For this last day on the field, we decided to look further west from the station, an area we haven’t sampled yet. Smalegga Mountain proved to be a suitable location, as well as a significant point of interest, as it was at the foot of this mountain that the 1959 Belgian Antarctic expedition left a sledge. Once at the top of the first crest from the ski-doo track, we noticed a glacially eroded surface covered with fine-grained material, which is an ideal sampling site for micrometeorites. After taking the sample back to the laboratory of the station, we quickly found our first cosmic spherule of the day. However, it also turned out to be our last micrometeorite in this sample. Once back in Brussels, we will have more time and better equipment to determine the quality of this sample.
Now we keep busy preparing our trip back to Belgium, packing and labelling all the samples we have collected on the field. A tedious task, but an important one nonetheless.
After 450 km on the skidoo and 105 kg of sampled sediment, our Antarctic adventure has come to an end. As they say in French: “ce n’est qu’un au revoir!”.
Steven and Matthias
On Tuesday, we visited Wideroefjellet, where we know micrometeorites are abundant based on an earlier expedition in 2012. To reach a ridge near the highest summit of the Sør Rondane Mts., of course we need to make a small effort and climb this monster using crampons, ice picks and snow poles. We reach the ridge in 2.5 hours. The weather is good, yet the wind-chill factor goes down to -30˚C near the sampling site. Exhausted (except for robot Raphael!), we start our sampling. Even in only 5 years, this site has changed with significantly more snow accumulation. The soil and underlying rock are frozen, and we need to use the chisel and hammer to collect fine-grained sediment. Matthias points out that the other side of the valley may also be a good site to sample. Reluctantly, as it’s getting late and temperatures are starting to go down, we move in that direction to discover that this is indeed a perfect location! With backpacks full of sediment, we move down to the skidoo parking spot in 1h15m and return to the station after a skidoo ride of 1h. No need to say that again the collected samples appear full of micrometeorites using the microscope at the station?
What are we going to do with all these samples in the range of 70 kg? Well, pick out all the micrometeorites of course! Because the larger a micrometeorite collection is, the more chances of finding extremely rare material. Just think of unmelted micrometeorites, rare achondritic micrometeorites, airblast particles…? Who knows what secrets this now very large collection holds?
On the fifth day of the expedition, the target was a supraglacial moraine located near Walnumfjellet, which is the most micrometeorite rich site we have found so far. Previous moraine sampling has proved to be reasonably successful, so aiming for this moraine in particular made sense. Much to the surprise of the team members, what we found upon arrival to the site was a line of sparse rocks partially enclosed in ice, with no fine-grained material to be found. Steven and Raphael decided to take this opportunity to sample ice along the blue ice field the moraine was running along, while Matthias decided to explore the moraine further to find a micrometeorite sampling site. After walking along most of the moraine, only one suitable sampling site was found, which consisted of a centimeter-thick layer of icy fine-grained material. Upon returning to Princess Elisabeth Station, we stopped on the ridge of the Svindlandfjellet to sample more fine-grained material. Upon examination of the moraine in the laboratory, it turns out that this unique sample in surprisingly rich in micrometeorites! The sixth day of the expedition was a very demanding one, as it involved sampling ice along a steep glacier close to Wideroefjellet. But it was worth the effort, as these 22 samples will allow a better characterization of the ice dynamics in the area.
The weather was exceptionally good today, so we decided to take a long ski-doo trip to Walnumfjellet, a group of small mountains located 70 km from Princess Elisabeth Station. For this very technical trip, amongst glaciers leading to the high plateau, we were lucky to have Alain Hubert as our guide, next to Raphael. After a long ride, we eventually reached our destination, 2400 m above sea level and with wind-chill effects reaching -28°C. We quickly noticed glacially eroded summits popping out of the ice, which looked like ideal sampling sites. The cold temperature motivated us to quickly get to work, sampling a very promising looking fine-grained detritus. Promising because the surfaces of these flat summits have been stable and potentially exposed to the sky for approximately 2 million years, during which we surmise that they have been accumulating cosmic dust falling from the heaven. After sampling 5 different sites, we made our way back to the station, through steep glaciers and long stretches of icy flatland. Once back, we couldn’t hold our excitement and started looking through one of the sample. Much to our amazement, we found more than ten micrometeorites in less than 15 minutes, making this sample exceptionally rich. We can finally say that braving the cold and lack of oxygen was a small price to pay for such an exceptional find and day.
As the weather is on our side, the quest for the micrometeorites continues. On Thursday, we focus on a ridge on the Vengen Mountains. This ridge is on the southeast open to the plateau, the inner, higher part of the continent – composed purely of ice and snow, and from our previous campaign in 2013 we know these are the ideal locations to look for micrometeorites! The winds here are strong (~9 km/h), with wind-chill effects of -18˚C, and the exposed glacier shows beautiful structures. Once back at the station, with nothing more than a toothpick and an optical microscope, without washing or sieving the extracted sediment, 5 micrometeorites were extracted from one of the three samples in less than half an hour. This is highly promising!
Now that we know where to look, today (Friday the 16th) we decided to visit a moraine in the Gunnestadbreen that is exposed to the SE winds from the plateau (cf. map below). Even on this beautiful, sunshiny day, the 15 km/h winds never stop, leading to wind-chill effects of -18˚C. We don’t bother to take off the skidoo suites and go straight to work. Four different locations at the different ends of this moraine are sampled. Once back at the station, one of the deposits yields 3 very nice micrometeorites in no time. This brings the grand total to 11. Let’s keep on going at it!