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Meteorite Hunting & Collecting Magazine - September 2010



Meteorite Hunting & Collecting Magazine - September 2010

CONTENTS Worldwide Meteorite News & Information 4 Whetstone 6 by Jack Schrader - The discovery of The Whetstone Mountains Meteorite

A Note on Whetstone 10 by Eric Wichman

A Whole New World 11

Advancing Meteorite Science With High technology

What Is A Meteorite Strewnfield? 12 by Eric Wichman

Doppler Radar & Meteorite Recovery 17 By Marc Fries - 4 Recent Meteorite Falls on Doppler Radar

Backyard Meteorite 22 By Todd Smith - The Discovery of the New Deal Meteorite

Mifflin Meteorite Strewnfield Map 15 Contact

Visit us on the web at: Email: Meteorite Hunting & Collecting Magazine - September 2010


Photo Credit: NASA/JPL-Caltech

Meteorite Hunting on Mars On Sept. 16, 2010, NASA’s Mars Exploration Rover Opportunity may have found an iron meteorite on its way to Endeavour crater! This view was taken with the navigation camera on Sol 2368 (Sept. 21, 2010). This is one of 5 iron meteorites found by the Rover. They used the microscopic imager and the alpha particle X-ray spectrometer -- to inspect the rock’s texture and composition. Information from the spectrometer confirmed that the rock is a nickel-iron meteorite. The rock has been informally named “Oileán Ruaidh” and is about 20 inches long. High technology at it’s finest, used to learn more about meteorites, which are the foundation of planetary science, and the building blocks of knowledge and perhaps even life itself. 4

Photo Credit: Luigi Folco, Museo Nazionale dell’Antartide, Italy

Crater Found with Google Earth Could use of technology such as Google Earth lead us to finding ways to save our planet? Vincenzo de Michele located the Kamil Crater in 2008 in the remote Egyptian desert using Google Earth satellite imagery. It is estimated to be less than 5,000 years old, 148 ft wide and 52 ft. deep. Meteorite fragments totaling 1,764 lb were recovered by an Italian-Egyptian team and classified as an Iron, ungrouped named “Gebel Kamil”. The team thinks that the crater was formed by the impact of a 4.2-foot-wide solid iron meteor weighing 11,023 to 22,046 pounds. The existence of the newfound crater implies that up to 35 percent of these iron meteors may actually survive whole and therefore have greater destructive power. A large iron meteorite slamming into a city can cause great damage.

Meteorite Hunting & Collecting Magazine - September 2010

Photo Credit: Google Earth

Hickman Crater Located by Geologist Who would have thought 100 years ago you could sit at home and find a meteorite crater hundreds or thousands of miles away? Geologist Arthur Hickman, from the Geological Survey of Western Australia found a 270m (across) well preserved crater while roaming Google Earth. He was looking for Iron ore and came across this odd looking formation that was perfectly circular and had a raised rim. Dr Hickman is one of many worldwide that use the technology of Google Earth. It’s amazing how far we have come. Hunting for meteorite impact craters with high technology, literally.

Image Credit: NASA/JPL-Caltech

Photo Credit: Todd Smith

Image Credit: McREL

Oldest Rock From Space!

Backyard Meteorite!

A New DAWN In 2011

Todd Smith, of New Deal TX, spotted a very strange looking rock while mowing his front yard one day. But, it wasn’t until after watching the new What can meteorites teach us? TV show “Meteorite Men” on the Arizona State University researchScience Channel that he went back to ers Audrey Bouvier and Meenakshi look at it again. He then spent some Wadhwa analyzed Northwest Africa time investigating information on (NWA) 2364 meteorite and found identifying meteorites online, trying that the age of the Solar System presome home tests, and believed that dates previous estimates by up to 1.9 he did in fact have a rock from outer million years! The tests reveal that space! The main mass is now clasmineral lumps inside called calcisified as an H6 chondrite and is now um-aluminum inclusions are from a officially named “New Deal Meteortime before the asteroid belt existed ite” weighing 266 Grams. making it the oldest on record. BouMeteorites are found in every state vier and Wadhwa measured ratios of in the USA, in every country and on lead isotopes in a single “pristine” every continent on the planet. Meteinclusion to uncover its birth date. orites have been falling for billions of It’s important that we keep finding years. The distribution of meteorites and studying meteorites to open new across Earth’s surface is probably possibilities of knowledge about the near equal. Chances are good there’s world we are all part of. a meteorite near you. Perhaps even in your own backyard!

Oldest Material in Solar System Found

In 2011 the DAWN spacecraft will visit the asteroid belt. More specifically DAWN will orbit both Vesta and Ceres, the two largest and oldest bodies known in the asteroid belt between Mars and Jupiter. Asteroids within this zone are the leftovers from the early formation of the solar system and can tell us much about how the solar system formed. HED type (Howardite, Eucrite, Diogenite) meteorites are thought to come from Vesta. According to NASA the DAWN mission is a “journey to the beginning of the solar system”. DAWN is equipped with an array of advanced scietific instruments. The mission to Vesta and Ceres promises to further our knowledge about meteorites, planetary science, and the very dawn of our solar system.

