The U.S. Coast Guard announced via Twitter early Thursday that a remotely operated vehicle (ROV) deployed by the Canadian vessel Horizon Arctic has reached the sea floor, beginning its search for the missing submersible.

Meanwhile, the French vessel L'Atalante is preparing its ROV to enter the water in the search area, the U.S. Coast Guard said.

Time is running out as rescuers race to locate and save five people trapped in a submersible that vanished during a tour of the Titanic wreckage on Sunday morning.

The deep-sea vessel submerged at 8 a.m. ET on Sunday with a 96-hour oxygen supply, according to the U.S. Coast Guard. That amount of breathable air is forecast to run out on Thursday morning.

The search and rescue mission remains ongoing.

The New York Times traced the lineage of Wendy Rush, wife of missing OceanGate CEO Stockton Rush, and found that she's the great-great-granddaughter of a couple who died on the Titanic, Isidor and Ida Straus.

The executive director of the Straus Historical Society told ABC News that The Times article, which cites archival records, is largely correct with regard to Wendy Weil Rush's heritage.

-ABC News' Nic Uff

A U.S. Navy portable crane system capable of bringing up items from as deep as 20,000 feet has arrived in St. John's, Newfoundland, but is waiting to be welded onto a chartered ship to take it to the search area for the missing submersible, according to a U.S. Navy official.

The Navy has not yet contracted a ship for the salvage system, known as Fly Away Deep Ocean Salvage System or FADOSS, the official told reporters Wednesday. Once the ship is contracted, Navy teams will spend approximately 24 hours working around the clock to weld the system aboard the ship before it can leave port, the official said.

FADOSS is the salvage system the U.S. Navy uses for all of its deep-water recoveries. Last year, it was able to bring up an F/A-18 aircraft that had fallen into the waters of the Mediterranean Sea.

-ABC News' Luis Martinez

Samad Dawood, the brother of Shahzada Dawood, one of the passengers who died in the submersible, said losing his brother and nephew, Suleman Dawood, is heartbreaking.

"This is beyond what you could ever imagine in terms of the kind of hardships and struggle that we've had. I think what we've seen is enormous tragedy and devastation and a lot of emotions. Obviously we were hoping to hear some good news about the rescue and them coming back. It was heartbreaking to find out that that's not the case," Samad Dawood told ABC News.

Samad Dawood said his brother had a strong sense of adventure and curiosity about the world.

"He was always the kind of person who has this incredible love for the world," Samad Dawood said.

"He inspired us curiosity. And he was a guy who just wanted to go out there, experience what the world had to offer, even though he he himself pushed himself to do it. So they made adventures to go to Antarctica, to go to Greenland and to go to Africa and go to the rapids," Samad Dawood said.

This sense of adventure was passed on to Shahzada Dawood's son, 19-year-old Suleman Dawood, who was also in the submersible. Suleman Dawood had traveled to all seven continents, according to Samad Dawood.

"He was so filled with humbleness and gratitude," Samad Dawood said.

"We're deeply grateful for all the support and the love and the effort that the people have made, working tireless nights being optimistic in giving a sense of hope, giving that transparency to us. But obviously we were devastated as a family ... that we couldn't get them back safe," Samad Dawood said.

-ABC News' Octavio Cadenas, Dr. Jennifer Ashton and Victor Ordonez