The Space Reviewin association with SpaceNews

Submersibles like Alvin have charted a different path to deep sea exploration than space exploration, but the two fields are starting to look more like each other. (credit: Woods Hole Oceanographic Institution)

The spacecraft and the submarine

Deep sea explorers often compare what they do with space exploration, many times only superficially and rarely favorably to the space explorers, whom they believe get too much money. It is common for books on undersea exploration to include a throwaway comment about how we know far more about the surface of the Moon than the bottom of the ocean, or how more people have been into space, or on the Moon, than have reached the bottom of the sea. These comparisons are often not terribly accurate. Every year thousands of sailors travel under the oceans in military submarines, thousands of commercial divers work on pipelines, cables and oil rigs, thousands of hobbyists engage in recreational diving, and hundreds of researchers travel to great depths in the interests of science. Robots regularly venture where humans do not. What is usually fueling these claims is jealousy, or more politely, professional envy: the United States spends billions of dollars exploring space every year, and far less money exploring beneath the sea.

There are many similarities between deep sea exploration and space exploration, and also some important differences. Deep sea exploration has existed for nearly twice as long as space exploration, and followed a different path. But the differences are diminishing and the two endeavors are starting to look more and more like each other. More importantly, deep ocean exploration is having a major effect upon space exploration.

The first steps into the deep

In 1928, an American, Otis Barton, developed the first bathysphere, a steel sphere that could be lowered via cable from a ship. In June 1930 Barton and naturalist William Beebe descended to a depth of 245 meters (803 feet). In 1932 they descended to 923 meters (3,028 feet), a record that held for fifteen years. In his book, Half Mile Down, Beebe described seeing bizarre creatures that sounded so extraordinary that many people suspected he was lying. He was not; the ocean depths were indeed truly alien.

The differences between deep sea and space exploration are diminishing and the two endeavors are starting to look more and more like each other. More importantly, deep ocean exploration is having a major effect upon space exploration.

The next major deep sea technology development was the invention of the bathyscaphe, by Swiss explorer Auguste Piccard. The bathyscaphe combined the bathysphere with flotation and propulsion equipment to create a rather awkward form of deep-diving submarine. Whereas the bathysphere was equivalent to the Mercury spacecraft—limited in capabilities and maneuverability—the bathysphere was more akin to the Gemini. Piccard’s second bathyscaphe was named Trieste and was purchased by the US Navy in 1957. In 1960 Piccard’s son Jacques and US Navy Lieutenant Don Walsh descended into the Challenger Deep in the Mariana Trench, a depth of 10,916 meters (35,813 feet). Over the next two decades, an upgraded vehicle named Trieste II served the Navy in a variety of roles, including inspecting the USS Scorpion nuclear submarine wreck and recovering space equipment.

The most famous deep diving submersible is the Alvin, built for the US Navy in 1964 and operated by the Woods Hole Oceanographic Institution. Alvin is capable of diving to 4,500 meters (14,764 feet) and in over four decades in service it has made over 4,000 dives. The three-person submersible has recovered a lost thermonuclear bomb, explored deep ocean thermal vents, and was the first piloted craft to visit the Titanic. It also sank once, without loss of life, and spent nearly a year on the bottom of the ocean before being recovered.

The robots finally appear

Although there are some indications that robotically operated submersibles—essentially towed light and camera platforms—may have been developed for classified military use as early as the late 1960s, this technology did not really become useful until the 1980s. It was a robotic device that first visited the Titanic. But it really took off in the commercial world, where underwater robots were useful for inspecting oil platforms and undersea cables, and performing salvage operations. The technology became even more sophisticated by the 1990s, with improved mobility, visibility (including high definition video), and dexterity. Robotic vehicles have even acquired their own daughter vehicles which can be detached and used to access areas too small for the main craft to reach. Today they can reach a variety of depths, including deeper than the piloted submersibles, but their sophistication is measured not merely by how deep they can go, but the equipment that they carry.

In more recent years, the research community has placed their emphasis on developing autonomous vehicles that require little or no human intervention. One class of vehicles, known as gliders—although not really deep submergence vehicles—do not even require propulsion, instead rising and diving using internal bladders. Although it no longer has the deepest diving vessels—Trieste was retired in the 1980s—the United States leads in this newer technology. However, these are capabilities that in many ways existed in the space field decades before they were developed for undersea research.

In the past decade or so the difference in the ways researchers approach space and undersea exploration has narrowed further, with the development of networks. Early space and undersea science consisted primarily of point observations, taking measurements of a small area for a limited period of time. But now scientists in both environments are more interested in understanding the operation of systems, meaning the complex interaction of various physical phenomena. Earth observation has reached the era when fleets of satellites gather data on oceans, land, and air, and these measurements are combined in sophisticated models. In the past decade NASA has extended this approach to Mars, where a fleet of spacecraft take measurements that combined are greater than the sum of their parts.

