Geologist Trevor Williams, of Columbia University's , will be spending six weeks at Antarctica's McMurdo Station, taking part in of the sea-floor sediments beneath the Ross Ice Shelf. The results could aid our understanding of climate change. Williams will be filing reports here throughout the project. Listen to him live from the bottom of the Earth here.[link href='https://seniorhelpline.info/technology/upgrade/4198889.html' link_updater_label='external_hearst' target='_blank']
ROSS ISLAND, Antarctica, Dec. 21 — From a distance, the ANDRILL rig (pictured at top right) looks like an icy pinnacle or a yacht sailing on the snowy plain of the Ross Ice Shelf. The rig's white cover, aside from being pleasing to the eye, serves the very practical purpose of keeping out the wind and keeping in the warmth. Drilling has just passed the 1000-meter mark—a record depth for Antarctic sediment drill holes—so it's high time to take a look under the cover and report on the technology and people who made this feat possible.
The 315-hp rig stands 65 ft. tall and is based on a model used in the mineral exploration industry, only customized for Antarctic conditions (it runs on jet fuel that won't freeze). It was tested last year in New Zealand, brought by ship to Antarctica in February, stored over winter and towed out to the drill site for the start of the field season in September.
First, a hot-water drill was used to melt a hole through 250 ft. of ice shelf. Then the "sea riser" pipe was lowered down through the ice—through 2800 feet of water—and bedded 50 feet into the sea floor; it's used to guide the drill pipes into the sea bed and return the "cuttings" to the rig (see illustration at right). The ice shelf moves sideways about one foot per day, which is no problem in this water depth, but it also moves up and down with the tides by three feet—tricky to deal with when your pipe is attached to the sea bed. To compensate, the sea riser is held up by cables that maintain a constant tension, so the riser stays still while the ice shelf moves.
Only then could the drill site team start the job of recovering cores—20-ft.-long cylinders of sediment or rock. The first pipe is fed down through the sea riser and drills down as deep as it can go, where it is cemented in place. The hole is then deepened by a four-inch-wide pipe, followed by a three-inch pipe—the set of pipes nested together like Russian dolls.
Each pipe has a diamond-impregnated drill bit to produce high-quality cores. So far, we have recovered about 98% of the drilled section. This provides great material to study the past behavior of the ice shelf, and keeps the scientists very happy.
The rig doesn't run itself, of course. It's managed by Antarctica New Zealand, with staff from Victoria University of Wellington and from drilling companies around New Zealand. Drill site manager Alex Pyne (with beard in bottom right photo) customized the rig and brings his wealth of experience from previous Antarctic drilling campaigns to the current project.
Fun fact: After a recent "fun-razor" charity evening at New Zealand's Scott Base, most of the drill site crew are bald. It's not the ideal continent for walking around with no hair, but they stepped up anyway and raised over 4000 New Zealand dollars (about $2800) for the Child Cancer Foundation. You can meet the team (pre-haircut) and see the rig in action in the [link href='http://www.andrill.org/iceberg/videos/6.html' link_updater_label='external' target='_blank']ANDRILL video journal.
The diamonds aren't just in the drill bits; they're in the air too. When the air is cold enough, tiny ice crystals form and sparkle in the sunlight as "diamond dust". With enough ice crystals, you get meteorological phenomena like sun halos and sun dogs (pictured at top right). Amazing! —Trevor Williams
With enough ice crystals at the McMurdo drill site, you get meteorological phenomena like sun halos and sun dogs. PHOTO BY CLIFF ATKINS (CLICK TO ENLARGE)
The "sea riser" pipe, bedded 50 feet into the sea floor, is used to guide the drill pipes into the sea bed and return the "cuttings" to the rig. ILLUSTRATION COURTESY OF ANDRILL (CLICK TO ENLARGE)
After a recent "fun-razor" charity evening at New Zealands Scott Base, most of the drill site crew are bald. PHOTO BY ANDREAS LAUFER (CLICK TO ENLARGE)