Advanced new undersea robots, using remote-controlled television, photography and sonar-mapping systems that can survive crushing pressure and pierce the inky darkness miles under the ocean surface, are poised to search the North Atlantic sea floor where the great ocean liner Titanic came to rest 73 years ago.
Two expeditions, one French and one American, will set out next month to make detailed surveys of the area, which has yielded only dim, tantalizing hints during earlier attempts to find the grave of the ill-fated ship. Although finding the Titanic is not the official goal of the American expedition, conducted by the research vessel Knorr of the Woods Hole Oceanographic Institution, it is widely expected that an attempt to locate it will be made.
The American expedition to the area will follow a search by the French research vessel Suroit, which will sweep the bottom with a new, high- performance side-scanning sonar in an attempt to pinpoint the Titanic's location. It also carries a bottom camera.
The mission will mark the first field tests of the new American deepsea robot Argo, one of a new generation of unmanned deep sea submarines and ''swimming eyeballs'' that are expected to vastly extend scientific knowledge of the mysterious ocean floor.
Unlike manned submersibles, which are essentially cramped elevators that can take one or two scientists to a tiny spot of ocean floor for a few hours at most, the new robots can dive to greater depths, roam across miles of territory and stay under water for weeks at a time while many scientists, working simultaneously, monitor date from the safety of a remote ''mission control'' room.
One such robot craft, the Scarab, was used this month to recover flight recorders from an Air-India jetliner that crashed in 6,700 feet of water off the Irish coast.
Although the Navy is now building an experimental diving sphere designed to carry scientists to depths of more than 19,000 feet, current manned submersibles, such as the Navy's titanium-hulled Alvin and the French ship Cyana, are considered unsafe below 12,000 feet. This means scientists are now unable to visit half the world's ocean floor, which in its deepest trenches falls to more than 35,000 feet.
A key figure in both the French and American efforts is Dr. Robert Ballard of Woods Hole, who has worked with Emory Kristof, an experienced undersea photographer of National Geographic magazine, to perfect a variety of systems for producing high-quality television and photographic images of submarine features and activities. Kristof will be aboard the Knorr, as well as the Suroit.
Argo, roughly the size of an automobile, is the first and larger half of a dual undersea unmanned exploration system being developed by Ballard's group at Wood's Hole. Construction will begin later this year on a smaller robot craft, the Jason, that will be sent out from the Argo for even closer examination of sea-floor features: sunken wrecks, military installations or natural phenomena.
The design calls for Argo to be lowered to within 65 feet of the sea floor, a distance at which its searchlights should be able to illuminate the bottom and allow specialists aboard the mother ship to scan the area through its sensitive television eyes. By maneuvering the mother ship with precision, scientists would be able to ''walk'' with Argo along the sunken ship bow to stern, taking photographs along the way. Eventually, Argo may be able to illuminate the bottom from 100 feet, permitting a wider field of view.
If interesting features are seen, Jason will be sent on scouting missions, its progress controlled by Argo's video camera.
A robot probe similar to Jason has been tested in recent weeks in the Sea of Cortez, also known as the Gulf of California. The eyeball was carried down by the deep submersible Alvin and cast loose on a long tether to explore the sea floor off the Mexican coast. It moves about under control of an operator aboard Alvin, with power provided through the tether, and transmits what it ''sees'' back to the manned craft.
Although Ballard is widely known for making his own dives to the sea floor, he is one of the foremost champions of unmanned exploration. He said he expects the ultimate Argo-Jason system to replace manned deep-diving submersibles, using video, acoustic and still camera systems to sweep along the bottom, gathering samples and providing detailed images of long swaths of sea floor.