New paper

Andy Smedley | 23 March 2020

A little over two weeks ago the latest paper from the project was published. Given what’s happening in the world right now (it’s late March 2020), that seems a long time ago, but perhaps this short blogpost will provide some useful distraction whilst we all practise social distancing.

Occasionally meteorites will be found partly encased in the translucent ice, the ice underneath having melted and then refrozen [Credit: Katie Joy]

So our new study looks at how sunlight interacts with the blue ice where the vast majority of Antarctica’s meteorites are found. In the original paper that kicked off the project we used a simple mathematical model of how sunlight penetrates into the ice and how much is absorbed by the meteorite. How much sunlight is absorbed by a meteorite trapped in the ice determines how much it will heat up, and if it reaches the melting point of ice, how much the meteorite will then sink dow. In the original paper we used a fairly simple model of how sunlight is attenuated by blue ice and treated the system as one dimensional. In reality though it’s a 3D system and things are more complicated. One of the major ways in that it’s more complicated is that sunlight is made up of many different wavelengths (think the colours you see when it passes through a prism, or when a rainbow is visible, but extending beyond the range your eyes can see). Each of these wavelengths is affected by the ice properties slightly differently which means that the total attenuation is more subtle that we first assumed. When sunlight at infrared wavelengths hits the surface of the ice and passes into it, it’s rapidly absorbed by the ice. In contrast the part of sunlight corresponding to blue wavelengths is absorbed much less readily, and so is repeatedly scattered by the tiny bubbles within the ice. (These bubbles are actually tiny pockets of air trapped when snowflakes fell many thousands of years ago and their chemistry can help us understand how climate has changed on geological timescales.) As it so difficult for light at these blue wavelengths to be absorbed by the ice they continue to be scattered around inside the ice enhancing the amount of energy available to be absorbed by any dark meteorites present. As a result a meteorite sitting within the ice can act as a sink for nearby solar radiation, but, as well as absorbing more, because we now treat them 3-dimensionally, more energy is dissipated. To figure out how these different contributions balance out, we took the results of our sunlight modelling and added in the other things that might cause heating or cooling of the meteorite: the temperature of the air above the ice, the wind blowing over the surface, the motion of the ice, whether the meteorite gets warm enough to melt the ice and how far it then sinks and how these factors might vary over several years, plus the 3D nature of the problem.

It’s hard enough to find meteorites in Antarctica without them sinking into the ice. [Credit: Katie Joy]

All in, rather than iron meteorites being predicted to lie ~30 cm below the surface of the ice whilst their stony counterparts rise to the surface, this study suggests that the difference is much less, with iron meteorites being only 5-10 cm deeper than the stony ones. This isn’t a huge distance of course, and the blue ice is slightly translucent, but when you’re scanning from your skidoo for a speck of dark rock surrounded by the immensity of Antarctica, it’s enough to make spotting them virtually impossible. Interestingly though this new modelling shows the meteorite sinking mechanism is more nuanced than we first thought, with iron meteorites reaching the surface over the winter (when it is dark) before sinking into the ice early in the summer period after the sun rises. Though some questions remain, this seems more in line with what has been found in Antarctica as it gives the potential to find some iron meteorites if the conditions are right, and if the field expedition is during the early part of the summer.

If you fancy reading some of the technicalities of the paper, it can be found here.

Meanwhile in Manchester…

13 Jan 2020

Readers will have seen and read about a lot of goings on “down south” in Rothera and at the Outer Recovery ice fields, and the results of the team’s searches at the field site near the Shackleton Mountains. This is only part of the story (though a key one)!

Back in Manchester the rest of the Lost Meteorites of Antarctica team have been busy, so we thought it only right that we give a brief overview of the work going on behind the scenes. Recently mentioned, Liam and John provided support to Wouter with the technical glitches and have of course been instrumental throughout the project from its initial design, build, lab testing and field testing.

