Flying beneath the iceberg, Autosub used powerful sonar equipment to survey the underside of the ice and produce ultrasound images of its shape. Autosub is looking at ice thickness and krill abundance for scientists from British Antarctic Survey led by Dr Andrew Brierley. So far Autosub has completed three missions each around 60km under sea ice. Reports from the ship, the RRS James Clark Ross , indicate that early trials have been more successful than expected. As this research with Autosub has never been undertaken before, the scientists did not know what could be achieved and are delighted with the results.
Sea ice is loose pack ice that is often too unstable to carry research instruments safely.
However, to check that the Autosub results were accurate, Dr Mark Brandon from the Open University climbed onto a large ice floe and, instead of using sonar, used a pole and shovel to measure the ice thickness. This iceberg with 19 metres out of the water was 125 metres deep beneath the surface.