APLIS POSTCARD #7
18 March 2007
Greetings from APLIS, adrift in the Arctic Ocean. More precisely, the Beaufort Sea, as this part of the Arctic is known. The pack ice here in the far north is constantly in motion but our little part of it has been essentially stationary for the last several days. Then today we started drifting again - a whopping half-mile in the last 24 hours.
After spending the night hosting the VIP party, ALEXANDRIA surfaced this morning to allow them to debark. The VIPs, still in high spirits, passed through APLIS for a quick snack before boarding the planes to take them back to Prudhoe Bay. But they stayed long enough to sample some good camp food and to visit with Bruno, the APLIS mascot.
Secretary of the Navy Donald Winter with Bruno, the APLIS Mascot
While ALEX was entertaining the VIPs, TIRELESS continued her test programme. She spent the night and most of the morning testing the high-latitude performance of new navigation systems she has aboard.
Submarines operating in the Arctic face two navigational challenges not normally encountered by ships at sea.
Nowadays, most ships (along with many cars) use GPS satellite information to update their location. But when a submarine is operating submerged with a layer of ice overhead, it has no access to GPS signals. As a result, submarines up here are almost entirely dependent on Ship’s Inertial Navigation Systems (SINS) to keep track of their location. The only way to update their SINS is to surface to obtain a GPS fix. TIRELESS has the new NATO SINS system on board which is one of the items being tested.
The second challenge for anybody navigating in the polar regions stems from basic geography. We have delineated the world with lines of latitude (running east-west) and longitude (running north-south). Down in the lower latitudes where you are, these longitude lines are roughly parallel to each other and cross the latitude lines at right angles. But up here, the longitude lines all start to converge at the North Pole and the latitude lines turn into circles. The closer you approach the North Pole, the more that normal navigation conventions start to fall apart. For instance, near the pole you might start walking east and, if you continue in a straight line, find out that you’re heading nearly south.
Our submarines’ inertial navigation systems can remedy this. Using software, we can lie to the system about the location of the North Pole, allowing them to work in a completely different system of latitude and longitude, called the polar transverse system. The NATO SINS ability to function in this mode will be evaluated as TIRELESS transits back across the Arctic after leaving APLIS.
Ok, enough technology talk. One of the many unique things about the Arctic region is the Aurora Borealis, or northern lights. This wavering green light in the night sky is caused by the interaction between solar wind and the earth’s magnetic field. Because the earth’s magnetic field is so concentrated here in the far north, we see the effect frequently. Whoops, technology talk again. Anyway, the lights have been out and beautiful almost every night since we arrived. Here’s a sample, courtesy of Barny Revill, part of the UK documentary crew from Tigress Productions.
Sweet Borealis Dreams to you all.
Arctic Submarine Laboratory