Five people, including the company CEO, were aboard the sub when it imploded.
All passengers are believed to be lost after a desperate dayslong search for a submersible carrying five people that vanished while on a tour of the Titanic wreckage off the coast of Newfoundland, Canada.
The 21-foot deep-sea vessel, operated by OceanGate Expeditions, lost contact about an hour and 45 minutes after submerging on Sunday morning with a 96-hour oxygen supply. That amount of breathable air was forecast to run out on Thursday morning, according to the United States Coast Guard, which was coordinating the multinational search and rescue efforts.
NASA released a statement Tuesday on the Titan, saying it remains "hopeful the crew will be found unharmed."
"NASA’s Marshall Space Flight Center had a Space Act Agreement with OceanGate, and consulted on materials and manufacturing processes for the submersible. NASA did not conduct testing and manufacturing via its workforce or facilities," the agency said.
-ABC News' Gina Sunseri
The U.S. Navy said it's sending to the search site experts and equipment "designed to provide reliable deep ocean lifting capacity for the recovery of large, bulky, and heavy undersea objects."
The equipment, which can lift up to 60,000 pounds, and the experts will arrive in Canada Tuesday night, the Navy said.
National Security Council spokesperson John Kirby said earlier Tuesday that the Navy was"on standby" to help with the search for the missing submersible, because the Navy has "some deep-water capabilities that the Coast Guard wouldn’t necessarily have."
President Joe Biden is "watching events closely," Kirby said, adding that Biden and the White House offer their thoughts "to the crew onboard, as well as to the -- what is no doubt -- worried family members back on shore."
Three U.S. Air Force C-17 cargo aircraft will be transporting commercial equipment from Buffalo, New York, to Newfoundland, Canada, to help with the search efforts, according to a U.S. official.
-ABC News' Luis Martinez
Efforts to locate the missing submersible are ongoing, and the "complex" search covers an area larger than the state of Connecticut, Coast Guard Capt. Jamie Frederick said at a news conference Tuesday.
Crews are scouring the ocean 900 miles east of Cape Cod and 400 miles south of St. John's, Canada, he said.
The missing five-person crew on the submersible has about 41 hours of oxygen left, Frederick noted.
"We will do everything in our power to effect a rescue," Frederick said.
"We have a group of our nation's best experts," he said, and once the sub is located, "those experts will be looking at what the next course of action is" to rescue the crew members.
"Our thoughts and prayers are with the crew and their families and their loved ones," Frederick added.