Meteorite Hunting & Collecting Magazine - September 2010


While attending the University of Arizona, I had developed a very early interest in meteorites during a visit to the Flandrau Planetarium on the U of A campus. There were several highly polished small Canyon Diablo irons in a glass case for sale at the time but as a struggling college student in 1969, there was just quite simply no leisure money available with which to purchase one at the time. Tuition, books, food and rent were all necessary priorities. How times and my priorities have now changed! I really wanted so very badly to have one of those meteorites in my possession though. I was surprised at the time, as is the case with most people new to the field, that a real meteorite could be purchased by anyone and not just available to scientists! So I continued to simply visit the planetarium gift shop and gaze longingly at those meteorites in the case dreaming of the day when I would have the $70 in my pocket with which to buy one. Later on when I had a job and some disposable income, there were of course no longer any meteorites available as the planetarium had stopped the sales of meteorites from Canyon Diablo. The money and the availability of the meteorite were sadly not coinciding and happening for me. Twenty eight years later in 1997, I was on my then state of the art pre Pentium computer looking over the many different esoteric things for sale on the newest sensation “eBay” when I found a Dalgety Downs meteorite for sale by a dealer in Tucson. I called my son Devin into the room exclaiming “Look, they have a meteorite for sale on eBay! Would you like me to bid on it for you?” I was excited to find, after all of these years, another meteorite for sale. I was not going to let this one get away. My son 6

Devin, 13 at the time, had expressed an interest in space and space sciences and I thought he might be interested in owning an actual piece of the cosmos. He immediately said yes and we anxiously bid for the sliver of Dalgety Downs and soon we were the proud winners for the grand total of $40! You may have guessed by now that the dealer was none other than Michael Farmer. Mike, Devin and I still laugh at the fact that I paid four times what the meteorite was worth! Devin still has that bench mark meteorite. As it turned out, that eBay purchase from Mike was the best $40 I have ever spent. Devin and I anxiously drove to Tucson to pick up the stone and meet Mike Farmer and the rest is history. Dalgety Downs led Devin and I through Mike to Gold Basin and some of the best father and son trips you could ever imagine. Devin and I spent many years together traveling to Gold Basin, Holbrook, Franconia and other known meteorite strewnfields to hunt meteorites while our knowledge, our many friendships with the likes of Jim Kreigh, John Blennert, O. Richard Norton, Twink Monrad and many others along with our passion for these rocks from space continued to grow. The drive, while enjoyable, was long taking at least seven hours or more to get to the area of the hunt. As we were happily driving out of Sierra Vista with many hours on the highway ahead of us, we would jokingly talk about the one that “some day” would fall near home so we wouldn’t have to drive so far to start

Meteorite Hunting & Collecting Magazine - September 2010

THE FIRST STONE! - 155.6g Whetstone Jack Schrader on June 25th 2009 at 6:20pm, “ sighted” Notice the white “scuff” markings on ground. Photo: J

hunting! by Jack Schrader - Discov Little did I Mountains Meteori know that that rare occurrence would actually become a reality merely twelve years into the future. My wife Katie and I had just returned home from a late dinner at a local restaurant. The time was 9:10 and the day was Tuesday, June 23, 2009. Katie had opened the upstairs bedroom door to the balcony to get some fresh air propping herself up with some pillows and a laptop to get some work done. I had

Mountains H5 Chondrite meteorite found by “44 hours and 58 minutes after the fireball was n the outer surface caused by impact with the Jack Schrader

gone into my man cave across the hallway and was surfing around on my computer for a while before going to bed. Luckily, I had stayed up later that night than usual when the announcement came through on the Meteorite List around 10:30 pm that a fireball had been spotted south of Tucson traveling from west to east with sonic booms being reported! The report ended with the call “Meteorite hunters, start your engines!” I immediately jumped up and rushed

verer of the Whetstone ite Strewnfield

into the bedroom exclaiming to my wife “There was a fireball in the area tonight around 9:20 with sonic booms!” The next words I heard from my wife were all the motivation I needed, “So that’s what I heard! I thought it was thunder but there were no clouds in the sky!” Not even a very restless night with little to no sleep could dull my energy or enthusiasm the next morning! I knew that stones just had to be on the ground and close by too! I had let my work and my schedule keep me from going to West to hunt the fall there and I regretted not taking to time to drive the day it would have taken me to get to Texas. I was not going to sit still for this one though. I knew that I had to at the very least, give this opportunity my best very best effort and not sit by while someone else discovered the area of the fall. If someone else discovered the area, I could at the least be at peace knowing that I had given it my best. As I walked into my office at 7 am Wednesday morning, the only thought on my mind was “Okay, so how are you going to do this? Where do you start?” That question was answered for me the moment I looked at the door to my office. My office door, which is usually the color of a stained walnut, was now pink with post it notes! While I am treating my patients, I often talk to them about meteorites to keep their minds occupied and I have found that ninety nine out of a hundred people find the topic interesting. My patients, well aware by now of my passion for meteorites, had been

calling in all morning with reports of having seen the fireball! I immediately collected the notes and began returning the phone calls. Soon, I had formed a list of the best possible sighting reports and had scheduled home/location visits to collect data on the sightings. I was amazed by the utter excitement and enthusiasm shown by the many people who had witnessed this truly amazing event and by their willingness to take the time to explain to me exactly what they had seen. They would sit in the patio chair, lawn chair, stand in the parking lot, yard or on the porch in the same spot they were in at 9:20 pm that Tuesday night and explain in great detail their memory of the incredible sight they had witnessed that night. My advantage was in recording their memories of the event within less than 24 hours in most cases. I would then ask the person being interviewed at the time to please move now and let ME sit in the chair or stand in the spot while they pointed out landmarks from over my shoulder. I would then GPS the position and with the use of a yardstick and my eyewitness shoot compass azimuths recording the position of the first sighting of the fireball, the point where it became brightest and the point at which it extinguished as well as height in degrees of elevation from the horizon. From Sierra Vista, the fireball was seen to travel from left to right. My excitement really began to peak when I began to interview people who had witnessed it as traveling from right to left! I knew then that I had it bracketed and my next efforts were spent working to continue to narrow down the possible area of the fall. I was relentless at this point talking to anyone and everyone I could find in the area. No one was immune.

