit if a couple of MAKE magazine readers have blueprints for a homemade mini-sub on the drawing boards! But it's important to be realistic. The vast majority of meteorites contain a large amount of iron, and that iron will begin to rust in humid environments, eventually causing the meteorite to decompose. So, the DIY meteorite hunter might consider limiting his or her searches to arid environments where meteorites could last hundreds or even thousands of years. Open spaces with little plant growth are easier to hunt that forests and grasslands, which is one of the reasons why Antarctica, the dry lake beds of the American Southwest, and the deserts of Northwest Africa have produced so many meteorite finds. The easiest way to begin your own personal hunt is to head out to a barren area that is devoid of vegetation, with few indigenous rocks, and see if you can spot anything unusual.
What kind of research would you recommend doing before you set out on a meteorite hunt?
The most important weapon in the meteorite hunter's arsenal is knowledge. There are many different types of common earth rocks that are frequently mistaken for meteorites. Before commencing a search, the would-be meteorite hunter should become familiar with what meteorites look like, and also practice a few simple field tests that can help in identifying suspected space rocks. Our Guide to Meteorite Identification [ SUGGESTED LINK http://www.aerolite.org/found-a-meteorite.htm ] is a good place to start.
In addition, there are a number of excellent meteorite books on the market. For someone wanting a comprehensive but readable introduction to meteorites, we recommend Rocks from Space by O. Richard Norton — a friend of ours, and an important science writer who passed away recently. Richard also wrote The Cambridge Encyclopedia of Meteorites, a more detailed reference work for those wishing to delve more deeply into the field. And a more recent addition to the list of must-have meteorite books was published last year by Penguin. The Fallen Sky, written by Chris Cokinos (another friend of ours), takes the reader on a lyrical and unforgettable journey through the history of meteorites, meteorite hunters, and some of the major discoveries in meteorite history.
What are the must-have tools for meteorite hunting?
The single most useful meteorite hunting tool is a good magnet. As mentioned earlier, the vast majority of meteorites are rich in iron, and they will easily adhere to a powerful magnet. We use magnets in the field, on a regular basis, to check suspected space rocks. There are plenty of terrestrial rocks that contain iron, so if an unusual-looking rock jumps to your magnet it doesn't automatically mean you've found a meteorite, but it's a step in the right direction.
We also rely heavily on metal detectors, as many of our hunt locations are the sites of old meteorites falls and we expect any surviving cosmic material to be buried. There are a number of good metal detector companies out there, but we have a particularly high regard for Fisher Labs in El Paso, Texas.
A good topographic map is important if you're hiking or driving in remote locations, as is a reliable GPS — not just to tell you where you are, but to mark find locations for future reference. We typically carry a small, portable digital scale with us so we can record the weight of finds, as well as plastic specimen bags, a notebook and a digital camera. Geoff is a photography nut and never goes anywhere in the field without one or more of his cameras.
What kind of meteorite-hunting tools can you make at home, instead of having to purchase them somewhere else?
As Steve is fond of saying: "There's no meteorite hunting aisle at your favorite mega-mart," so we end up designing and building much of the equipment that we use in the field. The simplest tool, and one of the most effective is a magnet cane, and this is used when hunting for meteorites that are on the surface. It's basically a walking stick with a powerful magnet affixed to one end. When you're hiking ten or fifteen miles a day, keeping your eyes peeled for unusual-looking rocks, it's a time saver and an energy saver if you don't have to bend down and pick up every one of them. We touch possible meteorites with the cane, and if a rock sticks to the magnet then it warrants a closer look. We have also designed and built more elaborate magnet rakes — a device that holds multiple magnets and can be carried close to the ground, or dragged, in areas where we suspect meteorites might be exposed. The more ambitious hunter might consider designing and building a custom metal detector (see below).
What are the identifying traits of a meteorite to look for when you are out on the hunt?
There are three broad classes of meteorites — stones, irons, and stony-irons. All have somewhat different characteristics, but nearly all meteorites will be strongly attracted to a powerful magnet. Meteorites typically feel heavier than earth rocks of the same size and a meteorite that has fallen recently will usually exhibit a black rind known as fusion crust, caused by burning in the atmosphere. Some meteorites display regmaglypts, which are small, round or oval indentations created while the meteorite's surface was partially molten. The most abundant type of meteorites are stones known as chondrites, and they take their name from the tiny chondrules — colorful, spherical, pre-solar grains — they contain. For a more detailed look at features unique to meteorites, please see the episode of Geoff's Meteorwritings column on Geology.com entitled "Meteorite Identification." [ SUGGESTED LINK http://geology.com/meteorites/meteorite-identification.shtml ]
What are the most common mistakes people make when hunting for meteorites?
