We return to the ocean the next day with better weather
The crew flies over our proposed site, descends to 300 feet and then climbs back to 2500 feet to check the wind speed and direction. While we turn around to return to the drop site, the cargo deck crew prepares the ALAMO float.
We scientists are seated along the sides (with our seatbelts fastened) and the loadmasters don harnesses and tether themselves to anchor points on the cargo deck. It’s time to open the cargo door!
When the navigator tells the loadmaster that we are at the proper location, they launch the ALAMO, its parachute deploys, and it drifts out of sight quickly, before we can see if it landed in the water.
Everyone wants to know that the ALAMO landed safely in the water, so Major Hicks circles back several times while we search the surface of the ocean for the orange parachute. We never saw any sign of it.
When we land, Kirsty comes on board with a smile on her face and says that the ALAMO float has already sent us an email to say that it has successfully made its first measurements!
In addition to mapping the properties of the Ross Ice Shelf with the IcePod, we measuring the ocean properties just north of the ice shelf. We will do this with ALAMO floats (Air Launched Autonomous MicroOberserver). ALAMO floats measure three critical properties of the ocean: temperature, salinity, and pressure. They do this while slowly sinking to the bottom of the ocean and then rising back to the surface. When they are at the surface, they place a phone call via Iridium satellites and literally email their data back to us.
ALAMO floats are a fairly new technology which has been used mostly in warm subtropical waters to date. A major complication in polar waters is the possible presence of sea ice. The ALAMO floats have a sea-ice-avoidance algorithm that detects whether there is likely to be sea ice as they rise upward, and to not surface if sea ice is likely to be present. The sensors and communications electronics are on top of the float, and we don’t want it to get damaged by running into sea ice from below.
The floats are deployed from the air, which makes it possible to go places that ships can’t go. A perfect example of such a location is the waters just north of the Ross Ice Shelf. In this region, the sea ice melts out near the ice shelf in late November while there is still lots of ice to the north, keeping ships away. An icebreaker, the Nathaniel B. Palmer, is the first ship scheduled to visit this region in late January. By deploying the ALAMO floats by airplane, we can make ocean measurements 6-8 weeks sooner than we could make them from a ship. These springtime measurements will contribute to our understand of the seasonal cycle of the sea ice in this region.
Our first challenge is that we need to be able to see where we are deploying the floats. In particular, we need a day without low clouds, which are quite common in this area. Our second challenge is that we need to be sure that we are dropping the floats into water and not onto sea ice. Satellite images help us in our planning, but in the end we just have to fly out there and look firsthand.
We finally get the word that we will get an airplane dedicated to flying the ROSETTA mission!
The LC 130 have a SABIR (Special Airborne Mission Installation and Response) arm, which allows attachment of specialized instrumentation packages like the IcePod.
The IcePod is controlled by electronic equipment that is installed in a custom-build rack that fits perfectly against the curved inside wall of the airplane.
So what does the IcePod do? It provides a top-to-bottom view of the ice shelf. First, it has visible and infrared cameras that take images of the surface of the ice shelf. It has a scanning LIDAR, which shines a laser beam on the surface of the ice shelf and measures the time it takes for the laser light to reflect back, which allows us to measure the height of features on the surface of the shelf. It has a shallow ice radar, which emits a powerful radio signal that penetrates into the ice, and it listens for the reflections, which tell us about different layers of snow and ice in the upper part of the ice shelf. There is also a deep ice radar, which is at a different radio frequency, and penetrates to the bottom of the ice shelf, telling us where the bottom of the ice shelf is in contact with seawater. Finally, there is a navigation system to tell us very precisely where we are so that we can make accurate maps of the ice shelf.
The Observation Tube (usually called the Ob Tube) is a gateway to another world. It is a vertical metal pipe, or tunnel, through the sea ice leading to a small (one person at a time!) glass observation platform about 10-15 feet below sea level.
The Ob Tube is located just a couple hundred meters offshore of town, but, because it is on sea ice, safety procedures must be followed to visit it. The rules require that one travel with a buddy, perform a safety sign-out at the firehouse, and carry a VHF radio. After dinner one night a small group of us went to check it out.
I went last. We had to tell each person when their 10 minutes was up. Everybody wanted to stay in the tube for longer, partly because it was much warmer underwater (just below freezing) than on the windswept surface of the ice. Mostly, though, they want to remain because it is really fascinating.
It was late evening, but the sunlight shone through the ice with a pretty greenish light.
Besides looking at the sea ice, I enjoyed looking at some large but delicate ice crystals that formed on the outside of the tube, and a large school of small fish that stayed just a little too far away to see very well. The most interesting thing, though, was hearing the pinging sound made by seals as they swam nearby. I did not see a seal underwater, but some people have.
McMurdo Station is the largest settlement in Antarctica. It is like a tourist town in that its population swells in summer, but the summertime visitors are scientists, not tourists. As the research season gets into full swing the population can grow to over 1000, and right now it is 910. Some scientists are just passing through town on their way to Deep Field Camps. Some stay longer. Our group will be here about 5 weeks.
In some ways it resembles any small town — it has a fire station
, a medical clinic, a chapel,
two bars, a coffeehouse,
a fitness center, a library, a power plant, a sewage plant, and so on. There is even an ATM (cash machine), although there isn’t much to spend money on.
The architecture is strictly practical — most buildings have metal siding and shed roofs, although some are “quonset hut” style. The only building that is architecturally distinctive is the Crary Lab (mostly because it steps down a steep hill), and it’s not going to win any awards for exterior aesthetics. Most buildings are labelled with nothing but a number, which is pretty confusing at first, but it doesn’t take long to become familiar with every building you are likely to ever go into.
The busiest building in town is Building 155. Perhaps because of its importance, it is painted bright blue, which makes it stand out from the dull earth tones of all other buildings. Building 155 is the home of most administrative offices and the galley, where everyone eats all of their meals. The galley serves 4 meals per day — breakfast, lunch, dinner on a normal schedule, plus an additional meal called “midrats” (midnight rations) for people on the night shift. In fact, at 7 am most people are eating breakfast, but people on the nightshift are eating dinner. Similarly at dinnertime, the night shift people are eating breakfast. One is not supposed to eat the breakfast food at dinnertime unless one is on midrats.
By the way, the food is actually pretty decent — I especially like the fresh baked bread. There is a good variety at lunch and dinner and it is possible to assemble a reasonably healthy meal and, at least for now (while there are still frequent flights to and from New Zealand), fresh fruit and vegetables are available.
There is not a lot of snow in town as we head into summer. Ross Island is a collection of volcanoes, and the ground in town is red-brown volcanic rock. As long as it remains cold (say below 15 degrees F), the rock stays frozen in place. When we have warm weather (as we have had lately), the snow melts and the ground becomes a muddy mess. There is no asphalt or concrete pavement.