Meteorite Hunting & Collecting Magazine - September 2010


People walking their dogs or just sitting quietly on their porches, watering their lawns, riding bicycles, jogging along on foot or on horseback or even the unwary happily bouncing along a rough dirt road in a beat up pick up truck were all falling prey to my enthusiastic questioning. Returning home after the sun had already set, I would grab a quick dinner and then rush off to the computer and start entering data points and drawing lines on Google

peared over that peak right there!” Time had lost its power over me. I was tireless. My wife sleepily walked into the room where I was still moving points around on a map when she said, “Do you realize that it is 4 in the morning? You need to be at work at 7:30 goofy!” Thursday morning came all too soon and the five hours of treating patients went by very quickly. Luckily, it was summer solstice and even though I finished up work

19.9g Stone Found by Devin Schrader - Photo: Jack Schrader

Earth. This data was then transferred to a paper map for reference in the field. Height of the event in degrees above the horizon was used to roughly guestimate distance. The higher in elevation, the closer I was getting! My most useful and encouraging interviews were the ones where the person with great excitement still remaining in their voices would say “It was coming straight at me!” Or “It went right over my wife’s and my head from behind us and disap8

about noon, I still had a good eight hours of daylight left! Countless home visits and many miles and hours of driving later, I had collected enough GPS and compass bearings translated into lines on a map to have a pretty good idea of where the fall may have come to its final resting place. It was by then 4 pm on Thursday June 25 and I was dead tired. I had already started the drive back home dreaming of a nice hot shower and a good dinner when I was suddenly struck by the thought

Meteorite Hunting & Collecting Magazine - September 2010

that “I have at least 4 good hours of daylight left! Just how serious am I about finding this?” I quickly pulled over to the side of the highway, pulled out my map, turned around and headed to the most likely area based on the data that I had at the time. Arriving at the area most defined by the lines on my map, I started my search bisecting the area outlined on my map with my first pass. After nearly two hours, I was beginning to

197.4g Stone Found by Jack Sc

question my data and had decided to return home, get some much needed sleep, revisit the maps and then return to the area the next morning bright and early to try again. Backtracking with no thoughts of actually finding anything at the time and day dreaming about just being home with my wife, suddenly something “really black” flickered just nearly out of the range of my peripheral vision off to my right. I had very nearly missed seeing it! My first pass had been from east to west and

my return track was now from the west to east with the sun at my back. The sun was also much lower and closer to the horizon at 6:20 pm. I then took a few steps back, turned and walked to my right and stared down in total shock and disbelief. The next few moments are really impossible to describe. Shock, joy, elation, disbelief, more shock. I was numb with excitement and not another person around for miles to share this excitement with! I just sat

chrader - Photo: Jack Schrader

down next to the stone and stared at it for a few moments. I then stood up and walked away to siphon off some adrenaline and when I returned, it was still sitting there! What an incredible sight! Right here, out in the middle of nowhere, a beautiful, black, perfectly crusted meteorite is sitting having fallen less than forty eight hours ago. The feelings, the emotions are truly indescribable. They are something I wish that each and everyone who reads this has the

opportunity to experience in their lifetimes for themselves. “I did it! I have actually done it!” I pulled out my cell phone and the first person I called was my wife Katie. She later described my call as “You were hysterical” which pretty much sums up what it felt like in a nutshell. After I had a chance to settle down and let the initial surge of adrenaline burn off, the reality and responsibility for the situation set in. I had discovered the first fall to be

help of Robert Ward, a team of the best meteorite hunters in the country to properly record and document this fall. What happens next with the recovery of the individual stones can be read about best in the Whetstone Mountains monograph written by Dave Gheesling. I will forever be grateful to Dave for his insight and his notion that this fall was of sufficient historic importance to warrant the efforts to produce a monograph about the event.

327.0g Stone Found by Robert Ward - Photo: Jack Schrader

discovered in Arizona in 97 years, the first being the Holbrook event of July19, 1912. My responsibility as the discoverer was easy to decide. I was sitting next to the tangible evidence of a very rare event and I was solely responsible for what happens to it now. The science was first and foremost, no question about that. The proper documentation and recording of this historic fall was of the utmost importance to me. I knew I could not do this properly by myself so I then assembled with the

What is this worth to science? I don’t know for sure other than the fact that I do know that each and every meteorite recovered is valuable to science in some way. Future methods and techniques may discover facts that we are presently unable to extract from the specimen. The stone is an ordinary chondrite H5 breccia. There is nothing really very remarkable about it other than it is a meteorite, which is remarkable wholly unto itself, and a very