We have, many, many times, been contacted by people who are certain they've found a meteorite. In most cases the hopeful have, in fact, picked up a piece of iron oxide, such a hematite or magnetite. Hematite, sometimes called kidney stone, can develop into unusual shapes and its surface often looks as if it's been, at one time, in a molten state (it hasn't). Magnetite is usually black, heavy and will adhere to a magnet, so this abundant earth rock is the most common "meteor-wrong." Early prospectors, in search of valuable metals like gold and silver, have left their mark across the planet, sometimes in the most remote and surprising places. Portable smelters were set up all over the United States, especially in the West, and the runoff, or residue, from those smelters is known as slag. Usually heavy, dark, with a burned appearance, slag is mistaken for meteorites all the time.
What are the top two or three things you wish you had known when you started hunting for meteorites?
We should have known how difficult it was actually going to be, so we could have been better prepared for the many disappointments and unsuccessful hunts that are part of a meteorite hunter's life.
It also would have helped if we had been more familiar the mechanics of strewnfields — zones in which numerous meteorites from the same parent body have fallen at the same time. Understanding how strewnfields form, and how meteorites are distributed within them can aid an experienced hunter with meteorite recovery.
How did you come up with the design for the large tow-behind-the-truck metal detector, and how difficult was it to construct?
The giant meteorite detector, which we affectionately call the "Big Rig" was designed and built by Steve with a very specific purpose in mind.
Metal detectors send either an electromagnetic pulse or a radio signal into the ground in search of metallic objects. That signal decays quickly, so the larger the transmitting coil, the deeper into the ground the detector can "see."
Steve was born in Kansas and was very interested in the Brenham pallasite meteorite site in Kiowa County, Kansas. Meteorites were first found there in the 1880s and for over 50 years the record for the largest Brenham mass was held by H.O. Stockwell, a meteorite hunter from Kansas who found a 1,000-pound complete specimen at the site in the 1940s. Steve believed that larger, deeply-buried masses were hidden in the strewnfield, out of range of conventional metal detectors, so he built the Big Rig as an experiment. He was tremendously successful and found a record-breaking 1,430-lb meteorite buried 7 1/2 feet underground in 2005. Steve and Geoff went on to work at the site together for several years, and recovered several other large masses, including a 230-lb and a 273-lb mass while filming the Meteorite Men pilot.
The electromagnetic coil for the Big Rig was built specially for us by an electrical engineer in Europe, and Steve constructed the sled himself. The sled has gone through many different iterations, and Steve has continued to experiment and refine the design. One of the problems inherent in the Big Rig's construction is that absolutely no metal can be used! Ball bearings, metal wheels, washers, wire, bolts, or screws would all interfere with the coil's operation, so the entire assembly had to be built using non-conductive materials, and that was quite a challenge. The Big Rig is also frequently towed over rough ground, and we've experienced many breakages. Rapid in-field repairs are just part of everyday life for the Meteorite Men.
When you've found a meteorite, what should/can you do with it? (are there any legal issues you need to consider - i.e. if you've found them on someone else's land, etc.)
It is very important that would-be meteorite hunters familiarize themselves with the legal issues associated with searching for space rocks. In the United States, meteorites generally belong to the person who owns the land upon which they fell. Meteorites found on Federal land belong to the Smithsonian Institution and should be turned over to them for study. Other ownership issues vary by state, and Bureau of Land Management offices have different policies in different parts of the country. So, if you're thinking of hunting on BLM, State, or Federal land, be sure you check with local offices first and get permission from owners of private land. Most National Parks and Monuments do not allow the removal of any material, including rocks, fossils, sand, plants, etc., and the use of metal detectors is illegal in many Federally-owned areas. There are severe penalties for people who do not follow regulations, so do your homework first.
In addition, it is extremely important that new meteorite finds be made available to academia for study. When we recover meteorites that are new to science, we donate representative samples for study. There are a number of prominent research labs in the country that can identify and classify new meteorites, and these include the Center for Meteorite Studies at the University of Arizona, Tempe; the UCLA Department of Earth and Space Sciences in Los Angeles; and the Institute of Meteoritics at the University of New Mexico in Albuquerque.
What is the best tidbit of advice you can give to someone who wants to hunt for meteorites on their own?
Be prepared to put in a lot of time, and a lot of hard work, and also do your research. Meteorite hunting isn't easy and there is a lot of strategy and science involved. Understanding what meteorites are, where they come from, and how they fall, will help improve your odds of finding that rarest of wonders — a rock that has travelled to our planet from outer space.
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