Meteorites classified!

We have news…. its a big day for the project as we have our first batch of meteorites that have been formally classified by the Meteoritical Society Nomenclature committee and have now been published in the Meteoritical Bulletin Database!

A list of the newly classified meteorites can be found here https://ukantarcticmeteorites.wordpress.com/meteorite-discoveries/ , and you can click on each meteorite name to learn more and see some pictures of the samples. So far all of those classified from our 1st field season come from parent bodies in the asteroid belt: all are undifferentiated ordinary chondrite types. This means that they come from some from asteroids that represent some of the earliest Solar System building block rocky material that never got big enough to completely melt (hence they are undifferentiated), but they are all are from quite a common type of meteorite group (the ordinary chondrites). So far all the types classified are stony and not metal types – meaning that they are dominantly made up of silicate minerals rather than metal. In case you get lost with all the terms used – an overview of the different types of meteorites can be found at https://ukantarcticmeteorites.wordpress.com/meteorite-classification/

The first classified batch include nine meteorites: two were recovered from from the Hutchison Icefield area (these ones are called HUT), and seven from the Outer Recovery icefield area (these ones are called OUT). The number after the acronym name specifies the particular sample type. If you want to read more about the names of icefields we visited you can read here https://ukantarcticmeteorites.wordpress.com/2021/04/15/new-meteorites-new-names/

This has been the cumulation of a lot of hard work from the field search teams from the 1st 2018-2019 field season (Julie Baum and Katie Joy) and logistics support personnel, the BAS cargo transfer team, the local meteorite lab and classification team – lead by Jane MacArthur with help from Thomas Harvey, Rhian Jones and Katie Joy. A huge thanks to the local analytical lab leads who have kept the instruments we use to image the samples and determine their chemistry (Lewis Hughes and Jon Fellowes), those who support the labs we use to prepare our samples (John Cowpe and Lydia Fawcett) and appreciate key advice from Andrew Smedley, Romain Tartese and Geoff Evatt. Thanks also to all the external help we have had from the Natural History Museum staff in helping these efforts, and to the Meteoritical Society Nomenclature team and Meteorite Bulletin teams for reviewing, approving and sharing the samples’ new names.

You can also read a blog from Jane on the lab curation approach where she will talk about how we go from picking up a sample in the field to working out what type of meteorite it represents.

We also have more samples under review by the nomenclature team so will announce what else we have found in the near future… stay tuned for more meteorites to come…

Photo of the largest sample found in season 1 – now called OUT 18021 (or still affectionately referred to as the melon on account of its large size). the scale cube is 1 cm in size. Image: Lost Meteorites of Antarctica / The University of Manchester

New meteorites need new names…

To be able to give the meteorites we have recovered a formal name we have to go through some procedures…

Dense meteorite stranding zones (areas where lots of meteorites are found) are awarded a name by the Meteoritical Society Nomenclature committee. The meteorites recovered from these areas are then named after these sites – for example the first recognised lunar meteorite Allan Hills (ALHA for short) 81005 is named after the Allan Hills icefield A in Antarctica. Thus, to be given a name we need the place that the meteorites are found to be called something!

Our issue is that the regions we visited in Antarctica had not been formally allocated names by the countries who administrate these areas. So we have gone through two different routes to formally assign names to the field sites we visited so that we can use the names of these geographical features in future research publications and use them to name the meteorites we recovered.

We are happy to announce that our two main field areas have been approved as the Outer Recovery Icefields in Dronning Maud Land by the Norwegian Polar Institute and Hutchison Icefield in Coats Land (British Antarctic Territory ) by the UK Antarctic Place-names Committee. Both of these field sites contain nunataks (mountain tops emerging from the ice), which have also been named after meteorite and meteor scientists (see below for details). The UK site names are included in the UK Antarctic Gazetteer (https://apc.antarctica.ac.uk/) and are available for use on all maps and charts and in all publications. They are also included in the Scientific Committee on Antarctic Research (SCAR) Composite Gazetteer of Antarctica (https://data.aad.gov.au/aadc/gaz/scar/ ).

These names have now also been approved by the Meteoritical Society as dense meteorite collection areas and we will be able to call the meteorites either OUT (for those collected at the Outer Recovery Icefields) and HUT for those collected from the Hutchison Icefield.