Meteorite Hunting & Collecting Magazine - September 2010


fresh one at that with no weathering whatsoever. It was a very small fall as well with only a little over 3 kilos recovered to date. I do know that the site was properly handled and that the location of each stone recovered was meticulously recorded for all posterity. I know that future generations can look back over the very accurately recorded data and see how this stone was distributed over the surface of the planet. I do know that there are photographs of each and every stone in situ as it was found that are recorded forever. I do know that there is a type sample at the U of A and that researchers will have access to the type sample for their studies in the years to come. What is this worth to science? I think it is worth a lot. I know it is worth a lot to me and my conscience to know that I handled this fall in the way I thought right. I was very happy to see the Mifflin fall scientifically recorded by my fellow meteorite hunters with in-situ photos, GPS coordinates and the subsequent development of a strewnfield map. I hope that the Whetstone Mountains meteorite recovery efforts had some small influence in the laudable recording and recovery efforts by Eric Wichman and the many excellent Mifflin Meteorite hunters. My hope for the future is to see subsequent falls given the respect that they so deserve as truly rare events, with the proper

recording of each stone in situ. Once the stone is plucked and pocketed as with an easter egg hunt, the data is lost to science forever. Accomplished? Yes, I do feel accomplished and happy that I was able to make a significant contribution to my hobby, my passion and the science of meteoritics. I also cannot help but feel very lucky. Dave Gheesling describes luck as “the intersection of opportunity and hard work”. The opportunity was presented to me and the hard work was a conscious choice and a decision that I will never regret.

by Eric Wichman I was extremely shocked to hear about the Whetstone Mountain meteorite being found a mere 48 hours after the meteorite fell from space. “This has to be a record!” You can read about Whetstone in the wonderfully prepared “PRELIMINARY NOTE ON THE SHOWER OF METEORIC STONES FOUND BY JACK SCHRADER, NEAR WHETSTONE MOUNTAINS, COCHISE COUNTY, ARIZONA.”

ABOUT THE AUTHOR: Jack Lee Schrader was born July 29, 1950 in Douglas Arizona. He attended University of Arizona 1968 to 1971. UCLA School of Dentistry 1971-1975 DDS degree. Residency VA Sepulveda Hospital Los Angeles Ca, 1975-1976. Associate in dental practice Burbank Calif. 1976-1978. Presently practicing dentistry in Sierra Vista, Arizona 1978 to present. Married to Catherine (Katie)

135g Stone found by Shauna Russel - Photo: Jack Schrader


A Note on Whetstone:

Meteorite Hunting & Collecting Magazine - September 2010

monograph written by Dave Gheesling. One day, not long after Dave released the monograph, him and I were talking on the phone and he asked if I’d like a copy. I of course said yes and thanked him. After reading through the monograph (the first time) I was impressed with the professionalism and the way the meteorites were recovered, how the strewnfield was mapped, and how the information was gathered and compiled. Material and information was also donated and shared with universities as well. The Whetstone meteorite fall, subsequent recovery and data collection had a profound impact on the way I view meteorite falls, meteorite hunting, and recovery. I hope we can expand on this knowledge and that others use it as a foundation example for future meteorite falls as well. The future of private sector meteorite hunting may depend on it.

by Eric Wichman A Whole New World of Meteorite Hunting. In February of 2009 the world of meteorite hunting changed forever. This is when Doppler Radar became publicly known as a useful tool for use in meteorite hunting and recovery. At 11am local time in the small town of West, TX there was a huge fireball in the sky, and a loud sonic BOOM which shattered windows, shook houses, and scared many locals. Reports of people running for cover, and even one man who almost got hit by a falling meteorite which hit the ground nearby while he was working on a fence in the fields of West. Not only was the fireball of February 15th 2009 captured on video from Austin, TX by News 8, Radar stations in Texas caught this fireball event at the moment of fragmentation, producing a wonderfully colorful return on the radar screens. This was the start of a whole new method of hunting for meteorites. Before this event, no other fireballs had ever been captured on Radar, as far as any knew. But it wasn’t the first. Doppler Radar has been

capturing events like these for years, it was just that no one had really been checking for meteor fireballs, much less use radar for hunting meteorites. The cat was now out of the bag so to speak. Meteorite hunters from all over the United States converged on the small town of West, TX to search for cosmic treasure. Not only are meteorites valuable to science, but they’re worth money too. Sometimes, meteorites can be worth a lot of money, though it’s rather like a car. Common meteorites aren’t worth near as much as rare types such as the Lunar (Moon) and Martian (Mars) planetary type meteorites. The hunt was on not long after, and meteorites were located on the ground directly beneath the radar return when plotted on a satellite map. Though radar is fallible, it’s the next best thing to an X marks the spot treasure map. Since then, no less than 3 meteorite falls have shown up on radar and have been recovered in the USA. More are being researched now, and people are realizing the potential for meteorite recovery, collection, and advancement of the science. The more people which hunt and re-

cover meteorites, the more we’ll learn. With growing popularity it’s very likely that meteorite hunting and recovery will see continued growth as a hobby and science. Google Earth is by far the most popular, easy to use, and useful tool for plotting data, fireball triangulation, location and recovery of meteorite specimens. Best of all it’s a free tool. Google Maps, Google Earth, Doppler Radar, and digital surveillance camera systems are the tools of the trade of modern meteorite hunter. In edition there are high performance and jumbo sized metal detecting equipment, ground penetrating radar, and high tech off road vehicles to get to remote areas where meteorites might be. Handheld GPS location devices, cell phones, laptops and home computers have not replaced, but have added to the essential tools every serious meteorite hunter has at his or her disposal. With this new information and the high technology, the high tech meteorite hunter was born. Out of this rises a new generation of better informed, and more scientifically oriented meteorite recovery.