Patches of blue ice at the base of cliffs in the Theron Mountains. Selecting the right spot is key to finding meteorites. [Credit: Romain Tartese]

In parallel with the detector system build, Andy has been working with lots of data analysis (using satellite datasets and climate model outputs) to figure out whereabouts the team was best searching for meteorites. Antarctica is a big place and meteorites are only found in a few spots. Sometimes people head out there to come back empty handed, so we wanted to do our best for last season to make sure we found a “blue ice area” that harboured meteorites. First of all, a selection of candidate sites were tracked down by Katie (before the current project was funded) and then reduced to a long-list of those accessible on a logistics basis with the help of BAS. Then, using a combination of estimates of snowfall (that tells us something about the rate at which meteorites accumulate in a given area), and the local surface ice flow and wind scouring (that tells about the rate of loss of meteorites), we came up with a prediction of what density of meteorites we expected across these candidate sites. That prediction enabled us to refine and rank our preferred areas for Katie to visit last year. Thankfully she and Julie Baum confirmed our estimates and found some meteorites! Once we had decided on particular areas, Andy was involved in making custom maps for the team’s GPSs from hi-res satellite imagery, more detailed estimates of which individual ice fields to return to (from the data and samples Katie collected last year), and the logistics involved in shipping and planning. At the moment he’s the main contact back in Manchester and has been responsible for posting updates sent through by satellite phone while Geoff, Katie, Wouter and Romain have been at the remote field site.

There’s lots of posts about trying to find meteorites on the blog, but once we find them — what happens to them? That job is being undertaken by Jane and Tom working with members of the isotope group.

Well, we’ve made sure the potential meteorites have all been collected following defined procedures to keep them as free from any contamination as possible, for example, they only come into contact with stainless steel equipment used to get them into polythene bags, and every sample is double-bagged. They are even kept at sub-zero temperatures throughout their journey back to the UK, giving us the best chance of keeping them in pristine condition for future science. Jane, working with Katie, Rhian Jones and with folks at the meteorite group at the NHM, has been working out the necessary steps for the preliminary examination plan for classifying the meteorites, to ensure the samples do not get contaminated, and that every stage of examination is thoroughly documented. In line with this, the first ten samples from last season have now been thawed and she is using “CT-scanning” to look inside the rock and get an initial idea of what it is made of, before deciding how to break or cut the sample. Small pieces will then be mounted on glass slides in order to examine them with microscopes so that they can be formally classified into their different classes.

The “light box” set up used to acquire the images for 3D photogrammetry scans. [Credit: Tom Harvey]

Now the first samples from last year’s reconnaissance trip have been defrosted, Tom has been working to scan the fresh sample exteriors with a technique called photogrammetry. Photogrammetry uses information in pictures of a sample (in this case a meteorite) which show overlapping surface features to position that bit of the sample in 3D space — meaning that we can generate an electronic 3D model of the sample! These models are really useful because they preserve a record of the sample exterior prior to analysis (or, if needs be, cutting), and mean that we can zoom in on parts of the surface that are particularly interesting, which is great for curation and initial characterisation purposes and gives a permanent record of what the meteorite looked like when it was found.

And as this post goes online, it sounds like this year’s samples might just be starting to make the long journey back to the UK… holding the promise of lots more interesting science.

The end of the sledge (but not the end of the story)…

Geoff Evatt | 08 Jan 2020

Hello from Outer Recovery, where with mixed emotions we bid farewell to our subsurface meteorite detector systems…. yep, today I had the honour of towing the single panel sledge system to the 0.75km2 area searched mark. Shortly after it errored out, a little way from where the 3 panel system finished two days earlier. We’re actually rather proud of the system, after all it did work amazingly well whilst it was working. It was the repairs between operational bouts which was the pain and has taken up our time, effort and energies.  However the undulating ice surface (see pics) took its toll: the accelerometers in the system constantly registering over 10g’s of acceleration!  In all previous testing locations (including last year’s testing on Antarctic blue ice at Sky-Blu) the system experienced always less than 6g’s, and even those were relatively rare occurrences. This constant battering from the ice meant that anything which could fail did, and once repaired as best we could, a weakness in components remained for further exploitation. Yet, the modular system of the detector had the advantage that we could continue in a fashion, and did so for 18 odd days.

Wouter in the expanse of Antarctica. [Credit: Geoff Evatt]

Fittingly, as I drove the sledge back to camp, I noticed a black dot on the ice. Yep, number 65 for the area this year. A lovely single stone, which even the sledge had a good view of. And best of all, this takes us to 101 samples for the Lost Meteorites project! It thus looks like we have almost certainly collected over 100 meteorites for return to the UK, all ready to be examined for their scientific worth and hopefully put on public display.