Undersea exploration has also begun to enter this networked era with the deployment of numerous sensors on the seabed, at mid-ocean depths, and on the surface, with their measurements sent to a processing center where the interaction of various phenomena can be studied. These interactions are far more complex because they include biological factors—scientists want to know how a current or salinity change may affect the plankton supply, which could affect the local whale population or even climate change.

Humans vs. robots/robots vs. humans

There is no simple and satisfying answer for why it took so long for underwater robotic technology to progress. At a time when NASA was landing robots on the Moon and sending them flying past Venus, Mars and Jupiter, underwater robots were virtually nonexistent in the commercial and scientific worlds. Part of the reason for this may have simply been access, or lack of it, to the environments of interest. NASA and the Soviet Union sent robotic spacecraft into deep space because it would have been extremely difficult and expensive to send humans there. Similarly, robots have been employed for Earth observation and other scientific missions because humans are so expensive to launch into space and keep alive. There was also a space race to keep things moving; the technology advanced because it was pushed. Finally, humans were not necessary to oversee the robots except from the ground using the ubiquitous “200 mile screwdriver.” Thus, the raison d’être for launching humans in space was less to have them do something useful than for them to be there—to plant the flag, speak inspiring words, and demonstrate the superiority of their political systems. They could accomplish useful research tasks—and a human is still more capable than a robot where innovation, intelligence, and assessment are involved—but relatively speaking, they just have not been as important for these tasks.

The explanation for why robots were adopted early for space and late for the oceans may be in the relative cost ratios for humans and robots in space and under the sea. Human spaceflight and human undersea exploration are both more expensive than their robotic counterparts. But the ratio between the costs of human spaceflight and robotic spaceflight is much greater than the ratio between the costs of human undersea exploration and robotic undersea exploration. Even in those early years of the 1960s robots could have been—indeed currently are—cheaper to operate than manned submersibles, but the cost of the manned submersibles was not so high as to be prohibitive. Eventually the convergence of a number of factors—commercial oil drilling technology, tight scientific budgets, technological advancement in related fields like imaging and robotic manipulation—led to the rise of undersea robotics.

The explanation for why robots were adopted early for space and late for the oceans may be in the relative cost ratios for humans and robots in space and under the sea.

An alternative explanation might be what social scientists call the social construction of technology, which posits that human actions determine how technology develops. When humans became capable of shooting objects into space, they already had a long history of putting electronic devices—robots—on the tips of missiles, so sending robots into space was not a major conceptual leap, and humans soon followed them. In contrast, humans went deep under the oceans before they ever developed robotic devices that could venture there, so it was easier to conceive, and develop, manned submersibles than it was to conceive and develop robotic ones, hence the undersea robots did not really appear until many decades after human submersibles.

Alien worlds

Despite their similarities, for decades ocean exploration had only limited impact upon space exploration, and vice versa. But that began to change, particularly in the 1990s. Scientists studying deep ocean thermal vents in the late 1970s discovered that bizarre life forms could exist at temperatures and pressures that are literally beyond comprehension. By the 1990s, NASA-sponsored scientists focused on all forms of extreme lifeforms, from the edges of Yellowstone geysers and deep inside the Earth to the black smokers at the bottom of the Pacific. Today it is not unusual to meet a scientist who is interested in life on Mars or under the ice of Europa who has been to the bottom of the ocean in Alvin, looking for aliens. Alvin, in a way, has become a spaceship, prowling not only the ocean depths, but the extremes of life.

Budgets have not met ambitions in the space sciences, but neither have they met the desires of undersea researchers and explorers. Plucky little Alvin, although completely taken apart and serviced every few years, is restricted in how far it can dive and in the past decade scientists have begun developing its successor, unofficially designated Alvin II. Whereas Alvin can descend to only 4,500 meters (2.8 miles), Alvin II is supposed to be capable of diving to 6,500 meters (over four miles), where it can reach 98 percent of the ocean floor. This will also put it in the same class as the Japanese Shinkai 6500 submersible, and make it more capable than the Russian Mir I and II and French Nautile submersibles, which can currently reach 6,000 meters. The United States will no longer suffer a gap in how far it can send humans beneath the waves.

Alvin, in a way, has become a spaceship, prowling not only the ocean depths, but the extremes of life.

A few months ago a specialty forge in Cudahy, Wisconsin produced Alvin II’s thick titanium pressure sphere, which glowed purple as it cooled. But the submersible’s costs have risen substantially, from around $22 million in 2004 to $50 million today; the price of titanium alone is five times what it was when the project started. Needless to say, this is less than the cost of even a cheap satellite, illustrating one reason why ocean researchers are so resentful of space scientists.

It now appears that Alvin II may be delayed, or not built at all. The new pressure sphere may be fitted into the 44-year-old Alvin, extending the workhorse submersible’s lifetime for many years. In addition to the setback to the research field, it would delay the day when Alvin finally gets to rest, retired to a museum. Although it won’t happen, my vote is to put it in the National Air and Space Museum, next to the Mercury, Gemini, and Apollo capsules, and the rest of the explorers of the great unknown.