Meteorite Hunting & Collecting Magazine - September 2010


To understand what a meteorite strewn field is you must first understand what a meteorite is and how it ends up on the Earth. So where do meteorites come from? The Origin of Meteorites Meteorites are fragments of asteroids and meteoroids which have impacted the Earth. This debris,

by Eric Wichman Once a meteoroid or asteroid enters our atmosphere it’s subjected to extreme pressure and heat which produce the phenomenon known as a meteor or fireball. The high rate of speed at which the body is traveling coupled with the enormous strain these pressures exert on the asteroid can cause it to break apart into hundreds of smaller pieces. Some pieces can still be rather

Asteroid P/2010 A2 - Asteroid collision like this could cause asteroids to be perturbed out of orbit and into the path of Earth’s orbit. - Photo Credit:

Leonid Meteor - Most meteoroid are very small grain of sand or pebble sized particles and burn up high in the atmosphere causing beautiful light shows. Photo Credit:

at one time was floating around the solar system orbiting the Sun. Most of this material is located in the asteroid belt between Mars and Jupiter. Some meteorites are from planets or larger celestial bodies like the Moon, or Mars. From time to time asteroids within the asteroid belt bump into one another effectively changing their orbits. Eventually some of this material loses it’s orbit around the Sun and is pulled into Earth’s atmosphere by the massive forces of our planets gravitational field.

large and weigh many kilos or even tons depending on how large the original asteroid is, but most are small in size usually just a few grams in weight. Most meteors are caused by small meteoroids no bigger than a grain of sand and never reach the ground, burning up in the upper reaches of our atmosphere before they can impact Earth’s surface. When a larger piece of debris collides with our planet sometimes it can survive the trip all the way to the ground.

What is A Meteorite Strewnfield?


Meteorite Hunting & Collecting Magazine - September 2010

A large meteoroid or small asteroid made of stone can produce a large fireball visible from the ground from hundreds of miles away. Typically it will flash a bright and brief fireball, break apart high above the Earth, blink out and then fall invisibly to the ground. While in flight an asteroid that breaks apart will incandesce until

Large Fireball - Fireballs are larger than meteors. Sometimes they drop meteorites & the area they fall is called the distribution ellipse or strewnfield. Photo Credit: Wikipedia.

is slows below what scientists call cosmic velocity. This is tremendously fast and can be from 10,000 mph to 50,000 mph or more. The asteroid will reach a point in our atmosphere where the air acts as a braking mechanism and slows the descent. The extreme pressures can break the asteroid apart into many pieces in a few milliseconds and brilliant flashes of light called the terminal burst point. Dark Flight At this point the asteroid fragments, blinks out or extinguishes and is no longer

incandescent. Not fast enough to produce the energy and pressures to incandesce. It slows very rapidly from cosmic velocity (tens of thousands of MPH) to what scientists call terminal velocity (only hundreds of MPH). It’s now in a stage of atmospheric entry known as dark flight. The meteoroid is falling to the Earth invisible to the naked eye. Logically more fireballs are seen during night-time hours because they are easily noticeable. Blackened by it’s passage through the upper atmosphere, the meteoroid is al-

stones flying through the air. Some people have even been so close to hear the stone as it passes through the air above them. Fewer still have seen them impact. Even rarer, some people have been hit by meteorites. While in dark flight a meteoroid travels at speeds around 200-300 MPH. Not nearly fast enough to do much more than bounce off the ground if it only weighs just a couple few grams. However a larger stone of say 100 grams or more could do some serious damage if it hit a house, car, or person. Just recently there was a 308 gram

farther than the smaller lighter pieces which fall first since they lose their inertia faster than the more massive pieces. The resistance or drag produced by the debris passing through the air slows the smaller pieces first since they have less mass. The larger pieces can continue on much further beyond where the smaller impacted the Earth. If a meteoroid falls at a very sharp angle then the strewnfield it produces will be smaller and harder to locate as the material will be spread over a smaller distribution

This graphic shows the terminal burst point and distribution of material vertically. Not all fireballs generate a terminal burst, or an explosive fragmentation at the end of the fireball’s incandescent stage. Many meteoroids simply fragment throughout the fiery flight path dropping meteorites all along the way. Fragmentation events during flight typically correspond to “clusters” of meteorites on the ground within the strewnfield.

most impossible to see in the night sky. A brief red glow immediately after a fireball enters dark flight has been reported by some eyewitnesses on rare occasions as the meteoroid cools. During daylight hours fireballs are of course harder to see and fewer are reported. Once the meteoroid slows to terminal velocity, and it nears impact with the Earth, eye witnesses have reported sighting black or gray

stone that crashed through a roof of an office building in Lorton VA. If the ground is soft it will embed itself deep into the Earth, leaving nothing more than a tiny hole. When a rock the size of a baseball traveling at only a few hundred MPH impacts the ground it doesn’t do much more than bounce or fragment upon impact. Distribution of Meteorites: Larger pieces of debris will travel

ellipse. Picture a handful of rocks thrown straight down at the ground. The distribution of pieces won’t cover much area at all. But if you throw a handful of pebbles straight out in front of you the distribution ellipse becomes much greater in size. A Meteorite Strewnfield: A strewnfield is a section of ground (usually in a long elliptical or semi-circular shape) covering a few

Meteorite Hunting & Collecting Magazine - September 2010



Meteorite Hunting & Collecting Magazine - September 2010

Meteorite Hunting & Collecting Magazine - September 2010


This graphic dipicts a typical meteorite strewnfield’s material distribution density. Inertia will cause pieces of material with higher mass to travel farther along the path before being overcome by air resistance and gravity. This simply means there is a “Big end” and a “Little End” of the textbook type of strewnfield. It is possble that larger pieces can be found near the center depnding on a number of variables. The dispersion of material is not always greater in the center of the distribution ellipse. It greatly depends on many factors including composition, speed, mass, and angle of descent. Wind also has an effect on the location of smaller pieces and can “push” debris off center of the flight path or cecnter “line”, causing the field to appear curved, or “banana” shaped.

