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May 2015

BAS Javelin Probes Pine Island Glacier

December 3, 2013

On Monday December 3rd Dr. David Jones, technical leader of the British Antarctic Survey's "Javelin" project, flew out to the Antarctic with instrumentation and comms boards using VM2 controllers, for testing initially and then dropping a batch on to the Pine Island Glacier in late December.

The "Javelin" is dropped from an aircraft and designed to embed itself in the snow with its transmitting antenna rising vertically above the snow surface.

Technical Contribution from Micro-Robotics

Prior to that, Micro-Robotics advised Dr Jones on Venom programming and dealt with some special problems raised by this unusual project.

The remote devices use an Iridium satellite communications link to set up a connection, and FTP to transfer the file data. We investigated problems with PPP on the Iridium modem, caused by the slow speed of the link and also the fact that the satellite link comes and goes at regular intervals as the satellites (on a low polar orbit) pass overhead.

As a result we introduced new PPP Timeout configuration options to match the response speed better and to cope with the possibility of the link being lost during negotiation. We also implemented a new timeout message in the FTPClient object so that the system would recover if the link was lost in the middle of a transfer.

The result was a communications link that promised to be robust enough to be dropped on to an inaccessible glacier where it will have to run unattended transmitting position data regularly until the battery runs out. (up to 2 years)

The new timeout features are, of course, now incorporated in the latest release of Venom.

See Application Stories page for a description of the BAS project and link to a story on the BBC news site.