Looking Into The Abyss
Just as machines, not man, will carry out the new wave of Martian exploration, scientists are designing and testing new and smarter robots to explore another mysterious and hostile environment--the depths of our own oceans.
With only seven manned submersibles worldwide able to dive more than 12,000 feet into the ocean--but just one capable of reaching 21,000 feet--a fleet of unmanned vessels is being developed to extend human beings’ reach into the unchartered abyss.
The robots--some on tethers, others programmed to operate without direct human control--will seek clues to such fundamental questions as how the Earth’s plates are regenerated and shift, how bodies of water influence climate, and how the Earth’s first life forms developed in superheated, deep-sea toxic plumes.
Advances in robotics do not suggest that there isn’t still a need for man to personally visit the ocean floor.
Indeed, Graham Hawkes, an ocean engineer from Port Richmond, Calif., has designed a winged, single-occupant submersible that he says will be able to return divers to a place that has been reached only once before--35,000 feet down, to the bottom of the Mariana Trench, which lies east of the Philippines and is the deepest spot on Earth.
That goal is steeped more in symbolism than science, reflecting our frustration that we have less access to most of our own planet than to distant ones. The ocean covers two-thirds of the Earth, and only 1% of the sea floor has been mapped to a detail of 10 to 20 meters.
But because manned submersibles--and their support ships on the surface--are so expensive to maintain and operate, have limited dive time and are too large to quickly deploy across the oceans, scientists will have to rely on portable and more affordable robots to carry on much of their work.
The biggest cheerleader in that strategic shift is Bob Ballard, whose explorations of the Titanic and hydrothermal vents were evidence of the discreet prowess of the famous Alvin, the workhorse--albeit not the deepest-diving--of deep-sea submersibles.
“But we’re in a paradigm shift, and I am convinced that ROVs [remotely operated vehicles] are now actually superior to manned submersibles,†said Ballard, a scientist at the Woods Hole, Mass., Oceanographic Institution, a leader in undersea robotic development.
ROVs, which are tethered by a control, power and data transmission cable to a mother ship and operated by shipboard scientists, have been used for years for offshore oil rig and pipeline work.
But they have been redesigned and equipped for science missions so that oceanographers, biologists and geologists can see what is on the ocean floor through live video hookup, map it with sonar, make chemical analyses, take temperature and other readings, drill cores into the sea floor and return with samples of rocks or plant and animal life.
With ship-to-satellite hookup, even scientists at home can monitor an ROV’s data and provide immediate consultation.
The granddaddy of sophisticated ROVs is Jason, maintained by Wood’s Hole with government funding. Jason once logged a mission of more than 60 continuous hours at depths of more than 18,000 feet while sending data and video back to the ship via fiber optics.
The Monterey Bay Aquarium Research Institute is testing its newest tethered deep-ocean vessel, called Tuburon. Capable of diving more than 13,000 feet, it is equipped with stereoscopic cameras and is minimally obtrusive to animal life because its virtually odorless hydraulic fluid will not give away its presence. It can also spy on fish and other organisms by benignly floating alongside them.
But ROVs also have their limitations, besides simply becoming entangled in their cables. Not only can they reach only as far as the cable allows, but they require a mother ship and support crew overhead, which is the most expensive operating cost of deep-sea research.
So scientists are developing yet another complement to their research fleet: autonomous underwater vehicles (AUVs). These smaller robots would be dropped into the water and, guided by pre-programmed software and underwater navigational transponders, dive without a tether to a chosen site.
One such device, called ABE and developed by Wood’s Hole, is designed to remain “on station†for up to a year--and make periodic sweeps over a field of hydrothermal vents, considered the sites of primordial life, to take pictures and make measurements. ABE would then park itself in a low-power “sleep†mode, reawaken in a week and make another sweep through the same area to monitor changes.
“Currently, with ROVs or Alvin, we can only visit a hydrothermal vent field maybe once a year, and we miss the processes that occur in the meantime,†said Andy Bowen, a Wood’s Hole engineer. “That’s like visiting Los Angeles only once every five years, seeing the changes but not knowing how they occurred.â€
But if an AUV can take measurements and photographs over time, “we can see the birth of tube-worm colonies, or how quickly species multiply. It would be like receiving the data equivalent of time-lapse photography,†Bowen said.
The Massachusetts Institute of Technology is not only developing a small fleet of AUVs for wholesale mapping of the sea floor on yearlong missions, but is also working on “rapid-response†AUVs. Weighing just 300 pounds, they could be dispatched by air--and then transferred to fishing trawlers--so that within a day or so they can monitor such events as volcanic eruptions as they occur--something that has eluded science so far.
AUVs also are being designed to float in deep ocean currents that affect climate. By monitoring oxygen circulation and temperature variations in the water, scientists hope to predict weather up to a year in advance. Such knowledge, notes MIT physicist James Bellingham, would help farmers know what kinds of crops to plant and when to plant them.
Rover, an autonomous vessel used by the Scripps Institution of Oceanography in La Jolla, is something of a 12,000-foot-deep bottom crawler, measuring the oxygen consumption of sea floor organisms. When its work is done, it floats to the surface and transmits data from its mini-chemical lab to a satellite.
Ocean engineers at the Monterey Bay Aquarium Research Institute are developing AUVs to serve as data couriers: They will dock to stationary, sea floor observatories, upload data and return to the surface. Other scientists are working on better acoustic modems to transfer sea floor data through the water.
Even the Jet Propulsion Laboratory in Pasadena--a place more commonly associated with the heavens, not the sea floor--is getting into the act with a program to transfer space technology to ocean research.
It has developed microprocessors to help AUVs navigate similarly to the smart robots destined for Mars’ surface. JPL scientists are researching stronger, lighter and more cold-resistant batteries, developing new video technology and studying how to use blue-green lasers for two-way communication between sea floor monitors and surface ships.
But human beings must always maintain a presence in the deep ocean, most agree.
Jim Head, a Brown University planetary geologist who helped train the lunar astronauts, visited the deep ocean aboard Alvin and relishes the experience.
“You have to rely on both manned and unmanned technology, and each has its advantages, but there’s no substitute for being there yourself because of the three-dimension perspective it gives you,†Head said. “Whenever I see data or video from the ocean floor, I first think of what I saw when I was down there myself.â€
Deep-sea technology consultant Don Walsh agrees that a human brings a “total sensory package†to the deep ocean that videos and computers, samplers and manipulator arms still cannot.
Walsh and Jacques Piccard were aboard the bathyscaph Trieste when it touched the bottom of the Mariana Trench in 1960.
Walsh would like to revisit it--perhaps inside Deep Flight II, the one-person, plane-like submersible now under development.
“But I imagine that the line will be exceedingly long.â€