A small meteorite next to the now ex-sledge detector system. [Credit: Geoff Evatt]

So, did we find the layer of lost meteorites? No, the layer of lost meteorites hasn’t been found by the metal detection system, but we do seem to have found a curious fraction of iron-rich meteorites nonetheless. The immediate consequence being that further laboratory and statistical analysis is required to figure out what this implies. I say this because it raises some interesting questions both about the particular environment of the ice field the team has been searching and how this might effect the processes by which meteorites become exposed upon the ice surface. So not the in-situ grand finale we were hoping for, but equally it is not the end of this particular story…

Geoff and meteorite number 101. [Credit: Katie Joy]

In the meantime there will still be plenty of updates from the field, as we’re planning on collecting some ice samples tomorrow (much easier than collecting meteorite samples) for analysis back in the UK. After that we pack up and move camp back to the runway area, and should fuel allow, we’ll head to another neighbouring blue ice area to see what meteorites reside there. And then we await the planes (around 16th, in theory), and the statistics……

The return of blue ice

Geoff Evatt | 03 Jan 2020

Good afternoon from Outer Recovery, where I’m lying in the tent I share  with Wouter and Taff, having enjoyed a lunch of biscuits brown, soup and sardines.  Yep, austerity is in full swing! Even the cloud is down outside,  but it’s not too cold today (probably –10ºC or so).

Geoff waits out a low contrast day at camp.

We have been continuing with our search, and have covered almost 0.7 km2 with our system hanging on by its shoelaces (in fact, gaffer tape and cable ties). For clarity, that is the area our metal detector has sensed, whereas the area we have travelled over visually searching for surface meteorites is several times that. Our second system had to be decommissioned yesterday, as the huge batteries (car battery-sized) have now given up the ghost, such is the thumping the blue ice surface has been giving to everything, day in, day out. I’m hoping we will reach 1 km2 before it is no more…

Taff drives a skidoo, towing the metal detection array. [Credit: Geoff Evatt]

Simultaneous to this,  we had a bit of wind return the other evening, just long enough to remove some of the snow that recently fell (plus maybe a small bit of sublimation caused by the sun). This meant that some blue ice became visible again, and allowed for 6 meteorites to be collected yesterday and one more this morning. I think the total from this ice field is about 54, which is pretty good and spot-on for the number we had predicted given the area searched — at least the statistics are more or less behaving themselves! Weather tomorrow is forecast to be overcast again, with good weather after that. If that holds I think we’ll head to a small ice field adjacent and north of camp. There we will look for any surface meteorites,  climb the nunatak (the mountain top just poking through the ice) which we officially named Halliday, and generally get a change of scene.  And given it’s the only bit of non-meteorite rock I will have seen in over a month, it will hopefully be a welcome jaunt.

The benefits of snow…

Geoff Evatt | 02 Jan 2020

The cloud has lifted and progress has been made. Yep, in a true A-team style our patched-up systems seem to be working (as in, two systems with a combined searching width of 4 meters). And we searched for almost 8 hours. No subsurface meteorites,  yet (statistically,  we are only expecting a handful of iron meteorites over the entire 12km2 ice field). But what is certain is that if we’re not searching then we can’t be finding them.

As for conditions, well, it’s now all snow covered,  meaning no blue ice is visible anywhere. Whilst this makes the subsurface searching easy to progress (because you can see where you’ve been and removes vibrations in the system), it makes seeing any surface meteorite impossible. Personally I’m hoping the snow cover lasts for the rest of the trip!

The next couple of days are forecast to be similar nice weather with low winds. So let’s see if our relative fortune holds for tomorrow.

New year, new start?

Geoff Evatt | 31 Dec 2019

Hello from Outer Recovery as we approach the end of the decade. Low cloud and poor contrast abounds today, so we’re confined to the camp, giving us the chance to tinker with the system and get some rest (the ambiance outside is currently Nordic,  and not unwelcome). The last few days has seen clear positive progress.  As in, we seem to have salvaged a working core of the detector system. And we have been out doing systematic searches with it, covering a reasonable area, all things considered. Issues seem to pop up every 3 hours or so, but in those hours the system is working amazingly well. In fact, after some re-engineering of a sledge yesterday, we finally have two operating systems (one as 5 panels although only three of these are working, and the other is now a single panel system), meaning we can search a width of 4 metres as we travel along. Let’s hope those 3 hours of search time start creeping upwards…. this whole project is a numbers game: the larger area of the ice field we can search, the more likely we are of finding a lost iron meteorite.