Regional context of the fieldsites for the Lost Meteorites of Antarctica project. See below for details of the two areas highlighted with black boaxes. Base map is Landsat Image Mosaic of Antarctica. Image: Katherine Joy.

Outer Recover Icefields Area

Outer Recovery Icefields. named because of its proximity to the Recovery Glacier found adjacent to the northern extent of the area. Link to online Norwegian record.

Halliday Nunatak (81°24’32.97″S, 18° 1’59.88″W): Located in the Outer Recovery Icefields. named after Canadian astronomer Dr Ian Halliday (1928-2018) who was a Canadian astronomer with expertise in meteor (asteroid and comet) delivery rates to the Earth. Link to online Norwegian record

Outer Recovery Icefield area showing locations of the nunatak and four separate blue ice fields. Base map is Landsat Image Mosaic of Antarctica overlain with high resolution Sentinel 2 image. Map scale is 1:250,000 Image: Katherine Joy.

Hutchison Icefield Area

Hutchison Icefield (81°30′ 30″S, 26°10’W): Named after British meteorite scientist Dr Robert Hutchison (1938-2007) who was the Curator of Meteorites at the Natural History Museum, London. He was Head of the Cosmic Mineralogy Research Programme at the NHM, and responsible for the national meteorite collection, one of the most significant meteorite collections in the world. Awarded the Gold Medal of the Royal Astronomical Society in 2002; asteroid 5308 named Hutchison by the International Astronomical Union. Named in association with names of pioneering meteoriticists grouped in this area. Link to online SCAR record.

Turner Nunatak (81°27′ 50.42″S, 26°24’48.88″W): Located in the Hutchison Icefield. Named after Professor Grenville Turner FRS (b. 1936) pioneering lunar and meteorite scientist, Emeritus Professor at the University of Manchester. He established the University of Manchester Isotope Cosmochemistry group and his pioneering work on rare gases in meteorites led him to develop the argon–argon dating technique that demonstrated the great age of meteorites and provided a precise chronology of rocks brought back by the Apollo missions. He was one of the few UK scientists to be a Principal Investigator of the Apollo samples during the time of the US manned Moon missions. Link to online SCAR record.

Pillinger Nunatak (81°34’40″S, 26°24’15″W): Located in the Hutchison Icefield. Named after Professor Colin Pillinger FRS (1943-2014), English planetary scientist who was a founding member of the Planetary and Space Sciences Research Institute at Open University in Milton Keynes, and through his career studied stable isotopes in Apollo Moon samples, martian meteorites and asteroidal meteorites. He was also the Principal Investigator for the British Beagle 2 Mars lander project. Link to online SCAR record.

Map showing Hutchison Icefield area with Turner nunatak to the north and Pillinger nunatak to the south. Karpenko massif is a region of disturbed ice named after a Russian Engineer Aleksei Illaryonovich Karpenko (1940-82). Base map is Sentinel 2 image. Image: Dr Adrian Fox (UK Antarctic Place-names Committee)

With many thanks to Dr Adrian Fox (UK Antarctic Place-names Committee), Dr Oddveig Øien Ørvoll of the Norwegian Polar Institute for all of their help with the naming of these regions and advice from Laura Gerrish at the British Antarctic Survey.

New paper: The spatial flux of Earth’s meteorite falls found via Antarctic data

By Geoff Evatt:

So, how many new meteorites are landing from space each? How much total mass of them are we gaining? And where about’s on Earth are we most likely to be hit? (especially timely this week given the news story about a 1 km asteroid passing within 4 million km of the Earth! ) This are just some of the questions answered in our latest publication, as published by the journal Geology this week.

In this study, we combined glaciology, mathematics and physics, and sprinkled it all with meteorite collection data, to produce an accturate estimate of these quantities. The headline figure being we estimate over 17,000 falls each year weighing over 50 gr (that is to say, some 17,000 objects fall from space and hit the earth every year, where each component fragment is known as a meteorite, and the summed mass of these meteorites are over 50 gr), and this equates to over 16,000 kg per year landing on the Earth. As for the regions most likely to be impacted, then this, it turns out, appears to be at the equator, where the poles receive about 60% of the equatorial flux.

