The Antarctic Sun - Features Section United States Antarctic Program United States Antarctic Program Logo National Science Foundation Logo
 

A good point

South Pole geographic marker changes with the times

 

On the first day of January each year, the South Pole moves.

Well, that’s not entirely accurate. The geographic South Pole — 90 degrees south latitude — doesn’t really go anywhere. But the place on the ice sheet where a specially designed geographic marker sits on a metal stick pitched in the ground doesn’t stay put after Jan. 1 of each calendar year.

That’s because the ice sheet on which the entire South Pole Station resides moves about 10 meters per year. The day after the station’s crew, with the help of the U.S. Geological Survey (USGS), resets the location of the marker, it will have moved about 2.7 centimeters.

At that rate, in about 140,000 years, the current geographic marker and the rest of the research station will slip into the Weddell Sea.

Another thing that changes at the South Pole is the geographic marker itself. Each crew that winters over at the station designs and builds a new marker, which the following summer crew places during a ceremony to reposition the marker on Jan. 1.

Over the years, the markers have grown in complexity from simple brass discs.

For example, for the 2009 marker, winter-over Polie David Postler designed and fabricated a brass marker in the shape of a globe, with the continent of Antarctica raised above the surface. This particular marker doubles as a time capsule, as the top can unscrew, and with enough room for a jump drive containing various electronic files — not to be downloaded until 2058.

The new 2010 marker also breaks the mold on the traditional disc shape. Polie machinist Steele Diggles designed and fabricated a bronze and aluminum marker that features the South Pole’s two premiere science experiments — the South Pole Telescope and the IceCube Neutrino Observatory.

A replica of the telescope sits on top of the neutrino detector, connected through a cut-out of the continent to a cube below, with 43 IceCube detectors raised on the surface to represent all the winter-overs in 2009. It was set in a place during a ceremony on Jan. 1, 2010 (local time) at 90 degrees south.

Marking time

The first geographic marker created for the South Pole was never meant to be placed at 90 degrees south but inside the station back in 1959.

In an Associated Press story dated Nov. 6, 1959 — and later reprinted in the December 1959 Polar Times – the government announced it would set up a permanent three-inch bronze marker at its station “next door to the South Pole.”

An image of the disc — its whereabouts today unknown — shows the station at latitude 89 degrees, 59 minutes, 43.6 seconds south and longitude 24 degrees, 8 minutes west. That was about 1,650 feet north of the South Pole at the time.

The U.S. States Coast and Geodetic Survey — now the National Geodetic Survey under NOAA — was in charge of the fabrication and placement of the marker in 1959. The location was determined from 52 sets of astronomical observations made during the Antarctic’s long night by Maj. Palle Mogensen, the scientific leader during at Pole that year, according to the AP report.

“Maj. Mogensen made his observations through a slot in the roof of the station hut. At times the temperature was 100 degrees below zero outside the hut and zero inside the hut,” the AP report said.

Bill Spindler, a long-time Polie and unofficial historian on everything South Pole, notes that in 1959 no one knew that the icecap was moving relative to the Earth’s surface, “something that would confound the celestial observations used at the time to determine the Pole location.”

While the whereabouts of the original 1959 marker are unknown — though it’s possibly buried in the ice-entombed International Geophysical Year (IGY) station built in 1956-57 and used for nearly 20 years — an apparent sister piece to the bronze disc has recently turned up in the Washington, D.C. area.

Scott Sturiale found a similar geographic marker to the 1959 piece in his grandfather’s collection among survey equipment dating to the 19th century. Edmund Duringer was a machinist for the U.S. States Coast and Geodetic Survey 50 years ago, according to Sturiale. He contacted Spindler about the find, unaware of the historical significance.

“I’m assuming he made this. He worked for the government, as a machinist downtown (in D.C.),” Sturiale said.

The pieces aren’t identical. Part of the longitude is missing on Sturiale’s copy, and the words “South Pole” appear at the top of his marker. In the one apparently sent to southernmost research station, the words are at the bottom.

“It may have been a mistake, or it may have just been practice,” Spindler said of the differences between the two bronze discs in an e-mail to Sturiale. “In any case, it is unique among the extant Pole markers in that it was NOT intended to be placed at the geographic pole, but rather inside the station. Well, otherwise it would have said 90° South!”

Other machinists have been known to make multiple markers, perhaps in case they would make a mistake, or perhaps to keep or give away.

Marking the pole

Many years passed before another geographic marker returned to South Pole. Finally, during the 1976-77 season, the USGS installed a marker at 90 degrees south to mark the nation’s bicentennial birthday.

From then until 1991, the USGS operated a continuous Doppler satellite measurement and positioning system near the South Pole. The project accurately recorded the positions of low-orbiting Navy satellites. Based on known orbital parameters, USGS staff was able to use this information to determine very precisely the location of the Doppler antenna, according to Spindler.

From there, the location of the Pole was surveyed conventionally from the antenna location. Or, more practically, determined by calculating the annual movement of the antenna and then translating this same measurement to the previous year’s Pole marker.

In 1991, more accurate measurements began with observations on satellite signals of the Global Positioning System (GPS), according to the USGS document “A Summary of Geodetic Satellite Measurements at the South Pole and Relationship to the Annual Pole Marker Location.” The previous system was accurate within about a meter. GPS is precise within centimeters.

Leaving a mark

There was always some sort of marker where people thought the Pole was located, such as a flag or sign post, according to Spindler. During IGY, it was a ring of barrels, he said.

“The first 1959 marker is unique, and as far as I know, there was not another fancy one like that until the USGS one that was set in November 1976. That was the only real USGS marker as far as I know,” he said. “And there weren’t any more until some point in the 80s [when] they started making the fancier markers (during the summer); it was a rather secretive activity that I was not privy to.”

Andy Martinez, South Pole Operations manager, said there are currently 22 markers dating back to 1984 at the station, most locked up in a display case. The missing years include 1985, 1986, 1991, 1994 and 2003. The 2003 marker stand is in the display case with all of the winter-over signatures on it and a photo of the marker.

“From the case, it appears that 1990 was the first year the creativity started,” Martinez said in an e-mail. “As for the USGS stamp, the first marker without the USGS stamped on it is 2004.” The NSF stamp replaced the USGS one, he added.

The United States has had a continuous presence at the South Pole since 1956, when it constructed a research station there in less than two months for the IGY, a worldwide science campaign that focused on polar discoveries.

The bottom of the world has always been a goal of explorers since the first men risked — and lost — their lives to reach it in the early 20th century. Norwegian Roald Amundsen was the first to claim the honor on Dec. 14, 1911. He was followed by Robert F. Scott’s expedition on Jan. 18, 1912. Of course, neither man had satellites to help him locate 90 degrees south.

Instead, both used an astronomical method that involved observations of the sun, according to the USGS.

“When at the geographic location for the South Pole, the sun is above the horizon six months of the year. Through a 24-hour period, the sun moves parallel to the horizon a complete rotation around the geographic pole. It gradually rises to its highest angle above the horizon on Dec. 21. 

Observations to measure the angle of the top edge of the sun above the horizon were made with a sextant or similar instrument. When the angle or altitude above the horizon is equal, the observer is standing at the geographic location for the South Pole. The accuracy for this method is estimated to be about 300 meters (about 1000 feet).”

No matter how you find it or mark its location, there’s perhaps no more unique place on the planet than the South Pole.

Share on Facebook Share on Twitter Share on Google Plus Share This Site on Pinterest Subscribe to USAP RSS Feeds Share Via Email
Curator: Peter Rejcek, Antarctic Support Contract | NSF Official: Winifred Reuning, Division of Polar Programs