Katie and Wouter soldering. [Credit: Geoff Evatt]
Wouter using parts of one metal detector to fix other. [Credit: Geoff Evatt]

Other than that, our surface meteorite count for this season is now 42, which is great, especially given the relatively small area we are searching (this blue ice field is just under 12 km2, but maybe a fifth is hidden by sastrugi, making it impossible to search). After strong winds the other day, some of the snow cover altered, and Katie and I found a nice chondritic meteorite where a sastrugi existed the day before.

Sledge Evatt getting some TLC. [Credit: Geoff Evatt]

Food-wise we seem to be doing OK.  It appears the vast number of calories we had at Rothera cause our metabolisms to increase, meaning that when we first hit the field with far less food, we rapidly got thin. But now our bodies seem to have taken the hint, and the weight loss seems to have slowed. Or maybe we’re just eating more biscuits brown and porridge. Does this mean we’ll balloon as soon as we hit civilisation again? Either way I’m desperate for a run or cycle, but conscious that the general wear and tear on the body may mean it’ll take a while to be back to normal. Yet I can now drag metal detector panels for Britain. Maybe we now have the world record for doing so down here?!

Romain driving one of the detector arrays. [Credit: Geoff Evatt]

The weather outside is frightful…

Geoff Evatt | 26 Dec 2019

Hello from Outer Recovery,  where we are spending Boxing Day cooped up in our tents as the weather outside is not so great today…. meaning I have the chance to give a status update.

Working on the detector system. [Credit: Katie Joy]

All of a mixed bag really. The positive news is that we have begun searching for the lost meteorites! And when searching, the system is performing rather well (we can see our trial targets down to almost 20cm in real time, with minimal false positives). The bad news is the combination of vibrations, cold, and extended periods of operation are battering the system, meaning we are spending most of the time patching it up.

Views from a Christmas Day walk. [Credit: Geoff Evatt]

To give an example, yesterday we found the main power cable from the solar panels to the batteries had snapped clean through, in two places.  This cable was Antarctic rated and successfully used in other projects. But the high pitch vibrations being put through the system by the scalloped ice surface, means that even the tiniest of weaknesses are soon exploited. And this particular one has consequences: as it snapped it caused the solar panel regulator to be permanently damaged, meaning we can no longer use the solar panels to charge the batteries, so we have to rely on a generator, which in turn means it takes much longer to charge the system…. and that’s after several hours of trying to identify and fix the problem…. This example shows what we ‘re up against. And with the whole search being a numbers game (for this particular ice field, we have predicted 3-4 subsurface iron meteorites) then, we have to search a large area to stand even a slight chance of finding one. But we are progressing, albeit haltingly.

Meteorites in hand! [Credit: Geoff Evatt]

In other news the surface search is moving forwards well, with over 30 meteorites collected so far. From their appearance we seem to have collected a good diversity of samples, which is welcome news. We had predicted around a hundred meteorites on the surface for this icefield (give or take), and as that includes the 15 found by Katie here last year, then we are moving steadily towards that estimate. And that’s not taking into account that the blue ice area has over a 20% snow covering, meaning over a fifth of the predicted meteorites are out of view.

We also managed to ascend the ridge overlooking our camp yesterday, to find a stunning view down over the blue ice plains below, with (surprise!) yet more Antarctic plateau behind. It was a great way to round off Christmas Day, before heading back to a lovely smorgasbord of food and cake.

In the meantime we’re sitting out the bad weather, and about to commence with yet more repairs on the system….

Hello from Outer Recovery!

Geoff Evatt | 19 Dec 2019

It has been a while since we gave an update on matters here, mainly because we have gone from prolonged inaction to lots of action. To recap, we (Wouter, Rob and I) were originally dropped in at the southern end of the Outer Recovery Ice Fields, but without skidoos.  This meant that any exploring was confined to a very short distance from the tent. And without a generator to charge our batteries, it meant occupying our time was slightly challenging. Once we had tested all we could with the science gear we had, we were left with no choice but to build an igloo (it is glorious). Adding to the amusement of matters is finding about one in ten of the dried food sachets gives instant food poisoning; when trapped in a three person tent this does add spice to life.

Then after a week, a couple of skidoos were brought out to us by pilots Dutch and Mark.  We were then free…. free to move to our intended camp location on a blue ice area in the middle latitudes of Outer Recovery.  Conscious of lots of crevasses, we slowly made our way there. It took two days to shift all of the science gear and camping stuff, but in so doing it allowed us to commence with the first stage of the project: testing the gear (yes, again). Without going into too many details yet, the electronic side of the system is not loving the conditions at present. The mechanical side is fairly relaxed and proving reliable enough. This means the next few days will be critical for us.

