An Actual Field Trial

Andy Smedley | 10 Aug 2018

Since our April visit to Svalbard and the first real test of the detection equipment, things have been busy in the electronics lab. Away from the cold we had a chance to review the results of the Svalbard trip – most of the set-up works really well: it is indeed possible to drag detector panels behind a skidoo and detect metal objects hidden under the surface, but certain elements of the system were a little too sensitive to being dragged around in the cold.

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Liam readying the electronics. [Image: A R D Smedley]

To remedy this Liam and John have been busy with a redesign of one of the electronics boxes that form part of the detection system, adding some resilience to the more temperamental parts of the circuit. However we need to check this redesign works as expected – both in the subzero temperatures, and whilst in motion. Whilst another trip to Svalbard might be tempting, summer time in Svalbard means the snow cover is much reduced and rules out the use of skidoos. Instead, in the heat of the hottest UK summer since 1976, we headed for the relatively electrically noise free hills of the near-by Peak District.

Here a suitable field was made available to the team: not too sloping, not too long grass, a little bumpy, not too ferrous (metallic) soil – in its own way a reasonable approximation to the surface of a glacier or a blue ice area (but warmer). This had its own benefits – no need to put on several layers of clothing on every trip outside only to hurriedly remove them as soon as you stepped back inside base, and no Arctic foxes playing havoc with the equipment. No the Peak District is far more civilised than that.

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Close up of the metal detector electronics. [Image : A R D Smedley]

Experimentally though we essentially the same set up: a runway with surrogate meteorites (i.e., metal weights) buried to different depths at 5 to 10 m intervals. The panel and associated electronics are then dragged along this runway at different speeds and with slight adjustments to check the system’s behaviour. As a stand in for a skidoo we went for a 4×4… and everything seem to work pretty much as expected. We’re getting ‘pings’ back from the system for metal objects buried to depths of at least to 20 cm, with less electrical noise than we were seeing before. The tests have allowed us to tune the system before the upcoming field trials in Antarctica later this year.

We’re definitely heading in the right direction! There’s still some tuning to be done, and testing of the different parts of the system in a freezer, but for now all eyes are focussed on preparing for the upcoming Antarctic shipping deadline.

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Field trialling: instead of snow the panel gets a light covering of cut grass.  [Image: A R D Smedley]

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