A deep sea probe, designed to withstand crushing pressures and extreme temperatures in its search for life, is to be tested in prototype in a Californian aquarium's giant kelp forest.

The new device houses underwater cameras, temperature sensors, optics and a spectrometer to analyse light. It will be lowered into the aquarium to test its ability to explore the interior of volcanic vents.

Tested in an aquarium

These fissures in the sea floor are known to be home to a wide variety of organisms. As well as hardy micro-organisms, there are small animals, which have learned to live in crushing pressures, temperatures over 200 degrees Celsius and alongside toxic chemicals.

"These instruments will be able to record water temperatures in the throat of a vent, capture video and still images of the walls of the vent, and record spectral or fluorescent signatures of minerals and bioluminescent life dwelling in these crevices," said Dr. Arthur Lane, manager of the Underwater Volcanic Vent Mission at Nasa.

"In August and September we will probe the Pitcairn, McDonald and Teahitia seamounts near Tahiti, where hydrothermal vents are found in depths of 900 to 3,600 metres (3,000 to 12,000 feet)."

Scientists say that data obtained from the tests will aid in the future exploration of many extreme liquid and ice environments. The under-ice Lake Vostok in Antarctica will be one target. Eventually they hope to send probes to the Martian polar caps and the ocean thought to exist under the ice-crust of Jupiter's moon, Europa.

Strange life

Hydrotermal vents: life may survive inside them

The recent and unexpected discovery of gelatinous material in underwater volcanic vents has opened a new avenue in the search for life and organisms that can survive in extreme environments.

Before it was seen, it was assumed that organisms only lived on the outside of the vents. However the layers of gel attached inside the vents are presumed to be the product of living organisms.

Researchers have even reported that the gel appeared to come directly from a vent throat.

"If there are indeed life forms present inside these vents, their presence may challenge accepted notions of the temperature ranges at which life can function," Lane said.

The ice-crust of Europa

"This year we're also testing a new light source and spectrographic instrument to see if we can gather more information about the bacterial growth we observed last year around the Loihi vent, what looked like thin veils of jellyfish-like material."

During this autumn's mission, scientists will use the French research vessel L'Atalante to test their instrument probe in several deep ocean volcanic vents in the South Pacific.

Once the technology has been developed and demonstrated to work at depths of 4,000 metres (13,200 feet), the probe's external shell will be modified for use in sub-glacial lakes like Lake Vostok. This is a two million-year old freshwater lake that exists deep beneath Antarctica's surface.