Space Chronicles on Ice #9
by Don Pettit
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Dec 11, 2006:
Today we searched blue ice glaciers for meteorites. Blue ice is old, glacier-made from compacted snow and found in multi-square kilometer areas in the Antarctic interior. Blue ice is where meteorites are found (and preserved) in concentrations well above their intrinsic fall rate. Blue ice is the reason why we are here.
We search, once again, using our mechanized sledge dog equivalents. Forming a classic search line at the foot of the blue ice region, we slowly drive across with our snow mobiles, looking for any black spot. If you see a black spot, it is a rock. If you find a rock, there is a good chance it is a meteorite. There are many theories for why this is so, mainly designed to satisfy the techno-mind of man. The bottom line is that meteorites are somehow concentrated and preserved in these blue ice regions. We are here to harvest these bits of extra-terrestrial rocks, each in its own way a small piece of the cosmic puzzle which helps answer who we are and where we came from (but not why).
So we sit up on our knees to improve our visibility while advancing over the irregular surface of robin egg blue. The snow mobiles take a real pounding and in turn, pass it on to us. The winds in the Antarctic interior have a special name. They are called katabatic. Driven by masses of cold, dense air, they blow generally northwards towards the coast where it is (relatively speaking) warmer. These winds, blowing at 20 to 30 kilometers per hour, decrease the temperature from a reasonable -20 degrees C to something that will frost bite bare skin in a matter of minutes. Relatively speaking, -20 degrees seems warm. Man and woman alike, as if nature’s version of affirmative action, grow beards of fuzzy ice around our balaclavas, turning everyone into a personified version of old man frost. Even though chilled to the core, the realization of where we are and what we are doing drives us on, warming at least the soul and the spirit.
One hundred meters away, one of our team mates is waving hands over head, the signal for "come to me." It means that a person has found some bit of interesting rock, perhaps a meteorite, and needs a second opinion. We all converge to the spot, and after a detailed look by several of our experts proclaimed, "It’s a rock," and we start our search once again. Some time later, another hand wave signal is seen. Again, another standard rock was found. This is not to be confused with crying wolf; this is all a valid part of searching. We leave no rock unturned.
Another waving hand was seen, but this time there was a certain fever, a certain energy; that said, this was something different. It also happened to be from one of our teammates who was a meteorite expert. We all converge to the spot and there in the ice was a small button of black rock. This rock looked different than just a rock, it had a special character that said it was not of Earth. Glazed with black patina, there were crazed marks as if it had been fired in a kiln at the wrong temperature. It had an odd shape; one sculpted by a fiery entry into Earth's atmosphere and naturally shaped into something similar to what rocket engineers design for the heat shields on spacecraft. Yes, this bit of rock was definitely not of Earth.
With our first meteorite, we forgot about the cold while faces lit up with the smiling excitement of a child. Then it was time to get to work. The process of collection is as rigorous as we can make it considering the location and working conditions. We record its location via GPS and take a photograph as it was found with an assigned sample number and length scale visible in the image. We write a simple description in a log book, also recording the sample number. Only then do we pick it up with sterilized tongs, and place it in a Teflon bag. A metal stamped sample number goes into the bag, folded in a separate compartment. The bag is sealed with freezer tape (normal tape does not work at this temperature) and placed in a backpack. All meteorites are kept frozen so as not to have contact with liquid water (this is easy to do while in the field). They are stored in freezer boxes in camp (just in case it might warm up above freezing) and ultimately get shipped back to NASA Johnson Space Center in freezer storage. They are not allowed to thaw until safely in, what was the original Lunar Receiving Laboratory, under conditions fitting for best preserving meteorites. This treatment may seem excessive; however, these precious bits of rock can tell us stories about who we are and where we came from and we do not want to alter the possible outcome by careless contamination from human contact.
It took four people working with numb fingers a few minutes for the whole process of collection. Then it was back on the snow mobiles and onwards in search of another galactic Easter egg.
This day, our first day of searching, we found four meteorites in an area about two square kilometers, an amazing number considering the rather small area of search and the intrinsic fall rate. We drive back to camp cold, tired and ready for a hot meal and a sleeping bag that will not be warm until after you have been in it a few minutes.
But first we have to feed our mechanized sledge dogs. We pumped gas, tightening bolts shaken loose in the undercarriage, and put them to bed with the same care that an explorer 100 years ago might have done with his sledge dog team. We realize, independent of the technology of the time, that our very existence depends on our ability to travel. As a last touch, we tuck them away with snow covers, protection from the katabatic winds, which can pack everything from the air intakes to the cylinder cooling fins with snow that sets up seemingly as hard as cement.
Only after our mechanic dogs are put to bed do we do the same with ourselves. The howling wind shaking our tents becomes our ever present lullaby.