The first part of the study was to work out the flux of extraterrestrial material in Antarctica. With it having the most documented meteorites on earth, and collected in a very systematic fashion, this meant we were able to harness the data from thousands of samples. However the nature of meteorites in Antarctica means that working out the area they originally landed on is not simple (because the ice is flowing). Combining mathematics with glaciology, we were able to invert for the effective surface area of ice which feeds into Meteorite Stranding Zones (the areas from which they are collected). And since we know flow speeds of the ice, and the number of meteorites collected from them, we were then able to solve for the flux of meteorites falling on a typical square kilometre of ice. Such a figure is useful, but beggars the question: how does that relates to elsewhere on Earth?

Schematic of meteorite stranding zone ice flow and loss used to help build our model of Antarctic meteorite stranding zone data. Image Andrew Smedley (as published in the supplementary materials of Evatt et al., 2020)

Solving for the places most likely to be impacted (the latitudinal variation) was a lovely problem, as the answer was not obvious because competing effects pulled the result to either the poles or the equator. Why the poles? Well, because material orbiting the sun might do so above/below the Earth, yet when in the vicinity of the Earth gravitational attraction, the  objects would be deviated towards the polar regions. Conversely, the equatorial regions face head-on into the asteroid belt, and thus more surface area is available for receiving the material. As it turns out (after much old-school orbital mechanics) the equator still dominate for earth, but with the polar region receiving a decent whack – about 60% of the equatorial flux. This computed variation ties in very neatly with observations of the spatial distribution of fireballs across the globe – which was extremely reassuring.  With us knowing a good estimate for the flux at the poles, is was then straight forward to use the derived latitudinal variation curve to estimate it for everywhere else.

Now, despite the equator being more likely to be hit, in regards being hit by anything dangerously big, this is not anything to worry about for many many years. This is because such events are extremely rare. And since the whole planet is receiving so many non-dangerous falls each year (17,000+), and each event creating a glorious fireball (much brighter than the shooting stars we see which are formed from dust-sized grains) it really tells us to head outside and look up: there is a good chance of seeing such a fireball event if you give it just a few nights. 

Stay safe and look up!

Read the article (open access): G.W. Evatt, A.R.D. Smedley, K.H. Joy, L. Hunter, W.H. Tey,I.D. Abrahams, and L. Gerrish (2020) The spatial flux of Earth’s meteorite falls found via Antarctic data Geology https://doi.org/10.1130/G46733.1

Read a BBC Science online news story about the study

Avoiding the Italian Job

Geoff Evatt | 19 Dec 2018

At the end of the Italian Job, the looted gold is left at the rear of a coach that dangles dangerously over a precipice; tangentially close, yet also so far away: “Hang on boys, I’ve got an idea….”. Well, I too have had an idea. Chainsaws. OK, so that might not have helped Michael Caine in his predicament, but hopefully it’ll help us should we locate any englacial meteorites.

2018-12-04_08-57-36 chainsaw training GWE small
Essential course material: chainsaw, underlying theory, vape… [Credit: G W Evatt]

To be ready for sawing out some meteorites in a year’s time, I will give it a practise this coming January down at the BAS base, Sky-Blu. (the chainsaw bar length is 40 cm, the meteorites could be 50 cm deep: hmmm). And before I can even practise in the field, I was sent on a chainsaw course on an industrial estate in Chesterfield. Yes, it was a long long way from Antarctica, but it was freezing and the corrugated iron all around had a certain monotonous colouring, so maybe that will all come in useful. More importantly, I learned a lot about fixing basic chainsaw issues, how to sharpen chains, and how to cut logs the correct way (I’ve done a reasonable amount of chainsawing at home, but now I know sooo much more). The course instructor, James, also gave good suggestions as to how to cut ice and deal with the cold. In short, I feel much more prepared and confident about using the saw down there.

2018-12-04_10-32-06 chainsaw training GWE small
Tools of the trade. [Credit: G W Evatt]

And what if it’s a total failure (as in does not let me extract lumps of ice)? Well, I’ve also sent down a farm-shop of ironmongery, saws and ice drills. Between these, I hope that we will find an efficient method that allows us to extract any iron meteorites we detect. After all I want be prepared and confident, and we don’t wan’t to face any Italian Job conundrums….