square miles where “two or more” width of a meteorite strewnfield meteorites of the same type and depends largely on the angle of declass fall and have been recovered. cent, speed at which the meteoroid Most meteorite strewnfields are is traveling and the compositional smaller 1 to 15 miles in length and mass of the body. In other words, about ½ to 5 miles in width. Some the heavier it is and the faster it’s can be as large as 100+ miles long going the further it will travel at a and 10+ miles wide. There are also shallow angle of decent, thereby single stone meteorite falls which producing a large and long distribudon’t produce a strewnfield. Techtion ellipse where debris may be nically, there might be more stones found on the ground. because a “single stone meteorite The Elusive Meteorite Strewnfall” is such because only one stone field was found, or witnessed to fall. Finding a meteorite strewnfield is There might be others, and the like- perhaps the holy grail of meteorite lihood that there are more is good, hunting. Meteorite hunters dream but the chances of finding another of finding their own meteorite is slim. strewn field because of the personal Typically, the larger a meteoroid satisfaction and sheer excitement or asteroid is that enters our atmoof finding such a rare thing. Metesphere the larger the strewnfield orites are rare. Very rare. Finding that is produced. This however deone meteorite is hard enough, but pends on a number of factors. Not to find two in the same area is even all meteoroids and asteroids break more rare. Finding an entire meup when entering the atmosphere teorite fall area where meteoritic but when they do the length and material has fallen over a wide area 16 Meteorite Hunting & Collecting Magazine - September 2010

is a superb achievement, and gives one a wonderful sense of accomplishment. Above is a graphic depicting a distribution ellipse and the pattern in a which meteorites typically fall. For the example we’ve used artistic license on the physics of it but this is how meteorites are usually dispersed over a wide area when a meteor or large fireball event turns into a meteorite fall. Debris from the meteoroid falls over a wide area sometimes tens of miles long and a mile or more in width. If you do find a real meteorite, mark the spot and be sure to search the entire area where you found it. You might have found only a single meteorite from a single fall, but there’s a small chance you might have discovered what scientists and veteran meteorite hunters call a meteorite strewnfield!

by Marc Fries, Ph.D. Planetary Science Institute San Diego, CA The new technique of using Doppler weather radars to assist in finding meteorite falls has the potential to transform the art of meteorites hunting for a simple reason – when it does work, it gives “X marks the spot” accuracy to the location of fallen meteorites. Several recent meteorite falls have appeared on radar, and the easy availability of radar data is quickly making this technique a standard feature of meteorite hunting. The “Ash Creek” fall outside of West, TX in February of 2009 appeared clearly in weather radar data, and since then it has been joined in radar imagery by the Grimsby, Ontario fall in September 2009, the Lorton, VA fall in January 2010, and the Mifflin, WI fall in April 2010. More falls are sure to come, and as they appear they will help us address some of the basic questions about this technique. For example, how sensitive is this technique? Is there a lower limit to the size of a fall below which it won’t reliably turn up on weather radar? And if so, what is that limit? Can we distinguish between different meteorite types in weather radar data? And what, if any, are the “ironclad” signatures of a meteorite fall in weather radar imagery? As we learn more about radar imagery of meteorite falls, the potential rewards will grow in turn. Knowing the lower mass limit of meteorites produced for an observed fall (if there is such a limit) will allow improved “triaging” of potential fall events to quickly determine whether they’re suitable for a ground search. The possibility also exists that ground searches can be tailored towards individual, larger meteorites in a given fall. The same triaging and tailoring can be performed if

we learn to identify meteorites by their type from radar data, as well. And if there are unique signatures of meteorite falls in weather radar imagery, then perhaps the substantial archives of radar data could be “mined” for unidentified falls. There is a lot of room for further work with radar data, but for now we can examine the falls that have occurred since the West, TX fall and learn from them. West, TX (“Ash Creek”), 09 Feb 2009*: This meteorite fall featured a total of about 9.5kg of L6 breccia meteorites, according to the Meteoritical Society database. It was also the first fall that we were actively searching for in radar data, as my brother Jeff Fries and I had been searching through radar data associated with bright meteor events for several years up to the fall. We had been working our way up the learning curve up to then, and were joined in observing the fall by National Weather Service meteorologist Mr. Jason Dunn who recognized it in radar data and published the images online at the time of the fall. Several people that were involved in the ground search later stated that the radar images were very helpful in rapidly locating fallen meteorites, and Jeff and I were pleased to note that the radar images turned out to overlie the location and extent of the strewn field on the ground. Weather radar images of the West, TX fall record the behavior of the falling meteorites. Basically, larger meteorites fall fastest because their terminal velocity is highest and so they appear first as the radar sweeps out the area of the fall, and smaller, slower-moving stones appear later in the sequence of images. Both the KFWS and KGRK radars outside Fort Worth and Fort Hood, respectively, recorded the fall with high resolution. The first radar returns oc-

