Getting surface meteorites in the bag

Katie Joy | 27 Dec 2019

Whilst the panel testing is continuing (see Geoff’s last blog post) we have also been making steady progress with searching the ice surface for meteorites that have emerged from the blue ice. As of today the count is at 35 stones from Outer Recovery — one off the total for the whole of the last recon field season.

Katie and a large meteorite “find”. [Credit: Romain Tartese]

Every rock we locate at this particular ice field is a meteorite — there are no terrestrial rocks at all, so it makes identification very easy. What is tricky is actually spotting them in the first place — often the meteorites are hiding at the bottom of suncups (small depressions made as the ice is ablated by the wind and sublimated on warmer days), and for those less than a couple of cm in size you have to be lucky to see them as you drive past on your skidoo and be looking in the right direction (for this reason we swivel our head continually as we drive like watching an end-to-end tennis match). Samples bigger than ~3 cm are easier to spot, but again can sometimes be nestled down between snow patches or in suncups. Whether you are driving into the sun, and the angle of the shadows cast at different times of the day comes into play, so although we are systematically trekking back and forth across the ice surface, not every search session results in a meteorite find: between 2 and 7 meteorites seems to be the rate of daily collection at the moment.

A small but perfectly formed flight orientated stone. [Credit: Katie Joy]

The meteorites themselves vary from a small bean-sized one we found yesterday (a lovely perfectly fusion crusted stone, suggesting that this tiny meteorite is a complete piece), to another complete stone which preserves a fusion crust that is flight shaped (i.e. we can tell which in orientation the meteorite was delivered as it travelled down through Earth’s atmosphere — these type of samples are very aesthetically pleasing, and are really cool to find), to some larger blocky stones (around the 8-20 cm size range) that look like they are pieces of a large meteorite that broke up either in space, or through erosion as it was transported through the ice [NB I am guessing that they are from the same parent meteorite at this stage based only on the colour and texture of their exterior surface, and the very similar colour and texture of their interior — this will all need to be confirmed when we do the formal classification back in the lab]. Several of the samples we found this year are like some of those we found last year, suggesting that again there might be some relationships between the samples we have collected, and others look completely different which is exciting as it means we have good diversity across the sample set collected.

So, all in all, we are progressing steadily, and hopefully will continue to get more meteorites bagged up. Today the weather has turned snowy so will have to see how this effects our search plans over the next few days.

Hope that everyone had a Happy Christmas — we had a tasty meal last night together complete with an amazing Christmas cake provided by chef Olly at Rothera (many thanks — you are a star!), and had a team drive out after testing the panel array to visit a cool ice rise (which is a bit of ice that has been squeezed up to look like a pointy mountain tip) next to the search area.

Geoff driving the detector panel arrays on the ice surface. [Credit: Katie Joy]
The team visiting a nearby ice rise on Christmas Day. [Credit: Katie Joy]

PS Many congratulations to my Aunty Angie and Tommy for getting engaged. Sorry I cant be there to celebrate with you all, but raising a cup of tea to you from the field.

PPS Thanks Isotope Group crew for sending down the birthday card. Very sweet of you all to get so organised in advance. 🙂 Much appreciated. Hope that you are all well and looking forward to the BPSC.

PPPS Dutch, we found some pina-colada flavoured energy bars in the manfood box. Definitely not as exciting as the real thing.

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….