2018-12-04_14-02-45 chainsaw training GWE small
Practising for Antarctica [Credit: G W Evatt]

PS For those of you really into their chainsaws, I’ll be using battery powered DeWalt one. Whilst it cut the Chesterfield logs very effectively, it may be a totally different matter in the cold, in which case I’ll have to opt to using a petrol one instead next season.

Finalising the field procedures

Katie Joy | 13 Dec 2018

We have done a final run through of the metal detector electronic assembly system that connects up to our five detector panel array. Practice makes perfect and it is much easier to do a dry run through in the electronics lab in Manchester before getting to the cold and windy field site. Liam, John and Wouter (our fab electronic engineers) carefully ran Geoff and Mike through which cables to connect to which connector so that the instrument powers up in the right order in the field (marginally less complicated than booting up the Apollo 13 command module), and the procedure has been documented.

Andy and Katie have been working hard finalise our fieldsite maps and ensure that our GPS system is working well for logging our skidoo tracks and meteorite collection locations.

Our fieldwork is nearly upon us – Katie heads out next Tuesday on the 18th December and Geoff in the New Year.

Training for life on the Ice (Sept 2018)

Katie Joy | 01 Oct 2018

Fieldwork in Antarctica is a massive logistical and human challenge – from getting scientists to the continent, ensuring that they are trained to go out into the middle of the continent, and actually living and working on the ice, it takes a vast number of highly trained people. Fortunately, BAS are really good at this and have an amazing bunch of people that we are working with – from their Cambridge headquarters, on the bases we will visit and into the field.

To help get us prepared for our upcoming trip Geoff and I joined the new BAS staff for pre-season training. During our four-day intensive course we met a wide range of people from vehicle mechanics, chefs, science support crews, boat swains, base managers and field guides, seal and penguin tagging and monitoring teams, doctors – many of whom have signed up for an amazing 18 month stints down on the ice. We also met some of the other science crews who in the 2018 austral season will be undertaking deep ice drilling and hot ice drilling operations to study past climate on the continent, and others who are studying seal populations on South Georgia Island to understand communities and breeding patterns.

_65723869_antarctic_bbc
Locations of the BAS bases [Image: BBC]

The training was split into several sessions. First up was and introduction to BAS history, operations, science and practice: BAS operate out of five bases – Rothera, on the peninsula, Halley, on the eastern side of the Weddell Sea, Bird Island and King Edward Point on South Georgia island and  Signy island. People on the bases, on the ships and in the field undertake different science projects – some (like ours) are very seasonal, some run all year round. We got a chance to hear from BAS scientists who run some of these longer term projects,  looked around the Cambridge BAS building and met people who run the archive facility, ice core storage facility and the geology prep and rock stores.

We also got a chance to try on our field kit and check that it all fitted – from insulating boots (very important to get the size and fit right), through to thermal underwear, outer layers and woolly hats – everything was reviewed and items swapped out as needed.


BAS issued polar insulating boots and field kit bags

The last couple of days focused on an intensive and rapid introduction to medical situations and protocols. The polar medical office (British Antarctic Survey Medical Unit ) is run out of Plymouth NHS Hospital and the team travelled up to Cambridge for the training event. In small groups we ran over recognition of life signs and medical problems through to how to bandage up a broken limb, deliver an injection (into an orange!), learn about pain relief options, and about mental health in remote, often stressful, environments. The course were rounded off by undertaking practicals where actors delivered a series of medical scenarios for our group to try and deal with (imagine fending off an imaginary seal whilst trying to deal with someone with a broken leg – that sort of thing…).  Frankly I hope that I never have to put anything I learnt as part of the sessions into practice – but it was an incredibly useful quick fire overview of what to do and how to relay information with people back on station and back in Plymouth if needed.

sdr
Geoff and Katie practising how to get out of a Scott polar tent without creating a medical emergency

————————————

For further information:

BAS science projects https://www.bas.ac.uk/science/our-research/research-projects/

BAS fieldwork https://www.bas.ac.uk/polar-operations/life-in-the-polar-regions/camping-and-deep-field-working/