Meteorite Hunting & Collecting Magazine - September 2010


Figure 1: A composite view of all the radar returns from the West, TX fall. All altitude information has been removed to produce a map of the extent of the fall, so this image does not take into account any drift of the falling meteorites due to wind. Even so, the size, shape, and location of the strewn field is obvious. Credit: Google Earth

cur at 10.8 km above local ground level at 16:59.23 UTC, in a location where kg-mass meteorites were later recovered. As the two radars continued to sweep the airspace, additional radar returns appeared from the “big end” of the fall and worked their way towards the “little end” where the smallest meteorites were found. The last radar return appeared at 17:06.51 UTC about 28.5 km from the first radar return, and the radar returns feature a maximum width of about 5 km. Figure 1 shows a composite image of all the radar returns recorded by both radars without regard to the altitude of those returns, showing the extent of the fall. The West, TX fall was superb in that it occurred on a cloudless day almost halfway between two radars. The timing of the appearance

Figure 3: Composite image of the Lorton, VA fall. The bright pixel farthest to the west is from the KDOX radar and may be too early to be a part of the fall, but there is room for discussion on that point. Credit: Google Earth


of the radar images also reveals that the breakup of the meteorite was uncomplicated. This is a best-case scenario for recovering meteorites on the ground because the locations of masses of various sizes is reasonably predictable. Compare this to the Mifflin, WI fall, where multiple detonations scattered meteorites of a wide range of sizes down the length of the strewn field. Grimsby, Ontario, 26 Sep 2009: This fall has produced 215 g of H5 chondrites to date, although the total mass may rise as search efforts continue. While this fall occurred in Canada, it was in range of the KBUF weather radar outside of Buffalo, NY. Radar returns from KBUF show a fall area that is roughly 5 x 4 km in size. Grimsby is a smaller event than West, TX in both area and recovered mass, which is actually more useful as a learning tool since smaller fireball events are more common than larger ones. This fall was generated by a fireball moving roughly NW to SE with winds in about the same direction. Lorton, VA, 18 Jan 2010: This fall generated considerable media attention because the only recovered stone punctured the roof of a doctor’s office while the office was occupied. Radar data includes a series of returns from the KLWX radar near Dulles International Airport. Two minor returns from the KDOX and KAKQ radars in Dover, DE and Norfolk, VA, respectively, have been suggested as a part of this fall, but including these two returns in the data set extends the timing of the fall over a period from 2226 to 2255 UTC, which seems to be too long for meteorites greater than 1g in mass. In other words, in order to cover 29 minutes’ worth of radar returns, much of the last material to appear would have to be dust-sized. The KAKQ return is uncertain because it consists of a single pixel and is not inlcuded in the figure shown here, but the KDOX return features a velocity anomaly that may be consistent with atmospheric turbulence from a falling body. If we exclude these two returns, however, then the timing of the fall extends from 2240 to 2255 UTC (15 minutes total), which appears to be more reasonable for potential meteorites covering a size range from kg-sized down to <10 g in mass. Collectively, these radar returns describe a potential strewn field approximately 18 km long and extending towards the ESE in accordance with local winds. To date, however, no additional meteorites have been recovered. A series of snow storms soon after the fall complicated recovery efforts because the snow was removed and much of it was dumped in local rivers. Meteorites from the fall may have been

Meteorite Hunting & Collecting Magazine - September 2010

collected along with the snow and disposed of. The possibility exists that meteorites from this event may still lie on the ground and/or rooftops in the area, but much of the strewn field is occupied by a military facility where access is restricted. Mifflin, WI, 15 Apr 2010: The extraordinary Mifflin fall produced >3.5kg of brecciated L5 meteorites and was observed on radar in high detail. By a stroke of luck, the KARX radar in La Crosse, WI was operating in a high-resolution mode due to a band of storms on the opposite side of the radar from the fall, completing seventeen 360Âş sweeps every 4 minutes and 6 seconds to include sweeps of up to 19.5 degrees above horizontal. KARX actually captured the fireball at an altitude of 28.5 km above local ground level while it was still optically bright and roughly 18 km up-track from where the closest meteorites were found. Remarkably, the radar did not record a velocity for this radar return. It might be that the velocity of the fireball at that point was greater than the upper measurable velocity threshold for the radar. The time of the first observation was exactly 0306:17 UTC as the fireball was moving SE across Grant county, WI. From there, KARX and three other NEXRAD radars observed the fall at approximately 9.35 km altitude and again at less than 2.5 km above local ground level. This last set of radar returns in particular tends to overlie the locations of meteorites collected on the ground with correction for drift due to wind. Multiple detonations toward the end of the fireballâ&#x20AC;&#x2122;s path scattered meteorites over a very large strewn field on the ground, along a path that is apparently well in excess of 20 km long. Weather radar observations of meteorite falls provide two important pieces of information. For one, they allow a new method for observing falls in exquisite detail to include the behavior of falling meteorites as affected by wind. For another, the freely available NEXRAD data rapidly and accurately provides the locations of meteorites from an observed fall. For meteorite hunters, this cuts down on the amount of time spent locating a new fall through more traditional methods such as eyewitness interviews and removes much of the guesswork from the initial stages of ascertaining the size of a strewn field. In turn, the easier it is to collect meteorites, the more new hunters and hobbyists there will be. For scientists, weather radar techniques will provide more freshly fallen meteorites for study. Fresh falls have a special place in the science of meteoritics because scientists can focus their various beams on them and

Figure 4: The Mifflin, WI fall as a composite of data from the KARX, KDMX and KMKX radars. The cluster of pixels in the NW corner is a radar return 28.5 km above local ground level that was collected while the fireball was still optically bright. Most of the rest of the pixels occur at less than 9.35 km. Credit: Google Earth

start prying information out before terrestrial weathering sets in. That, and itâ&#x20AC;&#x2122;s just downright entertaining. I can pretty much guarantee that the various people involved in setting up the NEXRAD system did not pay much attention to using their system to find meteorites. They were looking for hailstorms and such, but their foresight in building a system that works well and produces data that anyone can access has allowed an entirely unanticipated new technique to blossom. Kudos to them! From this point, we all get to benefit from the free flow of information. The next meteorite fall awaits!

