Large drifting pieces of ice are called ice fields. By contrast, ice smaller than 6 miles (10 kilometers) in its greatest dimension is called ice floe. Several ice fields or ice floes packed together are called pack ice. Since Arctic ice forms over open water (the Arctic Sea), ice floes significantly change their shape and size during the seasons or while they are floating south to warmer climates.

Expeditions using ice floes to study currents, salinity and acidity levels, and potential climate changes expose themselves to the risk of literally falling "through the cracks." Russia is using ice floes since 70 years to set up year-round camps in the Arctic. It is the third time that a team of scientists faces imminent danger and needs to be rescued.

The Russian icebreaker Rossiya already left the port of Murmansk to evacuate the members of the North Pole-37 station. Russia does not plan to set up a new Arctic drifting station in 2010, according to several news reports.

The graphic shows a typical section of an ice flow. As the ice drifts in the Arctic Ocean, the shape and form changes constantly. Warmer climates or waters reduce the ice thickness, and warmer fresh water in the melt pond can cause sections of the flow to break off.

Illustration: Amanda & Hannes Grobe, Alfred Wegener Institute for Polar and Marine Research, Germany / Wikimedia Commons

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One of the last samples was collected through a hole drilled manually through the ice at the North Pole. "We called it our Hole at the Pole," said Daniels. "Getting the science work done has always been our top priority, but it is absolutely fantastic to reach the Pole as well. We're ecstatic."

The team started on March 14th and reached their target only hours before a Twin Otter plane was scheduled to land on the ice to collect them. "It has been an unbelievably hard journey over the ice," so Daniels. "Conditions have been unusually tough and at times very frustrating with a frequent southerly drift pushing us backwards every time we camped for the night. On top of that we've had to battle into head-winds and swim across large areas of dangerously thin ice and open water."

Results from the two-month expedition will be made available to scientists in Europe, Canada and the US.

The picture shows explorers Ann Daniels (left) and Charlie Paton collecting water samples at the North Pole.

Photo: Martin Hartley

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"Space exploration presents many unique challenges to humans. In order to prepare astronauts for these extreme environments in space, NASA engineers and scientists use comparable environments on Earth," says NASA in a mission fact sheet. "One of the most extreme environments is the ocean. Not only is the ocean a harsh and unpredictable environment, but it has many parallels to the challenges of living and working in space."

The Aquarius Laboratory, which is owned by the National Oceanic and Atmospheric Administration (NOAA) and managed by the University of North Carolina at Wilmington, allows the crew to perform experiments focused on performance, physiology, and human behavior. The main goal of the mission will be a series of extravehicular activities (EVAs), simulating activities that astronauts would perform during missions in space. The 400 square foot habitat will simulate tight quarters the crew will encounter while in space. NASA says that the size of the laboratory is similar to that of the Zvezda Service Module of the International Space Station.

A team of aquanauts did already set the stage for NEEMO 14 during a mission in October 2009 by placing mockups of a lander, rover and robotic arm near the habitat, NASA says in a press release. Chris A. Hadfield, Thomas H. Marshburn, Andrew Abercromby and Steve Chappell will live aboard the underwater laboratory and venture out on simulated spacewalks. They will maneuver the vehicles, retrieve small payloads, and use the robotic arm (a small crane is used to simulate the functionality) much like explorers would in setting up a habitat on other planets. The team will also simulate the transfer of an incapacitated astronaut from the ocean floor to the deck of the craft.

The NEEMO 14 expedition will start on May 10 and lasts for 14 days. Detailed mission information with a daily Extra Vehicular Activity Summary is available on NASA's website.

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The goal of the "2010 Expedition to the Ellis Basin" was to survey the cave system beneath the top entrance, called Tomo Thyme. Water from the cave system emerges in a huge spring at the head of the Pearse River, over 5 miles (8 kilometers) away. The team says that the Pearse Resurgence must be replenished from unknown caves that drain thousands of acres of terrain, full of deep shafts and disappearing streams.

During the three week expedition, the team managed to survey a total of 1.6 miles (2.5 kilometers) and discovered and documented blue stalactites in the Tomo Thyme area of the cave system.

The Ellis Basin is currently in the top 80 of the world’s deepest cave systems. Kieran hopes that future connections will eventually bring the system into the top-10 of the world’s deepest caves.

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The two-story tall vents called "black smokers" are underwater hot springs that release superheated water from below the Earth's crust. Minerals dissolved in the up to 750 degrees Fahrenheit (399 degrees Celsius) water precipitate when it cools down and form a black chimney-like structure around the vent. Some scientists believe that live on earth may have originated in such hostile environments.

"Seeing the world's deepest black-smoker vents looming out of the darkness was awe-inspiring," said Jon Copley, a marine biologist at the University of Southampton's School of Ocean and Earth Science (SOES), in a press release. "We are proud to show what British underwater technology can achieve in exploring this frontier - the UK subsea technology sector is worth £4 billion [$6.2 billion] per year and employs 40,000 people, which puts it on a par with our space industry."

The Cayman Trough, also called Bartlett Deep, is a complex transform fault zone that contains a small spreading ridge on the floor of the western Caribbean Sea between Jamaica and the Cayman Islands. With a maximum depth of 25,217 feet (7,686 meters), it is the deepest point in the Caribbean Sea. The pressure three miles deep equals almost 500 times the normal atmospheric pressure, allowing nature to heat water to much higher temperatures before it can boil.

"It was like wandering across the surface of another world," says geologist Bramley Murton of the National Oceanography Centre (NOC), who piloted the underwater vehicle called HyBIS. "The rainbow hues of the mineral spires and the fluorescent blues of the microbial mats covering them were like nothing I had ever seen before."

The team aboard the Research Ship includes scientists and students from the UK, Ireland, Germany and Trinidad. The expedition will continue until April 20 and is part of a research project funded by the UK Natural Environment Research Council to study the world's deepest undersea volcanoes. Daily updates are available here.

A video showing the deep-sea smoker and the command center aboard the James Cook is available here.

An interesting paper showing pictures of the underwater vehicle used to discover the vents and explaining how HyBIS works is available here.

Picture: National Oceanography Centre, Southampton (UK)

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