A narrower passage to the sea bottom

Ask Janet Voight about diving in a research sub, and her initial scientific detachment gives way to a tinge of awe at marine biology's light show.

"You're sitting in a bubble," she says of the plexiglass dive chamber. "The bioluminescence on the way up makes everything worthwhile. You just see the density of life in the water column."

This diversity of life, most of which remains undiscovered, has fascinated scientists like Dr. Voight, associate curator at the Field Museum of Natural History in Chicago, for at least seven decades. Ever since 1934, when scientist William Beebe first peered into the deep ocean from a hollow ball of steel 923 meters below the surface, manned and unmanned deep-sea submersibles have been resurfacing with one stunning discovery after another.

But the underwater craft have proved so useful that these days there aren't enough to go around. Some researchers warn that today's deficit could become a dearth if scientists move ahead with plans for increased ocean exploration as well as the development of permanent undersea observatories.

It's a resource dilemma that has confronted many scientific disciplines as they have moved into the era of "big science."

Two major independent reports have proposed expanding ocean exploration and observatories in the past 18 months. Both objectives would require ready access to the deep ocean. Will the pace of discovery slow without more deep-sea research vehicles?

Some researchers are worried. The sub shortage is hitting just as nations are beginning to realize the oceans' importance and their role as global grocery store, potential pharmacy, and a storage "sink" for industrially produced carbon dioxide, widely seen as a key factor in global warming.

"We are at an important decision point," says Bruce Robison, a senior scientist at the Monterey Bay Aquarium Research Institute (MBARI) at Moss Landing, Calif.

Over the past 40 years, researchers have "confirmed the scientific value of having both human presence and telepresence available for conducting research in the deep sea," he notes. But progress has been hampered by a shrinking number of submersibles available to the broadest cross section of marine researchers. The gap "has been slowing things down for years," he says.

One solution sits in a binder on Robert Brown's conference table here at the National Deep Submergence Facility at the Woods Hole Oceanographic Institution, in Woods Hole, Mass. Mr. Brown is the project manager for a replacement for the venerable deep-sea submersible Alvin. When completed in 2008, the $21.6 million sub will dive deeper than Alvin while giving researchers increased flexibility at shallower depths to stop and take samples on the way up or down. While Alvin can reach depths that in principle allow researchers to study upwards of 63 percent of the ocean floor, Alvin's replacement would boost that proportion to 99 percent.

The design is the result of roughly a decade's worth of discussion in the marine-science community about a new human-occupied vehicle (HOV). Researchers had considered other options, including the use of mothballed US Navy deep submersibles. But they were too big and cumbersome to be of much use around fragile, tightly packed vents and valleys along mid-ocean ridges.

"A new vehicle was the best way to regain the depth capabilities" the Navy's subs represented, says Mr. Brown, a former Navy submariner.

The new research sub will boast improvements in capacity, sub-to-ship communications, speed, endurance, and other features that will make her the most capable research sub available. And then, there are the creature-comforts - relatively speaking - like a larger dive chamber, where the pilot and two scientists operate.

"When people ask me what it's like on Alvin, I tell them to pull two desks together, open the drawers, then sit underneath for seven hours with the air conditioner at full blast," says Voight, the Field Museum curator who heads to Oregon today to serve as chief scientist on a cruise where Alvin will be used to gather samples of marine life off the Oregon coast.

Once Alvin dives beneath the warmest layers of seawater, the outside chill seeps through the dive chamber's titanium sphere, driving temperatures inside from a mild 55 degrees F. at the start of a dive to a brisk 37 degrees at depth. The viewing ports for the pilot and for each of two scientists share very little overlap. If a geologist is scanning a cliffside, the pilot will turn the sub so he and the geologist can work together. Scientist No. 2 either watches the proceedings on a small video screen or is stuck looking out a port that stares at the black void of open ocean.

Alvin's replacement will provide the pilot and both scientists with views that overlap substantially, at best allowing for more teamwork, and at worst preventing the odd scientist out from getting too bored.

In addition, the National Science Foundation (NSF) is backing the construction of an autonomous vehicle that can span the distance between 6,500 meters, the maximum design depth for Alvin's replacement, and 11,000 meters, depths to which some of the deepest ocean trenches plunge. Compared with mid-ocean ridges, where new material wells up from deep inside the Earth to replenish the planet's crust, the deepest trenches have been harder to explore. Here, old crust plunges back into the mantle to be recycled. Scientists are eager to scoop up water and soil samples and explore and study trench walls through video links to the surface.

"That vehicle would give us our first look at some of the environments that have only been visited once by a bathysphere many years ago," says James Yoder, director of the NSF's division of ocean sciences.

Yet even with these two projects under way, researchers worry that without adequate support, ocean exploration may get shortchanged as a new generation of ocean observatories places its demands on manned and unmanned deep-sea submersibles for deployment and maintenance.

It's a lament scientists have uttered before in fields ranging from physics to astronomy. As questions become more complex, the larger and more sophisticated facilities built to answer them threaten to shoulder aside worthy but smaller-scale projects.

A first look at the intensity of the competition within marine science could emerge in Monterey Bay. There, MBARI is preparing to build a sea-floor observatory as a testbed for more ambitious projects, such as a plan to "wire" an entire crustal plate off the coast of Washington state. One point of contention: the allocation of remotely operated vehicles (ROVs).

"One of the internal debates here is how much of our ROV time is going to be taken from general users to support the sea-floor observatory," says MBARI's Robison. "We're going to learn all this stuff the hard way."

Over the past six months MBARI researchers have identified new marine species in the undersea canyon off the bay and in the Gulf of California, highlighting how little is known about the globe's largest ecosystem. "It's really staggering how much there is yet to explore," Robison says. "If we're going to ramp up that program, we're going to need vehicles to do it, and we don't have them at the moment."