Figure 2: Composite image of radar returns from the Grimsby fall. One thing that is apparent from this image is just how close this fall came to dropping all of its meteorites into Lake Ontario! Credit: Google Earth

Meteorite Hunting & Collecting Magazine - September 2010


*All dates are given following conversion to UTC time and so may vary from the local date.


Meteorite Hunting & Collecting Magazine - September 2010

Meteorite Hunting & Collecting Magazine - September 2010


by Todd Smith Discoverer of the New Deal meteorite. Todd found this meteorite in his yard in New Deal, TX.

“What a strange rock…” I thought while passing by on my riding lawnmower. I am not sure I had ever seen a rock that looked like rusty iron with such rounded edges. But it was already hot and going to get hotter on that Saturday in West Texas and my desire to finish the yard work outweighed my curiosity- so I kept on going. As I approached it again, something I had heard from the TV show “Meteorite Men” popped into my head: “It just doesn’t LOOK right”. So I stopped. I immediately noticed that the rock was partially buried with only a portion sticking out of the ground – it was a golf ball sized, rust colored stone like I had never seen before. As I pulled it from its resting place, it immediately came free and before I could start cross-referencing my memory for something that looked similar, something hit me: the WEIGHT! It was all wrong. I have been picking up and throwing rocks my whole life and never once thought about their weight, but I knew this was too heavy. I took it and tapped it 22

on the sidewalk and it sounded like most rocks but the feel was different. “It’s a meteorite”, I thought but the hours my kids and I spent watching “Meteorite Men” tempered this enthusiasm as I started calculating the odds of finding a meteorite in my yard. I knew it was a long shot at best but maybe it was worth looking at more. So I took it into the house and handed it to my 12 year old son, Payton, and told him to look on the internet to see if it was meteorite. I then returned to my yard work. After about 30 minutes, he came outside and told me that he thought it was indeed a meteorite. I am sure I rolled my eyes at this announcement and told him I would be in soon and we would look at it some more. I finished working and went into the house to see that my 15 year old daughter, Lindsey, was now involved in this mystery. Like me, she had her doubts. We began a real research mission at that time and found all sorts of home tests for the “rock”. The first was the magnetic test. We grabbed a refrigerator magnet and placed it on the find.

Meteorite Hunting & Collecting Magazine - September 2010

It wouldn’t stick. “It’s not a meteorite”, I announced but Lindsey remembered she had a stronger magnet in her room. The magnet jumped onto the rock. “Maybe it is a meteorite.” We moved on to any other tests we could find. The “windowing” test (grinding/filing a window to view the interior of the stone matrix) and the porcelain tile “streak” test followed and it seemed to pass but one term kept jumping into my mind; meteorwrong. We scoured the internet all weekend, looking at photos of

every meteorite we could find. Every time we found a meteorite that looked like ours we would find an earth rock that also looked like it. We used a grinder on it and it ground a reddishbrown but then left a disappointing red streak on porcelain. (this is caused by the oxidation) And that’s how the rest of the weekend went- “It’s not”, “Maybe it

is”, “No way”, “Could be”. Everything that said it was a meteorite was promptly followed by something that indicated it wasn’t. A two day rollercoaster ride to be sure. We finally decided it was best to get an expert opinion, so we photographed our find and started sending out emails. We found the meteorite expert community to be very patient and two really helped out - Dr. Melinda Hutson and Dr. Randy Korotev. They convinced me to cut a window into it in order to see what it looked like inside. Metal flakes were clearly visible and they then knew that it was probably a meteorite. They explained that a meteorite could be analyzed and if it was determined to be new discovery, it could be submitted for naming. We live in a very small town and decided that we should have the meteorite analyzed and possibly get our town on the “meteorite map”. Dr. Alan Rubin at UCLA graciously took the time to analyze the specimen and worked with me to submit the paperwork we needed for submission and possible naming by the Nomenclature Committee. Several weeks of waiting followed and on August 25th, the New Deal Meteorite joined the other 296 meteorites (as of this writing) found in Texas. What a strange rock it is… Not because it is rare or because it traveled millions of miles to land in our yard. It’s because of this rock that a new chapter in our lives has opened up. The kids have learned so much and our family has enjoyed the adventure associated with our find. We have purchased a metal detector and are beginning to look for other pieces of “our” meteorite and we have been researching the West Texas area and have trips planned for many hunts. We found something we all can do- together. Something we enjoy and something that will bring us closer. What a strange rock indeed. Meteorite Hunting & Collecting Magazine - September 2010



Meteorite Hunting & Collecting Magazine - September 2010

Meteorite Hunting & Collecting Magazine - September 2010



Meteorite Hunting & Collecting Magazine - September 2010

Meteorite Hunting & Collecting Magazine - September 2010



Meteorite Hunting & Collecting Magazine - September 2010

Meteorite Hunting & Collecting Magazine - September  

Meteorite Hunting & Collecting Magazine. A bi-monthly print magazine which focuses on the adventure and fun of meteorites, the joy of meteor...

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