Timothy Weihs received a rare opportunity last summer to use his skills as a materials scientist to help solve some of the mysteries surrounding one of the 20th century's greatest technological disasters: the sinking of the RMS Titanic.

Weihs, an assistant professor in the Whiting School's Department of Materials Science and Engineering, took part in a three-week sea expedition to the site of the wreckage. He and other researchers collected new pictures of the Titanic's rusting remains and retrieved pieces of the vessel for scientific analysis. Other investigators at the site included a naval architect, a marine engineer and a biologist.

The researchers sought answers to lingering questions about what happened to the huge "unsinkable" ship as it collided with an iceberg: Was its hull sliced open or did its steel plates simply come apart as rivets failed? Which was the weak link--the steel plates or the wrought iron rivets? After impact, how did the ship break up as its compartments flooded, and what happened to these pieces as they plunged toward the ocean's floor?

Materials scientist Timothy Weihs helps engineering student Bill Closkey examine the microstructure of metal taken from a rivet retrieved from the Titanic wreckage.

The team's findings are now being made public in a documentary airing on TV's Discovery Channel, which sponsored the research mission. The program, "Titanic: Answers from the Abyss," premiered Sunday and will air again several times in May.

During the two-hour film, Weihs is seen testing wrought iron rivets retrieved from the Titanic. On screen, he also joins the other researchers in discussing how the Titanic was damaged by the iceberg and how it broke apart afterward.

For Weihs, who teaches a Materials and Modern Technology course for freshmen and two graduate materials science courses, the expedition was an interesting change of pace.

"The organizers wanted to address unanswered questions about the Titanic disaster, like what happened on impact and how did the ship break up?" he says. "They also wanted to find out how quickly the wreckage is degrading."

The team's rivet research probably won't lead to better shipbuilding techniques because contemporary vessels are not constructed the way the Titanic was almost a century ago.

"Our goal was not to obtain better methods for making steel or wrought iron," Weihs acknowledges. "This expedition was driven by historical curiosity. This was a classic disaster of early 20th-century technology. It was interesting to be able to do metallography on such classic material. And it adds a lot to my classes here when I can share these things with the students."

To prepare them for analysis, some of the rivets were cut in half and polished on one side.

Weihs became involved in the voyage because he had collaborated on other research with Timothy Foecke, a metallurgist at the National Institute of Standards and Technology in Gaithersburg. Foecke received wide attention last year after he analyzed two rivets recovered from an earlier expedition to the Titanic.

Under a microscope, Foecke found that these wrought iron rivets contained too much slag, a glassy residue left behind after the smelting of ore. A small amount of slag helps strengthen wrought iron, but an excessive amount can make it brittle.

Foecke's finding reinforced a theory that the collision with the iceberg caused some of the Titanic's rivet heads to snap off, popping the fasteners from their holes and allowing water to seep in between the separated hull plates.

Foecke was invited to continue this line of research during last summer's expedition to the Titanic, but he was unable to take part in the voyage. He asked Weihs to take his place by supervising the recovery and preparation of additional rivets for testing.

Weihs persuaded Buehler USA, a leading manufacturer of scientific instruments and supplies, to lend him sophisticated materials analysis equipment for use on the ship and for follow-up research. He joined the other scientists aboard a 200-foot research vessel that set off from Newfoundland for the site where the Titanic flooded and sunk 12,000 feet to the floor of the Atlantic Ocean in 1912, killing more than 1,500 people.

At this site, the crew sent an unmanned robotic sub to explore the wreckage and send pictures to the surface via cables. Technicians on the ship were able to guide the sub to areas of the wreckage that the scientists hoped would reveal clues to what happened when the ship hit the iceberg. The sub's robotic arms also were able to retrieve additional rivets and other pieces of metal from the Titanic's remains.

Most of these rivets were turned over to Foecke for additional testing at his NIST lab. His analysis supported his earlier finding that the high slag content in the Titanic's rivets may have weakened them and contributed to the speedy flooding of the vessel.

Weihs has kept a few rivets here at Homewood for still more tests to help verify Foecke's results. The Hopkins engineer is rounding up student volunteers to assist with the rivet research this summer. Researchers will use a microscope and special computer software to identify the amount of slag in the rivets, its shape and location--all of which could have affected how the rivets responded when the iceberg was hit. Mechanical tests will be performed as well.

"Given the microstructure that we've seen, our best guess is that the rivets failed before the steel plates cracked, and the seams between plates simply opened up," Weihs says.

Near the end of last summer's expedition, he and his shipmates had to ride out the powerful forces of Hurricane Bonnie, including fierce winds and 35-foot waves. The storm gave the crew yet another reminder of how vulnerable human beings are in the face of nature's fury.

Weihs believes this may be the key lesson to be learned from the Titanic, whose builders stubbornly believed they had created a vessel that could withstand any assault from the forces of nature. "That's the humbling aspect of this," the Hopkins engineer says. "This was clearly a wake-up call."