NASA News: International Team To Drill Beneath Massive Antarctic Ice Shelf
WASHINGTON -- An international team of researchers funded by NASA andthe National Science Foundation (NSF) will travel next month to one
of Antarctica's most active, remote and harsh spots to determine how
changes in the waters circulating under an active ice sheet are
causing a glacier to accelerate and drain into the sea.
The science expedition will be the most extensive ever deployed to
Pine Island Glacier. It is the area of the ice-covered continent that
concerns scientists most because of its potential to cause a rapid
rise in sea level. Satellite measurements have shown this area is
losing ice and surrounding glaciers are thinning, raising the
possibility the ice could flow rapidly out to sea.
The multidisciplinary group of 13 scientists, led by Robert
Bindschadler, emeritus glaciologist of NASA's Goddard Space Flight
Center in Greenbelt, Md., will depart from the McMurdo Station in
Antarctica in mid-December and spend six weeks on the ice shelf.
During their stay, they will use a combination of traditional tools
and sophisticated new oceanographic instruments to measure the shape
of the cavity underneath the ice shelf and determine how streams of
warm ocean water enter it, move toward the very bottom of the glacier
and melt its underbelly.
"The project aims to determine the underlying causes behind why Pine
Island Glacier has begun to flow more rapidly and discharge more ice
into the ocean," said Scott Borg, director of NSF's Division of
Antarctic Sciences, the group that coordinates all U.S. research in
Antarctica. "This could have a significant impact on global sea-level
rise over the coming century."
Scientists have determined the interaction of winds, water and ice is
driving ice loss from the floating glacier. Gusts of increasingly
stronger westerly winds push cold surface waters away from the
continent, allowing warmer waters that normally hover at depths below
the continental shelf to rise. The upwelling warm waters spill over
the border of the shelf and move along the sea floor, back to where
the glacier rises from the bedrock and floats, causing it to melt.
The warm salty waters and fresh glacier melt water combine to make a
lighter mixture that rises along the underside of the ice shelf and
moves back to the open ocean, melting more ice on its way. How much
more ice melts is what the team wants to find out, so it can improve
projections of how the glacier will melt and contribute to sea-level rise.
In January 2008, Bindschadler was the first person to set foot on this
isolated corner of Antarctica as part of initial reconnaissance for
the expedition. Scientists had doubted it was even possible to reach
the crevasse-ridden ice shelf. Bindschadler used satellite imagery to
identify an area where helicopters could land safely to transport
scientists and instrumentation to and from the ice shelf.
"The Pine Island Glacier ice shelf continues to be the place where the
action is taking place in Antarctica," Bindschadler said. "It only
can be understood by making direct measurements, which is hard to do.
We're doing this hard science because it has to be done. The question
of how and why it is melting is even more urgent than it was when we
first proposed the project over five years ago."
The team will use a hot water drill to make a hole through the ice
shelf. After the drill hits the ocean, the scientists will send a
camera down into the cavity to observe the underbelly of the ice
shelf and analyze the seabed lying approximately 1,640 feet (500
meters) below the ice. Next the team will lower an instrument package
provided by oceanographer Tim Stanton of the Naval Postgraduate
School in Monterrey, Calif., into the hole. The primary instrument,
called a profiler, will move up and down a cable attached to the
seabed, measuring temperature, salinity and currents from
approximately 10 feet (3 meters) below the ice to just above the seabed.
A second hole will support a similar instrument array fixed to a pole
stuck to the underside of the ice shelf. This instrument will measure
how ice and water exchange heat. The team also will insert a string
of 16 temperature sensors in the lowermost ice to freeze inside and
become part of the ice shelf. The sensors will measure how fast heat
is transmitted upward through the ice when hot flushes of water enter
the ocean cavity.
Sridhar Anandakrishnan, a geophysicist with Pennsylvania State
University in University Park, Pa., will study the shape of the ocean
cavity and the properties of the bedrock under the Pine Island
Glacier ice shelf through a technique called reflective seismology,
which involves generating waves of energy by detonating small
explosions and banging the ice with instruments resembling
sledgehammers. Measurements will be taken in about three dozen spots
using helicopters to move from one place to another.
For more information and related images, please visit:
http://www.nasa.gov/topics/
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NASA To Hold Media Briefing About Upcoming Mars Rover Launch
WASHINGTON -- NASA will hold a media briefing at 1 p.m. EST onThursday, Nov. 10, to discuss the upcoming launch of the Mars Science
Laboratory (MSL), the largest and most capable rover to be sent to
another planet. The televised briefing will take place in the
agency's television studio at NASA Headquarters, located at 300 E St.
S.W. in Washington.
The MSL mission is scheduled to launch at 10:25 a.m. EST on Nov. 25.
The launch period extends to Dec. 18. The spacecraft will deliver a
car-size rover named Curiosity to the surface of Mars in August 2012.
Briefing Participants are:
-- Doug McCuistion, director, Mars Program, NASA Headquarters,
Washington
-- Ashwin Vasavada, MSL deputy project scientist, NASA's Jet
Propulsion Laboratory (JPL), Pasadena, Calif.
-- Pete Theisinger, MSL project manager, JPL
Media planning to attend the briefing must contact
dwayne.c.brown@nasa.gov to gain access to the event. Reporters may
ask questions from participating NASA locations or by telephone. To
reserve a telephone line, contact steve.e.cole@nasa.gov.
For NASA TV streaming video, scheduling and downlink information, visit:
http://www.nasa.gov/ntv
For more information about the mission, visit:
http://www.nasa.gov/msl
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