Field guide Rob tows the metal detector array across blue ice [Credit: Geoff Evatt]

Yet during the first trials of our equipment on the blue ice field, Rob suddenly gave a yell: a large black lump some 100m away. Yes, he had spotted our first meteorite! A real whopper as well. And as the day went on we found more and more (all within a couple of hours search time). As it stands we appear to have found, we think, some 8 meteorites — and five of them are relatively sizeable. We were all extremely excited to have found them and to be off the mark: we will not be going home empty handed!

One of the first meteorite finds [Credit: Geoff Evatt]
Off the mark. [Credit: Wouter van Verre]
Another! Rob Taylor with another ‘find’ from foot searching [Credit: Geoff Evatt]

As for everyone else? Well, it looks like we’re suddenly going to be all together tomorrow. The logistics behind this project have been huge (thank you all at BAS), and hopefully we’re near the end of the to’ing and fro’ing. All hands will then be focused on getting the camp fully set up, and then seeing what we can do with the detector system (our science tent will primarily be an electrical engineer workshop).

As for weather? Slightly mixed, but on the whole rather sunny. This certainly helped keep us sane during the close quarters camping. The temperatures are probably down towards –20ºC, although without any of us having a thermometer it’s a bit of a guess: when the nostril hairs freeze up (slightly) as you inhale, then you know it’s below –15.

We’ll be in touch again shortly with updates on sledge matters, and hopefully some more meteorite news.

In the meantime we will say goodbye to our field guide Rob Taylor, who Wouter and I have been fortunate to have look after us — especially his “Spamghetti” surprise dinner (can you guess the surprise?). Thank you Rob, you have been fantastic. He now heads back to Halley for a shower and some non freeze-dried food (he was only expecting to be out here a couple of nights) and gets swapped for field guide Taff.

Answering some questions from Hope Valley College

Geoff Evatt | 19 Dec 2019

Many thanks to the students at Hope Valley College for their questions about Antarctica and what it’s like living out there for our field work. Thanks for your interest!

Q1. What is it like to survive in such cold conditions?

A1. It does indeed feel like survival! After all there’s no chance of growing your own food here, and we have to melt ice to make drinking water. As such, when here in Antarctica we are, by necessity, reliant on technology from the warmer parts of the world: travel is generally by planes and skidoos, we wear several layers of clothing and very thick boots, food is freeze-dried food, and ice is melted by burning kerosene. Even going to the bathroom (in a very cold toilet tent) is a different process, as there are no bacteria to break the waste down. And so when camping out here on the ice sheet, some 800km from the nearest base, we are constantly taking advantage of the latest advancements from back home — including the Iridium satellite device that allows me to send this message. But the advantage of all this is that it allows us to do science in a very special place (when the weather is tolerable) — in this particular case, to look for meteorites.  Without these technologies and advancements we would not be able to survive here for long, it’s just too cold and lifeless for us to live without outside help.

Q2. Do you think that climate change is a problem in the Antarctic and if so, do you think it is a problem we need to address as a country?

A2. Yes, climate change is causing the ice sheet to loose mass at an increasing rate and become even less stable (meaning large amounts of ice break off from the continent and into the oceans). The upshot being increasing sea levels  which impacts upon people, towns, and cities elsewhere on earth, particularly in low lying countries. In addition, with larger amounts of fresh water leaving Antarctica and entering the salty oceans, it can make the oceans currents behave differently which can then cause even more heating of the Earth’s atmosphere, and thus even more melting of the ice sheet, and so the problem gets worse and worse. The cause of this is not Antarctica itself, but the level of carbon dioxide that we are all pumping into the atmosphere. Yet given the scale of the problem, it will be change at the national and international government level that is the strongest weapon we have to reduce the impact.  That all said, we don’t need to wait for politicians to get their act together: we can all do our bit, we can all plant trees, which are the ultimate weapon against climate change and help restore the natural world — how about planting some in your garden?

Q3. How do you cope with 24 hour a day sunlight?

A3. It’s hard! Our body clocks are messed up by it. The sun is always high in the sky, making it very hard to sleep. And sleeping in a tent means we can’t escape it by pulling the curtains. The best we have are eye masks, which aren’t too comfortable.