Life under extreme conditions - space research at the bottom of the ocean
Kristina Beblo: doctoral researcher at DLR
Kristina Beblo gives an account of her research in the field of radiation biology. The young biologist and DLR staff member is investigating if life could be possible elsewhere in the universe, even under extreme conditions. In order to answer this question, she also conducts research at the bottom of the Pacific Ocean. In her travelogue, she describes an expedition to a place many thousands of kilometres away and several thousand metres below the surface.
By Kristina Beblo
28 December 2007, Manzanillo, Mexico: The American research vessel ATLANTIS sets out on a three-week excursion. On board are the 50 members of its international crew, which on this expedition also includes me, and the mini submarine ALVIN. Our destination: 9 degrees north, 104 degrees west. There is nothing at those coordinates - no archipelago, no island, not even a small atoll, nothing but the wide open ocean. But a few thousand metres below the water surface, at the bottom of the ocean, there is a place that is interesting in several ways. This is the location of the East Pacific Rise, the tectonic boundary between the Pacific Plate and the Cocos Plate. These plates are slowly drifting apart, in a geological process known as seafloor spreading. Magmatic stone continually rises up to the ocean floor's surface through the resulting rift, forming new oceanic crust.
ALVIN is launched
After a three-day voyage, we arrive at our destination and ALVIN is deployed for the first time. The crane on the stern of the ATLANTIS lifts ALVIN off the deck and lowers it into the water, and the submarine - now no longer connected to the research vessel - slowly dives towards the bottom of the ocean, at a speed of about two kilometres per hour.
Diving to the bottom of the ocean in the submarine
ALVIN can accommodate three people - two researchers and a pilot. It has only been equipped with the bare necessities, which means that it does not have a heating system or toilets on board. During a ten-hour dive, this could well become problematic. Restricted in my movements, I huddle in my seat, eagerly waiting for the moment we reach our destination: the bottom of the ocean. Until we reach a depth of 150 metres, we can still see some greenish residual light coming from the water surface, but then it becomes pitch black all around us. After a little more than an hour, ALVIN reaches the bottom of the ocean, hovering above the floor of the Pacific at a depth of 2500 metres. The underwater landscape revealed in the glare of the searchlights strongly resembles a desert. Large pieces of rock are strewn everywhere, bizarre and tall rock formations are protruding from the ocean floor, and at first there appears to be no life at all down here. But thanks to GPS and the coordinates provided by previous expeditions we quickly reach our actual goal: a group of so-called black smokers.
Thick clouds of black "smoke" billow from a vent (also known as a chimney) resembling a stone tube. It is in fact not real smoke: the clouds consist of black, dust-like particles dissolved in the water. The water, which has been heated to a temperature of over 300 degrees Celsius in the Earth's interior, erupts through the chimney and mixes with the surrounding water which has a temperature of just 2 degrees Celsius. It is immediately noticeable that there are far more organisms in the warmer area around the black smokers than in areas further removed from them. You could even say that the place is teeming with life - very unusual for a place 2500 metres below the water surface! You can see tube worms, fish and crabs everywhere, standing out as ghostly white silhouettes against the black stone.
Kristina Beblo in the mini submarine ALVIN
ALVIN comes equipped with a lot of technology, both on the inside and on the outside - including the cameras and manipulator arms attached to the hull. Using these mechanical arms, we take samples of the black smokers and of other rocks and put them in a box that has also been fixed to the exterior of the submarine. We also do a few other tests, such as measuring the temperature and pH value at all sampling sites and also right where hot water is coming from the porous rock.
Crabs near a black smoker
Space research in the deep ocean
After we spent four hours at the bottom of the ocean, the weights are released and ALVIN starts to rise back up to the surface, carrying the crew and the samples that were taken. As we emerge from the ocean, the tension and excitement have ebbed away and I feel relaxed again. Only now do I notice how cold it has become inside the small submarine in the meantime. The uninsulated titanium sphere which forms the submarine's pressure hull becomes very cold due to the vessel's exposure to the water.
But why would one want to take rock samples in such an extreme location anyway? We have known for over 20 years now that some microorganisms can be found in very extreme habitats. New, previously unknown organisms that can only reproduce at very high temperatures of over 85 degrees Celsius are discovered all the time. These hyperthermophile ("extreme heat-loving") microorganisms exist in the hot, volcanically heated wells of marine or terrestrial hydrothermal systems, for instance in mud volcanoes and in extremely acidic or saline environments. The black smokers on the East Pacific Rise constitute a similarly extreme habitat. By now, it is generally assumed that these microorganisms, the so-called Archaea or Archaebacteria, in fact represent a very ancient evolutionary lineage. It may well be that all other known life forms that exist on Earth today originated from these organisms.
Rock sample from 2500 metres below the ocean surface
This suggests a question which I find very exciting: Could these organisms, which live under such apparently "hostile" conditions, perhaps also survive under the extreme conditions in space or on another planet, and could they perhaps even reproduce there? In order to come closer to answering this question, I am studying the survivability of different extremophile microorganisms under simulated space conditions in the context of my doctorate at the Radiation Biology Department of the DLR Institute of Aerospace Medicine (DLR-Institut für Luft- und Raumfahrtmedizin, Abteilung Strahlenbiologie), in close cooperation with the Archaeenzentrum of the Universät Regensburg. This means that my research forms part of a larger exobiological context, in which the fascinating question of extraterrestrial life is explored. It might just be teeming with life out there in space, in places which we so far considered to be hostile to all life, just like it does around the black smokers at the bottom of the Pacific Ocean. Life, which happens to grow and thrive under extreme conditions rather than under conditions of "well-tempered", moderate temperatures and sunlight...